-
x:r
r b
This phenomenon was common in the Peruvian and Chilean Andes
during the Uppermost Jurassic and Lower Cretaceous. The
marginalbasin was trapped during the collision of the
CaribbeanColombian Cretaceous oceanic plateau, which accreted west
of the Arqua Com-
Atwater, 1978; Tarney et al., 1981; Saunders and Tarney,1982).
Such basins commonly occur in intra-oceanic set-tings, but examples
also are associated with continental-
Dalziel, 1981; Atherton et al., 1983; Saunders and Tarney,1984;
Miller et al., 1994). During the Uppermost JurassicLower
Cretaceous, the continental margin was on the brinkof splitting
from the continent, and basin formation withthe eruption of
mantle-derived basalts was an outstandingfeature. A rosary of
NS-elongated, ensialic marginal
* Corresponding author.E-mail address: [email protected]
(A. Nivia).
Journal of South American Earth Sciplex in the Early Eocene.
Dierences in the geochemical characteristics of basalts of the
oceanic plateau and those of the QuebradagrandeComplex indicate
these units were generated in very dierent tectonic settings. 2006
Elsevier Ltd. All rights reserved.
Keywords: Continental active margin; Back arc basin; Extensional
tectonics; Ophiolitic complexes
1. Introduction
A characteristic feature of many convergent plate mar-gins,
especially those aected by the subduction of old,dense, oceanic
lithosphere, is the development of backarcbasins resulting from
extensional tectonics (Molnar and
based magmatic arcs. Throughout the Mesozoic and prob-ably much
of the Paleozoic, the western side of SouthAmerica and the
Antarctic Peninsula formed a semicontin-uous magmatic arc along the
margin of Gondwana, wherethe formation of volcanic arcs and
marginal basins clearlyplayed an important evolutionary role
(Dalziel et al., 1974;a Instituto Colombiano de Geologa y Minera
INGEOMINAS, Unidad Operativa Cali, A.A. 9724, Cali, Colombiab
Department of Geology, Royal Halloway University of London, Egham,
Surrey TW20 0EX, UK
c School of Earth, Ocean and Planetary Sciences, Cardi
University, Main Building, Park Place, Cardi CF1 3YE, UKd
University of Leicester, Department of Geology, Leicester LE1 7RH,
UK
Received 1 October 2004; accepted 1 January 2006
Abstract
The Quebradagrande Complex of Western Colombia consists of
volcanic and AlbianAptian sedimentary rocks of oceanic anityand
outcrops in a highly deformed zone where spatial relationships are
dicult to unravel. BerriasianAptian sediments that
displaycontinental to shallow marine sedimentary facies and mac and
ultramac plutonic rocks are associated with the Quebradagrande
Com-plex. Geochemically, the basalts and andesites of the
Quebradagrande Complex mostly display calc-alkaline anities, are
enriched inlarge-ion lithophile elements relative to high eld
strength elements, and thus are typical of volcanic rocks generated
in supra-subductionzone mantle wedges. The Quebradagrande Complex
parallels the western margin of the Colombian Andes Central
Cordillera, forming anarrow, discontinuous strip fault-bounded on
both sides by metamorphic rocks. The age of the metamorphic rocks
east of the Quebra-dagrande Complex is well established as
Neoproterozoic. However, the age of the metamorphics to the west
the Arqua Complex ispoorly constrained; they may have formed during
either the Neoproterozoic or Lower Cretaceous. A Neoproterozoic age
for the ArquaComplex is favored by both its close proximity to
sedimentary rocks mapped as Paleozoic and its intrusion by Triassic
plutons. Thus, theQuebradagrande Complex could represent an
intracratonic marginal basin produced by spreading-subsidence,
where the progressivethinning of the lithosphere generated
gradually deeper sedimentary environments, eventually resulting in
the generation of oceanic crust.The Quebradagrande Complemarginal
basin in the Central Co
Alvaro Nivia a,*, Giselle F. Marrine0895-9811/$ - see front
matter 2006 Elsevier Ltd. All rights
reserved.doi:10.1016/j.jsames.2006.07.002A Lower Cretaceous
ensialicdillera of the Colombian Andes
, Andrew C. Kerr c, John Tarney d
www.elsevier.com/locate/jsames
ences 21 (2006) 423436
-
basins of Tithonian to Albian age from Cape Horn andSouth
Georgia Island to southwestern Mexico the lattercontinuous with
South America in most TriassicJurassicPangea reconstructions (Coney
and Evenchick, 1994) remain as scars of a generalized extensional
episode.
In Colombia, a sequence of pillow lavas, diabases, andassociated
volcaniclastic materials, the Diabase and Daguagroups (Nelson,
1957; Barrero, 1979) is postulated to con-tinue this belt of
marginal basins northward (Aberg et al.,1984; Aguirre, 1987;
Aguirre and Atherton, 1987). Howev-er, these materials correspond
to younger (Upper Creta-ceous) accreted terranes of oceanic plateau
anity(Millward et al., 1984; Nivia, 1987; Kerr et al.,
1996,1997a,b, 2001). The missing link in the chain of marginal
basins along the Northern Andes, according to the geo-chemical
results we present herein, is represented by theQuebradagrande
Complex that outcrops east of the accret-ed plateau in a more
ensialic position and has been errone-ously considered part of the
latter (Bourgois et al., 1982,1985, 1987; Toussaint and Restrepo,
1993; Kammer,1995; Kammer and Mojica, 1996).
2. Regional geology and stratigraphic nomenclature
On the western ank of the Central Cordillera of theColombian
Andes, a sequence of intermediate to basic vol-canic and
sedimentary rocks of lower Cretaceous ageappears. In northern
Colombia, this sequence was originally
.
PANAMA
OCEANPACIFIC
4oN
6oN
78 oW
Medelln
12
3
76oW
Armenia
80W 40W60W
0
20S
40S
LEGEND
Cenozoic rocks and deposits
Manizales
AtlanticOcean
SOUTH AMERICA
PacificOcean
AN1416
AN1417
AN1419
QBG95-7
14251426
QBG95-2QBG95-3
QBG95-10QBG95-11
AN1412AN1410AN1410A
0
424 A. Nivia et al. / Journal of South American Earth Sciences
21 (2006) 423436ECUADOR
2oN
Popayn
Cali
1
2
3
Pasto
ANAN
0 5Fig. 1. Geological sketch map of western Colombia to show the
distribution,and location of samples listed in Table 2.MAIN
STRUCTURAL ELEMENTSSan Jernimo Fault
Cauca-Almaguer FaultSilvia-Pijao Fault
123
Western Lithospheric OceanicCretaceous Province
Triassic plutons
Arqua Complex
Cajamarca Complex
Quebradagrande Complex - QGC
100 Kmspatial relationships of the Lower Cretaceous
Quebradagrande Complex,
-
ricadescribed as the Quebradagrande Formation (Botero,1963).
Although regionally exposed (Fig. 1), it is coveredin places by
recent volcanic and volcanoclastic deposits thatmake correlations
dicult. Parts of this sequence have beenmapped as the
Aranzazu-Manizales sedimentary Complex(Gomez et al., 1995) and the
Aranzazu-Manizales metasedi-mentary volcanic Complex (Mosquera,
1978); in other loca-tions, it was mapped (Paris and Marn, 1979)
within theDiabase Group (Nelson, 1957, 1962). The
Quebradagranderocks consist of imbricated slices of strongly
deformeddynamometamorphic rocks, with crenulation cleavage
andAndean milonitic foliation that bears NNE and dips 5070 to the
east (Lozano et al., 1984a; Kammer, 1995; Gomezet al., 1995).
Deformation in these rocks has caused them tobe described
erroneously as schists and included within theCajamarca belt of
metamorphic rocks (Nelson, 1957, 1962;Mosquera, 1978). Moreover,
deformation has preventedthe identication of sedimentary sequences
within theQuebradagrande rocks (Rodrguez and Rojas, 1985);though
they were originally dened as a formation with dis-tinct
sedimentary and volcanic members, these lithostrati-graphic units
lack precisely dened limits.
