160Ma of sporadic basaltic activity on the Languedoc volcanic line (Southern France): A peculiar case of lithosphere–asthenosphere interplay

Lithos 120 (2010) 202ndash222

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Lithos

j ourna l homepage wwwe lsev ie rcom locate l i thos

160 Ma of sporadic basaltic activity on the Languedoc volcanic line(Southern France) A peculiar case of lithospherendashasthenosphere interplay

Jean-Marie Dautria Jean-Michel Liotard Delphine Bosch Olivier AlardGeacuteosciences Montpellier UMR 5243 CC 60Universiteacute Montpellier 2 Place E Bataillon 34095 Montpellier cedex 5 France

Corresponding author Tel +33 467143293 fax +E-mail address dautriagmuniv-montp2fr (J-M D

0024-4937$ ndash see front matter copy 2010 Elsevier BV Adoi101016jlithos201004009

a b s t r a c t

a r t i c l e i n f o

Article historyReceived 21 July 2009Accepted 16 April 2010Available online 26 April 2010

KeywordsAlkali basaltsPeridotite xenolithsLithosphereAsthenosphereCarbonated metasomatism

The NndashS Languedoc volcanic province between the French Massif Central and the Mediterranean Sea ischaracterized by sporadic scattered low volume (sim2 km3) and geochemically homogeneous alkali basalticactivity spanning from 161 to 05 Ma The existence of magmatic activity of such a long duration within sucha small area (sim140 km long and sim60 km wide) in spite of the extensive shift to the East of the Europeanplate (about 2500 km during the last 160 Ma) is problematic Trace-element abundances in lavas suggest lowdegrees of melting (1ndash5) in the spinelndashgarnet transition zone of an enriched lherzolitic source The lavasdisplay rather large ranges in Sr isotopic ratios (070307ndash070436) The 143Nd144Nd ratio variations aresmaller (051268ndash051300) and these of 206Pb204Pb 208Pb204Pb and 207Pb204Pb are 18745ndash19515 38532ndash39228 and 15567ndash15680 respectively The Languedoc lithospheric mantle as sampled by xenoliths isglobally similar to the Pyrenees lithosphere The xenoliths show also rather large Sr Nd and Pb isotopicvariations (87Sr86Sr 070287ndash070578 143Nd144Nd 051256ndash051414 208Pb204Pb 37772ndash39041 206Pb204Pb 17901ndash19353) except for 207Pb204Pb (15570ndash15620) The 206Pb204Pb and LaSm ratios arepositively correlated both in xenoliths and lavas The increase of the 206Pb204Pb (which could be interpretedas participation of the European Asthenospheric Reservoir EAR) is probably related to volatile-rich(carbonated) fluid percolation This is corroborated by LILE and HFSE patterns observed in several xenolithsTherefore our data on lavas and xenoliths suggest a lithospheric origin for this long-lived magmatism Wepropose (1) that the role of the asthenosphere in the Languedoc volcanism was restricted to volatile-richfluid supplying and (2) that the fluid injection within the lithosphere may be related to the arrival of theCentral Atlantic Plume head beneath Western Europe about 70 Ma ago In this model the isotopic signatureof the oldest lavas (N 70 Ma) would be that of the mantle lithosphere inherited from Hercynian processesThe signatures of the subsequent lavas would be driven by the metasomatic component stored within thelithosphere and preferentially mobilized during incipient melting This metasomatised lower lithospherewas close to its solidus and small changes in P (or T) triggered incipient melting leading to basalticvolcanism Successive local re-adjustments of the lithospheric blocks which accompanied the Meso-Cenozoic evolution of the Thetys Ligurian margin towards the present Mediterranean margin are theprobable cause of these changes and so the sporadic volcanic activity in Languedoc is unrelated to deepasthenospheric processes

33 467143603autria)

ll rights reserved

copy 2010 Elsevier BV All rights reserved

1 Introduction

The origin of the Cenozoic alkali magmatism in Western Europe isstill widely debated and widely varying models include Miocene ldquohotspot(s)rdquo (eg Granet et al 1995) or ldquowet spot(s)rdquo (cf Wilson 2007)superposition of active (Oligocene) and passive (Miocene) rifting(Michon and Merle 2001) and Eocene impingement of the ldquoCentralAtlantic Plumerdquo on the European continent related to the opening ofthe Atlantic Ocean (Piromallo et al 2008) Inmost of thesemodels therespective contributions of lithosphere and asthenosphere in the

magma genesis are not clearly defined Furthermore the causes ofmelting eg thermal anomaly (Sobolev et al 1996) andor injectionof volatile-rich melts (eg Downes 2001) remain elusive Further-more the role of the Alpine orogenesis in determining the location ofthe volcanism and the magmatic development are still questionable(Michon and Merle 2001 Piromallo et al 2008)

Despite the low volume of erupted lavas (sim2 km3 on the whole)and their relatively uniform basaltic compositions the Languedocvolcanic district (Southern France Fig 1) is probably one of the bestplaces in Europe to shed new light on several of these issues becausemdash(1) the episodic volcanic activity spans from the Mid-Jurassic toQuaternarymdashthis long-term activity is seen nowhere else in Europe(2) its exceptional geological location (Fig 1) half-way between thePyrenean and Alpine belts on the Gulf of Lion rim and on the South

Fig 1 Geological setting of Languedoc volcanic districts with locations and ages of samples dated in this paper ROU sample name (see Table 2) () new age data (Ma) (see Table 1)CD Causses district ELD Escandorgue-Lodeacutevois district LHVD LowHeacuterault Valley District FMC FrenchMassif Central All volcanic rocks dated since 1974 and all samples analyzedfor this paper are given in Fig RM1

203J-M Dautria et al Lithos 120 (2010) 202ndash222

side of the French Massif Central lithospheric swell less than 200 kmsouthwards of its apex

The detailed study of the Languedoc basalts should thus bring newresults that may answer many questions Has the mantle sources of

European basalts evolved during the last 160 Ma Has it been affectedby the compressive and distensive geodynamic events related to theMesozoic and Cenozoic evolution of the Ligurian Tethys margin Hasit been modified by the opening of the Atlantic Ocean and the

204 J-M Dautria et al Lithos 120 (2010) 202ndash222

Pyrenean and Alpine orogenesis Has it been affected by the mantleevents responsible for the Oligocene Mediterranean rifting and theMiocene uplifts

In the present work an extensive petrological and geochemicalsynthesis of the Languedoc basalts has been carried out includingmajor- and trace-element data as well as Sr Nd and Pb isotopes forrepresentative samples of all age groups Further new whole-rock KndashAr ages have been obtained for key samples in order to refine thetemporal history of this volcanism Finally peridotitic xenolithshosted in several of these lavas were analyzed in order to provide apetrological and geochemical characterization of the Languedoc sub-continental upper lithosphere These data are compared with thetheoretical mantle source of the basalts inferred from our geochemicalcalculations from lavas and with the well-known lithospheric mantlerocks from the Pyrenees and the Massif Central

2 Geological setting

Languedoc is the region of France extending between the upliftedFrench Massif Central and the Mediterranean Sea coast (Fig 1) Thecentral part of Languedoc is almost entirely covered with Mesozoicsediments (mostly carbonates) deposed on the Northern Tethyanpassive continental margin Major NEndashSW strikendashslip faults ofHercynian age (re-activated during the Mesozoic and Cenozoic inconnection with the Pyrenean orogeny) crosscut the region (Fig 1)

The Languedoc volcanics only appear in the sedimentary basinsand are grouped inside a NS area sim140 km long and sim60 km wide(Fig 1) which can be geographically considered as the southernextension of the French Massif Central Mio-Plio-Quaternary volca-nism Inside this area several volcanic alignments are distinguishableThey are not clearly superimposed with faults but they probablycorrespond to major lithospheric scale structural discontinuities ofpossible Hercynian age

The area is usually subdivided into 3 districts

i The Causses District (CD) in the northern part of Languedoc(Fig 1) comprises small basaltic outcrops distributed alongtwo axes one WNWndashESE that approximately corresponds tothe current northern boundary of the Mesozoic basin ofWestern Causses the second NNEndashSSW roughlycorresponding to the present Central Causses basin axis(Fig 1) These outcrops indicated in Figs 1 and RM1 correspondeither to small lava lakes filling ancient maars (eg AZ)phreatomagmatic breccia pipes injected with dykes (eg EG)isolated dykes or sills (eg NT) or more rarely flows (eg Vi)Most of them have Miocene ages ranging between 58 and75 Ma (Fig RM1) Such ages are very common in WesternEurope and correspond to the paroxysmal volcanic activity inthe French Massif Central For instance the basaltic plateau ofAubrac that bounds the Languedoc province to the north(Fig 1) and is considered bymany authors (Brousse and Bellon1974 De Goeumlr de Herveacute et al 1991) as belonging to the FrenchMassif Central magmatic province displays such a Messinianage However previous work (Gillot 1974) has shown thatolder volcanic edifices (ie Dogger Palaeocene and Serraval-lian) are also present in CD and correspond to the precursors ofthe Languedoc magmatic activity (Fig RM1)

ii The EscandorguendashLodeacutevois District (ELD) in the central partof Languedoc corresponds to a NndashS continuous and narrowvolcanic trail about 35 km long and sim3 km wide (Fig 1) Thevolcanic activity was here essentially phreatomagmatic tosurtseyan and in minor part strombolian The age of theactivity in the northern and central parts of this district(Escandorgue plateau) is well documented (Figs 1 and RM1)more than 20 ages are available with values between 25 and15 Ma (Gillot 1974 Gastaud et al 1983 Brugal et al 1990

Ambert et al 1990) whereas no age is available at present forits southern end and its eastern side Lodeacutevois corresponds to asim12 km eastwards extension of the southern part of Escan-dorgue (Fig 1) and its activity (between 15 and 12 Ma) isslightly younger (Gastaud et al 1983)

iii The Heacuterault Low Valley District (HLVD) south of Lodeacutevoiscomprises about twenty small well-preserved monogenicstrombolian cones and hydromagmatic tuff rings of Quaternaryage (Von Frechen and Lippolt 1965 Gastaud et al 1983) Theyare grouped on the western bank of the Heacuterault river andconstitute a NndashS volcanic line about 35 km long this linecontinues up to the Mediterranean coast and is offset 15 kmeastward from the Escandorgue alignment (Fig 1) The south-ernmost volcano (CPA 073 Ma Fig 1) is a striking surtseyan tuffring outcropping along the present seaside but aeromagneticdata show that the HLVD line extends offshore under the sea

Two volcanic complexes belonging geographically to SouthLanguedoc have ages that are anomalous with regard to the HLVDactivityPOU (Fig RM1) 20 km East of the Heacuterault river a small-sizedbreccia pipe is dated to 46 Ma by Liotard et al (1991) MTF (Fig RM1)40 km to the East includes breccia pipes and dykes that intrudeEocene sediments and have ages between 23 and 25 Ma (Gastaudet al 1983) These two complexes are particularly interesting becausethey are the only volcanoes of Lutetian and Chattian ages

3 Sampling and analytical techniques

Fifty-two lava samples have been selected for this study on the basisof their ages and freshness This selection is representativeof thedistinctage groups in the various districtsWe also collected three samples fromthe Messinian basaltic plateau of Aubrac (Fig 1) for comparison

About one third of the exposed lavas whatever their age containperidotitic xenoliths Ten xenoliths included in the studied lavas havebeen selected on textural and petrological criteria to represent eachtype observed in Languedoc

The lava and peridotite samples were crushed and then powderedin an agate mill Whole-rock major elements were analyzed by X-rayfluorescence (XRF SARM Nancy) Trace elements and REE abun-dances were analyzed using a VG Plasmaquad II ICP-MS at theUniversity of Montpellier II (Ionov et al 1993)

Before undertaking the acid digestion for the Sr Nd and Pb isotopicanalyses all WRwere leached for 30 min with 6 N HCl at 80 degC After theleaching steps the residues were rinsed three times in purified milli-QH2O The total blank contents for Pb Sr and Nd were less than 35 40and 10 pg respectively for a 100 mg sample Pb and Nd isotopiccompositions were measured on the VG Plasma 54 and the Nu 500 MC-ICP-MS located at the Ecole Normale Supeacuterieure in Lyon (France) ThePb isotopic compositions were measured with an external precisionbetter than 300 ppm for 206 207 208Pb204Pb using the Tl normalizationmethod described byWhite et al (2000) Further details about analyticaltechniques accuracy and reproducibility are available in Bosch et al(2008) The NIST 981 standard was measured after every two samples(206Pb204Pb=169380plusmn00030 (2σ) 207Pb204Pb=154919plusmn00022(2σ) 208Pb204Pb=366925plusmn00055(2σ) n=20) the Nd isotopicmeasurementswere bracketed between the ldquoLyon in-houserdquoNd standardevery two samples with an average of 143Nd144Nd=0512132plusmn17(2σ)(n=55) The Sr isotopic compositions were measured on a FinniganTriton TImass spectrometer at the Laboratoire deGeacuteochimieGIS of Nicircmes(France) The NBS 987 Sr standard yielded a mean value of 87Sr86Sr=0710254plusmn09 (2σ) (n=16)

KndashAr analyses have been performed at LSCE CEA-CNRS Gif-sur-Yvette from phenocryst-free samples Age calculations arebased on the decay and abundance constants of Steiger and Jaumlger(1977) lb =4962times10minus10 aminus1 le=0581times10minus10 aminus1 40 KK=1167 10minus4 molmol

Table 1KAr ages of selected samples For sample locations see Fig 2 Age calculations are based on the following decay (Steiger and Jaumlger 1977) and abundance constants lbminus=4962times10minus10 aminus1 le=0581times10minus10 aminus1 40 KK=1167 10minus4 molmolminus1

