Ages and petrogenesis of the late Triassic andesitic rocks at ...

Gondwana Research 85 (2020) 103–123

Contents lists available at ScienceDirect

Gondwana Research

j ourna l homepage: www.e lsev ie r .com/ locate /gr

Ages and petrogenesis of the late Triassic andesitic rocks at the Luermaporphyry Cu deposit, western Gangdese, and implications forregional metallogeny

Xin Chen a, Youye Zheng a,b,⁎, Shunbao Gao c, Song Wub, Xiaojia Jiang a, Junsheng Jiang a,Pengjie Cai c, Chenggui Lin d

a School of Earth Resources, China University of Geosciences, Wuhan 430074, Chinab State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing 100083, Chinac Institute of Geological Survey, China University of Geosciences, Wuhan 430074, Chinad Development and Research Center, China Geological Survey, Beijing 100037, China

⁎ Corresponding author at: State Key Laboratory of GeResources, Faculty of Earth Resources, China University oChina.

E-mail addresses: [email protected] (X. Chen), zh

https://doi.org/10.1016/j.gr.2020.04.0061342-937X/© 2020 International Association for Gondwa

a b s t r a c t
a r t i c l e i n f o
Article history:Received 2 January 2020Received in revised form 25 April 2020Accepted 29 April 2020Available online 20 May 2020

Handling Editor: F. Pirajno

Keywords:LuermaPorphyry Cu depositTriassic andesitic rocksContinental arc settingGangdese

The Tibetan Plateau is one of the most significant Cu poly-metallic mineralization regions in the world and pre-serves important information related to subductional and collisional porphyry Cu mineralization. This study in-vestigates a new occurrence of Cu mineralization-related andesitic porphyries in the western domain of theGangdese magmatic belt and assesses its petrologic, zircon U-Pb geochronology, whole-rock chemistry, and Sr-Nd-Hf-Pb isotope data. Zircon U-Pb dating of three ore-related porphyries yields crystallization ages of212–211 Ma. These ages are consistent with previous molybdenite Re-Os dating, indicating a late Triassic mag-matic and Cu mineralization event in the western Gangdese magmatic belt. Nb, Ta, and Ti depletion, Th andLREE enrichment, and high La/Yb and Th/Yb ratios in addition to high U/Yb ratios from zircons suggest that themagmawas generated in an active continental arc setting. The porphyries have radiogenic isotopic compositionswith (87Sr/86Sr)i 0.70431–0.70473, εNd(t) +1.1 to +3.8, (207Pb/204Pb)i 15.601–15.622, and (208Pb/204Pb)i38.450–38.693, as well as high positive zircon εHf(t) values from+6.2 to+10.6 (mean value 8.3), correspondingtomodel ages (TDM) ranging from509Ma to 819Ma (mean 646Ma). This suggests that the andesiticmagmatismwas dominantly sourced from depleted mantle materials that were modified by subducted oceanic sediment-derived melts during the subduction of the Neo-Tethys Ocean. The mineralization-related porphyries containamphibole and epidote, as well as high whole-rock Fe2O3/FeO and zircon Ce4+/Ce3+ ratios, suggesting hydrousand highly oxidized parent magmas. Considering the existing Cu mineralization and highly oxidized magma ofthe well-preserved Triassic andesitic igneous rocks in the western Gangdese belt, the subduction-related conti-nental arcmagma system is favorable for subduction-related porphyry Cu deposits. The existence of Luerma por-phyry mineralization demonstrates that there are at least five generations of porphyry Cu-(Mo-Au)mineralization in the Gangdese magmatic belt, which advances the timeframe of porphyry mineralization tothe late Triassic.

© 2020 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

1. Introduction

Porphyry deposits are characterized by large tonnage, low grade,and large-scale hydrothermal alterations (Bissig and Cooke, 2014),and contain many of the copper (Cu), molybdenum (Mo), gold (Au)and rare element resources in the world (Sillitoe, 2010; Hou et al.,2015a, 2015b; Wang et al., 2018). The Tibetan Plateau, with a current

ological Processes and Mineralf Geosciences, Wuhan 430074,

[email protected] (Y. Zheng).

na Research. Published by Elsevier B.

elevation exceeding 3000 m above sea level, is the world's highest andwidest orogenic plateau. Therefore, it has become a natural laboratoryfor research on plate subduction and collision-related porphyry Cu-(Mo-Au) deposits. At present, the Tibetan Plateau is the largest copperresource in China (Mao et al., 2014; Zheng et al., 2015). Three large por-phyry copper deposit belts have been discovered: the Yulong porphyrycopper belt, including the Yulong and Malasong deposits (Du, 1985;Chang et al., 2017); the Bangong-Nujiang copper belt, represented bythe Duolong copper deposit (Ji et al., 2019b), and the Gangdese por-phyry copper belt, represented by the Qulong, Jiama, and Zhunuocopper deposits (Hou et al., 2015a; Yang et al., 2015; Zheng et al.,2015; Li et al., 2017; Wang et al., 2018). The Gangdese porphyry

V. All rights reserved.

http://crossmark.crossref.org/dialog/?doi=10.1016/j.gr.2020.04.006&domain=pdf

https://doi.org/10.1016/j.gr.2020.04.006

mailto:[email protected]

mailto:[email protected]

https://doi.org/10.1016/j.gr.2020.04.006

http://www.sciencedirect.com/science/journal/

www.elsevier.com/locate/gr

104 X. Chen et al. / Gondwana Research 85 (2020) 103–123

copper-belt mineralization can be divided into three main stages ac-cording to the evolution of the Tethyan tectonic domain in theGangdese magmatic belt: (1) Subduction of the Neo-Tethys Oceanduring the late Triassic-Middle Jurassic (213–170 Ma), (2) the earlyEocene Indo-Eurasian during continental collision (51–49 Ma), and(3) the late Oligocene-Miocene during the Indo-Asian continentalcollision and post-extension setting (23–12 Ma) (Hou et al., 2015a,2015b; Lang et al., 2014; J.X. Zhao et al., 2014; X.Y. Zhao et al.,2014; Wang et al., 2018). Several super-large porphyry Cu depositssuch as Qulong, Jiama, and Zhunuo are related to Indo-Asian conti-nental collision and post-extension setting in the Gangdese mag-matic belt. Rare subduction-related porphyry deposits(e.g., Xiongcun) have been proposed to be associated with the north-ward subduction of the Neo-Tethys oceanic crust. In general, subduc-tion oceanic slabs provide water, fO2, metals, and S required for theformation of porphyry Cu deposits (Audétat et al., 2012).Subduction-related magma is an excellent source for the formationof super-large porphyry Cu deposits; for instance, many porphyryCu deposits in the Andes are related to Pacific oceanic crust slab sub-duction (Hildreth andMoorbath, 1988; Bertrand et al., 2014). Thus, itis important to evaluate the porphyry metallogenic potential ofsubduction-related magma to predict potential porphyry Cu poly-metallic deposits in the Gangdese magmatic belt.

b

a

Fig. 1. (a) Tectonic map of the Tibetan Plateau (modified after Zhu et al., 2011 andWang et al.,2003 and Lai et al., 2019). JSSZ—Jinsha suture zone; SNMZ—Shiquan River-Nam Co Mélange zSiling Co thrust; GLT—Gugu La thrust; ST—Shibaluo thrust; ET—Emei La thrust; MCT—Main Ce—Great counter thrust; IYSZ—Indus-Yarlung Zangbo Suture zone; BNSZ—Bangong-Nujiang sut

The Gangdese magmatic belt (Fig. 1) is bounded by the Yarlung-Zangbo Suture Zone (YZSZ) and the Bangong-Nujiang Suture Zone(BNSZ) (Yin and Harrison, 2000). It extends N1500 kmacross the south-ern Lhasa terrane of Tibet, and the subduction of the Neo-Tethys Ocean,the Indian-Asian collision, and the Tibetanuplift have preserved vital in-formation through the formation of Mesozoic and Cenozoic igneousrocks. The southern Lhasa terrane of the Gangdese magmatic belt con-sists of Mesozoic to Cenozoic granitoids with depleted mantle-like Nd-Hf isotopic signatures, indicating significant Mesozoic or early Cenozoiccrustal growth (Ji et al., 2009a; Zhu et al., 2011, 2013; Ma et al., 2018).Several contrasting models have been proposed to explain the forma-tion of Mesozoic magma in the southern Lhasa terrane. The debateshave primarily differedwith regard to tectonicmodels and dynamic set-ting. Three alternative tectonic models have been proposed to explainthese magmatic origins: (1) The initial northward subduction of theNeo-Tethyan oceanic lithosphere (e.g., Ji et al., 2009a; Tang et al.,2015; Ma et al., 2018; Shui et al., 2018; Lang et al., 2019a, 2019b;Wang et al., 2019); (2) a back-arc basin related to the southward sub-duction of the Bangong-Nujiang oceanic lithosphere (Pan et al., 2012;Zhu et al., 2011, 2013; Liu et al., 2019a); and (3) melting of the mantlewedge with overlying crust in response to upwelling asthenosphericmantle caused by the breakoff or roll-back of the Sumdo oceanic litho-sphere (Dong and Zhang, 2013). This was previously positioned

2014). (b) Geological map of the Lhasa terrane (modified after Pan et al., 2004, Kapp et al.,one; LMF—Luobadui-Milashan Fault; SGAT—Shiquanhe-Gaize-Amdo thrust; GST—Gaize-ntral thrust; MBT—Main Boundary thrust; THFT—Tethyan Himalaya fold-thrust belt; GCTure zone; GT—Gangdese thrust.

105X. Chen et al. / Gondwana Research 85 (2020) 103–123

between the central and southern parts of the Lhasa terrane (Dong andZhang, 2013). Regarding the dynamic setting, the magmatic suite hasbeen proposed as an arc product; however, no consensus has beenreached as to whether it is an island arc (Aitchison et al., 2007), a conti-nental arc (Zhu et al., 2013; Zhang et al., 2014), or a back-arc basin (Songet al., 2014). Thus, accurate geochronology and detailed geochemicalstudies of subduction-related magmatic rocks are vitally important toestablish the geodynamic setting and evolutionary history of the south-ern Lhasa terrane.

The Luerma porphyry deposit (Fig. 2) is located in the Dajia Cuoarea of Angren County, in the western domain of the Gangdese mag-matic belt, about 200 km west of the Zhunuo deposit (Liu et al.,2019a, 2019b, 2019c) (Fig. 1b). Molybdenite Re-Os dating indicatesa mineralization age of ca. 213 Ma (late Triassic) (Liu et al., 2019b),thus representing the oldest known porphyry deposit in the south-ern Lhasa terrane. The presence of the deposit is expected to extendthe porphyry copper belt for about 200 km to the west in theGangdese magmatic belt, which is of great significance to researchon porphyry mineralization spatial distribution and genetic mecha-nisms. This paper presents zircon U-Pb ages, whole-rock geochemis-try, and Sr-Nd-Hf-Pb isotope data for ore-related Triassic monzoniteporphyry in the western segment of the southern Lhasa terrane. Themain aims are to provide insights into the petrogenesis of these por-phyries and to provide new constraints on the early Mesozoic tec-tonic evolution of the southern Lhasa terrane. Future studies basedon the framework of the current paper will help to further estimatethe porphyry Cu metallogenic potential of subduction-related Trias-sic igneous rocks in the western Gangdese belt.