To solve the problem of stratigraphic nomenclaturecaused by the
deformation of the Quebradagrande rocks,Maya and Gonzalez (1996)
propose a stratigraphic schemebased on lithodemic units (North
American Commission onStratigraphic Nomenclature, 1983). They
assign the rank ofstructural complexes to the former Cajamarca,
Quebrada-grande, and Arqua units (Table 1). Because the names ofthe
regional faults that bound these complexes also varyalong their
length, new names for the faults have been pro-posed. Thus, the
fault separating the Cajamarca Complexto the east and the
Quebradagrande Complex to the westhas become known as the San
Jeronimo fault, whereas thatwhich separates the Quebradagrande
Complex to the eastand the Arqua Complex to the west is called the
SilviaPijao fault (Fig. 1, Table 1). Another important fault isthe
CaucaAlmaguer fault that bounds the Arqua Com-plex to the west and,
according to some petrogenetic models(McCourt et al., 1984; Aspden
and McCourt, 1986; Aspdenet al., 1987), marks the limit between
Palaeozoic metamor-phic rocks of continental anity and Cretaceous
accretedterranes of oceanic character. The latter include the
Canas-gordas, Diabase, and Dagua groups, the Amaime and Vol-canic
formations, and so forth. For these, Nivia (1997) usesthe term
Western Oceanic Cretaceous Lithospheric Prov-ince (Fig. 1, Table
1), which corresponds to the southernextreme of the
CaribbeanColombian Cretaceous IgneousProvince (Kerr et al., 1996,
1997a,b) that has been accretedonto the Northern Andes.
The Quebradagrande Complex is composed of anassemblage of
metavolcanic and metasedimentary rocks.The protoliths of the
metavolcanic rocks were basaltic toandesitic lavas and pyroclastics
aected by the metamor-phism of zeolite, prhenitepumpellyite, and
greenschist
A. Nivia et al. / Journal of South Amefacies. The
metasedimentary rocks display a wide variationin grain size, from
breccias and conglomerates to coarsesandstones with clasts of
cobbles and pebbles of both vol-canic rocks and chert (Gomez et
al., 1995). The presence ofthese rocks suggests underwater
volcanoclastic sedimenta-tion produced by mass movements. The
metasedimentaryhorizons also contain lithic sandstones and
volcanoclasticarkoses. In the lithic sandstones, Gonzalez (1980a)
reportsbasic volcanic rock fragments as the main components,with
smaller quantities of mudstones and chert fragments,whereas the
clastic arkoses are dominated by plagioclase.Lozano et al. (1984b)
report black and grey graphitic meta-greywackes. Milonite slices,
up to 1 km thick, formed fromclay-rich carbonaceous mudstones,
intercalated with thinbeds of limestone and cherts (Gonzalez,
1980a).
Marine fossils found in these metasedimentary rocksinclude
ammonites, gastropods, bivalves, radiolarians, bra-chiopods, and
residues of plants (Gomez et al., 1995).According to Gonzalez
(1980a), faunas within the Quebra-dagrandeComplexwould have lived
in epineritic to brackishwaters. However, Gonzalez (1980a)
interprets these rocks aspart of a turbiditic sequence, whereas
Lozano et al. (1984a),on the basis of the lack of maturity of the
sedimentary com-ponents, suggest they accumulated in deep trenches.
The fos-sils range in age from Valanginian to Albian (14097
Ma)(Gonzalez, 1980a; Gomez et al., 1995). Toussaint and Rest-repo
(1978) report a KAr (whole-rock) age of 105 10Mafrom a basalt of
the Quebradagrande Complex. AlthoughKAr dating is notoriously
unreliable in volcanic rocks asaltered as those of the
Quebradagrande Complex, the agereported by Toussaint and Restrepo
(1978) nonethelessagrees well with paleontological ages.
Areno-rudaceous clastic sequences also are associatedwith the
Quebradagrande Complex. In northern Colombia,these rocks are known
as the Abejorral (Burgl and Radelli,1962), Valle Alto (Gonzalez,
1980a), and La Soledad (Hallet al., 1972) formations; to the south,
they are known as theSan Francisco (Orrego et al., 1976) and Rojiza
(Orrego,1993) sedimentary sequences (Table 1). The
stratigraphicrelationships among these units are dicult to
establish,but their discordant deposition on top of the
CajamarcaComplex and general transgressive character have
beendescribed in several localities (Burgl and Radelli, 1962;
Hallet al., 1972; Gonzalez, 1980a). Within the Valle Alto
andAbejorral formations, Rodrguez and Rojas (1985) recog-nize
sedimentary facies that vary with time from continen-tal to oshore
marine to brackish, marine-brackish, andlittoral-marine. The
fossils in these rocks indicate theyare not older than
Berriasianmiddle Albian (Etayo, 1985).
Imbricated slices of gabbro and ultramac rocks areclosely
associated with the Quebradagrande Complex inseveral localities and
often show the same degree of defor-mation. The most studied
outcrops are the Liborina andSucre peridotites, the Pereira gabbro,
the Pacora and Cor-doba complexes, and a series of small bodies
mapped as theRomeral gabbros (Calle et al., 1980; Gonzalez,
1980b,c;Meja et al., 1983a,b). Toussaint and Restrepo (1974)
n Earth Sciences 21 (2006) 423436 425group some of these
intrusive rocks and volcanic rocks ofthe Quebradagrande Complex
within the Cauca ophiolitic
-
Table 1Stratigraphic units of western Colombia
Western OceanicCretaceous LithosphericProvince
Arquia Complex Quebradagrande Complex Cajamarca Complex
(Upper Cretaceous) CaucaAlmaguerFault
(Neoproterozoic - ?) SilviaPijaoFault
(Berriasian to middle Albian) San JeronimoFault
(Neoproterozoic)
N
S
Marine sediments Areno-rudaceous clastic sequences
Penderisco Fm.: Abejorral Fm. Cajamarca SeriesUrrao Member Valle
Alto Fm. Cajamarca GroupNutibara Member La Soledad Fm.
Dagua Group: San Francisco sed. sequenceCisneros Fm. Rojiza
sedimentary sequenceEspinal Fm.
Rio Piedras Fm.Ampudia Fm.Marilopito Fm.Aguaclara Fm.
N
S
Plateau volcanics Mainly meta-volcanics and meta-sediments Lavas
and pyroclastics
Barroso Fm. Arquia Group Quebradagrande Fm.Diabase Group
Bugalagrande Schists Aranzazu-Manizales
(meta)-Sedimentary ComplexAmaime Fm. La Mina
GreenschistsVolcanic Fm.
N
S
Mac-ultramac rocks Metamorphic basic plutonics Mac- ultramac
rocks
Bolivar Ultramac Complex Rosario Amphibolites Liborina
peridotiteGinebra Ophiolitic Massif Bolo Azul Metagabbroids Sucre
peridotite
San Antonio Amphibolitesand Metagabbroids
Pacora Complex
Romeral GabbrosPereira gabbro
426A.Nivia
etal./JournalofSouth
America
nEarth
Scien
ces21(2006)423436
-
as Th. The scatter of the Quebradagrande Complex sam-ples on a
variation diagram (Fig. 2) suggests that the alkalishave been
relatively mobile in the rocks, which might havedisplaced some
samples to the mugearite eld in the totalalkali-silica diagram
(Fig. 3). Similarly, the only samplethat contains greater than 62
wt% SiO2 is petrographicallyidentical to the andesites but looks
far more altered in thinsection. It is generally considered that
large-ion lithophileelements (LILE), such as K, Ba, Sr, and Rb, are
relativelymore mobile during low-grade metamorphism than higheld
strength elements (HFSE), such as Ti, P, Nb, Y, Zr,and rare earth
elements (REE) (Wood et al., 1979; Pearce,1983). Consequently, we
place more emphasis on the geo-chemical behavior of the relatively
immobile, trace HFSE.Five samples that show petrographical evidence
of alter-ation and scatter on variation diagrams that include
the
Fig. 2. Th versus K2O diagram for Quebradagrande Complex
volcanicrocks. Solid triangles, Group 1; stars, Group 2; solid
circles, Group 3;solid diamonds, Group 4.
rican Earth Sciences 21 (2006) 423436 427Complex and suggest a
possible cogenetic relationshipbetween them (see also Gonzalez,
1980a).