Sample RQH1 AG AR CX BR VI

1 2 1 2 1 2 1 2 1 2 1 2 3

K (wt) 0930 0930 1428 1428 1971 1971 1511 1511 1190 1190 1934 1934 1934plusmn2s 0009 0009 0014 0014 002 002 0015 0015 0012 0012 0020 0020 0020Weight molten (g) 097699 099675 107422 206563 101983 119612 079319 100750 099371 101408 112587 017263 01648040Ar () 7978 5564 14233 1617 12342 11456 18694 17587 6954 15732 89087 71823 8433740Ar (10ndash12 molg) 9009 9129 1714 1698 4164 4154 3854 3806 3118 3135 5741 5550 567240Ar mean weight 9063 1705 4159 3823 3127 56541s 0083 0007 0007 0018 0012 97Age mean value (My) 0562 0688 122 146 151 16117plusmn2s 0015 0015 003 003 002 178

Sample CE2 819 742 ROL1 EG1 TS

1 2 1 2 1 2 1 2 1 2 1 2

K (wt) 0843 0843 1330 1330 1978 1978 1610 1610 1777 1777 0917 0917plusmn2s 0008 0008 0013 0013 002 002 0016 0016 0018 0018 0009 0009Weight molten (g) 096414 097481 103807 104300 101402 111561 092130 047516 100979 051514 047808 03946840Ar () 7045 22054 16203 20899 23164 20349 9663 19357 79216 6497 79135 8287940Ar (10ndash12 molg) 2267 2182 4241 4151 6607 6884 6301 6245 43384 43430 9528 947840Ar mean weight 2245 4196 6746 6274 43407 95031s 006 0064 0196 0025 0154 035Age mean value (My) 152 182 197 225 1403 5879plusmn2s 003 003 003 005 03 083

Table 1 (continued)

205J-M

Dautria

etal

Lithos120

(2010)202

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4 Results

41 Lavas

411 GeochronologyTwelve new KndashAr ages have been obtained on selected key-

samples (Table 1 locations in Fig 1) Fig RM1 shows the ages of alllavas dated since 1965

The Vi volcanic outcrop located in the northern part of CD (Fig 1)is unique in Languedoc (and in Western Europe) both for its fieldstructure and its age It is a lava delta with massive basalt sheets andbrecciated pillow-lavas interbedded within a Dogger coastal carbon-ate series Baubron et al (1978a) using the KndashAr method determinedan age of 155plusmn6 Ma for this basalt Our new KndashAr data (Table 1)indicate a slightly older age of 1612plusmn18 Ma corroborating theexistence of a magmatic event in Languedoc at the CallovianndashOxfordian boundary

TS (Fig 1) is an intrusive complex located 20 km NW from ViA new KAr age of 588plusmn08 Ma has been obtained for this samplein agreement with the age of 57 Ma previously measured by Baubronet al (1978b) Palaeocene and Eocene lavas are very uncommonin western Europe and only six occurrences are known in France Allare highly SiO2-undersaturated basalts (nephelinites) sometimescarbonated (melilitites) and they are distributed along the faultsbounding the future Oligocene rifts According to Lenoir et al (2000ab) this magmatism is related to the initiation of the major mantlemelting event leading to the MiocenendashPliocenendashQuaternary volca-nism of French Massif Central

The volcanic complex of Eglazine (EG) (Fig 1) is one of the two sitesforwhich a Serravalian agewasmeasured in Languedoc It is a relativelywell-preservedbreccia pipe exposed at thebottomof the Tarn canyonAdyke crosscutting these breccias yields an age of 140plusmn03 Ma almostsimilar to the age (130plusmn04 Ma) previously estimated byGillot (1974)The EG volcanic complex is thus contemporaneous with the firstvolcanic activity phase in Cantal and Velay the largest volcanic districtsof French Massif Central (Nehlig 1999 Mergoil et al 1993)

Five new dates have been obtained for ELD in order to fill theage gap in the southern and eastern parts of this district (Fig RM1)A glassy cauliflower bomb (ROL1) from the southernmost tuff-ring(Fig 1) yields an age of 225plusmn005 Ma suggesting that no agegradient exists along the Escandorgue NS axis BR (lava lake) 819 (aflow) and 742 (dyke) are samples collected along the eastern side ofEscandorgue their ages (151plusmn002 182plusmn003 and 197plusmn003 Marespectively) do not differ from those of the central part of the massifSample AR corresponds to an isolated phreato-volcanic complexbelonging to East Lodeacutevois its age (122plusmn003 Ma) is one of the mostrecent for this district

Finally four flows from the Quaternary HLVD have been datedduring this study two come from its northern part (CX the longestflow of Languedoc 11 km and CE) and two from its southern end (AGand RQH) (Fig 1) The CX and CE lavas yield similar ages (146plusmn003 Ma and 152plusmn003 Ma respectively) and are contemporaneouswith the Lodeacutevois activity AG and RQH are younger (069plusmn0015 Maand 056plusmn0015 Ma respectively) RQH represents the most recentvolcanic event known in Languedoc As shown by Figs 1 and RM1 theyoungest volcanoes (b075 Ma) are all situated close to the coast

412 Major and trace elementsAll analyzed samples (Table 2) belong to the alkaline series and

most of them are alkali basalts or basanites according to theclassification of Cox et al (1979) (Fig 2) The degree of SiO2-undersaturation is globally high and variable inside each lava group2b(Ne+Lc)normb15 for the basalts 15b(Ne+Lc)normb26 for thebasanites In the ldquobasalt tetrahedronrdquo of Yoder and Tilley (seeRingwood 1975) all Languedoc lavas except samples RQH and AGwould plot either in the basanitic (NenormN5) or in the nephelinitic

(NenormN15) fields Only three samples (ROM CAB AZ) plot in thehawaiite field (Fig 2) but their high MgO contents (69 87 and 83respectively Table 2) contradict this classification (hawaiite MgOcontents are usually around 5) Samples RQH and AG plot in the sub-alkaline domain (Fig 2) and they can be considered as olivinetholeiites

The lavas as a whole display [mg] numbers ranging from 056 to075 SiO2 and alkali contents between 41 and 52 and 37 and 76respectively (Table 2) The lack of truly differentiated lavas constitutesone major difference with the French Massif Central volcanic districtThis feature thus suggests both of the absence of magma chambersbeneath the Languedoc area and relatively fast ascent of the magmasBoth features are consistent with the very low volume of the emittedlavas and the common occurrence of abundant mantle xenolithsThus the major-element variations of the Languedoc basalts can beexplained by different degrees of partial melting and to a lesser extentby the extraction or accumulation of olivine crystals during themagma ascent This observation is corroborated by the trace-elementdata (see Section 53)

From a petrographic point of view only two uncommon mag-matic rocks have been found a basanite containing very large (up to3 cm) phlogopite megacrysts (recently dated at 188plusmn002 Ma bythe ArAr method Monieacute unpublished data) and Ti-rich magnetitemegacrysts (up to 5 cm in size) from Lodeacutevois (LO Table 2Fig RM1)and a camptonitic lamprophyre (POU3) occurring as clasts in the46 Ma-old breccia pipe POU (Liotard et al 1991) (Table 2Fig RM1)

The Languedoc basalts display very variable K2ONa2O ratios(between 016 and 140) and their trace-element contents are alsovery variable (eg 35bThb17 21bLab108 38bNbb144 Table 1)Only RQH shows the low trace-element contents typical of tholeiites(eg Th=3 ppm La=21 ppm Table 1) Sample AG in spite of itstholeiite-like major-element chemistry has trace-element contents(Th=7 ppm La=39 ppm) similar to the less enriched basanites (ieTS Th=6 ppm La=40 ppm) As shown in Fig 3 the KRb ratios ofsome Plio-Quaternary lavas belonging to Group 2 (Table 2) (VA FORO LC1 BA ROL2 TAU COL SM GR MIC BAS) are anomalously low(KRbb200) compared to the mean OIB value of Sun and McDonough(1989) KRb=400 This suggests a loss of K (andor a Rb increase)that we tentatively relate to late-magmatic andor weatheringprocesses The possible impact of late alteration is corroborated bythe relatively high LOI contents (N2) measured in most low-KRbsamples (Table 2) Moreover this loss of K could explain why mostsamples with anomalously low KRb ratios plot in the alkali basaltfield instead of the basanitic field (Fig 2) in spite of their high degreeof SiO2-undersaturation

The trace-element patterns of the studied lavas are remarkablyparallel (Fig 4) and typical of alkali basalts implying enriched OIB-type mantle sources This indicates that weathering has not sig-nificantly affected the amounts of the incompatible elements exceptfor the most mobile ones such as Rb Ba and K As expected thetransitional basalts (RQH and AG) display less enriched patterns [(LaYb)Nle15] while the Ne normative-rich lavas show themost enrichedpatterns (eg FO LO 742 and VA with (LaYb)N ratios up to 33Table 2) However the lavas with the highest trace-element contentsare not those with the highest K and Lc normative contents (N5)(Table 2) The K enrichment of these lavas would result consequentlyfrom melting of a K-rich and Th- U- Nb- and LREE-poor phase likephlogopite Slight negative anomalies in Th and U (eg (UNb)NPOU=0738 NDG=0748 MTF=0843 PP1=0567) and ZrndashHf(eg (ZrSm)N MRS=104 TS=0925 NT=0948) are observed inseveral samples (Fig 4) Small positive spikes in Pb are shown by thetransitional and low alkali basalts [(PbCe)N NDG=138 Vi=186]

413 Isotope dataThe isotopic data are reported in Table 3 The initial 87Sr86Sr ratios

display rather large variation ranging between 070307 and 070436

Table 2Major- and trace-element compositions of selected Languedoc lavas The analytical methods are given in the text Ne Lc nepheline and leucite normative content respectively for the samples with LOIb4 [mg] Mg(Mg+Fe2+) withFe3+=015Fe2+ The abbreviations correspond to selected samples located in Fig 2 Legends are (i) isotopic composition corrected for in-situ decay data from this study [] published ages (for references see text) interpolatedage according to field observations Note that samples NDG and AG belong to the same flow

Group 1b08 My 12bGroup 2b23 My

RQH bNDG AGN MRS CPA E12 VA PA RO LC1 LC2 CE1 CE2 MCL FO CX AR SM

Long E 3deg22 11 3deg27 44 3deg28 17 3deg24 29 3deg31 07 3deg21 52 3deg21 40 3deg21 32 3deg17 47 3deg24 47 3deg24 34 3deg23 48 3deg23 39 3deg24 13 3deg23 23 3deg21 58 3deg29 33 3deg23 49

Lat N 43deg1801 43deg17 31 43deg17 52 43deg22 52 43deg16 28 43deg25 33 43deg25 36 43deg31 22 43deg30 30 43deg35 21 43deg34 47 43deg32 53 43deg32 49 43deg33 02 43deg33 08 43deg31 53 43deg43 39 43deg50 28

age (My) 056 069 069 068 073 14 14 2 2 15 15 15 152 15 146 122 2

SiO2 5106 5106 4968 4578 4733 4434 4274 4318 4387 4404 4158 4459 4567 4391 4082 4466 4243 4390Al2O3 1237 1325 1399 1297 1396 1375 1302 1189 1344 1277 1165 1205 1226 1171 1088 1266 1407 1266Fe2O3 1123 1067 1092 1281 1189 1236 1203 1352 1185 1218 1332 1154 1201 1190 1310 1296 1279 1230MnO 014 014 015 019 017 019 017 018 016 017 019 016 016 016 023 020 015 016MgO 900 792 849 1067 834 693 804 984 869 867 971 1141 1030 1039 1050 926 907 1022CaO 884 836 890 1009 922 1042 1115 1009 1006 987 1186 1008 1008 1094 1284 989 1057 1047Na2O 328 353 353 367 392 482 484 406 435 439 408 342 361 337 466 368 374 367K2O 090 156 154 153 166 083 085 075 094 097 098 155 090 147 087 173 229 078TiO2 206 205 210 225 233 290 277 260 297 299 270 234 232 254 263 246 353 265P2O5 042 059 061 076 076 091 112 121 083 091 139 093 092 083 125 101 075 084LOI 002 033 minus030 minus057 minus026 242 332 223 314 240 234 182 095 322 245 137 067 200Total 9932 9946 9962 10015 9931 9987 10005 9955 10030 9936 9980 9989 9918 10044 10023 9987 10006 9965[mg] 065 063 064 065 061 056 060 062 063 062 062 069 066 067 065 062 062 065Lc 00 00 00 00 00 00 00 00 00 00 00 00 00 00 42 00 00 00Ne 00 00 07 103 69 135 174 108 123 118 166 98 62 110 221 103 174 93Rb 1936 1946 3311 3333 3983 3869 4685 6492 2076 4368 5358 2744 4372 2269 1401 57 4671 575 7423Sr 4800 4949 6465 6886 7819 8164 127030 124420 107890 105460 96425 119350 90328 96740 9693 1078 1020 938 96304Y 2121 2168 2335 2362 2606 2531 2603 3095Zr 1467 1518 2028 2057 2142 2349 37586 39424 34910 36683 34275 38187 29944 30788 2685 343 2828 258 31357Nb 3813 5710 5817 7246 7341 14373 15152 11086 11225 10950 12019 9595 9808 7998 113 8236 948 9441Cs 0099 0141 0179 0259 0650 0558 100 117 093 114 089 092 072 076 1320 093 0843 065 097Ba 2935 3042 5143 5100 6061 5987 98831 102010 72479 91582 85079 88662 71054 74398 7448 689 7032 816 74009La 2105 2157 3730 3929 5136 4861 9197 10801 7836 7338 6401 8762 6732 7229 5307 7987 6863 471 6012Ce 4311 4381 7009 7478 9848 9192 16885 18575 14625 13471 12385 16195 12246 13023 1037 154 1300 927 11129Pr 4985 5075 7693 8189 1073 1005 1821 1945 1598 1451 1380 1795 1342 1423 1155 1753 1403 105 1238Nd 2118 2157 3097 3251 4193 3970 7040 7303 6298 5798 5451 7129 5233 5473 4735 6909 5655 439 5054Sm 5088 5208 6455 6536 8120 7828 1206 1210 1101 994 968 1244 903 965 8646 1187 1005 836 904Eu 1829 1877 2109 2134 2620 2578 371 386 368 336 317 409 304 319 2725 375 3151 273 308Gd 5535 5584 6236 6415 7482 7405 1071 1100 1058 960 874 1124 918 932 7601 1028 8957 806 877Tb 0789 0789 0861 0889 1020 0999 133 137 132 123 112 140 117 118 1016 144 1186 102 116Dy 4793 4849 5290 5227 6082 5837 723 773 735 696 628 773 666 679 5492 709 6472 538 661Ho 0849 0842 0935 0944 1059 1015 123 131 121 120 105 127 116 115 0961 121 1114 090 112Er 2065 2048 2316 2353 2573 2482 301 311 281 293 256 286 278 275 2363 285 2731 217 266Tm 0270 0267 0313 0312 0344 0325 039 039 034 037 032 036 036 036 0303 036 0369 0265 034Yb 1562 1545 1853 1883 1985 1905 228 230 201 220 198 204 211 214 1655 211 2014 154 199Lu 0231 0227 0282 0282 0303 0285 034 032 028 033 027 029 031 031 0253 031 0299 0216 029Hf 3593 3563 4547 4604 4705 5112 841 778 701 780 743 780 605 621 5936 742 5910 570 666Ta 1838 1825 2731 2762 3577 3608 765 764 603 689 626 712 502 529 4537 625 4259 489 534Pb 2280 2056 3859 4078 3239 3513 555 537 379 427 359 425 443 433 3223 408 4150 320 277Th 3537 3442 6674 6957 7705 7419 1567 1719 987 1018 852 1129 982 980 7608 1021 9460 627 873U 0683 0729 1256 1294 1721 1482 368 390 237 252 211 273 227 233 2089 255 2493 180 229