2. Geological setting

The Lhasa terrane, which extends for N2000 km, is a major con-stituent of southern Tibet. It is situated between the YZSZ in thesouth and the BNSZ in the north, and is composed of northernLhasa, central Lhasa, and the southern Lhasa terrane. These are

ZhimaTotel

To Saga

To Cuoqin

To Rusa

E d1

Q

Cu-1

Au(Cu)-2

2.5km

85°39′E 85°47′E

30°0

0′N

30°0

5′N

Dajia Co

ZK03

ZK04

ZK02

ZK01

P3

P2

Fig.2b

Fig. 2. Geological map of the Luerma porph

bounded by the Shiquanhe-Nam Tso Mélange zone (SNMZ) and theLuobadui-Milashan fault (LMF) (Fig. 1b) (Zhu et al., 2011). It is com-monly assumed that the terrane was rifted from Gondwanaland dur-ing the Carboniferous-Early Permian, then drifted northward, andfinally collided with the Qiangtang terrane (Yin and Harrison,2000). The crystalline basement within the Lhasa terrane crops outalong the northern margin of the terrane as an orthogneiss(e.g., the Amdo orthogneiss) aged 530 to 850 Ma (Guynn et al.,2006). Ordovician-Triassic strata mainly occur in both the northernand southern terranes. The northern Lhasa subterrane is assumedto consist of a juvenile crust, with overlying Middle Triassic to Creta-ceous sedimentary rocks and an abundance of early Cretaceousmedium-K calc-alkaline arc volcanic rocks and granitoids (Zhuet al., 2013). The central Lhasa subterrane is characterized by ancientcrust, and represents a possible microcontinent that experiencedmulti metamorphic events during the Neoproterozoic (Guynnet al., 2012). The overlying strata include Carboniferous-Permianand Upper Jurassic-Lower Cretaceous sedimentary rocks. SouthernLhasa is dominated by juvenile crust (with local ancient crust), cov-ered by Cretaceous-Tertiary Gangdese batholith and PaleogeneLinzizong volcanic succession with minor sedimentary rocks (Moet al., 2007, 2008; Zhu et al., 2011). Based on the magmatic evolutionhistory, the following three major phases have been identified:(1) From 220 to 70Ma, magmatic rocks were generated through par-tial melting of the Neo-Tethys oceanic crust and subduction,followed by slab rollback, resulting in asthenosphere upwelling andthe formation of granitoids and related volcanic rocks (Ma et al.,2018; Lang et al., 2019a, 2019b; Wang et al., 2019). (2) The India-Eurasia collision was initiated at around 65 Ma (Mo et al., 2003).The syn-collision magmatism produced granitoid batholiths of Pa-leocene age (66–55 Ma; Chu et al., 2006), the 5000-m-thickLinzizong volcanic succession (65–43 Ma; Mo et al., 2007, 2008),and smaller volume Eocene Dazi picritic-basalt lavas (40–38 Ma;Gao et al., 2008) (Fig. 1). These magmas formed in the context ofnorthward subduction (Ding et al., 2003), a subsequent roll-back

Cu-3

Lake

Quaternary

Paleogene

Triassic limestone

Permian limestone

Permian conglomerate

Permian sandstone

Monzonite porphyry

monzodiorite

Triassic gabbro

Permian gabbro

Fault

Porphyry Cu orebodiesCu-1

Vein-like Cu-Au orebodyAu(Cu)-2

Vein-like Cu orebodyCu-3

Profile and drilling

800m0

Sample location

yry Cu deposit (after Liu et al., 2019a).


(Chung et al., 2005), and finally the break-off of the Neo-Tethyanoceanic slab (Gao et al., 2008). (3) Post-collision magmatism formedMiocene potassic and ultrapotassic magmas (Turner et al., 1993),and associated porphyritic granitoid stocks with abundant Cu-(Mo-Au) poly-metallic ores, including those of the Qulong, Zhunuo, andJiama deposits (Hou et al., 2015a, 2015b).

The geological features of the Luerma Cu-Au deposit have been de-scribed previously by Liu et al. (2019a, 2019b). Themain exposed stratainclude sandstone, limestone of the lower Permian, Triassic quartz con-glomerate and bioclastic limestone, and volcaniclastic rock from the Pa-leocene Dianzhong formation. Three main igneous rock units arepresent in the deposit (Figs. 2 and 3): (1) Monzodiorite batholith ac-counts for ~50% of the surface outcrop area across thewhole district. Iso-topic ages for a number of these intrusions have recently been reported:two monzodiorite samples collected from the batholith yielded LA-ICP-MS U-Pb zircon ages of 212.1 ± 0.6 Ma and 212.8 ± 0.7 Ma (Liu et al.,2019a). Bulk geochemical and Sr-Nd isotopic compositions ofmonzodiorite have shown that they formed by partial melting of the ju-venile crust during the northward subduction of the Yarlu Zangbo oce-anic crust in the Neo-Tethys Ocean (Liu et al., 2019a); (2) two samplesfrom a Middle Permian gabbro, located in the northern part of the de-posit, provided LA-ICP-MS U-Pb zircon ages of 262.7 ± 2.3 Ma and263.9 ± 2.4 Ma (Li et al., 2012); (3) ore-related porphyries, comprisingmonzonite porphyry dykes, are composed of several small irregularstocks and dykes, with an exposed area of about 0.1 km2. They contain

52

00

53

00

54

00

55

00

56

00

NZ K01

Z K02

52

00

53

00

54

00

55

00

56

00

100 200 300 400 500

Z

Z K01

52

00

53

00

54

00

55

00

56

00

100 200 300 500

100 200 300 400 500 600 700 800 900 10000

b

a

0 10

Ele

va

tio

n(m

)

Ele

va

tio

n(m

)

Ele

va

tio

n(m

)

CCu-11

ηs(%)

Fig. 3. (a) Geologic cross section P3 showing rock types at the Luerma. (b) Apparent polarizabiliCu mineralization north of P3 (Xiang et al., 2020). Legend as in Fig. 2.

plagioclase (~50–60 vol%), potassium feldspar (~30–35 vol%), amphi-bole (~10–15 vol%), and epidote (~5–8 vol%) with minor Fe-oxides(e.g., hematite) (Fig. 4f–i). The ages and petrogenesis of these porphy-ries are not well known.

Three copper orebody groups were identified according to thetrench and drilling (Fig. 2). Cu-1 is located northwest of the studyarea and is distributed in an axial shape on top of the monzonite por-phyry (Fig. 3). Its length along the strike is 200–300 m, its extensionis N550 m, the orebody edge is not controlled by drilling (Fig. 3), andthe thickness is 1.36–7.66 m with a Cu grade of 0.21–0.52%. The in-vestigated samples are located around the Cu-1 orebody group. TheAu (Cu)-2 orebody group is located in the middle of the miningarea (Fig. 2), in the NE trending structural fracture zone. The fracturewidth is 2–15 m, the length exceeds 1.5 km, the control length ex-ceeds 200 m, and the extension is N100 m. There are four layers oforebodies ranging from 0.42–1.01 m in thickness, and with Augrades of 1.2–37.7 g/t and Cu grades of 0.26–0.73%. The Cu-3 orebodyis located in the southeastern part of the mining area (Fig. 2). It is amagmatic-hydrothermal vein-type copper orebody and occurs inthe nearly east-west structural fracture zone with a length ofN560 m and a thickness of 1.28–8.63 m. The scale of the fracturezone suggests that the orebody extends on both sides and is deep,with a Cu grade of 0.20–0.44%. The ore minerals from theseorebodies are mainly chalcopyrite, bornite, malachite, and nativegold (Fig. 4i–l). Bornite and chalcopyrite display interaction growth

52

00

53

00

54

00

55

00

56

00

N

Z K02

Z K01

0 600 700 800 900 1000

K02

0 600 700 800 900 1000(m)

100 200 300 400 500 600 700 800 900 10000

c

N

0 4800

1

ps(Ω·m)

ty and (c) apparent resistivity of cross section P3, suggesting the existence of undiscovered

Fig. 4. Hand-specimen photographs and photomicrographs illustrating the petrographic and mineralization characteristics of the monzonite porphyries and monzodiorites. (a–b) themonzonite porphyries intruded into monzodiorites. (b) The hand-specimen of the monzonite porphyries. (c) The hand-specimen of malachite-bearing monzonite porphyries. (d) Thehand-specimen of monzodiorites. (f–i) Cross-polarized light images showing the occurrence of plagioclase, amphibole, epidote, and chalcopyrite in the monzonite porphyries. (j–l)Reflected light images showing that the interaction growth of bornite and chalcopyrite, and their rim has turned into hematite. (l) Some malachite has been recognized in thereflected light images. Abbreviations: Ccp-chalcopyrite; Mal-malachite; Bn-bornite; Ep-epidote; Hem-hematite; Amp-amphibole, Pl-plagioclase, Kfs-K-feldspar.


textures with rims that have turned into hematite (Fig. 4j–k). Mala-chite was identified from reflected light images (Fig. 4l). Re-Os isoto-pic dating of the mineralizing events in the deposit was recentlyconducted by Liu et al. (2019b). Molybdenite samples collectedfrom the ore-related porphyry yield a distinct Re-Os isochron ageof 213 Ma. In-situ S-Pb pyrite, chalcopyrite, and arsenopyrite iso-topes show that the ore-forming materials were mainly derivedfrom Late Triassic magmatism (Liu et al., 2019c).

The Cu-1 ore body in the Luerma deposit exhibits typicalporphyry-type alterations on top of the monzonite porphyry(Fig. 3). The alteration, mineralization, and hydrothermal veinshave been documented in detail by Liu et al. (2019c) and only abrief review is presented here. Hydrothermal alterations enclosingthe Cu-1 ore body broadly exhibit inner potassic and silicic zones,surrounded by an outer argillic and propylitic zone. Vein formation,

Cu mineralization, and ore-related alterations in the Cu-1 ore bodycan be grouped into three stages (quartz-potash feldsparpolymetallic sulfide stage (S1), quartz-polymetallic sulfide stage(S2), and late quartz‑carbonate mineral polymetallic sulfide stage(S3)). The S1 stage consists of K-feldspar, quartz + K-feldspar ± bi-otite ± magnetite ± chalcopyrite ± pyrite ± molybdenite, andquartz ± magnetite ± chalcopyrite ± pyrite ± molybdenite veins.This stage mainly occurs in the monzonite porphyry. Quartz, quartz+ pyrite, and quartz + pyrite + chalcopyrite + bornite ±molybde-nite veins from the S2 stage are dominated by quartz and chalcopy-rite + pyrite+ bornite, and represent the main Cu mineralizationevents. More than 80% of Cu at the Luerma deposit are deposited instages S1 and S2. S3 late-stage calcite, calcite ± chalcopyrite + pyrite±molybdenite ±magnetite ± hematite, and quartz + calcite + ep-idote± chalcopyrite± pyrite ±molybdenite veins are characterized


by argillic and propylitic alteration halos and have little economicsignificance.

3. Materials and analytical methods

3.1. Materials

Thirteen andesitic rock samples were collected from surface ex-posures in the Luerma area, including five monzonite porphyry sam-ples (MP0106-b2, MP0106-b3-1, MP0106-b3, MP0108-b6, andMP0106-b3) and eight monzodiorite samples (MD-01, MD-02, MD-03, MD-05, MD-06, MD-07, MD-08, and MD-09). All samples wereexamined by optical microscopy, and whole-rock major elementsand rare earth elements were assessed. All monzonite porphyrysamples (MP0106-b2, MP0106-b3-1, MP0106-b3-2, MP0106-b3-4,andMP0106-b3) were selected for bulk-rock Sr-Nd-Pb isotopic anal-ysis. Three monzonite porphyry samples (MP0108-b6, MP0106-b3,and MP0106-b2) and one monzodiorite sample (MD-01) were se-lected to test U-Pb zircon ages. Additionally, two monzonite por-phyry samples (MP0106-b3 and MP0106-b2) were subjected tozircon Hf isotope analysis. Sr-Nd-Hf-Pb isotopic analysis of barrenmonzodiorites has been reported by Liu et al. (2019a) and their re-sults were used for comparative analysis.

3.2. Analytical methods

Whole-rock major and trace elements and Sr-Nd-Hf isotopiccompositions of the samples were measured by the Beijing ResearchInstitute of Uranium Geology. The zircon morphology and U-Pb dat-ing results were investigated by Wuhan Sample Solution AnalyticalTechnology Co., Ltd., China. Zircon Hf isotopic analysis was carriedout using laser ablation sampling and multiple collector inductivelycoupled plasma mass spectrometry by the State Key Laboratory ofGeological Processes and Mineral Resources, University ofGeosciences, Wuhan, China. Analytical procedures and several ofthe parameters used in the calibration process are presented in “Ap-pendix A. Analytical methods”. Detailed data are shown in Supple-mentary Tables 1–5.

3.3. Zircon oxygen fugacity and Ce4+/Ce3+ ratio estimation

Trail et al. (2011, 2012) proposed a new calibration method fordetermining the absolute oxygen fugacity of magmatic meltbased on the cerium anomaly in zircon and the Ti-in-zircon tem-perature, which can be expressed by the following empirical equa-tion:

InCeCe�

� �D¼ 0:1156� 0:0050ð Þ � In f O2

� �þ 13860� 708T Kð Þ −6:125

� 0:484 ð1Þ

where T is the absolute temperature calculated using Ti-in-zirconthermometry (Ferry and Watson, 2007) and fO2 is the oxygen fu-gacity. (Ce/Ce*)D is the Ce anomaly in zircon and is determinedby the lattice strain model (Blundy and Wood, 1994). Low LREEconcentrations can be distorted by small inclusions, typically caus-ing large analytical errors. Alternatively, the lattice strain model,which quantifies the relationship between partition coefficient log-arithms and ionic radii (Blundy and Wood, 1994), allows Ce/Ce* tobe calculated from more enriched Gd to Lu together with Nd andSm, which provides more reliable estimates of Ce anomalies andoxygen fugacities (Ballard et al., 2002; Qiu and Qiu, 2016).