3. Geochemistry
3.1. Sampling localities
The volcanic rocks of the Quebradagrande Complexwere sampled on
a regional basis (Fig. 1) between latitudes635 0N (Santa Fe de
Antioquia) and 145 0 N (El RosalCauca). Sampling was performed
along main roads thatcut the Quebradagrande Complex outcrop areas,
such asSanta Fe de AntioquiaPlanadas (635 N), MedellnEbej-ico (622
0N), ItaguHeliconia (613 0N), FredoniaSantaBarbara (555 0N),
ArmaAguadas (537 0N), AguadasPacora (535 0N), PacoraSan Bartolome
(533 0N), Pac-oraSalamina (527 0N), SalaminaLa Merced (524
0N),ArmeniaCajamarca (430 0N), PijaoCordoba (420 0N),and BolvarEl
Rosal (145 0N).
3.2. Analytical methods
Twenty-six samples from the Quebradagrande Complexwere analyzed
for major and trace elements at the geo-chemistry laboratories of
Royal Halloway University ofLondon and University of Leicester.
Samples were brokeninto chips using manual and hydraulic jaw
splinters toremove weathered surfaces and thin veins of altered
mate-rial. The samples were further crushed using a ypress of
asteel die and shoe. Some 150 g of the coarse material wasground
into a ne powder (
-
latter elements were discarded for
geochemicalconsiderations.
3.4. Major and trace element geochemistry
Representative major and trace elements analysis of
theQuebradagrande Complex samples appear in Table 2. Ana-lyzed
samples were separated into four groups on the basisof their trace
element characteristics. On a total alkali-silicadiagram (Le Bas et
al., 1986), most samples plot in thebasaltic andesite eld, but some
also fall in the basalt,mugearite, and andesite elds (SiO2 =
48.2561.7 wt%),and one sample is a dacite (Fig. 3) whose SiO2
content(66.35 wt%) might be modied by alteration, as
indicatedpreviously. The diagram suggests the eld dened by
186samples from the Amaime and Volcanic formations ofthe Western
Oceanic Cretaceous Lithospheric Provincereported by Nivia (1987)
and Kerr et al. (1997b, 2001).
Compared with these samples, the Quebradagrande Com-plex rocks
display a greater range in SiO2 contents.
In an AFM diagram (Fig. 4), the Quebradagrande Com-plex samples
straddle the tholeiiticcalk-alkaline boundary;most follow a
calk-alkaline dierentiation trend, but someevolved along a
tholeiitic trend, as indicated by iron enrich-ment. The eld denedby
the samples from theWesternOce-anic Cretaceous Lithospheric
Province also indicates adierence in the geochemical evolution of
the two provinces.In a variation diagram includingTi (Fig. 5), the
higher degreeof dierentiation comparedwith the eld denedby
theWes-tern Oceanic Cretaceous Lithospheric Provinces
samplescontrast with the low TiO2 (1.30.42 wt%) concentration,which
shows that the Quebradagrande Complex samplesare not dierentiated
components of tholeiitic mid-oceanridge or plateau series, which
show higher Ti contents.
Fig. 6 shows primordial mantle-normalized multielementdiagrams
(Sun and McDonough, 1989) for representative
Table 2Representative XRF analyses of Quebradagrande Complex
volcanic rocks
Sample QBG95-1 QBG95-3 AN1410A AN1425 AN1426 AN1409 AN1414
AN1412 AN1416
SiO2 52.03 52.48 49.29 53.54 48.25 57.64 61.72 52.04 54.11Al2O3
20.77 17.11 19.59 16.8 18.42 16 16.53 15.67 18.13Fe2O3
a 9.33 11.52 13.07 11.7 13.16 11.91 7.76 8.01 10.07MgO 3.33 5.13
7.16 7.93 7.97 5.22 2.77 10.54 4.02CaO 10.83 8.57 8.33 7.31 9.79
2.07 6.06 9.73 9.15Na2O 2.96 3.04 0.74 1.33 1.02 4.08 3.26 2.01
2.49K2O 0.3 1.29 0.38 0.4 0.35 1.46 0.7 0.39 0.81TiO2 0.66 0.78
1.05 0.6 0.74 0.96 0.82 1.03 0.85MnO 0.18 0.16 0.08 0.14 0.19 0.18
0.18 0.13 0.21P2O5 0.29 0.25 0.1 0.08 0.08 0.14 0.16 0.14 0.12
Total 100.67 100.34 99.94 100.02 100.12 99.94 100.07 100.01
100.14
LOI% 4.38 3.2 4.54 2.14 6.2 3.11 2.26 3.93 2.42
Trace elements in ppm
Ni 1.9 2.2 18.5 28.9 21.1 3.1 4.9 295.1 7.2Cr 8 23.4 35.4 39.2
28.8 4 5.8 851.8 13.7
428 A. Nivia et al. / Journal of South American Earth Sciences
21 (2006) 423436V 210.4 336 399.5 315.5Sc 27.4 33.5 39.9 39.6Cu
88.7 114.3Zn 90.8 77.4Ga 19 17.2 17.6 14.2Pb 8.5 4.7 3.1 4.4Sr
268.5 483.5 261.6 336.5Rb 7 28.2 4 8.3Ba 212 553.8 122.5 209.2Zr
63.1 86.7 46 19.4Nb 0.7 1 1 2.5Th 4.2 3.3 0.4 0.4Y 17.6 17.3 17.9
11.4La 8.6 9.4 1.9 2.2Ce 18.7 22.8 8.7 7.9Nd 13 15.1 6.5 4.6
Interelement selected ratios
La/Nb 12.3 9.4 1.9 0.9Ba/Zr 3.4 6.4 2.7 10.8CeN/YN
b 2.9 3.7 1.3 1.9
Major elements recalculated to a volatile-free total.
a Total iron reported as Fe2O3. LOI Losses on ignition.b
Chondrite-normalized values.398 266.5 214 239.5 27141 37.9 26.8
36.8 38.8147.5 29.4 91.5 53.3 71.894.9 112.5 116.2 60.2 112.916.2
17.9 14.3 13.5 18.23.3 2.6 6.1 0.8 6.6
189.3 125.7 242.5 445.3 325.76.8 11.6 12.2 5.2 15.1
143.1 1658.7 175.8 199.2 443.327.7 67.8 71.8 72.6 64.30.9 1.3
4.7 2 1.41.1 1.8 1.9 0.8 112.4 29 24 23.2 26.72.9 6 5.7 2.6 3.610.7
16.4 15.1 9.3 11.76.3 11.8 10.7 10.7 9.3
3.2 4.6 1.2 1.3 2.65.2 24.5 2.4 2.7 6.92.4 1.6 1.7 1.1 1.2
-
ricaFig. 4. AFM diagram for Quebradagrande Complex volcanic
rocks.Symbols as in Figs. 2 and 3.
A. Nivia et al. / Journal of South Amesamples of the
Quebradagrande Complex. All the diagramsdisplay LILE enrichment
relative to HFSE, particularlyNb. Also, Ba, K, and Sr enrichments
are conspicuous bytheir pronounced peaks in the diagrams that may
reach,as in the case of Ba and Sr, up to 237 and 58 times
themantle-normalized concentrations (1659 ppm Ba and1228 ppm Sr).
Conversely, the depletion in Nb is outstand-ing by the throat it
displays in all diagrams. The LILEenrichment relative to HFSE is
usually coupled with LREEenrichment relative to HREE. The degree of
enrichment inLREE can be monitored using the
chondrite-normalized(Nakamura, 1974) CeN/YN ratio that, in the
Quebrada-grande Complex, varies between 1 and 4 times the
chon-dritic values, suggesting at to enriched REE patterns(Fig.