207J-M

Dautria

etal

Lithos120

(2010)202

ndash222

12bGroup 2b23 My 12bGroup 2b23 My

LO 819 BR 742 BA GR 809 MA SVT ROL1 ROL2 TAU LR COL BGE SAL FES CAB


Lat N 43deg44 22 43deg48 52 43deg44 19 43deg19 29 43deg44 22 43deg45 26 43deg49 14 43deg44 48 43deg48 30 43deg34 14 43deg34 14 43deg36 31 43deg38 39 43deg45 53 43deg39 30 43deg39 05 43deg39 29 43deg45 45

age (My) 2 182 151 197 225 2 2 2

SiO2 3918 4271 4434 4172 4339 4262 4636 4160 4131 4397 4494 4488 4535 4297 4726 4401 4416 4690Al2O3 1203 1151 1281 1190 1248 1137 1312 1349 1262 1452 1424 1473 1482 1350 1387 1309 1337 1454Fe2O3 1335 1378 1242 1208 1307 1320 1159 1390 1394 1228 1199 1183 1043 1197 1200 1243 1256 1034MnO 017 019 021 019 020 020 017 022 018 019 019 019 018 020 018 019 019 018MgO 889 1274 860 1169 948 1338 1117 883 973 640 751 713 621 909 798 1048 952 866CaO 1130 931 1029 1190 1031 988 870 954 1075 970 977 986 892 1101 925 877 896 850Na2O 250 346 329 234 405 306 325 356 374 305 494 425 430 490 392 369 320 473K2O 240 174 146 242 108 062 196 233 207 245 125 112 311 103 194 250 244 271TiO2 382 312 302 308 274 257 276 371 392 317 303 313 276 328 248 271 281 245P2O5 072 101 107 066 100 075 050 095 078 097 085 085 087 093 099 090 095 084LOI 464 057 293 189 223 310 089 267 086 371 178 259 249 170 084 162 203 046Total 9900 10014 10044 9987 10003 10075 10047 10080 9990 10042 10048 10055 9944 10057 10073 10040 10018 10031[mg] 060 068 061 069 062 070 069 059 061 054 059 058 058 063 060 066 063 066Lc 92 00 00 101 00 00 00 00 30 00 00 00 00 00 00 00 00 00Ne 123 128 67 111 125 81 66 151 175 75 146 96 150 190 72 135 94 152Rb 54 42 57 61 62 83 49 55 745 6900 7957 14101 8379 9422 5021 5617 6564 8082Sr 902 817 1142 1011 1011 929 687 1033 996 2391 1043 1141 1352 1243 9589 8925 1017 105850Y 3354 2876 3179 3010 3259 3088 2611 3011 2880Zr 256 345 377 354 300 284 301 317 4136 4014 3856 4220 4083 2874 2690 3097 38921Nb 84 106 110 110 95 82 85 113 1236 1051 1098 1243 1258 9026 7276 9976 11545Cs 054 098 084 103 088 094 113 076 0991 1021 1627 1183 1049 1225 0918 1004 131Ba 767 568 863 808 843 684 599 723 936 9945 9859 9611 1011 1081 7277 7599 8845 90734La 414 5248 62 6256 7131 5416 4154 5373 603 7570 6573 7218 7782 8190 6675 5490 6410 7603Ce 839 1025 1206 1228 1385 1058 7807 1048 117 1443 1248 1384 1440 1575 1233 1058 1258 13977Pr 1194 1375 1415 1568 1224 889 1208 133 1560 1360 1485 1514 1698 1341 1187 1367 1437Nd 411 4862 5494 5664 6249 4919 3563 4841 544 6219 5412 5953 5893 6682 5350 4791 5570 5499Sm 83 897 1005 1038 1101 893 699 876 995 1101 9631 1056 1000 1142 9551 8712 9846 921Eu 227 289 322 33 347 286 228 28 322 3346 2902 3192 3121 3512 3027 2695 3166 290Gd 826 91 935 966 798 667 8 932 9264 8293 9047 8437 9711 8556 7471 8535 785Tb 093 115 129 134 136 114 097 114 118 1229 1078 1200 1120 1255 1156 0993 1133 105Dy 58 659 683 696 582 512 576 630 6722 5910 6593 6168 6836 6389 5541 6346 583Ho 099 115 118 12 1 09 1 107 1164 1024 1159 1064 1182 1116 0971 1088 102Er 238 277 295 29 238 225 24 264 2980 2570 2926 2727 3002 2850 2428 2794 264Tm 031 036 038 038 032 031 032 0338 0399 0347 0405 0360 0388 0371 0324 0356 035Yb 147 18 22 225 225 187 183 191 191 2308 1928 2293 2156 2328 2179 1836 2094 212Lu 025 027 032 034 034 027 028 028 0285 0346 0312 0350 0335 0346 0319 0277 0311 033Hf 52 578 759 808 818 678 62 647 716 8511 8480 8872 8589 8739 6346 6108 7011 816Ta 468 6 651 675 577 474 508 646 6881 6086 7055 7122 7350 4756 3924 5752 684Pb 36 332 392 443 547 35 372 428 351 4547 5251 4981 5873 4637 5385 3586 3969 534Th 52 67 834 869 979 748 744 762 821 1054 9847 1073 1251 1279 1007 7708 8533 1256U 227 185 23 243 251 185 203 208 220 2502 2481 2399 3520 3293 2732 2057 2215 328

Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222

12bGroup 2b23 My 5bGroup 3b75 My 13bGroup 4b161 My AUBRAC Group

BAG BAS GUI MIC ROM AZ SAU PP1 EG MTF POU1 POU3 TS bNT(1) NT(2)N VI 02 AU2 AU3 AU4


Lat N 43deg44 11 43deg39 06 43deg44 35 43deg43 14 43deg49 03 44deg08 48 43deg58 32 44deg03 24 44deg12 22 43deg40 43deg31 34 43deg31 34 44deg24 25 44deg28 29 44deg16 16 44deg44 05 44deg35 53 44deg31 01

age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65

SiO2 4473 4479 4375 4231 4624 4698 4420 4398 4552 4526 4088 4190 4508 3953 4769 4368 4731 4488Al2O3 147 1306 139 1306 1513 1436 1346 1388 1340 1464 1290 1287 1063 1037 1477 1376 1649 1473Fe2O3 1285 1163 1284 1296 1194 1135 1262 1255 1109 1230 1251 1287 1111 1055 1080 1303 1248 1183MnO 02 019 02 021 019 018 018 016 018 018 015 017 019 015 014 019 018 019MgO 751 983 815 918 689 829 1052 1002 1181 836 921 938 1434 1179 761 927 573 713CaO 939 997 978 1108 87 736 897 900 914 826 1120 1095 1057 1316 741 1018 836 986Na2O 442 408 416 418 462 386 314 434 257 370 161 256 272 268 366 372 387 425K2O 269 128 264 066 285 267 191 173 196 225 226 225 091 175 206 207 176 112TiO2 321 283 329 319 316 222 277 256 189 259 354 322 211 258 280 319 324 313P2O5 09 083 094 108 084 100 077 069 056 063 065 059 053 064 068 087 072 085LOI 007 159 031 232 minus008 250 237 107 137 147 410 232 223 660 231 008 minus008 259Total 10067 10008 9996 10023 10048 10078 10091 9998 9949 9964 9901 9903 10042 9980 9993 10003 10005 10055[mg] 057 066 059 062 057 062 066 065 071 061 063 062 075 072 062 058Lc 00 00 00 00 00 00 00 00 00 00 00 00 00 88 00 00 00 00Ne 168 114 172 138 151 70 81 153 49 93 69 118 60 133 22 140 38 96Rb 8549 5653 6806 1468 8455 7279 568 3241 4839 6284 4075 2501 262 446 3888 5612 6585 3685 3432Sr 1047 1097 1007 1045 1062 1197 2498 88955 7536 7915 7860 9353 744 1124 1006 703 8716 8036 6745Y 3216 2886 3220 3517 3132 2691 243 2322 2563 263 2444 2649 2328 3044 2897 2578Zr 4117 3960 4136 4179 4583 4071 3337 31346 2168 3152 2484 2709 177 227 241 2538 3094 3008 2497Nb 1077 1100 1128 1183 1186 1055 1157 10175 7064 6704 5935 6423 606 906 7376 6316 9477 7439 6568Cs 105 113 099 388 103 141 103 076 126 0762 2633 1305 081 337 333 1746 1147 0366 0484Ba 9012 8093 8171 8891 8816 2060 7208 59900 6039 5382 7385 5993 503 980 943 2707 6603 4513 4325La 6485 6761 6561 8279 6691 6880 5256 4878 4326 4251 3996 4317 397 604 5895 3544 6075 4507 5120Ce 1273 1280 1296 1586 1303 1333 1017 9421 8427 8845 8599 9289 753 115 1128 7576 1223 9664 1013Pr 1390 1390 1409 1652 1380 1476 1129 1047 934 1027 1025 1086 86 129 1259 919 1345 1120 1101Nd 5666 5444 5682 6455 5519 5628 4443 4132 3823 4225 4174 4610 362 525 5249 4044 5453 4748 4442Sm 1030 969 1031 1139 1006 1042 855 779 745 8344 8451 9380 760 949 925 882 9866 9130 7881Eu 319 296 320 346 311 324 274 257 244 2735 2770 2978 249 295 287 289 2900 2742 2360Gd 892 807 898 941 837 843 736 698 706 7624 7785 8428 747 879 751 814 8522 7921 6971Tb 122 111 121 131 117 114 098 092 097 1036 1018 1124 099 105 100 106 1127 1046 0927Dy 683 625 675 735 647 607 544 511 573 6053 5785 6454 538 549 487 587 6222 5888 5252Ho 116 106 117 126 113 103 092 087 105 1076 0968 1079 093 093 089 096 1092 1039 0928Er 297 266 293 313 284 250 226 207 281 2593 2282 2471 218 219 216 229 2712 2676 2400Tm 039 035 039 041 038 032 028 026 037 0356 0295 0315 0287 0266 027 028 0366 0356 0321Yb 237 211 231 246 229 190 166 148 227 2043 1649 1809 167 153 153 16 2078 2057 1896Lu 037 032 036 037 035 028 024 022 034 0307 0228 0262 0238 0231 023 0226 0315 0323 0296Hf 729 689 713 719 795 910 740 678 518 6741 5618 6206 403 541 540 595 6927 6568 5453Ta 619 628 669 591 715 635 692 617 399 3698 3170 3420 301 491 476 342 5493 4159 3682Pb 393 489 398 419 441 534 354 344 351 3104 4105 3076 323 493 450 565 4056 3232 2924Th 914 1021 926 1151 988 987 768 670 637 5970 4544 4985 604 836 806 608 8199 4891 6513U 238 231 242 244 256 296 207 170 164 1661 129 1367 143 199 186 165 2109 1303 1696

Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222

Fig 4 Extended trace-element patterns of selected Languedoc lavas The normalizingvalues of Primitive Mantle (N) and incompatibility sequence are from Sun andMcDonough (1989) For samples location see Fig 1RM1 and Table 2

Fig 2 (K2O+Na2O) vs SiO2 diagram for the Languedoc lavas Boundaries are fromCox et al (1979) Four groups of samples have been defined according to their age (seeTable 2) Group 1 b08 Ma Group 2 12ndash23 Ma Group 3 5ndash75 Ma Group 4 13ndash161 Ma AUB Aubrac (a) line separating alkaline and subalkaline domains is fromIrvine and Baragar (1971) Anhydrous recalculated values


(except for sample SAU which has 87Sr86Sr=07072) The initial143Nd144Nd ratios are more homogeneous (051269ndash051298) Theinitial Pb-isotope ratios also show significant variation (206Pb204Pb18735ndash19658 208Pb204Pb 38422ndash39434 and 207Pb204Pb 15594ndash15680) In Figs 5ab and 6ab the Languedoc basalts define relativelylarge fields included within the fields of Western and Central Europelavas (Piromallo et al 2008) and superimposed on the French MassifCentral and Catalunya fields (Downes 1984 Chauvel and Bor-Ming1984Wilson and Downes 1991 Briot et al 1991 Lenoir et al 2000ab Dautria et al 2004 Cebria et al 2000)