The zircon Ce4+/Ce3+ ratio can provide qualitative and relative esti-mates of the magma oxidation state (Ballard et al., 2002; Zhang et al.,2017). Ce belongs to variable valence elements in magma, and Ce4+ ispartitioned into zircon in strong preference to Ce3+ because of its

identical charge and similar size in eight-fold coordination (0.97 Å) toZr (r= 0.84 Å) (Ballard et al., 2002). The ratio of Ce4+ to Ce3+ in zirconis:

Ce4þ=Ce3þ� �

zircon¼

Cemeit−Cezircon

Dzircon=meltCe3þ

CezirconDzircon=meltCe4þ

−Cemelt

ð2Þ

To solve Eq. (2) for the Ce4+/Ce3+ ratio in zircon, four values areneeded: Cezircon, Cemelt, and the zircon-melt distribution coefficientsfor Ce4+ and Ce3+ (DCe3+

zircon/melt and DCe4+zircon/melt). Cezircon was mea-

sured directly using in-situ LA-ICP-MS. Cemelt was assumed to be equiv-alent to the whole-rock (as a proxy for melt) Ce concentration, andzircon-melt partition coefficients for DCe3+

zircon/melt and DCe4+zircon/melt

were estimated using the lattice strain model of Blundy and Wood(1994).

4. Results

4.1. Major and trace element geochemistry

Five ore-related monzonite porphyries were collected from theLuerma area. The SiO2 and Na2O + K2O contents range from 54.17 wt% to 57.81 wt% and from 4.06 wt% to 8.95 wt%, respectively (Supple-mental Table 1). According to the total alkalis vs. silica TAS diagram(Fig. 5a), all samples (except forMP0106-b3-1) exhibit sub-alkaline fea-tures. The rocks are plotted in the basaltic andesite and trachy andesitefield (Fig. 5a). In the K2O vs. SiO2 diagram, the rocks showmedium-K af-finities except for one sample that has a shoshonitic character (Fig. 5b).The samples have high Na2O/K2O values (1.42–6.00) (Fig. 5c) and a rel-atively wide range of Mg# from 25.61 to 40.09 (Fig. 5d). In the Harkerdiagrams (Fig. 6), SiO2 exhibits a good linear relationship with theother major elements (e.g., Fe2O3, CaO, P2O5, and MgO), indicatingthat magmatic crystallization played a significant role in the evolutionof ore-related monzonite porphyries. These rocks have high contentsof Al2O3 (17.38–18.54 wt%), Na2O (3.22–5.26 wt%), and Sr(600–1149 ppm), low contents of MgO (1.39–2.94 wt%), Yb(1.69–2.28 ppm), and Y (16.6–21.8 ppm), and high Sr/Y (36.22–62.75)ratios. On the chondrite-normalized REE diagram, they show LREE-enriched patterns ((La/Yb)N=8.79–16.24) and negligible Eu anomalies(Eu/Eu* = 0.88–0.95; Fig. 7a). Primitive mantle-normalized trace ele-ment curves show enrichment in large ion lithophile elements (LILEs;e.g., Rb and K), positive Sr anomalies, and depletions in high fieldstrength elements (HFSEs; e.g., Nb, Ta, and Ti) (Fig. 7b).

The remaining eight monzodiorites have relatively high SiO2 con-tents (61.32 wt% and 62.23 wt%), compared to those previously re-ported by Liu et al. (2019a). In the total alkalis vs. silica TAS diagram,the samples exhibit sub-alkaline features and are found in the andesiteand trachy andesite field (Fig. 5a). In the K2O vs. SiO2 diagram, the rocksexhibit high K and shoshonitic affinities (Fig. 5b). The samples have highNa2O/K2O values (0.75–1.34) and a relatively wide range of Mg# from42.75 to 44.84 (Fig. 5d). Chondrite normalized REE patterns from thebarren monzodiorites are characterized by an enrichment of light rareearth elements (LREEs) and depletion of heavy rare earth elements(HREEs) with weak negative Eu anomalies (Eu/Eu* = 0.84–0.90) and(La/Yb)N ratios ranging from 14.46–17.68 (Fig. 7c). The REE contentsare higher than in Xiongcun ore-related rocks (Fig. 7c). Primitivemantlenormalized spidergrams (Fig. 7d) show that LILEs, such as Ba, Sr, K, andK, as well as Sr, are highly enriched and depleted in HFSEs with Nb, Ta,Ti, and P, which are typical characteristics of arc magmas.

M

Crust

AF

C

Ore-related porphyries

Barren monzodiorite

Xiong cun ore-related

porphyries

Fig. 5. Classification diagrams for the monzonite porphyries and monzodiorites: (a) SiO2 vs. Total alkalis diagram; (b) SiO2 vs. K2O diagram; (c) Na2O vs. K2O diagram; (d) SiO2 vs. Mg#

diagram; Pure crustal partial melt at 7 kbar and 825–950 °C are from Sisson et al. (2005). Pure crustal partial melt at 7–13 kbar and 825–950 °C are from Patiño Douce and Johnston(1991). Pure crustal partial melt at 8–16 kbar and 1000–1050 °C are from Rapp and Watson (1995). Xiongcun ore-fertile granitoid from Qu et al. (2007), Lang et al. (2010) and Huanget al. (2011). Part barren monzodiorites from Liu et al. (2019a)


4.2. Sr-Nd-Pb isotopic compositions

The whole-rock Sr-Nd-Pb isotopic data of the ore-related monzo-nite porphyries are presented in Supplementary Table 2. They ex-hibit uniform (87Sr/86Sr)212 Ma ratios ranging from 0.704309 to0.704738 and εNd(t) values ranging from +1.1 to +3.8, with two-stage Nd model ages of 690–913 Ma and a mean age of 788 Ma(Fig. 8). Similarly, the calculated (87Sr/86Sr)213 Ma ratios of the barrenmonzodiorite samples range between 0.705531 and 0.706134; fur-ther, the εNd(t) values range from +1.9 to +2.9 (Liu et al., 2019a),with two-stage Nd model ages of 764–852 Ma and a mean age of792 Ma (Fig. 8). The ore-related monzonite porphyries exhibit rela-tively homogeneous Pb isotopic compositions and (206Pb/204Pb)212Ma ratios of 18.385–18.494, (207Pb/204Pb)212 Ma ratios of15.591–15.622, and (208Pb/204Pb)212 Ma ratios of 38.355–38.693(Fig. 9). Furthermore, the Pb isotopic compositions of the barrenmonzodiorite samples from Liu et al. (2019a) are also uniform; sub-sequently, the (206Pb/204Pb)213 Ma, (207Pb/204Pb)213 Ma, and(208Pb/204Pb)213 Ma ratios are 17.96–18.536, 15.566–15.652, and37.647–38.607, respectively (Fig. 9).

4.3. Zircon morphology, U-Pb ages, and trace elements

The zircons from the porphyries andmonzodiorite samples are gen-erally colorless and transparent, euhedral to subhedral, and ranged insize from 80 to 150 μm with length-to-width ratios from 2:1 to 1.5:1(Fig. 10). The CL images demonstrate that most of the zircons haveclear and oscillatory growth zoning (Fig. 10). Several inherited zircongrains and relict cores occur in zircons from the monzonite porphyrysample (MP0106-b3) (Fig. 10c).

Analysis of 15 different grains from porphyry sample No. MP0108-b6 had high Th (275–1551 ppm) and U (348–1081 ppm) contents,with Th/U ratios of 0.52–1.43 (Supplementary Table 3; Fig. 11a). Theyhave matching 206Pb/238U ages ranging from 213.9 ± 2.2 to 210.5 ±4.3Ma, yielding a weightedmean of 212.1± 1.2Ma (n= 15, MSWD=0.17; matching values from 89.99 to 99.67%; Fig. 11a). In contrast, 20tests from 20 different grains from porphyry sample No. MP0106-b3yield variable concentrations of Pb (16–153 ppm), Th(116–1355 ppm), and U (154–674 ppm) with Th/U = 0.75–2.02 (Sup-plementary Table 3; Fig. 10b). The 206Pb/238U zircon ages range from210.3 ± 4.6 to 213.9 ± 3.1 Ma with a weighted mean of 212.4 ±

Fig. 6. (a) SiO2 vs. Al2O3; (b) SiO2 vs.MgO, the plots for the discrimination of fractional crystallization andmagmamixing (Keller et al., 2015); (c) SiO2 vs. CaO; (d) SiO2 vs. TFeO; (e) SiO2 vs.P2O5; (f) SiO2 vs. (Dy/Yb)N; (g) SiO2 vs. Sr; (h) SiO2 vs. Ba; (i) SiO2 vs. Zr/Sm. HPFC, high-pressure fractional crystallization involving garnet (Macpherson et al., 2006); LPFC, low-pressurefractional crystallization (Castillo et al., 1999); Due to the incompatibility of Zr and compatibility of Sm in amphibole (Drummond et al., 1996), the fractional crystallization will cause theincreasing of Zr/Sm ratios in residual magmas; Data sources are as in Fig. 4.


1.2 Ma (n= 20, MSWD= 0.13; matching values from 90.02 to 99.57%)(Fig. 11b). Two zircon populations in porphyry sample No. MP0106-B2could be distinguished: i) The first population is composed of smallcrystals, 80–150 μm in size, with a clear dark core and an oscillatorygrowth rim in CL images; and ii) the second population has oscillatory

growth zoning in CL images (Fig. 11c). These dark inherited coreshave low Th (26–375 ppm) and U (37–505 ppm) contents that resultin high Th/U ratios of 0.21–2.19 (Supplementary Table 3; Fig. 11c).The 206Pb/238U ages of these inherited cores range from 1768.9 ±18.1 Ma to 374.7 ± 4.3 Ma. Eleven analyses of oscillatory growth rims

Fig. 7. Chondrite-normalized REE patterns for (a) ore-related monzonite porphyries and (c) barren monzodiorite; primitive mantle-normalized multi-element diagram for the (b) ore-related monzonite porphyries and (d) barren monzodiorite. Xiongcun ore-fertile granitoid from Qu et al. (2007), Lang et al. (2010) and Huang et al. (2011).


produce Th (91–795 ppm) and U (117–412 ppm) contents, with Th/Uratios of 0.71–1.93 (Supplementary Table 3; Fig. 11c). Their 206Pb/238Uages range from 213.5 ± 3.0 Ma to 206.6 ± 2.3 Ma, with a weightedmean of 210.6 ± 1.7 Ma (n = 11, MSWD = 0.48; matching valuesfrom 91.72 to 99.57%; Fig. 11c). A total of 23 zircon analyses from

Fig. 8. Whole-rock εNd(t) vs. Age of ore-related monzonite porphyries and barrenmonzodiorite from the Luerma area and Triassic cumulate appinite with reference linesfor depleted mantle (DePaolo, 1981; Goldstein et al., 1984) and for the chondriticuniform reservoir (CHUR) (Bouvier et al., 2008). Reference TDM age evolution lines forCambrian, Neoproterozoic, Mesoproterozoic and Paleoproterozoic average continentalcrust were calculated assuming a typical crustal 147Sm/144Nd ratio of 0.12 (Liew andHofmann, 1988). Data of the barren monzodiorite are from Liu et al. (2019a). Triassiccumulate appinite in the Southern Gangdese belt are from Ma et al. (2018).

monzodiorite sample MD02 have medium Th (129–685 ppm) and U(129–350 ppm) contents with Th/U ratios from 0.97–1.96 (Supplemen-tary Table 3; Fig. 11d). These zircons yield a weighted mean 206Pb/238Uage of 201.4± 1.2Ma (MSWD= 0.39) (Fig. 5a). The U-Pb dating of themonzodiorite sample is younger than the ore-related porphyries.

4.4. Ti-in-zircon temperature, zircon Ce4+/Ce3+ ratio estimation, and oxy-gen fugacity

Zircon from the ore-related porphyries has Ti contents of0.82–5.48 ppm for sample MP0108-b6, 2.36–10.37 ppm for sampleMP0106-b3, and 3.91–7.7 ppm for sample MP0106-b2. Aside from out-liers, the average Ti-in-zircon temperature for sample MP0108-b6 is656 ± 36 °C; respective temperatures for samples MP0106-b3 andMP0106-b2 are 691 ± 26 °C and 696± 16 °C (Fig. 12a; SupplementaryTable 4). Zircon from sample MD2 has Ti ppm values ranging from 5.66to 9.68 and the corresponding temperatures range from 697 to 743 °Cwith a mean of 716 ± 12 °C (Fig. 12a; Supplementary Table 4).

The average whole-rock trace element data for ore-related porphy-ries and barren monzodiorites combined with zircon REE concentra-tions are used to calculate zircon Ce4+/Ce3+ ratios. Ages and ratios areplotted in Fig. 12b. The calculated Ce4+/Ce3+ ratios for zircon fromMP0108-b6 aged 212 Ma range from 178 to 1004 (average: 528). Incontrast, zircon ratios from sample MP0106-b3 mostly range from 155to 554 (average: 431). The values for new growth zircon from sampleMP0106-b2 range between 96 and 484, with an average of 263. Barrenmonzodiorites have Ce4+/Ce3+ ratios from 43 to 338, with a mean of197. Ore-related porphyries have higher Ce4+/Ce3+ ratios than barrenmonzodiorites, which were calculated using the lattice strain model ofBlundy and Wood (1994).