7).
According to the shape of their multielement-normal-ized
pattern, the samples can be divided into four dierentgroups (Fig.
6). This separation is based mainly on inter-HFSE ratios, which we
believe represent inherited featuresfrom the source of the magmas.
For example, Group 1 ischaracterized by its low Y/P ratio values
(Group 1 = 0.20.5; Group 2 = 0.30.9; Group 3 = 0.71; Group 4 =
0.61.1), and Group 2 is distinguished by its high Ti/Zr
ratios(Group 1 = 0.30.7; Group 2 = 12.1; Group 3 = 0.71;Group 4 =
0.71.2). However, groups are also homoge-neous in their LILE and
major element characteristics.
Fig. 5. Th versus TiO2 diagram for Quebradagrande Complex
volcanicrocks. Symbols as in Figs. 2 and 3.Group 1 possesses the
highest LILE enrichments relativeto HFSE, as indicated by their
highest Th contents (2.64.2 ppm) and La/Nb ratio values (112.3)
compared withthe other dened groups (Group 2: Th = 0.42.7, La/Nb =
0.93.8; Group 3: Th = 1.31.9, La/Nb = 0.74.6;Group 4: Th = 0.51.4,
La/Nb = 0.84.4). Fig. 7 suggeststhat Group 1 also displays the most
enriched LREE pat-terns and a general intergroup trend of
increasing CeN/YN ratios with increasing fractionation (Group 1 =
2.63.8; Group 2 = 12.7; Group 3 = 1.41.7; Group 4 = 0.61.3).
According to the FeO* and TiO2 contents, Group 1exhibits the most
calc-alkaline behavior, as also is indicatedby its position on the
AFM diagram (Fig. 4) and thedecreasing TiO2 content with increasing
fractionation(Group 1 = 0.420.78; Group 2 = 0.61.3; Group3 =
0.70.9; Group 4 = 0.61.3 wt%).
4. Petrogenesis
4.1. Fractional crystallization FeTi oxide arguments
Most of the analyzed Quebradagrande Complex sam-ples seem to
have evolved along two crystallizationtrends: a calc-alkaline and a
more tholeiitic (Fig. 4).The occurrence of calc-alkaline
characteristics supportsa supra-subduction zone environment of
origin for theQuebradagrande Complex. Although tholeiitic
crystalliza-tion trends are present in most environments where
basicvolcanic igneous rocks are generated, calc-alkaline trendsare
exclusive to magmatic environments with a conver-gent margin
(Wilson, 1987). Both trends are interpretedas the result of
fractional crystallization of olivine, pla-gioclase, and
clinopyroxene. The main dierence betweenthe two trends is the
control exerted over the FeTi oxi-des during crystallization (Gill,
1981). Experimental evi-dence (Grove and Baker, 1984) shows that
subalkaline,anhydrous magmas crystallizing in the crust under
geo-logically reasonable oxygen fugacity follow tholeiitic
dif-ferentiation trends. In hydrated basaltic magmas,dissolved
water reduces olivine, pyroxene, and plagio-clase stability without
aecting the thermal stability ofFeTi oxides (Sisson and Grove,
1993), which results inthe early crystallization of FeTi oxides
from a calc-alka-line magmatic system and lower Fe and Ti contents
inthe resultant magmas than in a tholeiitic crystallizationsequence
where the fractionation of FeTi oxide isdelayed, which increases
the Fe and Ti contents of themagma. Thus, water activity inuences
the early or latecrystallization of titaniferous magnetite, and
subalkalinemagmas with high water contents follow
calc-alkalinedierentiation trends, whereas those with low water
con-tents display tholeiitic trends.
4.2. Trace element arguments
n Earth Sciences 21 (2006) 423436 429The LILE enrichment in
volcanic rocks can be producedby several processes, such as oceanic
mantle contaminated
-
Fig. 6. Normalized multielement plot of Quebradagrande Complex
volc
Fig. 7. CeN/YN versus Th diagram for Quebradagrande
Complexvolcanic rocks. Symbols as in Fig. 2.
430 A. Nivia et al. / Journal of South American Earth Sciences
21 (2006) 423436by deeper, uncirculated mantle plumes; low
percentages offusion in the source; mantle metasomatism by
subductingplate-derived uids; or contamination. The
characteristicfeature of magmas originated from supra-subduction
zonemantle wedges is the LILE enrichment relative to HFSE(Saunders
et al., 1980; Tarney et al., 1981; Saunders andTarney, 1982;
Pearce, 1983). This feature, produced bychemical fractionation
between LILE and HFSE in thehydrous environment associated with
subduction zones, isoutstanding in the pronounced Nb negative
anomaly dis-played by the Quebradagrande Complex in the
spider-grams. The strong chemical behavior anity (i.e.,
similarincompatibility with the original mantle and basic
volcanicrocks mineralogies) of elements like La (LILE), Nb, and
Ta(HFSE) is well known, such that these elements usually areplaced
at adjacent positions in multielement-normalized
anic rocks. Normalizing values from Sun and McDonough
(1989).
-
diagrams (Bougault et al., 1985). These elements are
notfractionated by processes like partial fusion or
fractionalcrystallization. However, metamorphic processes actingon
the subduction zone produce dehydration of the sub-ducting oceanic
crust with consequent production ofhydrous supercritical uids that
transport water and solu-ble LILE (e.g., La) to the
supra-subduction zone mantlewedge (Saunders et al., 1980; Tarney et
al., 1981). TheHFSE (e.g., Nb) can be retained by the subducting
oceaniccrust (then an eclogitic assemblage) and returned to
themantle (Saunders and Tarney, 1982). The latter can beascribed to
the hydrous environment in the subductionzone, which favors the
stability of mineral phases such asrutile or ilmenite that retain
HFSE (Tarney et al., 1981).Fig. 8 shows a plot of La/Y versus Nb/Y
(La and Nb nor-malized to Y to eliminate the eects of fractional
crystalli-zation) for the Quebradagrande Complex samples.
Thisdiagram is useful for separating samples that contain a
sub-
A. Nivia et al. / Journal of South Americaduction-related
component (low La/Nb ratios) from thosederived from an oceanic
mantle source region, far from theinuence of a subduction zone
(e.g., mid-ocean ridge bas-alts, mantle plume-generated oceanic
plateau basalts). Thisdiagram also shows elds encompassing the
basalts fromthe Amaime and Volcanic formations of the Western
Oce-anic Cretaceous Lithospheric Province (Nivia, 1987; Kerret al.,
1997b, 2001) and lavas of the recent Andean volca-noes of Colombia
(Marriner and Millward, 1984). Theenvironment of formation for the
former rocks was unre-lated to a subduction zone (Millward et al.,
1984; Nivia,1987; Kerr et al., 1996, 1997a,b, 2001), whereas the
latterare modern examples of rocks produced in a destructiveplate
margin. In this diagram, the chemical dierencesbetween the basalts
of the Western Oceanic CretaceousLithospheric Province and the
subduction-related Quebra-dagrande Complex are evident. It is thus
highly unlikelythat the Quebradagrande Complex lavas and
pyroclasticsrepresent part of the same tectonomagmatic event.Fig.
8. Nb/Y versus La/Y diagram for Quebradagrande Complexvolcanic
rocks. Symbols as in Fig. 2.5. Discussion
On the basis of major element chemical analyses, Gon-zalez
(1980a) proposes that the Quebradagrande Complexis composed of
tholeiitic rocks generated in an oceanic rift.Bourgois et al.