In the 143Nd144Nd vs 87Sr86Sr diagram (Fig 5ab)most Languedoclavas plot along the Mantle Array From this diagram two importantobservations can be made (1) some sub-contemporaneous sam-ples from adjacent locations show very different isotopic signatures(eg LR and SAL that are 3 km from each other Table 3 Fig RM1)(2) conversely some samples with significantly different locationsand ages have similar isotopic compositions [eg AG (069 Ma) and Vi(161 Ma) separated by 150 km (Table 3 Fig 1) Thus at first sightthere is no regional or age control on the isotopic signatures of theLanguedoc lavas Nevertheless a large number of Group 2 (Table 2)samples are slightly more enriched in radiogenic Nd Most of thesesamples plot within or close to the Low Velocity Component (LVC)field as defined by Hoernle et al (1995) According to Wilson and

Fig 3 KRb vs (Na2O+K2O) wt diagram for the Languedoc lavas Dashed squarelavas with anomalously low KRb ratios For legend see Fig 2

Downes (1991) Granet et al (1995) and Downes (2001) such asignature corresponds to the asthenospheric component of theEuropean plume

In the 206Pb204Pb vs 207Pb204Pb diagram (Fig 6a) most samplesplot off the Northern Hemisphere Reference Line (NHRL) The Pre-Miocene lavas (from 161 to 25 Ma) define a horizontal trendcharacterized by a decrease in 206Pb204Pb with increasing agewhile the 207Pb204Pb ratio remains constant In the 206Pb204Pb vs208Pb204Pb diagram (Fig 6b) the lavas plot within a narrow areaalong the NHRL but no samples plot in the LVC field As previouslyshown for Nd and Sr isotopes significantly different Pb isotopicsignatures can be found in samples close in age (eg 819 and 742Table 3) while some samples of very different ages andor fromdistant locations have similar signatures [eg AG (069 Ma) and Vi(161 Ma) Table 3] However as shown by the 206Pb204Pb vs agediagram (Fig 7) lavas with ages between 669 and 236 Ma display Pbisotopic heterogeneities of same order of magnitude as those of theMiocenendashPliocenendashQuaternary lavas Thus these observations showthat the Languedoc lava sources are isotopically variable and suggestthat (1) the length-scale of variation is very small and (2) the isotopicheterogeneities were probably entirely acquired before the MioceneAs suggested by Fig 7 the first influence of the EAR componentappeared around 70ndash60 Ma which is in agreement with observationsmade in the post-collisional Cenozoic volcanic districts of the Adriaticdomain (Bianchini et al 2008) In this hypothesis only the oldestmagma (Vi 1612 Ma) sources could be considered as being free ofEAR influence

42 The peridotite xenoliths

Studies of the petrology and geochemistry of the peridotitexenoliths from the Languedoc basalts have shown that this part ofthe French sub-continental mantle lithosphere is rather heteroge-neous (eg Albert et al 1967 Brousse and Ildefonse 1970 Coisy1977 Berger 1981 Fabries et al 1987 Cabanes and Mercier 1988Jakni et al 1996 Dautria et al 2006) Harzburgites and lherzolites arefound in almost similar proportions and rare wehrlites have been

Table 3Sr Nd Pb isotopic compositions of selected Languedoc lavas Absolute ages are from this study and from literature data (Gillot 1974 Baubron et al 1978a) data from this study [] published ages (for references see text) interpolatedage according to field observations (i) in situ decay corrected For lead-isotope ratios isotopic composition uncertainties are better than 300 ppm

Sample RQH1 AG MRS CPA MCL FO CX LO 819 BR 742

Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197

87Sr86Sr 0703452plusmn08 0703917plusmn08 0703433plusmn07 0703574plusmn11 0703581plusmn05 070335plusmn50 0703253plusmn02 070399857plusmn06 070325plusmn60 0703370plusmn40 0703080plusmn3087Sr86Sr(i) 070345 070391 0703432 070357 070358 070335 070325 070399 070325 070337 070307143Nd144Nd 0512803plusmn10 0512789plusmn08 0512727plusmn09 0512847plusmn09 0512920plusmn06 0512910plusmn30 0512894plusmn04 0512912plusmn05 0512860plusmn30 0513000plusmn20 0512900plusmn20143Nd144Nd(i) 0512802 0512788 0512726 0512846 0512919 0512909 0512893 0512910 0512858 0512999 0512898208Pb204Pb 388690plusmn09 389800plusmn03 388810plusmn08 388790plusmn06 389400plusmn15 389760plusmn12 389480plusmn18 389780plusmn37 386290plusmn15 389880plusmn15 391680plusmn57208Pb204Pb(i) 38866 38976 38876 38874 38929 38964 38937 38969 38617 38977 39155207Pb204Pb 156340plusmn08 156390plusmn03 156250plusmn07 156250plusmn05 156221plusmn06 156310plusmn40 156227plusmn05 156157plusmn08 155670plusmn60 156361plusmn60 156810plusmn22207Pb204Pb(i) 15634 15639 15625 15625 15622 15631 15622 15615 15566 15636 1568206Pb204Pb 189500plusmn07 189000plusmn03 190490plusmn06 190250plusmn04 192682plusmn06 193150plusmn50 192718plusmn13 193321plusmn07 187450plusmn70 191230plusmn70 193790plusmn270206Pb204Pb(i) 18948 18898 19045 19022 19259 19306 19263 1932 18735 19114 19368

Sample BA GR 809 MA ROL1 ROL2 TAU LR COL BGE SAL

Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15

87Sr86Sr 0703360plusmn30 0703170plusmn40 0703210plusmn40 0704360plusmn40 0703614plusmn03 0703331plusmn03 0703274plusmn03 0703815plusmn03 0703224plusmn03 0703551plusmn05 0703363plusmn0287Sr86Sr(i) 070336 070316 070321 070436 070361 070332 070326 070381 070322 070355 070336143Nd144Nd 0512920plusmn30 0512920plusmn10 0512910plusmn20 0512930plusmn40 0512896plusmn03 0512877plusmn08 0512894plusmn05 0512914plusmn05 0512901plusmn04 0512877plusmn06 0512905plusmn04143Nd144Nd(i) 051292 051292 0512909 051293 051289 051288 051289 051291 05129 051288 05129208Pb204Pb 390720plusmn22 389600plusmn10 389040plusmn16 389840plusmn24 390323plusmn08 385317plusmn15 390355plusmn13 389959plusmn13 388937plusmn25 389375plusmn14 388703plusmn12208Pb204Pb(i) 39063 38949 38894 38972 39015 38518 390196 38987 38876 38928 3886207Pb204Pb 156670plusmn08 156040plusmn04 155940plusmn06 156550plusmn10 156236plusmn03 155990plusmn05 156349plusmn04 156171plusmn04 156178plusmn08 156332plusmn04 156210plusmn04207Pb204Pb(i) 15667 15604 15594 15655 15623 15599 15634 15617 15617 15633 15621206Pb204Pb 191870plusmnplusmn09 192620plusmn05 191590plusmn08 190920plusmn12 193771plusmn03 188164plusmn05 193201plusmn04 193416plusmn05 192247plusmn08 191577plusmn05 191747plusmn04206Pb204Pb(i) 19180 19254 19151 19082 19365 18806 19309 19334 19211 1915 19166

Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222

Sample FES CAB BAG BAS GUI MIC ROM AZ SAU PP1 MTF

Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]


Sample POU3 EG TS NT VI AU2 AU3 AU4

Age (My) [46] 140 588 [669] 1612 [65] [65] [65]

87Sr86Sr 0703799plusmn10 0703854plusmn08 0703582plusmn09 0704317plusmn09 0704271plusmn07 0703678plusmn03 0703589plusmn02 0703542plusmn0587Sr86Sr(i) 070375 070382 07035 070421 070374 070366 070358 070353143Nd144Nd 0512821plusmn07 0512872plusmn12 0512939plusmn10 0512855plusmn07 0512834plusmn07 0512864plusmn05 0512836plusmn04 0512871plusmn05143Nd144Nd(i) 051278 051286 051289 051281 051269 051286 051283 051287208Pb204Pb 391720plusmn04 392275plusmn07 393010plusmn09 390960plusmn08 390045plusmn06 394330plusmn12 391528plusmn10 394819plusmn14208Pb204Pb(i) 38925 391503 389364 387226 384222 393894 391204 394337207Pb204Pb 156260plusmn04 156480plusmn05 156290plusmn08 156280plusmn08 156430plusmn05 156494plusmn04 156449plusmn04 156420plusmn05207Pb204Pb(i) 15616 15645 15617 15615 15618 15648 15644 1564206Pb204Pb 195090plusmn04 192120plusmn06 193050plusmn07 190780plusmn05 187790plusmn04 195691plusmn05 192546plusmn08 196957plusmn05206Pb204Pb(i) 19305 19151 19044 18809 18309 19535 19229 19658

Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222

Fig 5 (a b) 143Nd144Nd(i) versus 87Sr86Sr(i) for Languedoc peridotitic xenoliths and host lavas Lavas groups (1 to 4) are those defined in Table 2 AUB Aubrac districtEG Eglazines spinelndashgarnet peridotite PYR Lith Pyrenean Lithosphere (Mukasa et al 1991) FMC xeno French Massif Central peridotite xenoliths (for references see text) Olotxeno (stippled area) peridotite xenoliths form Olot (Iberian plate NE Spain Bianchini et al 2007) Sardinia xeno (dotted area) Peridotite xenoliths from Sardinia (Beccaluva et al2001) EUR Lavas field of European lavas from Piromallo et al (2008) FMC lavas lavas of the French Massif Central (for references see text) CAT lavas Catalunya lavas (includingOlot) from Cebria et al (2000) LVC Low Velocity Component from Hoernle et al (1995) Sr and Nd isotopic compositons of the analyzed xenoliths have been reported bothuncorrected and corrected for in situ decay at 161 Ma (age of the oldest lava)


described All are equilibrated in the spinel domain except somelherzolitic samples (EG9 and 11 Table 4) from a single CD breccia pipe(EG Fig 1) which contain spinel and garnet in textural equilibrium(Berger 1981) Except for the coarse equant texture all the classicaltextural types are present (porphyroclastic eg PP-2 granoblastic egSOU mylonitic Pg-0 Table 4) Several poikilitic samples have beencollected in Lodeacutevois (eg PCV-9 Table 4) Most xenoliths displaygeochemical evidence of metasomatism and in several localitiessamples contain secondary phases such as amphibole (pargasiteto kaersutite eg Pg) Al-poor diopside (eg SOU) and more rarelyphlogopite andor alkali feldspar Calcite of secondary origin hasalso been described in some lherzolitic xenoliths from NE Languedoc(PP-2)

We have selected 10 mantle xenoliths out of 92 collected by Alardand Dautria unpublished These selected samples are representativeof the range of textures equilibrium conditions and geochemicalfingerprints (see REE patterns Fig 8) identified in Languedoc Theirmajor- and trace-element compositions as well as Sr Nd and Pbisotopic ratios are given in Table 4 along with their equilibriumtemperatures Several of these xenoliths were partially previouslydescribed by Lorand et al 2003 and by Dautria et al 2006

421 Major and trace elementsOverall the fertility of the xenoliths from the ELD and the HLVD

districts is comparable to those from the Southern French MassifCentral (south of 41degS as defined by Lenoir et al 2000ab) For

instance the average whole-rock Al2O3 content is about 24plusmn09 wt(n=49) for the HLVD-ELD indistinguishable from the composition ofxenoliths from the Southern French Massif Central (Al2O3=25plusmn10 wt n=134) The Causses xenoliths have whole-rock Al2O3

contents (29plusmn06 wt n=15) similar within error to those of theSouthern French Massif Central and the HLVD Although we cannottotally rule out a sampling bias the Montferrier xenoliths (n=17)appear to be more fertile with Al2O3 contents of 35plusmn07 wt Thenearby Pyrenees orogenic massifs have essentially a bi-modalharzbugitendashLherzolite composition volumetrically dominated by thelherzolite type with Al2O3 wt ranging between 25 and 45 (Le Rouxet al 2007)

Although there are significant variations in term of REE contentsdue to various degrees of depletion (eg YbCI 073ndash27 CI CI-1chondrite nomalised) the REE patterns of most of the Languedocmantle xenoliths (except poikilitic samples PCV-9) can be describedas a continuum between two types of REE patterns The firstillustrated by the Gt-Sp sample Eg-9 (Fig 8) shows a depletion inthe middle to light REE (MREE and LREE respectively) relative to theheavy REE (HREE) Such a pattern is reminiscent of the so-calledldquoDepletedMORBMantle (DMM) patternrdquo and is classically consideredas resulting from the extraction of partial melts The second ldquoend-memberrdquo pattern illustrated by sample SOU-6 is characterized by arelatively flat HREE to MREE segment [(EuYb)Nasymp1] and a markedenrichment of the LREE relative to MREE and HREE [(LaSm)NN3]Most of the other Languedoc xenoliths have REE patterns

Fig 6 (a b) Diagrams of 207Pb204Pb vs 206Pb204Pb and 208Pb204Pb vs 206Pb204Pb forLanguedoc peridotitic xenoliths and host lavas For identification of groups andabbreviations see Fig 4 The Group 4 lavas are plotted individually and identified bytheir ages (see Tables 1 and 2) MO-OR lavas Monchique and Ormonde lavas fromBernard-Griffiths et al (1997) EAR European Asthenospheric Reservoir (Granet et al1995)