The zircon log(fO2) values represent the oxidation state of the meltwhen zircon crystallizes. The log(fO2) results average −9.65 forMP0108-b6, −8.4 for MP0106-b3, and −10.12 for MP0106-b2

Fig. 9. Plot diagrams of (a) 207Pb/204Pbi vs. 206Pb/204Pbi, (b) 208Pb/204Pbi vs. 206Pb/204Pbi for the ore-related monzonite porphyries and barren monzodiorite from the Luerma area.Figures and compiled data are modified according to previously published work (Zhang et al., 2019). The data and Northern Hemisphere Reference Line (NHRL): 207Pb/204Pbi =0.1084 × 206Pb/204Pbi + 13.491; 208Pb/204Pbi = 1.209 × 206Pb/204Pbi + 15.627 207Pb/204Pbi. All data are recalculated to ca. 54 Ma.

Fig. 10. Representative zircon cathodoluminescence (CL) images ore-relatedmonzonite porphyries (a) MP0108-b6, (b) MP0106-b3, (c) MP0106-b2 (d) a barren monzodiorite (MD-02).The white and purple red circles denote the locations of LA–ICP–MS U-Pb dating and in situ Hf isotope analyses, respectively.


0.0

0.1

0.2

0.3

0 1 2 3 4 5

200

600

1000

1400

1800

.

0.026

0.030

0.034

0.038

0.042

0.18 0.20 0.22 0.24 0.26 0.28 0.30

170

190

210

230

250

270

(c)YWJG0106-B2

Mean=210.6±1.7 Ma

MSWD=0.48

0.022

0.026

0.030

0.034

0.038

0.042

0.15 0.17 0.19 0.21 0.23 0.25 0.27 0.29 0.31

150

170

190

210

230

250

270

.

Mean=201.4±1.2 Ma

MSWD=0.39

(d)YWJG-GS1-01

20

6P

b/2

38U

20

6P

b/2

38U

(a)MP0108-b6

Mean=212.1±1.2 Ma

MSWD=0.17

(b)MP0106-B3

(c)MP0106-B2 (d)MD-2

Mean=210.6±1.7 Ma

MSWD=0.48

Mean=201.4±1.2 Ma

MSWD=0.39

207Pb/235U 207Pb/235U

20

6P

b/2

38U

207Pb/235U

0.022

0.026

0.030

0.034

0.038

0.042

0.15 0.17 0.19 0.21 0.23 0.25 0.27 0.29 0.31207Pb/235U

20

6P

b/2

38U

150

170

190

210

230

250

270

204

208

212

216

Mean=212.4±1.2 Ma

MSWD=0.13

0.024

0.028

0.032

0.036

0.040

0.044

0.17 0.19 0.21 0.23 0.25 0.27 0.29 0.31207Pb/235U

20

6P

b/2

38U

160

180

200

220

240

260

205

207

209

211

213

215

217

193

197

201

205

209

Ag

e (

Ma

)

Ag

e (

Ma

)

Ag

e (

Ma

)

Fig. 11. LA-ICP-MS zircon U-Pb diagrams for the ore-related monzonite porphyries (a) MP0108-b6, (b) MP0106-b3, (c) MP0106-b2 (d) a barren monzodiorite (MD-02).


(Fig. 12a; Supplementary Table 4). Log(fO2) results range from −15.57to −7.55, with a mean of −10.17. A clear decreasing fO2 trend is de-tected from ore-related porphyries to barren monzodiorites.

4.5. Zircon Hf isotope composition

Thirteen Lu-Hf analyses are performed from sample MP0108-b6(Supplementary Table 5). They have relatively high 176Hf/177Hf ratios(0.282852–0.282954) and low 176Lu/177Hf ratios(0.001445–0.002660). At t = 212 Ma, the calculated εHf(t) valuesrange from +6.8 to +10.1 (Fig. 13). The TDM ages vary from 509 to699 Ma (Fig. 13). Zircons from the ore-related porphyries (MP0106-b3) have 176Lu/177Hf ratios of 0.001390–0.002560 and 176Hf/177Hf ratiosof 0.282835–0.282958 (Supplementary Table 5; Fig. 13). Assuming t=212 Ma for the core, the calculated εHf(t) values range from +6.2 to+10.6 (Fig. 13), with TDM from 526 to 819 Ma.

5. Discussion

5.1. Age of andesitic magmatism

Themagmatic rocks in the southern Lhasa terrane have been dividedinto five episodes, including late Triassic to early Jurassic (205–175Ma),early Cretaceous (130–100 Ma), late Cretaceous (100–80 Ma), Paleo-cene to Eocene (65–41 Ma), and Oligocene to Miocene (33–13 Ma) (Jiet al., 2009a; Mo et al., 2007, 2008; Zhu et al., 2011). Magmatic rocks

were mostly emplaced in the early Cretaceous to Paleogene (Mo et al.,2007, 2008; Chu et al., 2006; Ji et al., 2009a). Recently, however, an in-creasing number of Paleozoic to early Mesozoic magmatic rocks havebeen found in the southern Lhasa terrane. Prominent examples areZhengga amphibolite and granite (366–353 Ma) (Ma et al., 2019), lateTriassic cumulate appinite (Ma et al., 2018), Bima Tangbai granitoids(Guo et al., 2013), Quxu hornblende gabbros (Meng et al., 2016),Xiongcun (Lang et al., 2014), Naming granite pluton (Zhu et al., 2011),Dongga hornblende gabbros (Xu et al., 2017), Yeba Formation volcanicrocks (Zhu et al., 2008), and Sangri Group volcanic rocks (Kang et al.,2014). A few adakitic rocks were also reported among early Mesozoicmagmatic rocks in the southern Lhasa terrane, such as the Dongga andJiacha adakitic intrusions (Shui et al., 2018). Zircon CL images from theLuerma deposit show that most of the grains are euhedral with broadzoning and high Th/U ratios, typical of zircons in magmatic rocks (Wuand Zheng, 2004; Chen et al., 2019; Fig. 5; Supplementary Table 4). Zir-con U-Pb dating for the three ore-related monzonite porphyries yieldsweighted mean ages of 211.1 ± 1.2 Ma, 212.4 ± 1.2 Ma, and 210.6 ±1.7Ma (Fig. 11a–c). Although the three samples originate fromdifferentparts of the ore-related monzonite porphyries (Fig. 1c), their ages areindistinguishable (within analytical uncertainties) with a mean age ofca. 212 Ma, which corresponds to the timing of magma crystallization.One monzodiorite sample yields a weighted mean age of 201.4 ±1.2 Ma (Fig. 11a–d), which is much younger than previously reportedmonzodiorite (213–212 Ma) in this area (Liu et al., 2019a). Therefore,

Fig. 12. (a) Zircon log(fO2) vs. temperature diagram. (b) Zircon Ce4+/Ce3+ vs. Eu/Eu* diagram (fields of ore-bearing porphyries and ore-barren rocks are from Ballard et al. (2002), Lianget al. (2006), andWu et al. (2016)). (c)Whole-rock Fe3+/Fe2+ ratios vs. SiO2 for the ore-relatedmonzonite porphyries and barrenmonzodiorites at the Luerma. The dashed line representsthe boundary between magnetite- and ilmenite-series granitoids (after Hart et al., 2004). (d) log10(Fe2O3/FeO) vs. total FeO (after Blevin, 2004).

0 500 1000 1500

Age (Ma)

250 750 1250

Mesopro

tero

zoic

Mesopro

tero

zoic

Neo

Neo

pro

tero

zoic

pro

tero

zoic

Pale

ozoic

Pale

ozoic

( Vervoort and Kempt 2016)

Lu/Hf=

0.092

Lu/Hf=

0.092

Pale

oprote

rozoic

Pale

oprote

rozoic

DM

Bouvier et al., 2008Bouvier et al., 2008

CHURCHUR

0 500 1000 1500

Age (Ma)

250 750 1250

Mesopro

tero

zoic

Me

ciozoretorpos

Neo

Neo

( Vervoort and Kempt 2016)

Lu/Hf=

0.092

Lu/Hf=

0.092

Pale

oprote

rozoic

Pale

oprote

rozoic

DM

Bouvier et al., 2008Bouvier et al., 2008

CHURCHUR

-10

-5

0

5

10

15

20

-10

-5

0

5

10

15

20

ε(t)

Hf

ε(t)

Hf

Lu/Hf=0.116

Lu/Hf=0.009

Lu/Hf=0.079Lu/Hf=0.079Lu/Hf=0.116

(a) Ore-bearing porphyries (this study) (b) Compiled dataLu/Hf=0.079

Lu/Hf=0.11

Ore-related

porphyries(this study)

Monzodiorite

(Liu et al.,2019)

Triassic cumulate appinite

(Ma et al., 2018)

Pale

ozoic

Pale

ozoic

pro

tero

zoic

pro

tero

zoic

Continental

arc

Oceanic arc

Lu/Hf=0.009

Fig. 13. Zircon εHf(t) vs. Age for the ore-related monzonite porphyries, barren monzodiorite, and Triassic cumulate appinite with reference lines for the depleted mantle and for thechondritic uniform reservoir (CHUR) (Bouvier et al., 2008). Data of the barren monzodiorite are from Liu et al. (2019a). Triassic cumulate appinite in the Southern Gangdese belt arefrom Ma et al. (2018).



it could be inferred that the Luerma region witnessed a major andesiticmagmatic event during the late Triassic.

The ages of the three ore-related porphyry samples are consistentwith previous molybdenite Re-Os dating (Liu et al., 2019b), indicatinga late Triassic porphyry Cu mineralization event in the westernGangdese magmatic belt. The deposit, at present, represents the oldestknown porphyry deposit in the southern Lhasa terrane and is expectedto advance the starting time of the mineralization of the porphyry cop-per deposit to the late Triassic.

5.2. Petrogenesis

Epidote is distributed in the andesitic rocks, indicating that theyunderwent low-grade metamorphism or alteration. Therefore, it isimportant to evaluate the metamorphism and alteration effects be-fore discussing their petrogenesis and tectonic setting. Zirconium isgenerally considered to be least mobile during low to medium-grade alterations and low-grade metamorphism, and can thus beused as a criterion to evaluate the mobility of other trace elements(e.g., Wood et al., 1979; Pearce et al., 1992; Polat et al., 2002). The rel-atively immobile elements (e.g., Nb, Ta, Hf, Sm, Nd, Ti, and REEs) inthis study have relatively good correlations with Zr (not shown),suggesting that these elements are not affected by metamorphismand alteration. However, the concentrated distributions of LILEs(e.g., Rb, Ba, and Sr) also indicate low alteration effects. Moreover,the ore-related and barren andesitic rocks exhibit subparallel REEand spider diagram patterns (Fig. 7), indicating that REEs andHFSEs (e.g., Nb, Ta, Th, and Ti) in rocks were relatively immobile dur-ing alteration (e.g., Bienvenu et al., 1990). Bulk-rock Sr-Nd-Pb and Hf

0

50

100

150

200

250

300

0 1 2 3 4 5 6 7 8 9

Ba/Th

La/Sm

Sla

b d

eh

yd

ra

tio

n

Sediment melting

(a)

(c)

Sr/Y

Y(ppm)

Fig. 14. Diagrams of (a) Sr/Y vs. Y; and (b) (La/Yb)N vs. YbN (Defant and Drummond, 1990).sediment melting and slab dehydration (Labanieh et al., 2012; Woodhead et al., 1998).

isotopic analysis of zircon from magmatic rock are relatively immo-bile during low-grade metamorphism and are used to determinerock origins and the evolution of both crust and mantle (Griffinet al., 2002). Therefore, REEs and HFSEs, coupled with Sr-Nd-Hf-Pbisotopes, could be used to constrain the petrogenesis and tectonicsetting of andesitic rocks.

Crustal contamination is almost inevitable for mantle-derived meltsduring their ascent through the continental crust (Thorpe et al., 1984).Given that crustal components generally contain distinctly low εNd(t) and εHf(t) and MgO and high 87Sr/86Sr ratios (Rudnick andFountain, 1995), any crustal contamination that occurs during magmaascent would cause an increase in (87Sr/86Sr)i and a decrease in εNd(t) with increasing SiO2 in themagma suites. However, such a composi-tional trend is not observed for ore-related and barren andesitic rocks(Fig. 6j–k), suggesting that minimal crustal contamination occurredduring their formation. Moreover, the vast majority of ore-related andbarren andesitic rocks have small initial 143Nd/144Nd ratio ranges(0.512585–0.512729) and high, positive εNd(t) values (+1.1 to +3.8)(Supplementary Table 2), which are also inconsistent with significantcrustal contamination.