(1982, 1985, 1987) and Toussaint and Rest-repo (1993) propose the
same origin but also suggest thatthe Quebradagrande Complex had
been thrust from thewest onto the continental margin, along with
basic rocksthat outcrop west of the Cauca-Almaguer fault (i.e.,
theWestern Oceanic Cretaceous Lithospheric Province).According to
this model, a single common mantle sourceregion is responsible for
both the Quebradagrande Com-plex and the volcanic rocks of the
Western Oceanic Creta-ceous Lithospheric Province (Barroso, Amaime,
Volcanicformations, Table 1). Similarly, Kammer (1995) and Kam-mer
and Mojica (1996) consider a close anity between therocks of the
accreted Western Oceanic Cretaceous Litho-spheric Province and the
Quebradagrande Complex. Theresults presented herein clearly show a
subduction zone-de-rived component in the geochemical composition
of theQuebradagrande Complex. However, the
geochemicalcharacteristics of the Quebradagrande Complex dier
fun-damentally from those of the basic volcanic rocks of theWestern
Oceanic Cretaceous Lithospheric Provinceexposed in western Colombia
(Millward et al., 1984; Nivia,1987, 1989; Kerr et al., 1996,
1997a,b). In addition, thereported ages of the Western Oceanic
Cretaceous Litho-spheric Province indicate these rocks were formed
duringthe Late Cretaceous, whereas evidence for the Quebrada-grande
Complex indicates an Early Cretaceous age. Thus,the volcanic rocks
of the Quebradagrande Complex andthe Western Oceanic Cretaceous
Lithospheric Provincewere generated from two dierent, unrelated
mantle sourceregions; in turn, the geotectonic models and
interpretationsof a common genesis for both are inherently
incorrect.
Geochemical data suggest that the volcanic rocks of
theQuebradagrande Complex formed during the Lower Creta-ceous in a
supra-subduction zone environment, in an islandarc, marginal basin,
or active continental margin. To eval-uate these possibilities, the
regional relationships betweenthe Quebradagrande Complex and
adjacent rocks mustbe considered. The Quebradagrande Complex
outcropsare bounded by the metamorphic Cajamarca and Arquacomplexes
(Fig. 1, Table 1). The age of the CajamarcaComplex, to the east, is
constrained as Neoproterozoic(Gomez and Nunez, 2003), but the age
of the Arqua Com-plex to the west is controversial. Some
researchers believethe Arqua Complex was formed during the Lower
Creta-ceous (Toussaint and Restrepo, 1989, 1993; Restrepo et
al.,1991; Gonzalez and Nunez, 1991; Gonzalez, 1993, 2001),whereas
others think it Paleozoic in age (McCourt andAspden, 1983; McCourt
et al., 1984; Aspden et al., 1987).However, both the presence of
Triassic granitoid plutons,such as the Santa Barbara Batholith and
Amaga and Cam-
n Earth Sciences 21 (2006) 423436 431bumbia stocks, intruding
schists west of the Quebrada-grande Complex (Fig. 1; McCourt et
al., 1984; Meja
-
ricaet al., 1983b; Restrepo et al., 1991) and the occurrence
ofPaleozoic rocks west of the Quebradagrande Complex(Mosquera,
1978; Calle et al., 1980; Meja et al., 1983a,b;Gonzalez, 2001) are
strong arguments in favor of a Neo-proterozoic age for the Arqua
Complex. Assuming aPaleozoic age for the Arqua Complex, McCourt et
al.(1984) present an evolutionary model for the northernAndes.
According to this model, during the Carbonifer-ous, the continental
margin of the northern Andes wascomposed of an autochthonous block
(Cajamarca Com-plex) and accreted island arc (Bugalagrande
schists,Rosario amphibolites, and Bolo Azul metagabbroids;Arqua
Complex, Table 1). We concur with this modeland believe that the
data presented here support a modelin which the Quebradagrande
Complex is related to amagmatic environment associated with a
continentalactive margin.
Processes operating in subduction zones result in dehy-dration
of the subducting oceanic crust and transport ofgenerated uids into
the overlying mantle wedge. Theinux of such volatile-rich uids into
the mantle wedgelowers the solidus of the mantle, resulting in
meltingand the formation of hydrated magmas. However, thewater
(volatile) content of the magmas may vary accord-ing to the
distance between the centers of volcanic erup-tion and the trench.
For marginal basins, it depends onthe degree of evolution, that is,
the development of thebasin. As marginal basins (sensu stricto)
open andthe expansion center separates from the island arc,
thehydrous (subduction) component becomes less pro-nounced
(Saunders and Tarney, 1984; Atherton and Agu-irre, 1992). In this
way, the calc-alkaline and tholeiitictrends and the LILE/HFSE ratio
in the QuebradagrandeComplex could be controlled by the preeruptive
contentsof the hydrous component in the mantle. As we
notedpreviously, the samples can be separated into four dier-ent
chemical types (Fig. 6), which may be interpreted asheterogeneities
produced in the mantle during the evolu-tion of the basin. Thus,
Group 1 samples, which appearto contain more of the subduction
component(s) (higherLILE/HFSE ratios), could have been generated
duringthe initial stages of basin opening. During latter stagesof
basin opening, progressive dilution of this componentin the source
region, as reected in the lower LILE/HFSEratios of Groups 2 and 3,
culminates in the Group 4 sam-ples, which display the lowest La/Nb
and CeN/YN ratios(Figs. 7 and 8). Parallel trends between groups in
bivari-ate diagrams for the same degree of dierentiation favorthis
hypothesis. Furthermore, increasing values of theCeN/YN ratios with
increasing Th in a Th versus CeN/YN diagram (Fig. 7) could be
related to intersample var-iation due to dierentiation processes,
whereas parallelintergroup trends suggest dierent LILE enrichment
inthe mantle. However, the strong deformation of theQuebradagrande
Complex inhibits any reconstruction of
432 A. Nivia et al. / Journal of South Amethe basin that might
help evaluate this hypothesis in termsof geochemical
characteristics.To explain the Quebradagrande Complex genesis,
wepropose a petrogenetic model in which the rocks formedduring the
opening of a marginal ensialic basin. Aberget al. (1984) and
Aguirre (1987) propose that these basinsmight form by ensialic
expansion or subsidence mecha-nisms promoted by the rollback action
of the subductinglithosphere on the active continental margin.
These mech-anisms may lead to crustal thinning with consequent
adia-batic decompression melting of the mantle, whichproduced both
basins and magmatism. The volcanic prod-ucts erupt over the
continental crust or, in cases of extremeextension, result in the
complete rupture of the continentalmargin and generation of oceanic
crust (Aberg et al., 1984;Aguirre, 1987; Atherton and Aguirre,
1992).
Ophiolitic sequences proposed as generated by theseprocesses are
common to the Uppermost Jurassic andLower Cretaceous of the South
American Pacic margin,extending from its southernmost extreme in
South Geor-gia Island (Chile) to central-western Mexico; the latter
iscontinuous with eastern Colombia in most TriassicJu-rassic Pangea
reconstructions (Coney and Evenchick,1994). Well-documented
ensialic marginal basins arefound in the ophiolitic complexes of
the Larsen Peninsu-la, Tortuga and Sarmiento at South Georgia
Island,Tierra de Fuego, and Patagonia (Tarney et al., 1981;Saunders
and Tarney, 1982; Miller et al., 1994; Sternet al., 1976); the
Rocas Verdes of central and southernChile (Aberg et al., 1984); the
Puente Piedra and Casmaformations in Peru (Atherton et al., 1985;
Aguirre andOer, 1985; Atherton and Aguirre, 1992); the Celica
For-mation of southern Ecuador and northern Peru (Aguirreand
Atherton, 1987; Lebras et al., 1987); and the inter-bedded
calc-alkaline volcanics and sedimentary stratacontaining shallow
marine fauna and imbricated withserpentinite bodies, ultramac
cumulates, and podiformchromite of the Siuna Terrane of Nicaragua
and Hondu-ras, which extends northward into the Guerrero Terraneof
southern Mexico. In the latter, Elias-Herrera and Ort-ega-Gutierrez
(1998) posit the upper volcanoclasticsequence was generated in a
continental margin backarcbasin setting. The spatial, chronological
characteristicsand geochemical composition of the
QuebradagrandeComplex suggest they belong to this belt.