Fig 7 ln (agetimes10) vs 206Pb204Pb(i) Symbols and abbreviations as in Fig 6


intermediate between these two end-members (Fig 8) A fractionalmelting model (source composition and partition coefficients as forlava modelling) suggests that the Languedoc lithosphere hasundergone small to moderate amounts of partial melting (le4fractional melting) except for samples CX2 PP-2 and PCV-9 for whichthe degree of melting reaches 10ndash15 This slightly depletedldquoprotolithrdquo was subsequently metasomatized to a variable extent bypercolation of small-volume melts enriched in the most incompatible

elements (Navon and Stopler 1987) PCV-9 does not belong to thiscontinuum and shows an almost flat REE pattern consistent withprevious data reported for samples from the same locality (Lorandand Alard 2001) This pattern is typical of poiumlkilitic samples anddenotes meltndashrock interaction at high meltndashrock ratios with an OIB-like melt (Alard et al 1996 Xu et al 1998 Lorand and Alard 2001)

Abundances of Large Ion Lithophile Elements (LILE Ba Rb Th UPb Sr) are more variable and may depend upon the occurrence ofmetasomatic phases such as amphibole A detailed discussion of thebehaviour of these elements is beyond the scope of this contributionbut we note the distinct behaviour of U relative to Th and to a lesserextent of Sr and Pb relative to Ce The depleted patterns (eg GRM-2Eg-9) are marked by selective enrichment of U relative to Th yieldingextremely high UTh [(UTh]PM as high as 27 [ie Pg5)] Pb also showspronounced positive anomalies relative to Ce (Fig 9) Such anomalieshave been commonly described in the FrenchMassif Central xenoliths(Alard et al 1996 Lenoir et al 2000ab) In contrast LREE enrichedsamples such as Pg-0 and SOU-6 show concomitant enrichment in Uand Th and have broadly chondritic UTh ratios In these samples Pband Sr do not define marked anomalies

The distribution of High Field Strength Elements (HFSE Nb Ta Zrand Hf) in these samples allows us to identify other differencesbetween the two end-members LREE-enriched samples (SOU-6 PG-0 PP-2) have pronounced negative anomalies in Nb and Ta relative toTh and La [eg (NbLa)PM=003ndash041] Such negative anomalies areoften considered as symptomatic of carbonate metasomatism (egDautria et al 1992 2006 Ionov et al 1993) The HFSE abundance ofthe LREE-depleted end-member samples follows the general trend ofincompatible-element depletion except for the two garnet-bearingsamples [(NbLa)PM=034ndash20] The pattern of PCV-9 shows slightpositive anomalies inNbandTa relative to the LREE [ie (TaLa)PM=23(NbLa)PM=26)]

422 Sr Nd and Pb isotopesThe isotopic ratios of Sr Nd and Pb display rather large ranges

(b87Sr86Sr 070287ndash070578 143Nd144Nd 051256ndash051414 208Pb204Pb 37772ndash39041 206Pb204Pb 17901ndash19353) except 207Pb204Pbwhich shows little variation (15570ndash15620) Two garnetndashspinelperidotites (ie EG samples) show strongly positive εNd as high as 29Such positive values have only found in the North French MassifCentral and have been interpreted as the fingerprint of an old melt-depletion event (Downes et al 2003) However contrary to the N-MCF the EG xenoliths have highly radiogenic Sr (87Sr86SrN0705)which could then be interpreted as the signature of a time-integrated

Table 4Major- and trace elements and Sr Nd Pb isotopic compositions of selected peridotite xenoliths from Languedoc Sp spinel Gt garnet Lhz Lherzolite Hz harzburgite Granulogranuloblastic Porhyro Porphyroclastic TdegBampK(1991) 2 pyroxenes equilibrium temperature after Brey and Kohler (1990) TdegWells (1977) 2 pyroxenes equilibrium temperatureafter Wells (1977) The uncertainties for Pb isotopic ratios are better than 300 ppm

Samples CX-2 PCV-9 PP-2 SAM-6 GRM-2 SOU-6 Eg-9 Eg-11 Pg-0 Pg-5

Host lava ref CX MCL PP1 Non analyzed 819 BR EG EG MTF MTF

Rock type Sp Lhz Sp Hz Sp Lhz Sp Lhz Sp Lhz Sp Lhz Gt-Sp Lhz Gt-Sp Lhz Sp Lhz Sp Lhz

Texture Granulo Poikilitic Porphyro Porphyro Granulo Porphyro Porphyro Porphyro Mylonitic Porphyro

Tdeg BampK (1990) 800 1214 835 1010 925 950 1220 1230 641 8841σ 15 6 35 24 30 25 10 10 12 9TdegWells (1977) 832 1236 870 993 913 938 1165 1174 723 8661σ 22 18 20 25 32 25 14 16 15 15SiO2 (wt) 4434 4373 4336 4485 444 434 4389 4413 4389 4413TiO2 012 013 bLD 018 bLD 0092 006 008 006 008Al2O3 192 18 201 357 34 31 292 363 292 363Cr2O3 bLD bLD bLD 045 013 033 bLD bLD bLD bLDFe2O3 84 782 914 878 867 936 875 881 875 881MnO 012 011 013 014 0112 013 012 013 012 013MgO 4258 437 424 3815 394 397 4042 3858 4042 3858CaO 162 132 152 296 243 202 285 304 285 304Na2O 001 001 bLD 061 038 029 022 022 022 022K2O 004 001 bLD 002 000 004 bLD bLD bLD bLDP2O5 002 003 bLD 004 000 002 009 008 009 008LOI 111 147 03 084 036 035 023 098 bLD bLD

10028 10013 9886 10059 9928 9883 9955 9968 9932 987Rb (ppm) 059 013 057 039 020 176 025 141 021 030Sr 739 508 1500 1168 888 1522 887 920 2098 1351Y 132 083 104 346 292 220 250 290 306 342Zr 231 305 559 493 442 312 227 228 530 584Nb 028 061 047 019 005 020 008 065 005 010Cs 001 001 004 0005 0001 001 0008 002 0006 002Ba 672 432 329 082 216 290 109 094 148 186La 052 023 112 051 008 230 004 031 166 028Ce 057 069 162 061 040 453 013 061 264 054Pr 007 009 02 015 011 047 003 008 024 012Nd 036 047 086 081 068 173 022 039 092 072Sm 013 014 017 029 028 032 012 015 028 029Eu 005 005 005 013 011 010 0055 007 012 013Gd 021 017 017 048 043 036 024 030 048 048Tb 004 003 003 009 008 006 005 006 009 009Dy 029 019 019 065 054 042 041 049 061 066Ho 006 004 004 015 012 009 009 011 013 015Er 019 012 013 044 035 028 028 034 038 042Tm 003 002 002 007 005 004 004 005 006 007Yb 020 012 014 043 035 029 029 034 038 042Lu 003 002 002 007 006 005 005 006 006 007Hf 008 010 021 019 016 013 008 009 020 020Ta 001 003 004 003 0003 0008 0002 003 0005 001Pb 063 058 02 028 076 082 004 008 055 027Th 006 004 045 001 0007 020 0002 005 0185 0006U 002 001 015 001 002 005 0003 002 005 00487Sr86Sr 0703274plusmn05 0703619plusmn16 0704434plusmn08 0704199plusmn08 nd 0702867plusmn09 0705396plusmn06 0705777plusmn11 0703188plusmn12 0702972plusmn08εSr minus174 minus125 minus09 minus43 minus232 127 181 minus186 minus217143Nd143Nd 0513323plusmn19 0512922plusmn25 0512559plusmn14 0512890plusmn04 nd 0513191plusmn09 0514139plusmn17 0513499plusmn14 0513106plusmn20 0513336plusmn11εNd 134 55 minus15 49 108 293 168 91 136206Pb2046Pb 185988plusmn11 18654 193530plusmn67 187551plusmn09 nd 185897plusmn18 179012plusmn07 182673plusmn08 184871plusmn06 181341plusmn07207Pb204Pb 155705plusmn11 15594 156115plusmn85 156075plusmn10 nd 155959plusmn16 155755plusmn06 155919plusmn06 155977plusmn07 156196plusmn13208Pb204Pb 383478plusmn42 38557 390408plusmn87 384988plusmn18 nd 383603plusmn36 377719plusmn17 382098plusmn18 383741plusmn25 379633plusmn27


metasomatic enrichment in Rb With the exception of the EG samplesthe Languedoc xenoliths do not show any peculiar characteristicsrelative to the FrenchMassif Central xenoliths when plotted in the SrndashNd isotopic space (Fig 5 Downes et al 2003 references therein) Inthese diagrams the Pyrenees domain encompasses the Massif Centralfield and it is not possible to discriminate between the two domains

In the 206Pb204Pb vs 207Pb204Pb diagram (Fig 6a) the Languedocxenoliths clearly plot within the Pyreneacutees field off the NHRL TheLanguedoc mantle lithosphere is characterized by a relativelyconstant 207Pb204Pb (1558plusmn006) despite variable 206Pb204Pbratios (1748ndash1935) However 208Pb204Pb is positively correlatedwith 206Pb204Pb (Fig 6b) and discrimination between the two do-mains is difficult

5 Discussion

51 Age constraints

As clearly shown in Figs 1 and RM1 and as previously noted byBrousse and Bellon (1974) and Ghristi (1985) a progressive re-juvenation of the magmatic activity towards the South is clear inLanguedoc the lavas are essentially Miocene to the north PliocenendashLower Quaternary in the central part and Late Quaternary in the southAccording to Brousse and Bellon (1974) this rejuvenation resultedfrom the activity of the mantle plume that was emplaced during theMiocene beneath the French Massif Central (sim150 km North of theLanguedoc) and subsequently expanded southward

Fig 8 Chondrite-normalized Rare Earth Element patterns of selected peridotiticxenoliths from Languedoc The normalizing values are from Sun and McDonough(1989) For samples location see Table 4 and Fig 3

Fig 10 (a b) Primitive Mantle-normalized LaSm vs Yb (a) and LaSm vs YbEu(b) diagrams for the selected peridotitic xenoliths from Languedoc Symbols and datareferences as in Fig 5ab CD Causses district ELD EscandorguendashLodeacutevois district andHLVD Heacuterault Low Valley district Mtf Montferrier xenoliths Normalizing values forPrimitive Mantle as in Fig 9 Pyr Pyrenees peridotitic massifs N-FMC and S-FMC


Although the progressive rejuvenation of the magmatic activitytowards South is clear for the last 7 Ma such a spatial and temporalevolution is not obvious in the pre-Miocene activity The majorMessinian volcanic episode of North Languedoc (CD) has beenpreceded by several older magmatic events CallovianndashOxfordianboundary (Vi) Palaeocene (TS NT) Serravallian (EG) On the otherhand there wasmagmatic activity in the South before the Quaternaryin the Eocene (POU) and in the Upper Oligocene (MTF) Except for thecentral part of the volcanic line (ELD) where the magmatic activitymostly occurred between 25 and 12 Ma basaltic magmas wouldhave been generated periodically between 160 and 6 Ma beneathNorth Languedoc and 46 and 06 Ma beneath South Languedoc thisobservation suggests that the Languedoc magmatic activity is notrelated to the Miocene French Massif Central plume

peridotitic xenoliths from the Northern and the Southern French Massif Centralrespectively

52 Xenolith constraints

As shown in Fig 10 there is a geographic zonation of the REEfractionation between the peridotite xenoliths from the different

Fig 9 Extended trace-element patterns of selected peridotitic xenoliths from Languedoc TheMcDonough (1989) For samples location see Table 4 and Fig 3

French volcanic areas and the Pyrenean peridotitic massifs Thissuggests the existence of regional differences in composition withinthe French mantle lithosphere Four domains (North-French Massif

normalizing values for PrimitiveMantle and incompatibility sequence are from Sun and


Central (N-FMC) South-French Massif Central (S-FMC) Pyrenees(PYR) and Languedoc are distinguished in Fig 10 The geochemicaldifferences could be either inherited from the protolith or acquiredduring subsequent metasomatic events This zonationmay be due to adifference in the protolith and indeed Lenoir et al (2000ab) proposedthat the North-FrenchMassif Central protolithmantle lithosphere wassignificantly more depleted than the South-French Massif Central andthat this depletion occurred in Proterozoic time However thedifference in protolith is not as marked as Lenoir et al (2000ab)suggested ie Al2O3 contents of xenoliths from North-French MassifCentral = 20plusmn08 are within error of those from the South-FrenchMassif Central (25plusmn1) This is also supported by Fig 10a where thethree domains N-FMC S-FMC and Languedoc show comparable Yb-ranges However many of the South-French Massif Central xenolithsshow Yb contents twice as high as the Primitive Mantle value Suchldquohyperrdquo-fertility is relatively uncommon in the other domains evenwithin the extremely fertile Pyrenees Lherzolites A long-termdepletion of the North-French Massif Central mantle is supported bytheir highly positive εNd and εHf (Downes et al 2003 Wittig et al2007) which has not been found in the South-French Massif CentralHowever age zonation within the French Massif Central is notsupported by Os data as relicts of 22plusmn02 Ga age are found in allFrench Massif Central domains (Alard 2000 Alard et al 2002)Languedoc xenoliths (CD) like the North MCF xenoliths show highlypositive εNd (ie +293 this study)

Os melt-depletion ages of ca 24plusmn02 Ga (ie within the rangeof estimates for the French Massif Central melt-depletion age) havebeen obtained for the Pyrenees massifs (Reisberg and Lorand 1995Burnham et al 1998) Thus although it cannot be ruled out a NorthndashSouth variation in degree of melting and age zonation is not stronglysupported Rather Fig 10 suggests that the differences observedbetween the four domains are more likely to be related to subsequentmeltndashrock percolation reaction processes Indeed the REE fractiona-tions reported here are not consistent with a simple melt-depletiontrend Thus the differences between these lithospheric domainswould have been acquired during ldquometasomaticrdquo processes (depend-ing on percolationndashreaction characteristics and the nature of thepercolating fluid) A detailed discussion on the origin of this zonationis beyond the scope of this contribution However the differencesbetween the French Massif Central and the Languedoc are statisticallysignificant and consequently we suggest that the similarities with thePyrenees are meaningful The Languedoc xenoliths clearly showstrong affinities with the Pyrenees orogenic massifs Fabries et al(1987) through a study of the Montferrier xenoliths noted thesimilarity between these two lithospheric mantle domains in term offertility deformation equilibrium temperature and metasomatism(amphibole sulphide see also Alard et al in press) The similarities inREE patterns indicate that the Languedoc domain and the Pyrenees