A number of petrogeneticmodels have been suggested for the originof andesitic rocks: (a) partial melting of middle-thickened lower crust,from generally underplated mantle-derived magmas (Atherton andPetford, 1993; Wang et al., 2007); (b) partial melting of subductedyoung oceanic crust (Defant and Drummond, 1990); and (c) partialmelting of the metasomatized mantle wedge above the subductionzone, which was metasomatized by subduction fluids/melts. In addi-tion, mixing of mafic and silicic magmas (Streck et al., 2007) or high-pressure or low-pressure crystal fractionation and crustal

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10

Sr/Nd

Th/Yb

Sediment melting

Sla

b d

eh

yd

ra

tio

n

Ore-related porphyries

Barren

Continental

arc

Oceanic arc

(b)

(d)

YbN

(La/Yb)

N


(Ma et al., 2018)

(c) Source diagrams of Ba/Th vs. La/Sm and (d) Sr/Nd vs. Th/Yb distinguishing between


contamination of basaltic magmas present possible petrogenesis for an-desitic rocks (Castillo et al., 1999; Macpherson et al., 2006).

The ore-related monzonite porphyries are most likely generateddominantly from depleted mantle materials (metasomatized mantlewedge) that were modified by subducted oceanic sediment-derivedmelts during the subduction of the Neo-Tethys Ocean and underwentcrystal fractionation during the process. The following evidence corrob-orates this: First, the ore-related porphyries have high Na2O contentsand Na2O/K2O ratios (Fig. 5c), which are similar to rocks sourced fromthe partial melting of subducted oceanic crust that are generallyenriched in Na2O and depleted in K2O, with low K2O/Na2O (b0.5)(Defant and Drummond, 1990). Second, the typical product of slabmelting is adakitic rock with high Sr/Y and La/Yb ratios (e.g., Defantand Drummond, 1990), and these features are present in the ore-related porphyry. Third, previous studies have shown that slab-derived fluids have high Ba, Sr, U, and Pb contents (e.g., Labaniehet al., 2012; Woodhead et al., 1998). However, subducted oceanicsediment-derived melts contain high concentrations of both Th andLREE contents, but with distinctly elevated Th/Yb and La/Sm ratios(e.g., Labanieh et al., 2012). The ore-related porphyries have low Ba/Th and Sr/Nd ratios, but relatively high La/Sm and Th/La ratios(Fig. 14c–d), suggesting the potential involvement of sediment-derived melts in the generation of ore-related monzonite porphyries.The ore-related porphyries exhibit relatively low (87Sr/86Sr)i(0.704309–0.704738), (206Pb/204Pb)i (18.385–18.494), (207Pb/204Pb)i(15.591–15.622), and (208Pb/204Pb)i (38.355–38.693) ratios and rela-tively high εNd(t) (+1.1 to +3.8) and εHf(t) (+6.2 to +10.6) values(Figs. 8–9 and 13). These values are similar to those obtained fromYarlung Tsangpo ophiolites (Mahoney et al., 1998; Guilmette et al.,2009; Fig. 9), indicating that they were mainly sourced from partialmelting of the subducted Neo-Tethys oceanic slab. Therefore, the slab-derived melt-fluxed mantle melting model is favored. The hydrousmelts derived from altered oceanic crust/subducting sediment wouldmetasomatize the overlying mantle wedge, thus incorporating melt-mobile incompatible trace elements into the wedge and triggering itspartial melting for arc andesitic magmatism (Grove et al., 2012). Themelting, assimilation, storage, and homogenization (MASH) model ispopular for the study of andesite petrogenesis, suggesting that interme-diate to felsic continental arc magmas are formed by interactions be-tween hot, hydrous, mantle wedge-derived basaltic magmas, andlower crustal lithologies in MASH zones (Hildreth and Moorbath,1988; Wang et al., 2018). In this case, along with lithochemical andchronological constraints, we propose that the sub-arc mantle sources,metasomatized by slab-dominant hydrous melts, generated ore-related and barren andesitic rocks. Ti-in-zircon temperature can beused as an indicator of the crystallization temperature (Watson et al.,2006; Ferry and Watson, 2007). Zircon grains from the andesitic rockshad mean Ti-in-zircon temperatures of 682 ± 32 °C and 715 ± 11 °C,which are significantly lower than the andesitic magma temperatures,indicating that the magma may have undergone an evolutionary pro-cess. A good linear relationship between major, trace element, their ra-tios, and SiO2 is observed (Fig. 6), which was also reported for manyporphyry-related magmatic suites (Richards and Kerrich, 2007;Chiaradia et al., 2009), indicating crystal fractionation as an importantprocess during magma evolution.

The barren monzodiorite has similar Sr-Nd-Hf-Pb isotopes com-pared to the ore-related porphyries (Figs. 8–9 and 13), demonstratingtheir similar source. However, the barren monzodiorite had numerousmafic microgranular enclaves (MMEs), which may have undergonemagma mixing during formation or ascent. A comparison of observedtrends with differentiation trends and magma mixing of the ore-related porphyries and monzodiorites suggests that magma mixing in-fluenced magma petrogenesis (Fig. 6). In addition, the monzodioritehas high Sr-Nd-Pb-Hf isotopic composition variability and the εHf(t) variability (+5.0 to +14.1) (Liu et al., 2019a) was close to 10, indi-cating that magma mixing may have taken place.

The andesitic series have high Sr contents and Sr/Y and (La/Yb)N ra-tios, and no clear Eu anomalies, which indicated that plagioclase wasnot a residual phase during partial melting. Furthermore, because garnetis usually a residualmineral for slabmelting, in the case of rockswithmid-dle Y (16.58–21.81 ppm; Supplementary Table 1) and relatively flat HREEpatterns (Fig. 7a and c), it is likely a residualmineral.Most of the andesiticseries is plotted along with the partial melting trend for the amphiboliteor garnet amphibolite on Y vs. Sr/Y and YbN vs. (La/Yb)N diagrams(Fig. 14a–b), which may imply that the rocks formed under low meltingpressure (Douce and Beard, 1996). The low melting pressure is also evi-dent in the Zr/Sm-SiO2 diagram (Fig. 6i). Nb, Ta, and Ti are strongly de-pleted in these rocks, and experiments have shown that Nb-Ta-Ti areconcentrated in amphibole and Ti-rich minerals. This indicates that am-phibole is a residual phase during partial melting, further indicating thatthe protoliths are also likely garnet-bearing amphibolites.

Magma H2O content, oxygen fugacity, and source compositionare essential to the formation of porphyry Cu deposits (Richards,2003, 2011; Sillitoe, 2010). In general, subduction processes arethought to ultimately cause enrichment of metals (Cu and Au) andS (Griffin et al., 2013), and the relatively high oxygen fugacity (fO2)and high H2O contents in arc magmas (Kelley and Cottrell, 2009)that are critical to the formation of porphyry Cu deposits. A highwater content (N3 wt%) is required for hornblende to crystallize(Sisson and Grove, 1993). The water content in lithospheric and as-thenospheric mantle is b0.1 wt%, and b0.001 wt% in continentalcrust (Williams and Hemley, 2001). Therefore, the most likely sourceof additional hydration for the magma would be from the mantlewedge or a subduction zone (Gaetani and Grove, 1998; Murphy,2013). Moreover, continental and lower continental crust have esti-mated Cu abundances as low as 26–27 ppm (Rudnick and Gao,2003), which is much lower than that of the oceanic crust at74.4 ppm Cu (Hofmann, 1988). Recent experimental modeling re-sults have shown that partial melts of lower continental crust havelower Cu concentrations (40–85 ppm) than those of MORB(114–245 ppm). This suggests that rocks formed by partial meltingof the lower crust are less likely to form porphyry Cu deposits inthe source, because of both low Cu concentrations and lower oxygenfugacity (Sun et al., 2014). Mao et al. (2011) has also demonstratedthat magmas remelted from lower crust are beneficial to the forma-tion of porphyry Mo, but not Cu, deposits. These observations areconsistent with the conclusion that the porphyry Cu-Au mineraliza-tion in the Luerma area is probably not associated with the partialmelting of the lower continental crust. The mineralization-relatedporphyries and barren andesitic rocks have amphibole and epidote,indicating that high water contents also occurred in their parentmagma. In addition, arc magmas with high water content can crys-tallize large amounts of amphibole ± garnet during early differenti-ation in deep crustal MASH or hot zones (up to 90% amphibole;Tiepolo and Tribuzio, 2008; Alonso-Perez et al., 2009). This indicatesthat the high Sr/Y (and La/Yb) ratios may have been related to highH2O contents. Considering the oxygen fugacity of the investigatedsamples, the ore-related porphyries are characterized by higher zir-con log(fO2) and Ce4+/Ce3+ values (Fig. 12a–b), more similar to ore-related porphyries in the Gangdese magma than to barren andesiticrocks. The whole-rock Fe2O3/FeO results for ore-related and barrenandesitic rocks for the Luerma deposit indicate that ore-relatedmagmas have higher magmatic oxidation states than these barrenmagmas (Fig. 12c–d). This implies that a higher magmatic oxidationstate is required for the formation of the subduction porphyry Cu de-posits in the Luerma area.

5.3. Implications for continental arc models

As previously pointed out, various tectonic settings have beenproposed for the southern Lhasa terrane: (1) the melting of the man-tle wedge with overlying crust in response to the upwelling of the


asthenospheric mantle (Dong and Zhang, 2013); (2) a back-arc basinrelated to the southward subduction of the Bangong–Nujiang oce-anic lithosphere (e.g., Yang et al., 2011; Pan et al., 2012; Zhu et al.,2011, 2013; Song et al., 2014); or (3) the initial northward subduc-tion of the Neo-Tethyan oceanic lithosphere (e.g., Ji et al., 2009a;Tang et al., 2015; Ma et al., 2018; Shui et al., 2018; Lang et al.,2019a, 2019b; Wang et al., 2019). The first has been proposedbased on the eclogite that has been recognized in Songduo (Dongand Zhang, 2013). However, no eclogite has been reported in thewestern segment of the Gangdese magmatic belt, thus, the model isnot useful for the Luerma area. Song et al. (2014) proposed that thelate Triassic magma in Dajiacuo formed in a back-arc setting, whichmay have been related to the southward subduction of the BangongCo-Nujiang Ocean in the Gangdese magmatic belt margin. The open-ing of the Neo-Tethyan Ocean initiated during the Carboniferous-early Permian and was represented by the Panjal traps and Abor vol-canics related to rifting (e.g., Dewey et al., 1988; Garzanti et al.,1999). Substantial evidence indicated that the Lhasa terrane riftedfrom Gondwana prior to the Triassic (Garzanti et al., 1999;Sciunnach and Garzanti, 2012). Following this event, the Lhasa ter-rane was subjected to orogeny caused by the northward subductionof the Neo-Tethys and southward subduction of the Bangong-Nujiang oceanic lithosphere during the Triassic (e.g., Pan et al.,2012; Zhu et al., 2013; Ding et al., 2014). The Luerma area is locatedin the southern Lhasa terrane, which is relatively close to the YarlungTsangpo suture zone compared to the Bangong-Nujiang suture zoneat its current geographic location. Furthermore, the Sr-Nd-Hf isoto-pic compositions of the andesitic rocks have mantle-like isotopic

0.01

0.1

1

10

100

10 100 1000 10000 100000

U/Yb

Y(ppm)

0

1

U/Yb

Continental arc

Oceanic arc

0

5

10

15

20

25

30

0 2 4 6 8 10

La/Yb

Sc/Ni

Andean arc

(active continetal margin)

Continental island-arc

‘Other’ oceanic island-arc

Low-K oceanic island-arc 0

(a)

(c)

Fig. 15. (a) Whole-rock La/Yb-Sc/Ni diagram (after Bailey, 1981). (b) Whole-rock Th/Yb-Ta/YbMORB), E-MORB (enriched MORB) and OIB fields are from Sun and McDonough (1989). GloSYb vs. Y diagram (Grimes et al., 2007). (d) Zircon Nb/Yb vs. U/Yb diagram (Grimes et al., 2015

compositions, similar to the other rocks during this time in thesouthern Lhasa terrane, indicating that the magmatic origin of an-desitic rocks is related to the northward subduction of Neo-Tethyan oceanic lithosphere. Moreover, bulk-rock chemistry datashow enrichment in LILEs and LREEs, but depletion in HFSEs, indicat-ing that a subduction-related arc setting is favorable for magmagenesis.