The petrogenetic model proposed for the origin of
theQuebradagrande Complex is illustrated in Fig. 9. In thismodel,
subduction along the proto-Pacic Colombian mar-gin produced
distension and crustal thinning over the con-tinental margin. The
thinning resulted in the formation of abasin, as evidenced by the
accumulation of transgressivesedimentary sequences (e.g., Valle
Alto, Abejorral; Table1). The genesis of these arenorudaceous
clastic sequenceswould agree with the ensialic marginal basin model
if theyrepresent and show the rst stages of basin opening. On
theoceanic plate, the progressive increase of temperature
andpressure as subduction processes produced metamorphism
n Earth Sciences 21 (2006) 423436with consequent dehydration.
The corresponding subduc-tion-liberated uids moved upward, adding
H2O, LILE,
-
AB
C
D
Fig. 9. Diagrammatic sketch illustrating evolution of the
Quebradagrande ComplexQGC marginal ensialic basin. (A) Subduction
and consequentmetasomatism of subcontinental mantle under Paleozoic
crust of an oceanic crustal block (Arqua Complex) accreted to the
continental crustal block(Cajamarca Complex + shield). (B) Rollback
of the continental margin leads to lithospheric thinning and
subsequent generation of basins and adiabaticmantle melting. (C)
Formation of marginal basin by generation of oceanic oor in the
zone of backarc spreading. (D) Closure of basin, probably due
toforces produced on the continental plate during the aperture of
the South Atlantic.
A. Nivia et al. / Journal of South American Earth Sciences 21
(2006) 423436 433
-
Rodrguez, C., Munosz, J. Duran, J., 1980. Mapa Geologico de
ricaand LREE to the subcontinental mantle wedge. The addi-tion
of these uids lowered the solidus; combined with adi-abatic
decompression induced by crustal thinning, itresulted in mantle
melting. The magmas produced werecalc-alkaline basalts that
dierentiated at crustal levels toform andesites and dacites
(Quebradagrande ComplexGroups 1 and 2). Basin opening culminated in
the genera-tion of oceanic crust, represented today by ophiolitic
com-plexes. According to this petrogenetic model, more
basicvolcanic rocks (Groups 2 and 3) and sedimentary rocksof the
Quebradagrande Complex accumulated on top ofthe basin, whereas the
associated mac and ultramac plu-tonic rocks (Table 1) represent
deeper horizons of theophiolitic complexes developed by ocean oor
formationduring the opening of the basin.
The opening of the basin led to the gradual movement ofthe locus
of magmatism away from the trench, which mayhave resulted in the
dilution of the subduction zone-derivedcomponent and a change in
the magmatic products fromcalc-alkaline to tholeiitic. According to
Saunders and Tar-ney (1984), marginal basins are short-life
geotectonic fea-tures. Furthermore, Dalziel (1981) suggests that
inmarginal basins of southern Chile, collapse or closure coin-cides
with the opening of the South Atlantic. Thus, thechange in the
velocity of plate displacement induced bythe South Atlantic opening
also may have promoted theclosure of the Quebradagrande Complex
marginal basin.However, the accretion of the CaribbeanColombian
oce-anic plateau in the late Cretaceousearly Tertiary
likelycontributed signicantly to the closure of the basin
anddeformation of this unit.
6. Conclusions
Regional sampling of the Quebradagrande Complexbetween 635 0N
and 145 0N in Colombia shows that basal-tic andesites and andesites
have geochemical characteristicstypical of rocks formed in
supra-subduction zone magmat-ic environments. These rocks follow
two contrasting dier-entiation trends: One is calc-alkaline, the
other tholeiitic.
The geochemical characteristics of the QuebradagrandeComplex
rocks and their spatial and chronological rela-tionships with the
Cajamarca and Arqua complexes, theultramac and mac Cretaceous
rocks, and the arenoruda-ceous Lower Cretaceous related sequences
can be integrat-ed into an evolutionary petrogenetic model of
ensialicmarginal basin opening.
The model has global tectonic implications, in that itforms an
important link, through the northern Andes, ofthe chain of marginal
basins that extended from Tierrade Fuego to Mexico in the Early
Cretaceous. During thisstratigraphic interval, subduction was
active along theSouth American margin.
The results we present clearly demonstrate that thereis no
genetic relationship between the Quebradagrande
434 A. Nivia et al. / Journal of South AmeComplex and the Upper
Cretaceous volcanic rocks thatoutcrop west of the Cauca-Almaguer
fault rocks thatColombia Escala 1:100.000, Plancha 166 Jerico:
INGEOMINAS.Bogota.
Coney, P.J., Evenchick, C.A., 1994. Consolidation of the
Americanare well documented to have formed in an oceanic pla-teau
setting.
References
Aberg, G., Aguirre, L., Levi, V., Nystrom, J.O., 1984.
Spreading-subsidence and generation of ensialic marginal basins: an
examplefrom the early Cretaceous of central Chile. In: Kokelaar,
B.P., Howells,M.F., Roach, R.A. (Eds.), Volcanic Processes in
Marginal Basins:Geological Society of London Special Publication
16, pp. 185193.
Aguirre, L., 1987. Andean modelling. Geology Today 3,
4748.Aguirre, L., Atherton, M.P., 1987. Low grade metamorphism
and
geotectonic setting of the Macuchi Formation, Western Cordillera
ofEcuador. Journal of Metamorphic Geology 5, 473494.
Aguirre, L., Oer, R., 1985. Burial metamorphism in the
WesternPeruvian Trough: its relation to Andean magmatism and
tectonics.In: Pitcher, W.S., Atherton, M.P., Cobbing, E.J.,
Beckinsale, R.D.(Eds.), Magmatism at a Plate Edge, the Peruvian
Andes. Blackie, JohnWilley and Sons, pp. 5971.
Aspden, J.A., McCourt, W.J., 1986. Mesozoic oceanic terrane in
theCentral Andes of Colombia. Geology 14, 415418.
Aspden, J.A., McCourt, W.J., Brook, M., 1987. Geometrical
control onsubduction-related magmatism: the Mesozoic and Cenozoic
plutonichistory of Western Colombia. Journal of the Geological
Society,London 144, 893905.
Atherton, M.P., Aguirre, L., 1992. Thermal and geotectonic
setting ofCretaceous volcanic rocks near Ica, Peru, in relation to
Andean crustalthinning. Journal of South American Earth Sciences 5,
4769.
Atherton, M.P., Pitcher, W.S., Warden, V., 1983. The Mesozoic
marginalbasin of central Peru. Nature 305, 303306.
Atherton, M.P., Warden, V., Sanderson, M., 1985. The
Mesozoicmarginal basin of Central Peru: a geochemical study of
within-plate-edge volcanism. In: Pitcher, W.S., Atherton, M.P.,
Cobbing, E.J.,Beckinsale, R.D. (Eds.), Magmatism at a Plate Edge,
the PeruvianAndes. John Willey and Sons, Blackie, pp. 4758.
Barrero, D., 1979. Geology of the central Western Cordillera,
West ofBuga and Roldanillo, Colombia. Publicaciones Geologicas
Especialesde INGEOMINAS 4, 75.
Botero, A., 1963. Contribucion al conocimiento de la geologa de
la zonacentral de Antoquia. Anales Facultad de Minas (Medelln) 57,
101.
Bougault, H., Joron, J.L., Treuil, M. Maury, R., 1985. Local
versusregional mantle heterogeneities: evidence from
hygromagmatophileelements. In: Bougault, H. and Cande, S.C. (Eds.),
Initial Reports ofthe Deep Sea Drilling Project, U.S. Government
Printing Oce.Washington, 82, pp. 459477.
Bourgois, J., Calle, B., Tourmon, J., Toissaint, J.F., 1982. The
Andeanophiolitic megastructure on the Buga-Buenaventura transverse
(Wes-tern Cordillera Valle, Colombia). Tectonophysics 82,
207229.