Table 5Modal composition of the source melting proportions of the different phases and partition cclinopyroxene Gt garnet Sp spinel Phlo phlogopite C0 source composition PM primitivfrom Halliday et al (1995) except for spinel (Elkins et al 2008) interpolated values

Phases Ol Opx

Proportions in source 07 02Melting proportions 0 001

Elements Th

Ol 0000006Opx 000002

Partitioning Cpx 00021Coefficients Gt 00021

Sp b00002Phlo 0

Co (timesPM) 0085Co (times16 PM) 0136Co (times32 PM) 0272

mantle lithosphere share a similar protolith and have undergonecoeval melt-percolation reaction This is further attested by the factthat peridotites from both localities share the same 206Pb204Pbndash208Pb204Pb space (Fig 6b)

In Section 421 the trace-element patterns of the Languedocxenoliths have been described in terms of a continuum between (1) aMREE-LREE depleted pattern ascribed to partialmelting and (2) a LREE-LILE-enriched pattern without concomitant HFSE enrichment Previousauthors (Dautria et al 2006 Ionov et al 1993) have ascribed this typeof incompatible-element fractionation as due to the percolation of aldquocarbonatedrdquo metasomatic fluid through a variably depleted mantlelithosphere Petrographic evidence (ie carbonate secondary clinopyr-oxe sulphide plusmnmelt pockets) for such metasomatism has been foundin xenoliths from several localities throughout the Languedoc (Jakni etal 1996 Dautria et al 2006) and notably in sample PP-2 The 143Nd144Nd ratio decreases as LaSm increases and inversely the 206Pb204Pband 208Pb204Pb become more radiogenic as LaSm increases Theserelationships strongly suggest that the isotopic composition of theLanguedoc xenoliths is significantly affected by metasomatism (exceptfor EG samples) As thefingerprint ofmetasomatism becomesmore andmore predominant the isotopic composition is progressively shiftedtoward the European Asthenospheric Reservoir (EAR) compositionThus within the Languedoc mantle lithosphere the carbonatedmetasomatism is associated with the EAR isotopic signature We notethat PP-2 the only carbonate bearing xenolith shows the mostradiogenic Pb composition of all the xenoliths studied here Xenolithsfrom Montferrier display the two signatures depleted [ie low (LaSm)N low 206Pb204Pb (b185) and high εNd (N10)] and enriched [iehigh (LaSm)N high 206Pb204Pb (ge185) and low εNd (le10)]suggesting that the two signatures coexist in the same area Thisobservation precludes geographic variation Furthermore the occur-rence of the enriched signature in Montferrier xenoliths indicates thatthe carbonated and related metasomatism affected the Languedoclithosphere before 25 Ma It is noteworthy that themostmetasomatisedxenoliths have Pb-isotope compositions that overlap those of the oldestLanguedoc lavas (le45 Ma) This suggests that the isotopic signature ofthe oldest lavas was mainly driven by the mantle lithospherecomposition and that the asthenospheric component (EAR) becameprogressively predominant

53 Constraints from the lavas

In a previous paper devoted to the Lodeacutevois basalts (Liotard et al1999) we estimated from a trace element modelling of non-modalbatch partial melting that these lavas resulted from 1 to 2 of partialmelting of a lherzolitic source enriched in garnet (4) and phlogopite(05) In this modelling the source enrichment factor was16timesPrimitive Mantle (PM from Sun and McDonough 1989) for

oefficients used for the batch melting modelling Ol olivine Opx orthopyroxene Cpxe mantle composition according to Sun and McDonough (1989) partition coefficients

Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493


the most incompatible elements (eg LREE Th) and 1timesPM for the lessincompatible elements (eg Sr Sm and Yb)

Does the modelled source of the Lodeacutevois basalts account for thegeochemical characteristics of all Languedoc lavas The same trace-element modelling as used for Lodeacutevois shows that all Languedoclavas could be derived from the Lodeacutevois source but with significantchanges in both the extent of partial melting and the proportions ofgarnet and phlogopite either in the source or in the residue Howeverthis rather simple model does not account for the variations of severaltrace-element ratios (eg LaSm SmYb ThSr and SrYb) Theseratios are keys to distinguishing between the effects of source-enrichment processes and the degree of melting For this paper wehave calculated the theoretical melting curves for three enrichmentfactors (ie times1PM times16 PM times32 PM) and for different aluminousphases (ie pure garnet garnet+spinel and pure spinel) This rangeof enrichment factors has been chosen because it is similar to the LREEenrichment observed in several metasomatised peridotitic xenolithsfrom Languedoc (eg CX2 PP2 SOU6 Table 4) For the HREE weassumed an enrichment factor of 1timesPM as observed for instance inperidotite PP2 (Table 4) The modal composition of the source themelting proportions of the different phases and the partitioncoefficients used for this modelling are given in Table 5 The best fitis obtained for themelting of a lherzolitic source containing 2 garnet2 spinel and 1 phlogopite (Fig 11a b) This low phlogopite contentsuggests that the LILE enrichment of source is essentially cryptic andnot related to modal mineralogy Fig 11ab shows that the Languedoclavas plot between the PM and 32timesPM curves with degrees ofmelting ranging between 1 and 5 in the LaSm vs SmYb diagram(Fig 11a) or between 05 and 3 in the ThSr vs SrYb diagram(Fig 11b) These degrees of melting are low in comparison to thoseobtained experimentally by Green and Falloon (2005) for alkalibasalts (10) According to these authors they rather correspond tothe degrees of melting that would produce nephelinites (25) and

Fig 11 (a b) LaSm vs SmYb and [(ThSr)times1000] vs SrYb diagrams for the studiedlavas Curves for the partial melting of Primitive Mantle (PM) and two enriched sources(16 PM and 32 PM) are plotted Partial melting degrees (05 1 3 5 and 10) areindicated by dotted lines PM values are from Sun and McDonough (1989)

basanites (45) As noted above most Languedoc basalts display highlevels of SiO2 undersaturation [(Ne+Lc)norm up to 15 in basalts upto 26 in basanites] and high LILE concentrations (eg Th up to17 ppm) Such high contents of normative feldspathoiumlds and LILE aregenerally observed in basanites and nephelinites Thus althoughmostLanguedoc basalts plot within the alkali basalt field of Cox et al(1979) Fig 2 our calculated low degrees of melting remainacceptable These results confirm that the sources of the Languedoclavas are lithospheric and located at the spinelndashgarnet transition zone(70ndash90 km depth)

As shown by Fig 11ab the oldest lavas (between 161 and 14 Ma)display exactly the same range of degrees of melting and sourceenrichment factors as the youngest lavas (Plio-Quaternary) Thesefigures also show that the sources of lava for adjacent volcanoes candiffer in both LILE enrichment and degree of melting Such sourceheterogeneities and such variability in partial melting within a small(kilometre)-scale magmatic province strongly suggest a lithosphericsource for these lavas

This modelling suggests that the transitional basalts RQH and AGwould result from 3 to 5 of melting Such low degrees of melting donot agree with the high SiO2 contents of these samples (4970 and5106 respectively) which are more akin to melts derived by higherdegrees of melting (ge10) Thus this SiO2 enrichment results eitherfrom contamination by SiO2-rich crustal materials during the ascent ofthe magma or from melting of a mantle source dominated byorthopyroxene (harzburgite) Considering that the Sr and Nd isotopiccompositions do not indicate any significant crustal contaminationwe favour the second hypothesis However the relatively high LILEcontents of these lavas (eg La=21ndash39 Nb=38ndash58 and Th 34ndash69)imply that their hypothetical harzburgitic source was LILE-enriched(between times1 and times16 PM Fig 11b) The harzburgite xenoliths aregenerally LILE-impoverished for instance the only studied harzbur-gite from our xenolith set (PCV9 Table 4) displays an enrichmentfactor of 03timesPM However as observed in the Lherz massif veins ofLILE-enriched websterite and amphibole-rich veins commonly cross-cut the harzburgitic bodies (Bodinier et al 2004) The source of theLanguedoc transitional basalts may be such a veined and hydratedharzburgite

If the Languedoc lavas were of asthenospheric origin their isotopicheterogeneities would imply either contamination during magmaascent or source heterogeneities conflicting with a purely astheno-spheric origin The Sr and Nd isotopic compositions of the Languedoclavas preclude significant crustal contamination The variations in206Pb204Pb ratios at nearly constant 207Pb204Pb have been observedpreviously for the French Massif Central basalts and were interpretedas resulting from contamination by granulite-derived melts (Downes1984) or more recently to mixing between asthenospheric andlithospheric melts (Wilson and Downes 2006) Such a mixing modelcould be also applied to the Languedoc basalts and in this case thelithospheric melt would derive from melting of a lithosphere akin tothe Pyrenean lithosphere In the 87Sr86Sr vs 143Nd144Nd diagram(Fig 5) all Languedoc basalts are included within the field of theLanguedoc xenoliths and at a larger scale within the fields of boththe FrenchMassif Central and the Pyrenean lithosphere This feature israther consistent with a purely lithospheric origin but it can alsosimply indicate that the asthenospheric and the lithospheric compo-nents cannot be distinguished in such an isotopic space that iscorroborated by the position of the LVC field in Fig 5b

In the 208Pb204Pb vs 206Pb204Pb diagram (Fig 6b) most of thestudied basalts plot away from the field of Languedoc xenoliths and inthe Pyrenean lithosphere field In the 207Pb204Pb vs 206Pb204Pbdiagram (Fig 6a) all Languedoc basalts plot away from the two latterfields except for the two oldest (NT and Vi) which plot within bothfields (Fig 6a and b) This strongly suggests that the isotopiccharacteristics of the Vi and NT sources are ancient and similar tothe Pyrenean lithosphere These source characteristics may have been


acquired before 161 Ma perhaps during the Hercynian orogeny oreven before This also shows that an unmodified Pyrenees-likelithosphere was present beneath Languedoc until at least 67 MaThe basalts with intermediate ages (between 59 and 24 Ma ie TSMTF Group 4) show higher 206Pb204Pb ratios uncorrelated with207Pb204Pb and plot between the Pyrenean field and the EAR domainThis shift can be assigned to the increasing participation of an EAR-like asthenospheric component in their source The MiocenendashPliocenendashQuaternary lavas plot within or close to the Group 4 do-main (Table 2) Except for Vi the mantle sources of all Languedoclavas can be therefore described in terms of variablemixing between aPyrenees-like lithosphere and an EAR-like component

In the various diagrams showing trace-element contents versusisotopic ratios (eg LaSm vs 206Pb204Pb Fig 11) a weak correlationcan be observed for both lavas and xenoliths This suggests that (1) themechanisms responsible for the incompatible-element enrichmentand the isotopic variations are probably correlated implying that theEAR-like component must be LILE-enriched (2) the upper lithosphere(sampled by the xenoliths) and the lower lithosphere correspondingto the sources of the basalts have been similarly affected For thexenoliths the ldquoenrichedrdquo signature is clearly related to volatile-rich(carbonated) metasomatism Such metasomatic fluids are classicallyattributed to small-volume melts issuing from the underlyingasthenosphere As suggested by the presence of metasomatic phasesin many xenoliths (amphibole phlogopite K feldspar and carbonate)we propose that the EAR signature may be also partly stored inthe lower lithosphere within secondary metasomatic minerals How-

Fig 12 206Pb204Pb vs LaSm diagram for Languedoc xenoliths and host lavas Sym

ever the small-volume melts can be also responsible for a crypticenrichment bearing the EAR signature

The 206Pb204Pb vs age diagram(Fig 7) shows that (1) the injectionand percolation of the small-volume melts through the lowerlithosphere started around 67 Ma ago (2) the ranges of geochemicaland Pb isotopic heterogeneity observed in the lavas erupted between67 and 24 Ma (Group 4 Table 2) and in the MiocenendashPliocenendashQuaternary lavas (Groups 1 2 3 Table 2) are identical This wouldimply that the Miocene asthenospheric uprising beneath the FMC hasnot induced any significant geochemical (LILE and isotopes) modifi-cation in the sources of the Languedoc lavas

54 A model for the 160 Ma-long episodic magmatic activityin Languedoc

The only significant asthenospheric upwelling event underWesternEurope between 160 Ma and 25 Ma is the arrival of the Central Atlanticplume head (Oyarzun et al 1997 and Piromallo et al 2008) This majormantle event occurred sim70 Ma ago (Piromallo et al 2008) Oyarzunet al (1997) and Piromallo et al (2008) proposed that the CA plumehead was composed of asthenospheric material contaminated bylithospheric components entrained towards the East by the drift of theEuropean plate At the European scale Piromallo et al (2008) considerthat the Upper CretaceousndashEocene magmatism was derived entirelyfrom partial melting of the Central Atlantic Plume head while thesubsequent volcanic activity would be favoured by rifting and regional-scale convection related to the recent geodynamic evolution of Europe

bols as in Fig 5 Field of Cape Verde carbonatites is from Hoernle et al (2002)


However the geochemical and isotopic heterogeneities observedamong the European lavas would only reflect the heterogeneity of thisplume head

in contrast at the Languedoc scale our observations suggest thatthe alkali magmas result predominantly from partial melting of thelower lithosphere The role of the Central Atlantic Plume head wouldbe limited to supplying the EAR-like small-volume melts thatmetasomatised the overlying lithosphere However the chemicalnature (silicated or carbonated) of thesemelts remains questionableAt Cape Verde the Central Atlantic Plume has regularly producedcarbonated magmas in the past (Gerlach et al 1988) Many CapeVerde carbonatites have EAR-like 206Pb204Pb (Hoernle et al 2002)and high LaSm ratios (Fig 12) making them very good candidates forour Small Volume Melt component Furthermore carbonated meta-somatism has been directly and indirectly evidenced in the Languedoclithosphere following petrologic studies (Jakni et al 1996 Dautria etal 2006) and geochemical evidence (eg trace elements this study)In this model the increase in 206Pb204Pb ratios observed in theLanguedoc lavas between 67 and 24 Ma (Fig 12) would simply resultfrom an increasing participation during partial melting of thecarbonated small-volume melts stored in the lithosphere Significant-ly the two oldest lavas (Vi and NT) have Pb-isotope compositions inthe range of the Pyrenean lithosphere suggesting that they mayhave been produced without the addition of any small-volume meltsOn the other hand some younger Quaternary lavas (eg RQH AGROL2 819) display characteristics close to those of Vi and NT sug-gesting that the Languedoc basalt source has been affected hetero-geneously by melt percolation The 206Pb204Pb variability observed inthe Cenozoic lavas (Fig 7) is probably partly the consequence of thisheterogeneity