No consensus has been reached as to whether this arc is oceanic(Aitchison et al., 2007; Ma et al., 2018) or continental (Zhu et al.,2013; Zhang et al., 2014). Based on the following evidence, this paperproposes that the Triassic igneous rocks in the Luerma formed at thecontinental margin: (1) The current distance between the YarlungTsangpo suture and Luerma area exceeds 100 km, and the structure ofthe Lhasa terrane was clearly shortened during the Indian-Asian colli-sion and the Tibetan uplift (Tapponnier et al., 2001), which are difficultto explain by an oceanic island arc system. Moreover, the Luerma arealacks the typical rock assemblages of an oceanic island arc, such ashigh-Mg basalts, basaltic andesite, high-Al andesite, boninite, andsanukite. Furthermore, immobile trace element ratios, La/Yb, Th/Yb,and Ta/Yb have also been used to investigate the role of the subconti-nental lithosphere in magma genesis at active continental margins(Pearce, 1983). Magma from the continental arc, in general, has higherLa/Yb ratios (N7.0) than oceanic arc (Bailey, 1981). The samples investi-gated in the present study have La/Yb ratios exceeding 10.0, indicatingthat the magma may have formed in a continental arc setting(Fig. 15a). Magma from oceanic island arcs has low Th/Yb (0.05–1.0)and Ta/Yb (0.02–1.0) ratios, whereas magma in active continental mar-gins has higher Th/Yb (1.0–10.0) and Ta/Yb (0.1–1.0) (Pearce, 1983).

.01

0.1

1

10

00

0.0001 0.001 0.01 0.1 1

Nb/Yb

Mantle-z

irco

n arr

ay

Continental arc

MORB-type

OIB-type

.01

0.1

1

10

100

0.01 0.1 1 10

Th/Yb

Ta/Yb

yarrA

eltnaM

OIB

E-MORB

N-MORB

Subduction

enrichment

UCC

Gloss

Continental island-arc

Oceanic

island-arc

(b)

(d) Ore-related porphyries

Barren

Continental

arc

Oceanic arc


(Ma et al., 2018)

digaram for the studied rocks (Pearce, 1982; Pearce and Peate, 1995). N-MORB (normalS, global subducted sediments (Plank, 2014); UCC, upper continental crust. (c) Zircon U/).


Negative Nb and Ta anomalies, alongwith higher ratios of Th/Yb and Ta/Yb (Fig. 15b), suggest a continental arc setting for andesitic rocks(Pearce, 1983; Pearce and Peate, 1995). This is consistent with U/Yb-YandU/Yb-Nb/Ybplots of zircons (Fig. 15c–d), inwhich samples are plot-ted in the continental arc setting area. Furthermore, in the εHf(t) versus tdiagram (Fig. 13b), the εHf(t) values for Luerma andesitic rocks arelower than those fromTriassic cumulate appinite, which is a late Triassicinteroceanic island arc systemwithin the YZSZ (e.g., Ma et al., 2018). Re-cently, numerous inherited zircons of Proterozoic and Paleozoic ageshave been identified in the Gangdese granitic batholith and these zir-cons indicate a potential Precambrian basement beneath southernLhasa (e.g., Dong et al., 2010; Guo et al., 2016; Ma et al., 2019). Com-bined with previously published field geology, isotopic, geochemical,and geochronological data from the Gangdese magmatic belt, new geo-chemical, isotopic, and geochronological data on the arcmagmatic rocksin the eastern Gangdese orogen belt indicate that the andesitic rockslikely formed in a continental arc setting in the late Triassic during An-dean orogenesis.

Here, these detailed investigations in the western Gangdesemag-matic belt indicate that at ca. 210 Ma, andesitic rocks emerged in theLuerma. The andesitic rocks are geochemically similar to continentalarc rocks formed in an arc system. Several synchronous magmatic

Late Triassic

(ca.210 Ma)

Afr

Equator

South

American

Paleo-Pacific

Ocean Laurentia

Intra-oceanic

arc

Neotethys

Neotethys

Neotethyan slab

Intra-oceanic

arc

Neotethys

Neotethys

Neotethyan slab

Afr

South

American

Paleo-Pacifi

Ocean Laurentia

c

A

high Ba/Th,Sr/Nd, (143

Nd/144

Nd)t,ε

N

low La/Sm, Th/Yb,(87

Sr/86

Sr

Fig. 16.Geodynamicmodel for the double subduction systemwithin theNeotethys in the Late Tthe intra-oceanic subduction system within the Neotethyan Ocean in the time (modified after

rocks have been identified in a continental arc setting from the east-ern Gangdese magmatic belt (Wang et al., 2016), and their genera-tion correlates with the northward subduction of the Neotethyanoceanic lithosphere. In addition, several Triassic-Jurassic magmaticrocks exhibit geochemical similarities to island-arc rocks formed ina primitive arc system that was triggered by intra-oceanic subduc-tion (Ma et al., 2018; Lang et al., 2019a, 2019b). How can these mag-matic rocks, formed in continental and oceanic arc settings, beincorporated into the same Neotethyan realm? This paper supportsthe double subduction system inferred for the tectonic evolution ofthe northern Neotethyan Ocean (Ma et al., 2018). The Triassic-Jurassic arc-type basalt along the southern margin of the Gangdesemagmatic belt near to the Yarlung Tsangpo suture zone is assumedto have been formed in an intra-oceanic arc. Further north, andesiticbasalt and andesitic rocks in Guangguo are assumed to have formedwithin an active continental margin setting (Wang et al., 2016).Rocks from the intra-oceanic arc system have higher Ba/Th, Sr/Nd,(143Nd/144Nd)i, εNd(t), εHf(t), but lower La/Sm, Th/Yb, (87Sr/86Sr)ithan rocks from the continental arc setting (Fig. 16). Those studiescombined with the results of the present study favor the existenceof a double subduction system in the western Gangdese magmaticbelt during the late Triassic-Jurassic (Fig. 16).

TR

Ocean

ican

Paleo-Pacific

Ocean

Siberia

AustraliaIndia

Neotethyan

Lhasa terrane

Neotethyan slab

Gan

gdes

e

Lhasa terrane

Neotethyan slab

Gan

gdes

e

Ocean

ican

Paleo-Pacifi

Ocean

Siberia

AustraliaIndia

Neotethyan

c

Lhasa

terrane

Lhasa

terrane

A

B

B

intra-oceanic arc

Active

continental margin

d(t),ε

Hf(t)

)t

high La/Sm, Th/Yb,(87

Sr/86

Sr)t

low Ba/Th,Sr/Nd,(143

Nd/144

Nd)t,ε

Nd(t),ε

Hf(t)

LLLuueerrmmaa

riassic (ca. 210Ma) and paleogeographic reconstruction of theNeotethyan realm, showingMa et al., 2018).


5.4. Implications for five generations of porphyry Cu-(Mo-Au) mineraliza-tion in the Gangdese belt

The existence of the Luermadeposit offers evidence for a newgener-ation of porphyry Cumineralization in theGangdesemagmatic belt dur-ing the early Mesozoic. Ore-related magma in the Luerma area withhigh εHf(t) and εNd(t) values demonstrates that the ore-related por-phyry in the Luerma Cu-Au district was derived via partial melting ofa subducted oceanic slab. Moreover, high H2O contents, oxygen fugac-ity, and high Sr/Y ratios from ore-related magma fulfilled themain con-trolling factors for porphyry Cumineralization (Richards, 2011; Sillitoe,2010). Therefore, this suggests that the early Mesozoic subducted oce-anic slab-derived high H2O, enriched oxygen fugacity, and high Sr/Yadakitic rocks provided greater potential for porphyry Cu-Au minerali-zation than the early Mesozoic normal magmatic rocks in the southernLhasa terrane. Recently, large amounts of early Mesozoic magmaticrocks in the southern Lhasa terrane have been reported (e.g., Zhuet al., 2008; Xu et al., 2017;Ma et al., 2018). However, the economic sig-nificance of porphyry Cu-Au deposits of early Mesozoic rocks have gen-erally been neglected, especially in the late Triassic. These earlyMesozoic adakitic rocks with high H2O contents, oxygen fugacity, andhigh Sr/Y raitos were beneficial for the formation of subduction-related porphyry Cu-Au mineralization in the southern Lhasa terrane.Thus, it is of great scientific and economic significance to evaluatetheir metallogenic potential in the near future.

Fig. 17. (a) Re-Osdata ofmolybdenite of five generations of porphyryCu-(Mo-Au) and porphyryXiongcun (Huanget al., 2013; Lang et al., 2014), Sharang (J.X. Zhao et al., 2014; X.Y. Zhao et al., 20Sun et al., 2013), Tangbula (Wang et al., 2010), Qulong (Meng et al., 2003;Wang et al., 2006; Li2007). (b) Bulk-rock (87Sr/86Sr)i vs. εNd(t). Figures are modified according to previously publish2013, 2015a) Jiama-Nanmu-Tinggong (Hou et al., 2004), Chongjiang (Hou et al., 2013), Bairongsources: Xiongcun (Hou et al., 2013), Sharang (J.X. Zhao et al., 2014; X.Y. Zhao et al., 2014),Tinggong-Chongjiang (Xu et al., 2010), Bairong (Li et al., 2011), Qulong (Hou et al., 2013). Tchondritic uniform reservoir. (d) Plot of Re contents on the molybdenite from the porphyrpresented in Supplementary Table 7.

Based on the analysis of the Tethyan tectonic domain evolution,the genetic types of porphyry Cu-(Mo-Au) ore deposits and theirdistributions in space and moybdenite Re-Os geochronology, fiveporphyry Cu-(Mo-Au) deposits are identified (Fig. 17a; Supplemen-tary Tables 6 and 7). The first stage of the Triassic porphyry Cu-Audeposit was discovered in the Luerma area, with mineralizationages at 213 Ma (Liu et al., 2019a). The second stage of the Jurassicporphyry Cu-Au deposit formed in the Xiongcun area of theGangdese belt, with mineralization ages ranging from 175 to160 Ma (Tafti et al., 2009; Lang et al., 2014). The third stage of thePaleocene-Eocene (65–52 Ma) porphyry Mo-Cu deposits formedin the Jiru and Sharang areas of the Gangdese belt (J.X. Zhao et al.,2014; X.Y. Zhao et al., 2014). The fourth stage of Oligocene(30–23 Ma) porphyry-skarn Cu-Mo mineralization formed in theMingze-Chengba area of the Gangdese belt (Sun et al., 2013). Thefifth stage of Cu–Mo-Au porphyry mineralization is the most criticalperiod of mineralization in the Gangdese belt, with the formation ofvoluminous Cu-Mo-Au deposits, such as the Qulong, Jiama, Dabu,and Zhunuo deposits dated at 23–12 Ma (Hou et al., 2003, 2015a,2015b; Zheng et al., 2007, 2014a, 2014b; Wang et al., 2018). Ac-cording to the Neo-Tethyan Ocean evolution and subsequentIndian-Eurasian continental collision, the first and second stages ofporphyry Cu-Au mineralization during the late Triassic to MiddleJurassic were associated with island arc magmatism related to thenorthward subduction of the Neo-Tethyan oceanic slab. The third

Mo(-Cu) deposits in theGangdesemagmatic belt. Data sources: Luerma (Liu et al., 2019b),14), Jiru (Zheng et al., 2014a, 2014b), Bangpu (Menget al., 2003),Mengze (Yan et al., 2010,et al., 2017, 2018), Chongjiang, Lakange, and Dabu (Hou et al., 2003), Zhunuo (Zheng et al.,ed work (Hou et al., 2015a). Data sources: Xiongcun (Qu et al., 2007), Qulong (Hou et al.,

(Li et al., 2011). All data are recalculated to 15Ma. (c) Zircon εHf(t) values vs. U-Pb age. DataMingze-Chengba (Sun et al., 2013), Jiama (Chung et al., 2009), Nanmu (Ji et al., 2009a),he range of the northern, central, and southern Lhasa is from Hou et al. (2015b) CHUR-y Cu-(Mo-Au) and porphyry Mo(-Cu) deposits in the Gangdese belt. Data sources are


Paleocene-Eocene (65–51 Ma) porphyry Mo(-Cu) deposits formedduring the Indian and Eurasian collision stage. The fourth and fifthstages of Cu-Mo-Au porphyry formed in a post-collisional extensionsetting (Hou et al., 2003; Zheng et al., 2007, 2014a, 2014b).