Bourgois, J., Toussaint, J.F., Gonzales, H., Azema, J., Calle,
B., Desmet,A., Murcia, L.A., Alvarado, P., Parra, E., Tourmon, J.,
1987.Geological history of the Cretaceous ophiolitic complexes of
northernSouth America (Colombian Andes). Tectonophysics 143,
307327.
Bourgois, J., Toussaint, J.F., Gonzales, H., Orrego, A., Azema,
J., Calle,B., Desmet, A., Murcia, A., Alvarado, P., Parra, E.
Tourmon, J., 1985.Les ophiolites des Andes de Colombie. Evolution
Structural etsignication geodinamic, In: Mascle, A. (Ed.),
Geodinamic desCaraibbes, Symposium: Technip. Paris, pp. 475493.
Burgl, H., Radelli, L., 1962. Nuevas localidades fosilferas en
la CordilleraCentral de Colombia (SA.). Geologa Colombiana 3,
133138.
Calle, B., Gonzalez, H., De La Pena, R., Escorce, E., Durango,
J.,Ramrez, O., Alvarez, E., Calderon, M., Alvarez, J., Guarn,
G.
n Earth Sciences 21 (2006) 423436Cordilleras. Fifth Circum-Pacic
Terrane Conference (Santiago).Pergamon. pp. 241262.
-
ricaDalziel, I.W.D., 1981. Back-arc extension in the southern
Andes: a reviewand critical reappraisal. Philosophical Transactions
of the RoyalSociety of London 300, 319335.
Dalziel, I.W.D., de Wit, M.J., Palmer, K.F., 1974. Fossil
marginal basin inthe southern Andes. Nature 215, 291294.
Elias-Herrera, M., Ortega-Gutierrez, F., 1998. The Early
CretaceousArperos oceanic basin (western Mexico), Geochemical
evidence for anaseismic ridge formed near a spreading center
comment. Tectono-physics 292 (34), 321326.
Etayo, F., 1985. Documentacion paleontologica del Infracretacico
de SanFelix y Valle Alto, Cordillera Central, Proyecto Cretacico.
Publicac-iones Geologicas Especiales del INGEOMINAS 16,
XXV1XXV7.
Gill, J., 1981. Orogenic Andesites and Plate Tectonics:.
Springer Verlag,Berlin, 390 p.
Gomez, A., Moreno, M., Pardo, A., 1995. Edad y origen de
Complejometasedimentario de Aranzazu-Manizales en los alrededores
deManizales (Departamento de Caldas, Colombia). Geologa Colombi-ana
19, 8393.
Gomez, J., Nunez, A., 2003. Las metasedimentitas de Santa Teresa
y laedad del Complejo Cajamarca (Cordillera Central, Departamento
delTolima Colombia). IX Congreso Colombiano de Geologa, Resum-enes,
Medelln, 35 p.
Gonzalez, H., Nunez, A., 1991. Mapa Geologico Generalizado
delDepartamento del Quindio, INGEOMINAS, 42 p.
Gonzalez, H., 1980a. Geologa de las planchas 167 (Sonson) y
187(Salamina), Boletn Geologico INGEOMINAS, 23, 174 p.
Gonzalez, H., 1980b. Mapa Geologico de Colombia Escala
1:100.000,Plancha 167 Sonson, INGEOMINAS. Bogota.
Gonzalez, H., 1980c. Mapa Geologico de Colombia Escala
1:100.000,Plancha 187 Salamina, INGEOMINAS. Bogota.
Gonzalez, H., 1993. Mapa Geologico del Departamento de
Caldas,INGEOMINAS, 62 p.
Gonzalez, H., (2001). Geologa de las planchas 206, Manizales y
225,Nevado del Ruiz, Escala 1:100.000, Memoria explicativa.
INGEOM-INAS, Bogota, 92 p.
Grove, T.L., Baker, M.B., 1984. Phase equilibrium controls on
thetholeiitic versus calc-alkaline dierentiation trends. Journal of
Geo-physical Research 89, 32533274.
Hall, R.B., Alvarez, J., Rico, H., 1972. Geologa de parte de
losdepartamentos de Antioquia y Caldas (sub-zona II-A),
BoletnGeologico INGEOMINAS. XX, 85 p.
Kammer, A., 1995. Las fallas de Romeral y su relacion con la
tectonica dela Cordillera Central. Geologa Colombiana 18, 2746.
Kammer, A., Mojica, J., 1996. Una comparacion de la tectonica
debasamento de las cordilleras Central y Oriental. Geologa
Colombiana20, 93106.
Kerr, A.C., Tarney, J., Marriner, G.F., Nivia, A., Saunders,
A.D., Klaver,G.T., 1996. The geochemistry and tectonic setting of
late CretaceousCaribbean and Colombian volcanism. Journal of South
AmericanEarth Sciences 9, 111120.
Kerr, A.C., Marriner, G.F., Tarney, J., Nivia, A., Saunders,
A.D.,Thirlwall, M.F., Sinton, C., 1997a. Cretaceous Basaltic
Terranes inWestern Colombia: elemental, chronological and SrNd
isotopicconstraints on Petrogenesis. Journal of Petrology 38,
677702.
Kerr, A.C., Tarney, J., Marriner, G.F., Nivia, A., Saunders,
A.D., 1997b.The CaribbeanColombian Cretaceous igneous province: the
internalanatomy of an oceanic plateau, In: Mahoney, J.J., Con, M.
(Eds.),Large Igneous Provinces: Continental, Oceanic, and Planetary
FloodVolcanism, American Geophysical Union, Geophysical
Monograph100, pp. 123144.
Kerr, A.C., Tarney, J., Kempton, P.D., Spadea, P., Nivia, A.,
Marriner,G.F., Duncan, R., 2001. Pervasive mantle plume head
heterogeneity:evidence from the late Cretaceous CaribbeanColombian
oceanicplateau. Journal of Geophysical Research 107/B7.
doi:10.1029/2001JB000790.
Le Bas, M.J., Le Maitre, R.W., Streckeisen, A., Zanettin, B.,
1986. A
A. Nivia et al. / Journal of South Amechemical classication of
volcanic rocks based on the total alkali-silicadiagram. Journal of
Petrology 27, 745750.Lebras, M., Megard, F., Dupuy, C., Dostal, J.,
1987. Geochemistry andtectonic setting of pre-collision Cretaceous
and Paleogene volcanicrocks of Ecuador. Geological Society of
America Bulletin 99, 569578.
Lozano, H., Perez, H., Mosquera, D., 1984a. Prospeccion
geoqumicapara oro, plata, antimonio y mercurio en los municipios de
Salento,Qundio y Cajamarca, Tolima. Boletn Geologico INGEOMINAS
27,576.
Lozano, H., Perez, H., Vesga, C., 1984b. Prospeccion geoqumica
ygenesis del mercurio en el anco occidental de la Cordillera
Central deColombia, Municipios de Aranzazu, Salamina y Pacora,
Departamen-to de Caldas. Boletn Geologico INGEOMINAS 27, 77169.
Marriner, G.F., Millward, D., 1984. The petrology and
geochemistry ofCretaceous to Recent volcanism in Colombia.
Geological Society ofLondon 141, 473486.
Marsh, N.G., Saunders, A.D., Tarney, J., Dick, H.J., 1980.
Geochemistryof basalts from the Shikoku and Daito Basins, Deep Sea
DrillingProject leg 58. Initial Reports of the Deep Sea Drilling
Project. U.S.Government Printing Oce, Washington, 58, pp.
805842.
Maya, M., Gonzalez, H., 1996. Unidades litodemicas en la
CordilleraCentral de Colombia. Boletn Geologico INGEOMINAS 35,
4357.
McCourt, W.J., Aspden, J.A., 1983. A plate tectonic model for
thephanerozoic evolution of central and southern Colombia. In:
10thCaribbean Geological Conference Transactions: INGEOMINAS,
pp.3847.