The recurrence of partial melting episodes in the lower lithosphereover a 160 Ma timespan in the same restricted area (sim8000 km2)implies that the Languedoc lower lithosphere has been chemically andalso probably thermo-barometrically close to its solidus conditionssince at least the Mid-Jurassic These peculiar conditions could bepartly inherited from the Hercynian orogeny The sim67 Ma oldmetasomatic event which probably affected the whole lithospherewould be responsible for the crystallization of volatile-rich secondaryphases in the lower lithosphere that would enhance its meltingpropensity In such conditions subtle P andor T changes could triggerlow-degree partial melting and generate small volumes of magmaTwo heat sources can be considered to be operative in Languedoc thepassive mantle uprising associated with the Oligocene rifting in theGulf of Lions and the MiocenendashPliocene mantle upwelling of theFrench Massif Central Local decompression events (associated withthe evolution of the Languedoc sedimentary basins and the re-adjustment of lithospheric blocks) also occurred during the Mesozoicand Cenozoic due to the progressive movement of the Thetys Ligurianmargin towards the present Mediterranean margin These events arePaleocene uplift Lutetian relaxation and Oligocene rifting (Seacuteranne etal2002) Volcanic eruptions occur in the Languedoc area during all ofthese periods However the arrival of the Central Atlantic Plume headnear 70 Ma may also have induced sufficient perturbation to triggerlocal partial melting within the lower lithosphere The Paleocenevolcanic episode observed in North Languedoc (TS NT) may beattributed to this event

The 160 Ma volcanic episode (Vi) cannot be explained by the sameprocess The Vi basalt would be the only lava derived from a Pyreneanlithosphere that was unmodified since the Hercynian In this case Viwould be the only Southern France magmatic event related to theextension that affected the Ligurian Tethys passive margin duringDogger

The progressive rejuvenation of the volcanic activity towardsSouth during the last 7 Ma is also debatable We propose that thismagmatism is related to the distension migration related to theSouth-Southeastwards roll-back of the subduction of the Thethyan

oceanic crust beneath Southern Europe and associated back-arc rifting(Seranne 1999)

The succession of events that have affected Languedoc istentatively summarized in Fig RM2a and b

6 Conclusions

The sporadic volcanic activity of Languedoc spans the last 160 Maand consists of very small volumes of alkali basalts (b2 km3) Thesebasalts eruptedwithin the same small area (sim8000 km2) even thoughthe European plate shifted about 2500 km to the East during the sametime period Such details suggest (1) a lithospheric origin for thismagmatism as proposed by Beccaluva et al (2007) for the Adriaticvolcanism and (2) a relationship to regional tectonic events ratherthan to large-scale and deep mantle events This would imply that theLanguedoc lithosphere has been chemically and probably thermo-barometrically close to its solidus conditions from at least 160 MaThemantle event responsible for these characteristicsmust be prior toMiddle Jurassic and it may be a Hercynian heritage

Our new data and modelling confirm a lithospheric origin of theLanguedoc magmatism the lava sources are located in the lowerlithosphere at the transition between the garnet and spinel stabilityfields The EAR signature observed in both the Cenozoic lava sourcesand overlying xenoliths are suggested to be associated withmetasomatism involving the percolation of volatile-rich small volumemelts (probably carbonated) and heterogeneously affecting thewholemantle lithosphere Our isotopic data suggest that this metasomaticevent occurred sim67 Ma ago it may be related to the arrival of theCentral Atlantic plume head under southern France

The lower lithosphere beneath Cenozoic Languedoc was at thesame time close to its solidus conditions and metasomatised (whichenhanced its melting propensity) In such conditions subtle P andor Tchanges resulting from the MesozoicndashCenozoic tectonic evolution ofthe Thetys Ligurian margin towards the present Mediterraneanmargin would be able to trigger local low-degree partial melting

Finally we suggest that the role of the asthenosphere in theLanguedoc volcanism was minor It was probably negligible for theMesozoic activity and restricted to the supply of volatile-rich flux forthe Cenozoic basalts The sporadic volcanic activity of Languedocwould be one of the consequences of the tectonic evolution of ThetyanMargin vs the North Mediterranean margin

Acknowledgements

The technical assistance of Simone Pourtales was greatly appreci-ated during the running of the ICP-MS trace-element analyses (AETEPlatformGeosciencesMontpellier) The help of Philippe Teacutelouk duringthe acquisition Nd- and Pb-isotope data (Service Commun ENS Lyon)and Patrick Verdoux during Sr-isotope analyses (GIS LaboratoryNimes) as well as the efforts of Beatrice Galland in maintaining thechemistry clean room at Geacuteosciences Montpellier were greatlyappreciated This manuscript was greatly improved by the detailedand constructive reviews of Dr Costanza Bonadiman and Dr GianlucaBianchini We are also grateful to Prof Suzanne Y OReilly and ProfWilliam L Griffin for helpful editing and insightful comments

Appendix A Supplementary data

Supplementary data associated with this article can be found inthe online version at doi101016jlithos201004009

References

Alard O 2000 Chalcophile and siderophile elements in the mantle geochemicalcharacteristics amp distributions PhD Thesis Macquarie University Sydney 328 pp


Alard O Dautria J-M Bodinier J-L 1996 Nature and metasomatic processes of thelithospheric mantle on either part of sillon Houiller (French Massif Central)Comptes Rendu de lAcadeacutemie des Sciences de Paris 323 763ndash770

Alard O Griffin WL Pearson NJ Lorand J-P OReilly SY 2002 New insights intothe RendashOs systematics of sub-continental lithospheric mantle from in situ analysisof sulphides Earth and Planetary Science Letters 203 651ndash663

Alard O Lorand JP Reisberg L Bodinier JL Dautria JM OReilly SY in pressVolatile rich metasomatism in Montferrier xenoliths (Southern France) conse-quences for chalcophile and highly siderophile elements abundances in the sub-continental mantle Journal of Petrology

Albert D Albert R Brousse R 1967 Enclaves de peacuteridotites agrave pyrope chromifegravere dansles pipes de la reacutegion de Beacutedarieux (Heacuterault) Comptes Rendu de lAcadeacutemie desSciences de Paris 265 657ndash659

Ambert P Boven A Leroy S Loumlvlie R Seret G 1990 Reacutevision chronostratigraphiquede la sequence paleacuteobotanique de Bernasso (Escandorgue Midi de la France)Comptes Rendu de lAcadeacutemie des Sciences de Paris 311 413ndash419

Baubron JC Defaut B Demange J Maury RC 1978a a Une couleacutee sous-marine d acircgejurassique moyen dans les Causses le basalte alcalin des Vignes (Massif centralfranccedilais) Comptes Rendu de l Acadeacutemie des Sciences de Paris 287 225ndash227

Baubron JC Defaut B Demange J Maury RC 1978b Existence dun volcanismeanteneacuteogegravene dans les Causses (Massif central franccedilais) Sup Bulletin du BRGM RS627 29

Beccaluva L Bianchini G Coltorti M Perkins WT Siena F Vaccaro C Willson M 2001Multistage evolution of the European lithospheric mantle new evidence fromSardininanperidotitexenoliths Contribution toMineralogyandPetrology142284ndash297

Beccaluva L Bianchini G Bonadiman C Coltorti M Milani L Salvini L Siena FTassinari R 2007 Intraplate lithospheric and sublithospheric components in theAdriatic domain nephelinite to tholeiite magma generation in the PaleogeneVeneto volcanic province southern Alps In Beccaluva L Bianchini G Wilson M(Eds) Cenozoic Volcanism in the Mediterranean Area Geological Society ofAmerica Special Paper Vol 418 pp 131ndash152

Berger E 1981 Enclaves ultramafiques meacutegacristaux et leurs basaltes hocirctes encontexte oceacuteanique (Pacifique sud) et continental (Massif central franccedilais) ThegravesedEtat Univ Paris-Sud 466p

Bernard-Griffiths J Gruau G Cornen G Azambre B Maceacute J 1997 Continentallithospheric contribution to alkaline magmatism isotopic (Nd Sr Pb) andgeochemical (REE) evidence from Serra de Monchique and Mount Ormondecomplexes Journal of Petrology 38 (1) 115ndash132

Bianchini G Beccaluva L Bonadiman C Nowell G Pearson G Siena F Willson M2007 vidence of diverse depletion and metasomatic events in harzburgitendashlherzolite mantle xenoliths from the Iberian plate (Olot NE Spain) implication forlithosphere accretionary processes Lithos 94 25ndash45

Bianchini G Beccaluva L Siena F 2008 Post-collisional and intraplate Cenozoicvolcanism in the rifted ApenninesAdriatic domain Lithos 101 125ndash140

Bodinier JL Menzies MA Shimizu N Frey FA McPherson E 2004 Silicate hydrousand carbonate metasomatism at Lherz France contemporaneous derivatives ofsilicate meltndashharzburgite reaction Journal of Petrology 45 (2) 299ndash320

Bosch D Blichert-Toft J Moynier F Nelson BK Telouk P Gillot PY Albaregravede F2008 Pb Hf and Nd isotope compositions of the two Reacuteunion volcanoes (IndianOcean) a tale of two small-scale mantle ldquoblobsrdquo Earth and Planetary ScienceLetters 265 355ndash368

Brey GP Kohler T 1990 Geothermobarometry four-phase lherzolites II newthermobarometers and practical assessment of existing thermobarometers Journalof Petrology 31 (6) 1353ndash1378

Briot D Cantagrel JM Dupuy C Harmon RS 1991 Geochemical evolution in crustalmagma reservoirs trace-element and SrndashNdndashO isotopic variations in two conti-nental intraplate series at Monts Dore Massif Central France Chemical Geology 89281ndash303

Brousse R Bellon H 1974 Hot spot in France Nature 248 749ndash751Brousse R Ildefonse JP 1970 Pyroxenendashpyrolite and plagioclasendashpyrolite in

inclusions with norites in an alkali basalt (Causses France) Bulletin of Volcanology34 (4) 792ndash822

Brugal JP Ambert P Bandet Y Leroy S Roiron P Suc JP Vernet JL 1990Mammifegraveres et veacutegeacutetaux du maar pliocegravene final de Nogaret (Escandorgue HeacuteraultFrance) Geobios 23 231ndash247

Burnham OM Rogers NM Pearson DG Van Calsteren PW Hawkesworth CJ1998 The petrogenesis of the eastern Pyrenean peridotites an integrated study oftheir whole-rock geochemistry and RendashOs isotope composition Geochimica etCosmochimica Acta 62 2293ndash2310

Cabanes N Mercier JC 1988 Chimie des phases mineacuterales et conditions deacutequilibredes enclaves de lherzolite agrave spinelle de Montferrier (Heacuterault France) Bulletin deMineacuteralogie 111 65ndash77

Cebria JM Lopez-Ruiz J Oyarzun R Hertogen J Benito R 2000 Geochemistry ofthe quaternary alkali basalts of Garrotxa (NE volcanic province Spain) a case ofdouble enrichment of the mantle lithosphere Journal of Volcanology andGeothermal Research 102 217ndash235

Chauvel C Bor-Ming J 1984 NdndashSr isotope and REE geochemistry of alkali basaltsfrom the Massif Central France Geochimica et Cosmochimica Acta 48 93ndash110

Coisy P 1977 Structure et chimisme des peacuteridotites en enclaves dans les basaltes duMassif centralmdashmodegraveles geacuteodynamiques du manteau supeacuterieur Thegravese UnivNantes 115p

Cox KG Bell JD Pankhurst RJ 1979 The Interpretation of Igneous Rocks Eds Allenand Unwin London 450p

Dautria JM Dupuy C Takherist D Dostal J 1992 Carbonate metasomatism in thelithospheric mantle peridotitic xenoliths from a melilitic district of the SaharaBasin Contribution to Mineralogy and Petrology 111 37ndash52

Dautria JM Liotard JM Briot D 2004 Particulariteacutes de la contamination crustale desphonolites exemple du Velay oriental (Massif central) Comptes Rendus deGeosciences 336 971ndash981

Dautria JM Bosch D Liotard JM 2006 Mise en eacutevidence dun meacutecanisme decarbonatation secondaire dans le manteau supeacuterieur du Languedoc ComptesRendus de Geosciences 338 527ndash536

Downes H 1984 Sr and Nd isotope geochemistry of coexisting alkaline magma seriesCantal Massif Central France Earth and Planetary Science Letters 69 321ndash334

Downes H 2001 Formation and modification of the shallow sub-continentallithospheric mantle a review of geochemical evidence from ultramafic xenolithssuites and tectonically emplaced ultramafic massifs of western and central EuropeJournal of Petrology 42 233ndash250

Downes H Reichow MK Mason PRD Beard AD Thirlwall MF 2003 Mantledomains in the lithosphere beneath the French Massif Central trace element andisotopic evidence from mantle clinopyroxenes Chemical Geology 200 71ndash87

Elkins LJ Gaetani GA Sims KWW 2008 Partitioning of U and Th during garnetpyroxenite partial melting constraints on the source of alkaline ocean islandbasalts Earth and Planetary Science Letters 265 270ndash286