Previous studies have shown that porphyry deposits derivedfrom amantle source typically have high Re contents in molybdeniteand depleted Sr-Nd-Hf isotope compared with deposits related tothe continental crust (Mao et al., 1999; Stein et al., 2001; Hou et al.,2015a, 2015b). The mineralization related to porphyries from thefirst Luerma deposit generation has depleted mantle-like Sr-Nd-Hfisotopic compositions (Fig. 17). The deposit has higher εNd(t) andεHf(t) values than collision-related Cu-Mo-Au deposits, but lowerεNd(t) and εHf(t) values than the subduction-related Cu-Au depositin Xiongcun (Fig. 17). This demonstrates that the deposits mainlyoriginate from depleted mantle source in a continental arc setting.The Re and 187Re contents of molybdenites from the Luerma deposit(Liu et al., 2019b) are considerably higher than those from theZhunuo, Chongjiang, Dabu, and Qulong porphyry Cu-Mo-Au de-posits, but lower than the Xiongcun Cu-Au deposit, indicating thatthe deposits have high mantle source compositions comparable tothe collision-related Cu-Mo-Au deposits in the Gangdese magmaticbelt. The second generation of porphyry deposits in Xiongcun havedepleted mantle-like isotopic compositions (Lang et al., 2014; Houet al., 2015a, 2015b). The Re and 187Re contents of molybdenitesfrom the Xiongcun deposit are considerably higher than the por-phyry Cu-(Mo-Au) deposits, demonstrating that they mainly origi-nated from depleted mantle sources in oceanic arc settings (Langet al., 2019a, 2019b). The third stage of porphyry Paleocene-Eocene(65–52 Ma) porphyry Mo-Cu deposits such as Shangrang has rela-tively higher (87Sr/86Sr)i values, but lower bulk-rock εNd(t) values,lower zircon εHf(t) values, and older Hf model ages (J.X. Zhao et al.,2014; X.Y. Zhao et al., 2014; Fig. 17). They also have lower molybde-nite Re contents than the copper-related porphyries in the Gangdesebelt, indicating that the old continental crustal material plays a morecrucial role in the generation of porphyry Mo(-Cu) mineralizationthan porphyry Cu(-Mo-Au) mineralization (Zheng et al., 2015). Thefourth and fifth stages of post-collision related porphyry Cu-Mo-Audeposits have intermediate εNd(t) and εHf(t), Re values (Fig. 17),demonstrating that both the mantle and old continental crustal ma-terial contribute significantly to porphyry Cu(-Mo-Au) mineraliza-tion in a post-collisional extension setting (Meng et al., 2003;Wang et al., 2006; Sun et al., 2013; Hou et al., 2015a, 2015b; Wanget al., 2018).

6. Conclusion

Based on an integrated geological, geochronological, and geochemi-cal study of ore-related and barren andesitic rocks in the Luerma area,this study reached the following conclusions:

(1) Zircon U-Pb dating of three ore-related andesitic samples of thelate Triassic, combinedwith previous Re-Os isotopic dating, indi-cates a late Triassic magmatic Cu mineralization event in thewestern Gangdese magmatic belt.

(2) Andesitic magmatism formed in a continental arc setting. It wasdominantly sourced from depleted mantle materials,metasomatized by oceanic subducted sediment-derived meltsduring the subduction of the Neo-Tethys Ocean.

(3) The mineralized-related porphyries have a higher magmatic ox-idation state than contemporaneous barren monzodiorite. Thus,the highly oxidized magma of Triassic andesitic igneous rocks isfavorable for subduction-related porphyry Cu deposits in thewestern Gangdese belt.

(4) The existence of Luerma porphyry mineralization demonstratesthat there are at least five generations of porphyry Cu-(Mo-Au)

mineralizations in the Gangdese magmatic belt, which could ad-vance the porphyry mineralization time to the late Triassic.

CRediT authorship contribution statement

Xin Chen:Writing - original draft. Youye Zheng: Conceptualization,Methodology. Shunbao Gao:Data curation. SongWu: Visualization, In-vestigation. Xiaojia Jiang: Software. Junsheng Jiang: Software. PengjieCai: Writing - review & editing. Chenggui Lin: Writing - review &editing.

Declaration of competing interest

Wedeclare that we do not have any commercial or associative inter-est that represents a conflict of interest in connection with the worksubmitted.

Acknowledgments

We are greatly indebted to Editor-in-Chief Professor Prof. Dr. M.Santosh and associate editor Prof. Dr. Franco Pirajno for efficient han-dling and constructive comments, and to two anonymous reviewersfor their insightful comments that improved our paper greatly. Wewould like to thank Dr. Hong Liu for the help in data interpretationand other members in our team for assistance with the fieldwork. Weacknowledge the Fundamental Research Fund for Deep Resources Ex-ploration and Mining, National Key Research and Development Pro-gram of China (2018YFC0604104).

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.gr.2020.04.006.

References

Aitchison, J.C., Ali, J.R., Davis, A.M., 2007.When andwhere did India and Asia collide? Jour-nal of Geophysical Research: Solid Earth 112 (B5), 1–19.

Alonso-Perez, R., Müntener, O., Ulmer, P., 2009. Igneous garnet and amphibole fraction-ation in the roots of island arcs: experimental constraints on andesitic liquids.Contrib. Mineral. Petrol. 157 (4), 541–558.

Atherton, M.P., Petford, N., 1993. Generation of sodium-rich magmas from newlyunderplated basaltic crust. Nature 362, 144–146.

Audétat, A.N.D.R.E.A.S., Simon, A.C., Hedenquist, J.W., Harris, M., Camus, F., 2012. Mag-matic controls on porphyry copper genesis. Geology and Genesis of Major Copper De-posits and Districts of the World-A Tribute to Richard H. Sillitoe, pp. 553–572.

Bailey, J.C., 1981. Geochemical criteria for a refined tectonic discrimination of orogenic an-desites. Chem. Geol. 32, 139–154.

Ballard, J.R., Palin, J.M., Campbell, I.H., 2002. Relative oxidation states of magmas inferredfrom Ce(IV)/Ce(III) in zircon: application to porphyry copper deposits of northernChile. Contrib. Mineral. Petrol. 144 (3), 347–364.

Bertrand, G., Guillou-Frottier, L., Loiselet, C., 2014. Distribution of porphyry copper de-posits along the western Tethyan and Andean subduction zones: insights from apaleotectonic approach. Ore Geol. Rev. 60, 174–190.

Bienvenu, P., Bougault, H., Joron, J.L., Treuil, M., Dmitriev, L., 1990. MORB alteration: rare-earth element/non-rare-earth hygromagmaphile element fractionation. Chem. Geol.82, 1–14.

Bissig, T., Cooke, D.R., 2014. Introduction to the special issue devoted to alkalic porphyryCu-Au and epithermal Au deposits. Econ. Geol. 109 (4), 819–825.

Blevin, P.L., 2004. Redox and compositional parameters for interpreting the granitoidmetallogeny of eastern Australia: implications for gold-rich ore systems. Resour.Geol. 54, 241–252.

Blundy, J.D., Wood, B.J., 1994. Prediction of crystal-melt partition coefficients for elasticmoduli. Nature 372, 452–454.

Bouvier, A., Vervoort, J.D., Patchett, P.J., 2008. The Lu-Hf and Sm-Nd isotopic compositionof CHUR: constraints from unequilibrated chondrites and implications for the bulkcomposition of terrestrial planets. Earth Planetary Science Letter 273 (1), 48–57.

Castillo, P.R., Janney, P.E., Solidum, R.U., 1999. Petrology and geochemistry of Camiguin is-land, southern Philippines: insights to the source of adakites and other lavas in acomplex arc setting. Contrib. Mineral. Petrol. 134, 33–51.

Chang, J., Li, J.W., Selby, D., Liu, J.C., Deng, X.D., 2017. Geological and chronological con-straints on the long-lived Eocene Yulong porphyry Cu-Mo deposit, eastern Tibet:

https://doi.org/10.1016/j.gr.2020.04.006

https://doi.org/10.1016/j.gr.2020.04.006

http://refhub.elsevier.com/S1342-937X(20)30133-7/rf0005





































implications for the lifespan of giant porphyry Cu deposits. Econ. Geol. 112 (7),1719–1746.

Chen, X., Schertl, H.P., Cambeses, A., Gu, P., Xu, R., Zheng, Y., Jiang, X., Cai, P., 2019. Frommagmatic generation to UHP metamorphic overprint and subsequent exhumation:a rapid cycle of plate movement recorded by the supra-subduction zone ophiolitefrom the North Qaidam orogen. Lithos 350, 105238.

Chiaradia, M., Merino, D., Spikings, R., 2009. Rapid transition to long-lived deep crustalmagmatic maturation and the formation of giant porphyry-related mineralization(Yanacocha, Peru). Earth Planet. Sci. Lett. 288 (3–4), 505–515.

Chu, M.F., Chung, S.L., Song, B., Liu, D.Y., O'Reilly, S.Y., Pearson, N.J., 2006. Zircon U–Pb andHf isotope constraints on the Mesozoic tectonic and crustal evolution of southernTibet. Geology 34, 745–748.

Chung, S.L., Chu, M.F., Zhang, Y.Q., Xie, Y.Q., Lo, C.H., Lee, T.Y., Lan, C.Y., Li, X.H., Zhang, Q.,Wang, Y.Z., 2005. Tibetan tectonic evolution inferred from spatial and temporal var-iations in post-collisional magmatism. Earth Sci. Rev. 68, 173–196.

Chung, S.L., Chu, M.-F., Ji, J.Q., O’Reilly, S.Y., Pearson, N.J., Liu, D.Y., Lee, T.Y., Lo, C.H., 2009.The nature and timing of crustal thickening in Southern Tibet: geochemical and zir-con Hf isotopic constraints from postcollisional adakites. Tectonophysics 477, 36–48.

Defant, M.J., Drummond, M.S., 1990. Derivation of some modern arc magmas by meltingof young subducted lithosphere. Nature 347, 662–665.

DePaolo, D.J., 1981. Neodymium isotopes in the Colorado Front Range and implicationsfor crust formation and mantle evolution in the Proterozoic. Nature 291, 193–197.

Dewey, J.F., Shackelton, R.M., Chang, C.F., Sun, Y.Y., 1988. The tectonic evolution of the Ti-betan plateau. Philos. Trans. R. Soc. Lond. 327, 379–413.

Ding, L., Kapp, P., Zhong, D.L., Deng, W.M., 2003. Cenozoic volcanismin Tibet: evidence fora transition from oceanic to continental subduction. J. Petrol. 44, 1833–1865.

Ding, L., Xu, Q., Yue, Y., Wang, H., Cai, F., Li, S., 2014. The Andean-type Gangdese Moun-tains: paleoelevation record from the Paleocene–Eocene Linzhou Basin. Earth Planet.Sci. Lett. 392, 250–264.

Dong, X., Zhang, Z., 2013. Genesis and tectonic significance of the Early Jurassic magmaticrocks from the southern Lhasa terrane. Acta Petrol. Sin. 29, 1933–1948 (in Chinesewith English abstract).

Dong, X., Zhang, Z., Santosh, M., 2010. Zircon U-Pb Chronology of the Nyingtri Group,Southern Lhasa Terrane, Tibetan Plateau: implications for Grenvillian and PanAfrican Provenance and Mesozoic-Cenozoic Metamorphism. The Journal of Geology118, 677–690.

Douce, A.E.P., Beard, J.S., 1996. Effects of P, f (O2) and Mg/Fe ratio on dehydration meltingof model metagreywackes. J. Petrol. 37 (5), 999–1024.

Drummond, M.S., Defant, M.J., Kepezhinskas, P.K., 1996. The petrogenesis of slab derivedtrondhjemite–tonalite–dacite/adakite magmas. Earth and Environmental ScienceTransactions of the Royal Society of Edinburgh 87, 205–216.

Du, X.F., 1985. The character of the alteration and mineralization zones of the porphyrycopper-molybdenite deposit in eastern Tibet and its comparison with the J.D. Lowellmodel. Contribution to the geology of the Qinghai-Xizang (Tibet) Plateau 17,369–382.

Ferry, J.M., Watson, E.B., 2007. New thermodynamic models and revisedcalibrations forthe Ti-in-zircon and Zr-in-rutile ther-mometers. Contrib. Mineral. Petrol. 154,429–437.

Gaetani, G.A., Grove, T.L., 1998. The influence of water on melting of mantle peridotite.Contrib. Mineral. Petrol. 131 (4), 323–346.

Gao, Y.F., Wei, R.H., Hou, Z.Q., Tian, S.H., Zhao, R.S., 2008. Eocene high-MgO volcanism insouthern Tibet: new constraints for mantle source characteristics and deep process.Lithos 105, 63–72.

Garzanti, E., Le Fort, P., Sciunnach, D., 1999. First report of Lower Permian basalts in SouthTibet: tholeiitic magmatism during break-up and incipient opening of Neotethys.J. Asian Earth Sci. 17, 533–546.

Goldstein, S.L., Onions, R.K., Hamilton, P.J., 1984. A Sm-Nd isotopic study of atmosphericdusts and particulates from major river systems. Earth Planetary Science Letter 70(2), 221–236.

Griffin, W.L., Wang, X., Jackson, S.E., Pearson, N.J., O'Reilly, S.Y., Xu, X., Zhou, X.M., 2002.Zircon chemistry and magmamixing, SE China: in-situ analysis of Hf isotopes, Tongluand Pingtan igneous complexes. Lithos 61 (3), 237–269.

Griffin, W.L., Begg, G.C., O’reilly, S.Y., 2013. Continental-root control on the genesis ofmagmatic ore deposits. Nat. Geosci. 6 (11), 905–910.

Grimes, C.B., John, B.E., Kelemen, P., Mazdab, F., Wooden, J., Cheadle, M.J., Hanghøj, K.,Schwartz, J., 2007. Trace element chemistry of zircons from oceanic crust: a methodfor distinguishing detrital zircon provenance. Geology 35, 643–646.