McCourt, W.J., Aspden, J.A., Brook, M., 1984. New geological
andgeochronological data from the Colombian Andes: continental
growthby multiple accretion. Journal of the Geological Society,
London 141,835841.
Meja, M., Alvarez, E., Gonzalez, H., Grosse, E., 1983a. Mapa
Geologicode Colombia Escala 1:100.000, Plancha 130 Santa Fe de
Antioquia.INGEOMINAS. Bogota.
Meja, M., Alvarez, E., Gonzalez, H., Grosse, E., 1983b. Mapa
Geologicode Colombia - Escala 1:100.000, Plancha 146 - Medelln
Occidental.INGEOMINAS. Bogota.
Miller, C.A., Barton, M., Hanson, R.E., Fleming, T.H., 1994. An
EarlyCretaceous volcanic arc/marginal basin transition zone,
PeninsulaHardy, southernmost Chile. Journal of Volcanology and
GeothermalResearch 63, 3358.
Millward, D., Marriner, G., Saunders, A.D., 1984. Cretaceous
tholeiiticvolcanic rocks from the Western Cordillera of Colombia.
Journal ofthe Geological Society, London 141, 847860.
Molnar, P., Atwater, T., 1978. Interarc spreading and
cordilleran tectonicsas alternates related to the age of subducted
oceanic lithosphere. Earthand Planetary Science Letters 41,
330340.
Mosquera, D., 1978. Geologa del Cuadrangulo K-8. Informe
1763(unpublished): INGEOMINAS. Bogota. 63 p.
Nakamura, N., 1974. Determination of REE, Ba, Fe, Mg, Na and K
incarbonaceous and ordinary chondrites. Geochimica et
CosmochimicaActa 38, 757775.
Nelson, H.W., 1957. Contribution to the geology of the Central
andWestern Cordillera of Colombia in the sector between Ibague and
Cali.Leidse Geologische Medelelingen 22, 176.
Nelson, H.W., 1962. Contribucion al conocimiento de la
CordilleraCentral de Colombia. Seccion entre Ibague y Armenia.
BoletnGeologico INGEOMINAS, X, pp. 161203.
Nivia, A., 1987. Geochemistry and origin of the Amaime and
VolcanicSequences, Southwestern Colombia: Unpublished Master of
Philoso-phy thesis. University of Leicester, Leicester, UK, 163
p.
Nivia, A., 1989. El Terreno Amaime-Volcanica una provincia
acrecionadade basaltos de meseta oceanica. In: V Congreso
Colombiano deGeologa, Memorias, I, pp. 130.
Nivia, A., Galvis, N. Maya, M., 1997. Geologa de la Plancha 242
Zarzal. INGEOMINAS, Bogota. 73 p.
North American Commission on Stratigraphic Nomenclature,
1983.North American Stratigraphic Code. American Association of
Petro-leum Geologist Bulletin, 67/5, pp. 841875.
n Earth Sciences 21 (2006) 423436 435Orrego, A., 1993. Geologa
de la Plancha 364-Timbo. INGEOMINAS.36 p.
-
Orrego, A., Rossman, D., Paris, G., 1976. Geologa del
Cuadrangulo N-6Popayan. Informe 1711 (unpublished): INGEOMINAS.
Bogota. 179p.
Paris G., Marn, P.A., 1979. Generalidades acerca de la geologa
delDepartamento del Cauca. INGEOMINAS. Bogota. 38 p.
Pearce, J.A., 1983. The role of sub-continental lithosphere in
magmagenesis at active continental margins. In: Hawkesworth, C.J.,
Norry,M.J. (Eds.), Continental Basalts and Mantle Xenoliths.
Shiva,Nantwich, UK, pp. 230249.
Restrepo, J.J., Toussaint, J.F., Gonzalez, H., Cordani, U.,
Kawashita, K.,Linares, E., Parica, C., 1991. Precisiones
geocronologicas sobre elOccidente Colombiano. Memorias Simposio
sobre MagmatismoAndino y su Marco Tectonico I, 122.
Rodrguez, C., Rojas, R., 1985. Estratigrafa y tectonica de la
SerieInfracretacica en los alrededores de San Felix, Cordillera
Central deColombia. Publicaciones Geologicas Especiales del
INGEOMINAS16, XXI1XXI21.
Saunders, A.D., Tarney, J., 1982. Igneous activity in the
southern Andesand northern Antarctic Peninsula: a review. Journal
of the GeologicalSociety, London 139, 691700.
Saunders, A.D., Tarney, J., 1984. Geochemical characteristics of
basalticvolcanism within back-arc basins, In: Kokelaar, B.P.,
Howells, M.F.,Roach, R.A. (Eds.), Volcanic Processes in Marginal
Basins, GeologicalSociety of London Special Publication, 16, pp.
5976.
Saunders, A.D., Tarney, J., Weaver, S.D., 1980. Transverse
geochemicalvariations across the Antarctic Peninsula: Implications
for the genesisof calc-alkaline magmas. Earth and Planetary Science
Letters 46, 344360.
Sisson, T.W., Grove, T.L., 1993. Experimental investigations of
the role ofH2O in calc-alkaline dierentiation and subduction zone
magmatism.Contributions to Mineralogy and Petrology 113,
146166.
Stern, C.R., De Witt, M.J., Lawrence, J., 1976. Igneous and
metamorphic
implication for ocean oor metamorphism, seismic layering,
andmagnetism. Journal of Geophysical Research 81, 43704380.
Stern, C.R., Elthon, D., 1979. Vertical variations in the eects
ofhydrothermal metamorphism in the Chilean ophiolites:
theirimplications for ocean oor metamorphism. Tectonophysics
55,179213.
Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic
systematicsof oceanic basalts: implications for mantle composition
andprocesses, In: Saunders, A.D., Norry, M.J. (Eds.), Magmatism
inthe Ocean Basins, Geological Society of London Special
Publication,42, pp. 313345.
Tarney, J., Saunders, A.D., Mattey, D.P., Wood, D.A., Marsh,
N.G.,1981. Geochemical aspects of back-arc spreading in the Scotia
Sea andWestern Pacic. Philosophical Transactions of the Royal
Society ofLondon A300, 263285.
Toussaint, J.F., Restrepo, J.J., 1974, Algunas consideraciones
sobre laevolucion structural de los Andes Colombianos.
Publicaciones Espec-iales de Geologa, 4: Facultad Nacional de
Minas, Medelln, 17 p.
Toussaint, J.F., Restrepo, J.J., 1978. Edad KAr de dos rocas
basicas delanco noroccidental de la Cordillera Central.
Publicaciones Especialesde Geologa, 15: Facultad de Ciencias,
Medelln.
Toussaint, J.F., Restrepo, J.J., 1989. Acreciones sucesivas en
Colombia:Un nuevo modelo de evolucion geologica. Memorias V
CongresoColombiano de Geologia I, 127147.
Toussaint, J.F., Restrepo, J.J., 1993. Tectonica de terrenos
durante elCretacico en Colombia. Memorias VI Congreso Colombiano
deGeologa I, 97114.
Wilson, M., 1987. Igneous Petrogenesis: A Global Tectonics
Approach.Harper Collins Academic, London, 466 p.
Wood, D.A., Joron, J.L., Treuil, M., Norry, M.J., Tarney, J.,
1979.Elemental and Sr isotope variations in basic lavas from
Iceland and the
436 A. Nivia et al. / Journal of South American Earth Sciences
21 (2006) 423436processes associated with the formation of Chilean
ophiolites and their
surrounding ocean oor: the nature of mantle source
inhomogenities.Contributions to Mineralogy and Petrology 70,
319339.
The Quebradagrande Complex: A Lower Cretaceous ensialic marginal
basin in the Central Cordillera of the Colombian
AndesIntroductionRegional geology and stratigraphic
nomenclatureGeochemistrySampling localitiesAnalytical
methodsAlterationMajor and trace element geochemistry
PetrogenesisFractional crystallization ldquo Fe-Ti oxide
arguments rdquo Trace element arguments
DiscussionConclusionsReferences