Fabries J Figueroa O Lorand JP 1987 Petrology and thermal history of highlydeformed mantle xenoliths from the Montferrier basanites Languedoc southernFrance a comparison with ultramafic complexes from the North Pyrenean ZoneJournal of Petrology 28 887ndash919

Frechen VJ Lippolt HJ 1965 Kalium-Argon-Daten zumalter des Laacher vulkanismusder Rheinterrassen und der Eiszeiten Eiszeitalter und Gegenwart 16 5ndash30

Gastaud J Campredon R Feacuteraud G 1983 Les systegravemes filoniens des Causses et duBas Languedoc (Sud de la France) geacuteochronologie relations avec les paleacuteocon-traintes Bulletin Socieacuteteacute Geacuteologique de France 25 737ndash746

Gerlach DC Cliff RA Davies GR Norry M Hodgson N 1988 Magma sources of theCape Verdes Archipelago isotopic and trace element constraints Geochimica etCosmochimica Acta 52 2979ndash2992

Ghristi C 1985 Importances relatives de la fusion mantellique et de la cristallisationfractionneacutee dans le volcanisme des Causses Thegravese 3eme cycle Univ Paris-SudOrsay 330p

Gillot PY 1974 Chronomeacutetrie par la meacutethode KndashAr des laves des Causses et du Bas-Languedoc interpretations Thegravese Univ Paris Sud 88p

De Goeumlr de Herveacute A Baubron JC Cantagrel JM Makhoul J 1991 Le volcanisme delAubrac (Massif central) un bref eacutepisode basaltique (250000 ans) au Miocegravenesupeacuterieur (7 5 Ma) Geacuteologie de la France 4 3ndash14

Granet M Wilson M Achauer U 1995 Imaging a mantle plume beneath the FrenchMassif Central Earth and Planetary Science Letters 136 281ndash296

Green DH Falloon TJ 2005 Primary magmas at mid-ocean ridges hotspots andother intraplate settings constraints on mantle potential temperature GeologicalSociety of America Special Paper 388 217ndash247

Halliday AN Der-Chuen L Tommasini S Davies GR Paslick CR Fitton JG JamesDE 1995 Incompatible trace elements in OIB andMORB and source enrichment inthe sub-oceanic mantle Earth and Planetary Science Letters 133 379ndash395

Hoernle K Zhang YS Graham D 1995 Seismic and geochemical evidence for large-scale mantle upwelling beneath the eastern Atlantic and western and centralEurope Nature 374 34ndash39

Hoernle K Tilton G Le Bas MJ Duggen S Darbe-Schoumlnberg D 2002 Geochemistry ofoceanic carbonatites compared with continental carbonatites mantle recycling ofoceanic crustal carbonate Contribution to Mineralogy and Petrology 142 520ndash542

Ionov DA Dupuy C OReilly SY Kopylova MG Genschaft YS 1993 Carbonatedperidotite xenoliths from Spitsbergen implications for trace element signature ofmantle carbonate metasomatism Earth and Planetary Science Letters 119283ndash297

Irvine TN Baragar WRA 1971 A guide to the chemical classification of the commonvolcanic rocks Canadian Journal of Earth Sciences 8 523ndash548

Jakni B Dautria JM Liotard JM Briqueu L 1996 Mise en eacutevidence dun manteaucarbonateacute agrave laplomb du Bas-Languedoc les xeacutenolites peacuteridotitiques du complexevolcanique de Grand-Magnon (Lodegravevois) Comptes Rendus de lAcadeacutem ie desSciences de Paris 323 33ndash40

Le Roux V Bodinier JL Tommasi A Alard O Dautria JM Vauchez A Riches AJV2007 The Lherz spinel lherzolite refertilized rather than pristine mantle Earth andPlanetary Science Letters 259 599ndash612

Lenoir X Dautria JM Briqueu L Cantagrel JM Michard A 2000a Nouvellesdonneacutees geacuteochronologiques geacuteochimiques et isotopiques sur le volcanisme duForez relation avec leacutevolution ceacutenozoiumlque du manteau du Massif central ComptesRendus de lAcadeacutemie des Sciences de Paris 330 201ndash207

Lenoir X Garrido CJ Bodinier JL Dautria JM 2000b Contrasting lithosphericmantle domains beneath the Massif Central (France) revealed by geochemistry ofperidotite xenoliths Earth and Planetary Science Letters 181 359ndash375

Liotard JM Maluski H Dautria JM 1991 Un eacutepisode magmatique alcalin dacircgeeacuteocegravene en Languedoc la bregraveche volcanique de la Montagne de la Moure (Heacuterault)Bulletin Socieacuteteacute Geacuteologique de France 162 1067ndash1074

Liotard JM Briqueu L Dautria JM Jakni B 1999 Basanites et neacutepheacutelinites du Bas-Languedoc (France) contamination crustale et heacuteteacuterogeacuteneacuteiteacutes de la sourcemantellique Bulletin Socieacuteteacute Geacuteologique de France 170 423ndash433

Lorand JP Alard O 2001 Platinum-group element abundances in the upper mantlenew constraints from in situ and whole-rock analyses of Massif Central xenoliths(France) Geochimica et Cosmochimica Acta 65 2789ndash2806

Lorand JP Alard O Luguet A Keays RR 2003 Sulfur and selenium systematics ofthe subcontinental lithospheric mantle Inferences from the Massif Centralxenolith suite (France) Geochimica et Cosmochimica Acta 67 4137ndash4151

Mergoil J Boivin P Bles JL Cantagrel JM Turland M 1993 Le Velay sonvolcanisme et les formations associeacutes eds BRGM Geacuteologie de la France 3 3ndash96


Michon L Merle O 2001 The evolution of the Massif Central Rift spatio-temporaldistribution of the volcanism Bulletin Socieacuteteacute Geacuteologique de France 172 201ndash211

Mukasa SB Shervais JW Wilshire HG Nielson JE 1991 Intrinsic Nd Pb and Srisotopic heterogeneities exhibited by the Lherz alpine peridotite massif FrenchPyrenees Journal of Petrology Special Lherzolites Issue 117ndash134

Navon O Stopler E 1987 Geochemical consequences of melt percolation the uppermantle as a chromatographic column Journal of Geology 95 285ndash307

Nehlig P 1999 Histoire geacuteologique simplifieacutee du volcan du Cantal in Volcanismesseacutedimentations et tectoniques ceacutenozoiumlques peacuterialpins Doc BRGM 291 Eds BRGM49ndash78

Oyarzun R Doblas M Lopez-Ruiz J Cebria JM 1997 Opening of the central Atlanticand asymmetric mantle upwelling phenomena implications for long-livedmagmatism in western North Africa and Europe Geology 25 727ndash730

Piromallo C Gasperini D Macera P Faccenna C 2008 A late Cretaceouscontamination episode of the EuropeanndashMediterranean mantle Earth andPlanetary Science Letters 268 15ndash27

Reisberg L Lorand JP 1995 Longevity of sub-continental mantle lithosphere fromosmium isotope systematics in orogenic peridotite massifs Nature 376 159ndash162

Ringwood AE 1975 Composition and Petrology of the Earths Mantle McGraw-HillPub Krauskopf Ed New-York 618p

Rousset C Becq-Giraudon JF 1989 Geological map of Espalion Ed BRGM OrleacuteansFrance

Seacuteranne M 1999 The Gulf of Lion continental margin (NW Mediterranean) revisitedby IBS an overwiew In Durand B Jolivet L Horvath F and Seacuteranne M (Eds) TheMediterranean basins Tertiary extension within the Alpine orogene GeologicalSociety Special Publication 156 15ndash36

Seacuteranne M Camus H Lucazeau F Barbarand J Quinif Y 2002 Surrection et eacuterosionpolyphaseacutees de la Bordure ceacutevenole Un exemple de morphogenegravese lente BulletinSocieacuteteacute Geacuteologique de France 173 (2) 97ndash112

Sobolev SV Zeyen H Stoll G Werling F Altherr R Fuchs K 1996 Upper mantletemperatures from teleseismic tomography of French Massif Central includingeffects of composition N mineral reactions anharmonicity anelasticity and partialmelt Earth and Planetary Science Letters 139 147ndash163

Steiger RH Jaumlger E 1977 Subcommission on geochronology convention on the useof decay constants in geo- and cosmochronology Earth and Planetary ScienceLetters 36 359ndash362

Sun SS McDonough F 1989 Chemical and isotopic systematics of oceanic basaltsimplications for mantle composition and processes In Saunders AD Norry MJ(Eds) Magmatism in ocean basalts Geological Society Sp Pub Vol 42 pp 313ndash345

Wells PRA 1977 Pyroxene thermometry in simple and complex systems Contribu-tions to Mineralogy and Petrology 62 129ndash139

White WM Albarede F Telouk P 2000 High precision analysis of Pb isotope ratiosby multi-collector ICP-MS Chemical Geology 167 257ndash270

Willson M Downes H 2006 TertiaryndashQuaternary intra-plate magmatisms in Europeand its relationships to mantle dynamics In Gee D Stephenson R (Eds)European Lithosphere Dynamics Geological Society London Memory Vol 32 pp147ndash166

Wilson M 2007 EMAW Workshop presentation Ferrara ItalyWilson M Downes H 1991 Tertiary-quaternary extension-related alkaline magma-

tism in western and central Europe Journal of Petrology 32 811ndash849Wittig N Baker JA Downes H 2007 UndashThndashPb and LundashHf isotopic constraints on the

evolution of sub-continental lithospheric mantle French Massif Central Geochi-mica et Cosmochimica Acta 71 1290ndash1311

Xu YG Menzies MA Bodinier JL Bedini RM Vroon P Mercier JC 1998 Meltpercolation and reaction atop a plume evidence from the poikiloblastic peridotitexenoliths from Boreacutee (Massif Central France) Contributions to Mineralogy andPetrology 132 65ndash84

Fig 1 Geological setting of Languedoc volcanic districts with locations and ages of samples dated in this paper ROU sample name (see Table 2) () new age data (Ma) (see Table 1)CD Causses district ELD Escandorgue-Lodeacutevois district LHVD LowHeacuterault Valley District FMC FrenchMassif Central All volcanic rocks dated since 1974 and all samples analyzedfor this paper are given in Fig RM1


side of the French Massif Central lithospheric swell less than 200 kmsouthwards of its apex

The detailed study of the Languedoc basalts should thus bring newresults that may answer many questions Has the mantle sources of

European basalts evolved during the last 160 Ma Has it been affectedby the compressive and distensive geodynamic events related to theMesozoic and Cenozoic evolution of the Ligurian Tethys margin Hasit been modified by the opening of the Atlantic Ocean and the





















1 2 1 2 1 2 1 2 1 2 1 2 3



1 2 1 2 1 2 1 2 1 2 1 2


Table 1 (continued)

205J-M

Dautria

etal

Lithos120

(2010)202

ndash222


4 Results

41 Lavas






















age (My) 056 069 069 068 073 14 14 2 2 15 15 15 152 15 146 122 2


207J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 182 151 197 225 2 2 2


Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References





































































































1 2 1 2 1 2 1 2 1 2 1 2 3



1 2 1 2 1 2 1 2 1 2 1 2


Table 1 (continued)

205J-M

Dautria

etal

Lithos120

(2010)202

ndash222


4 Results

41 Lavas






















age (My) 056 069 069 068 073 14 14 2 2 15 15 15 152 15 146 122 2


207J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 182 151 197 225 2 2 2


Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References



















































































1 2 1 2 1 2 1 2 1 2 1 2 3



1 2 1 2 1 2 1 2 1 2 1 2


Table 1 (continued)

205J-M

Dautria

etal

Lithos120

(2010)202

ndash222


4 Results

41 Lavas






















age (My) 056 069 069 068 073 14 14 2 2 15 15 15 152 15 146 122 2


207J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 182 151 197 225 2 2 2


Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References


















































































4 Results

41 Lavas






















age (My) 056 069 069 068 073 14 14 2 2 15 15 15 152 15 146 122 2


207J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 182 151 197 225 2 2 2


Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References






















































































age (My) 056 069 069 068 073 14 14 2 2 15 15 15 152 15 146 122 2


207J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 182 151 197 225 2 2 2


Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References





















































































age (My) 2 182 151 197 225 2 2 2


Table 2 (continued)

208J-M

Dautria

etal

Lithos120

(2010)202

ndash222





age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References





















































































age (My) 2 2 126 2 164 575 71 64 14 236 46 46 588 669 1612 65 65 65


Table 2 (continued)

209J-M

Dautria

etal

Lithos120

(2010)202

ndash222













Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References





























































































Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References



















































































Age (My) 056 069 [068] [073] 15 15 146 2 182 151 197



Age (My) 15 15 15 2 225 225 225 [13] [2] 15 15


Table 3 (continued)

211J-M

Dautria

etal

Lithos120

(2010)202

ndash222


Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References


















































































Age (My) 15 2 2 2 [126] 2 [164] [575] [71] [635] [236]



Age (My) [46] 140 588 [669] 1612 [65] [65] [65]


Table 3 (continued)

Table 3 (continued)

212J-M

Dautria

etal

Lithos120

(2010)202

ndash222





























5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References













































































































5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References




































































































5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References



























































































5 Discussion

51 Age constraints
















Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References































































































Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References





















































































Phases Ol Opx


Elements Th

Ol 0000006Opx 000002


Sp b00002Phlo 0







Cpx Gt Sp Phlo

005 002 002 001077 0 005 017

La Sr Sm Yb

00002 000004 00009 002400031 00007 00037 00380054 0091 027 04300007 00007 022 6400002 00047 00047 000470003 0044 00059 0030687 211 0444 049310992 211 0444 049321984 211 0444 0493



























6 Conclusions





Acknowledgements




References











































































































6 Conclusions





Acknowledgements




References


































































































6 Conclusions





Acknowledgements




References

























































































6 Conclusions





Acknowledgements




References






















































































































































































160Ma of sporadic basaltic activity on the Languedoc volcanic line (Southern France): A peculiar case of lithosphere–asthenosphere interplay

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