Grimes, C., Wooden, J., Cheadle, M., John, B., 2015. “Fingerprinting” tectono-magmaticprovenance using trace elements in igneous zircon. Contrib. Mineral. Petrol. 170,46–71.

Grove, T.L., Till, C.B., Krawczynski, M.J., 2012. The role of H2O in subduction zonemagmatism. Annu. Rev. Earth Planet. Sci. 40, 413–439.

Guilmette, C., Hebert, R., Wang, C.S., Villeneuve, M., 2009. Geochemistry and geochronol-ogy of the metamorphic sole underlying the Xigaze Ophiolite, Yarlung Zangbo SutureZone, South Tibet. Lithos 112, 149–162.

Guo, L., Liu, Y., Liu, S., Cawood, P.A., Wang, Z., Liu, H., 2013. Petrogenesis of Early to MiddleJurassic granitoid rocks from the Gangdese belt, Southern Tibet: implications for earlyhistory of the Neo-Tethys. Lithos 179, 320–333.

Guo, L., Zhang, H.F., Harris, N., Xu, W.C., Pan, F.B., 2016. Late Devonian-Early Carboniferousmagmatism in the Lhasa terrane and its tectonic implications: evidences from detritalzircons in the Nyingchi Complex. Lithos 245, 47–59.

Guynn, J.H., Kapp, P., Pullen, A., Heizler, M., Gehrels, G., Ding, L., 2006. Tibetan basementrocks near Amdo reveal “missing” Mesozoic tectonism along the Bangong suture,central Tibet. Geology 34 (6), 505–508.

Guynn, J., Kapp, P., Gehrels, G.E., Ding, L., 2012. U–Pb geochronology of basement rocks incentral Tibet and paleogeographic implications. J. Asian Earth Sci. 43 (1), 23–50.

Hart, C.J., Goldfarb, R.J., Lewis, L.L., Mair, J.L., 2004. The Northern Cordilleran Mid-Cretaceous plutonic province: ilmenite/magnetite-series granitoids andintrusionrelated mineralisation. Resour. Geol. 54, 253–280.

Hildreth, W., Moorbath, S., 1988. Crustal contributions to arc magmatism in the Andes ofcentral Chile. Contrib. Mineral. Petrol. 98 (4), 455–489.

Hofmann, A.W., 1988. Chemical differentiation of the Earth: the relationship betweenmantle, continental crust, and oceanic crust. Earth Planet. Sci. Lett. 90 (3), 297–314.

Hou, Z.Q., Qu, X.M., Wang, S.X., Gao, Y.F., Du, A.D., Huang, W., 2003. Re–Os dating of theporphyry copper belt in Gangdese metallogenic belt: mineralization time andGeodynamic application. Science China (Ser. D) 33 (7), 609–618 (in Chinese with En-glish abstract).

Hou, Z.Q., Gao, Y.F., Qu, X.M., Rui, Z.Y., Mo, X.X., 2004. Origin of adakitic intrusives gener-ated during mid-Miocene east–west extension in southern Tibet. Earth and PlanetaryScience Letters 220, 139–155.

Hou, Z.Q., Zheng, Y.C., Yang, Z.M., Rui, Z.Y., Zhao, Z.D., Qu, X.M., Jiang, S.H., Sun, Q.Z., 2013.Contribution of mantle components within juvenile lower-crust to collisional zoneporphyry Cu systems in Tibet. Mineralium Deposita 48, 173–192.

Hou, Z.Q., Yang, Z.M., Lu, Y.J., Kemp, A., Zheng, Y.C., Li, Q.Y., Tang, J.X., Yang, Z.S., Duan, L.F.,2015a. A genetic linkage between subduction- and collision-related porphyry Cu de-posits in continental collision zones. Geology 43, 247–250.

Hou, Z.Q., Duan, L.F., Lu, Y.J., Zheng, Y.C., Zhu, D.C., Yang, Z.M., Yang, Z.S., Wang, B.D., Pei,Y.R., Zhao, Z.D., McCuaig, T.C., 2015b. Lithospheric architecture of the Lhasa Terraneand its control on ore deposits in the Himalayan-Tibetan orogen. Econ. Geol. 110,1541–1575.

Huang, Y., Ding, J., Tang, J.X., Lang, X.H., 2011. Tectonic setting and source of ore-formingmaterials of No.I orebody in the Xiongcun copper-gold deposit, Tibet. Journal ofChengdu University of Technology (Science & Technology Edition) 38, 306–312.

Huang, Y., Tang, J.X., Ding, J., Zhang, L., Lang, X.H., 2013. The Re-Os isotope system of thexiongcun porphyry copper-gold deposit, tibet. Geology in China 40 (1), 302–311 (inChinese with English abstract).

Ji, W.Q., Wu, F.Y., Chung, S.L., Li, J.X., Liu, C.Z., 2009a. Zircon U–Pb geochronology and Hfisotopic constraints on petrogenesis of the Gangdese batholith, southern Tibet.Chem. Geol. 262, 229–245.

Ji, W.Q., Wu, F.Y., Liu, C.Z., Chung, S.L., 2009b. Geochronology and petrogenesis ofgraniticrocks in Gangdese batholith, southern Tibet. Sci. China D 52, 1240–1261.

Kang, Z.Q., Xu, J.F., Wilde, S.A., Feng, Z.H., Chen, J.L., Wang, B.D., Fu, W., Pan, H.B., 2014.Geochronology and geochemistry of the Sangri Group Volcanic Rocks, SouthernLhasa Terrane: implications for the early subduction history of the Neo-Tethys andGangdese Magmatic Arc. Lithos 200, 157–168.

Kapp, P., Murphy, M.A., Yin, A., Harrison, T.M., Ding, L., Guo, J., 2003. Mesozoic and Ceno-zoic tectonic evolution of the Shiquanhe area of western Tibet. Tectonics 22 (4).

Keller, C.B., Schoene, B., Barboni, M., Samperton, K.M., Husson, J.M., 2015. Volcanic–plutonic parity and the differentiation of the continental crust. Nature 523, 301–307.

Kelley, K.A., Cottrell, E., 2009. Water and the oxidation state of subduction zone magmas.Science 325 (5940), 605–607.

Labanieh, S., Chauvel, C., Germa, A., Quidelleur, X., 2012. Martinique: a clear case for sed-iment melting and slab dehydration as a function of distance to the trench. Journal ofPetrology 53, 2441–2464.

Lai, W., Hu, X., Garzanti, E., Sun, G., Garzione, C.N., BouDagher-Fadel, M., Ma, A., 2019. Ini-tial growth of the Northern Lhasaplano, Tibetan Plateau in the early Late Cretaceous(ca. 92 Ma). Geological Society of America Bulletin 131 (11-12), 1823–1836. https://doi.org/10.1130/B35124.1.

Lang, X.H., Chen, Y.C., Tang, J.X., Li, Z.J., Huang, Y., Wang, C.H., Chen, Y., Zhang, Li, 2010.Characteristics of rock geochemistry of orebody No. I in the Xiongcun porphyrycopper–gold metallogenic district, Xietongmen County, Tibet: constraints onmetallogenic tectonic setting. Geol. Explor. 46, 887–898.

Lang, X.H., Tang, J.X., Li, Z.J., Huang, Y., Ding, F., Yang, H.H., Xie, F.W., Zhang, L., Wang, Q.,Zhou, Y., 2014. U–Pb and Re–Os geochronological evidence for the Jurassic porphyrymetallogenic event of the Xiongcun district in the Gangdese porphyry copper belt,southern Tibet, PRC. Journal of Asian Earth Science 79, 608–622.

Lang, X.H.,Wang, X.H., Deng, Y.L., Tang, J.X., Xie, F.W., Zou, Y., Huang, Y., Li, Z., Yin, Q., Jiang,K., 2019a. Early Jurassic volcanic rocks in the Xiongcun district, southern Lhasasubterrane, Tibet: implications for the tectono-magmatic events associated with theearly evolution of the Neo-Tethys Ocean. Lithos https://doi.org/10.1016/j.lithos.2019.05.014.

Lang, X.H., Liu, D., Deng, Y.L., Tang, J.X., Wang, X.H., Yang, Z.Y., Cui, Z.W., Feng, Y.X., Yin, Q.,Xie, F.W., Huang, Y., Zhang, J.S., 2019b. Detrital zircon geochronology and geochemis-try of Jurassic sandstones in the Xiongcun district, southern Lhasa subterrane, Tibet,China: implications for provenance and tectonic setting. Geol. Mag. 156 (4), 683–701.

Li, J.X., Qin, K.Z., Li, G.M., Xiao, B., Chen, L., Zhao, J.X., 2011. Post-collisional ore-bearingadakitic porphyries from Gangdese porphyry copper belt, southern Tibet: meltingof thickened juvenile arc lower crust. Lithos 126, 265–277.

Li, Q., Liu, W., Zhang, S., Wang, B., 2012. Chronology and geochemical characteristics ofYawa Mafic Complex in the Dajiacuo Area, Southern Gangdese. Acta Geologica Sinica86 (10), 1592–1603 (in Chinese with English abstract).

Li, Y., Selby, D., Feely, M., Costanzo, A., Li, X.-H., 2017. Fluid inclusion characteristics andmolybdenite Re-Os geochronology of the Qulong porphyry copper-molybdenum de-posit, Tibet. Mineralium Deposita 52, 137–158.

Li, Y., Li, X.H., Selby, D., Li, J.W., 2018. Pulsed magmatic fluid release for the formation ofporphyry deposits: tracing fluid evolution in absolute time from the Tibetan QulongCu-Mo deposit. Geology 46 (1), 7–10.

Liang, H.Y., Campbell, I.H., Allen, C., et al., 2006. Zircon Ce4+/Ce3+ ratios and ages forYulong ore-bearing porphyries in eastern Tibet. Mineral. Deposita 41, 152–159.

Liew, T.C., Hofmann, A.W., 1988. Precambrian crustal components, plutonic associations,plate environment of the Hercynian Fold Belt of central Europe: indications from aNd and Sr isotopic study. Contribution to Mineralogy and Petrology 98 (2), 129–138.

































































































































https://doi.org/10.1130/B35124.1

https://doi.org/10.1130/B35124.1







https://doi.org/10.1016/j.lithos.2019.05.014

https://doi.org/10.1016/j.lithos.2019.05.014
























Liu, H., Zhang, L., Huang, H., Li, G., Ou, Y., Lu, M., Li, H., Lan, S., Han, G., 2019a. Petrogenesisof Late Triassic LuermaMonzodiorite inWesternGangdise, Tibet, China. Earth Science44 (07), 2339–2356 (in Chinese with English abstract).

Liu, H., Li, G., Huang, H., Zhang, L., Lu, M., Lan, S., Xie, H., 2019b. The discovery of the LateTriassic porphyry type Cu deposit from Gangdise metallogenic belt, Tibet. ChineseGeology 46 (05), 1238–1240 (in Chinese with English abstract).

Liu, H., Li, G., Huang, H., Zhang, L., Lu, M., Lan, S., Fu, G., Zhou, W., Xie, H., 2019c. Sources ofore-forming materials of Luerma porphyry copper (gold) deposit, western Gangdise.Mineral Deposits 38 (03), 631–643 (in Chinese with English abstract).

Ma, X.X., Meert, J.G., Xu, Z.Q., Yi, Z.Y., 2018. Late Triassic intra-oceanic arc system withinNeotethys: evidence from cumulate appinite in the Gangdese belt, southern Tibet.Lithosphere 10, 545–565.

Ma, L., Kerr, A.C., Wang, Q., Jiang, Z.Q., Tang, G.J., Yang, J.H., Xia, X., Hu, W., Yang, Z., Sun, P.,2019. Nature and Evolution of Crust in Southern Lhasa, Tibet: transformation fromMicrocontinent to Juvenile Terrane. Journal of Geophysical Research: Solid Earthhttps://doi.org/10.1029/2018JB017106.

Macpherson, C.G., Dreher, S.T., Thirlwall, M.F., 2006. Adakites without slab melting: highpressure differentiation of island arc magma, Mindanao, the Philippines. Earth Plane-tary Science Letter 243 (3–4), 581–593.

Mahoney, J.J., Frei, R., Tejada, M., Mo, X., Leat, P., Nägler, T., 1998. Tracing the Indian Oceanmantle domain through time: isotopic results from old West Indian, East Tethyan,and South Pacific seafloor. J. Petrol. 39, 1285–1306.

Mao, J.W., Zhang, Z.C., Zhang, Z.H., Du, A.D., 1999. Re–Os isotopic dating of molybdenitesin the Xiaoliugou W–(Mo) deposit in the northern Qulian Mountains and its geolog-ical significance. Geochim. Cosmochim. Acta 63, 1815–1818.

Mao, J.W., Pirajno, F., Xiang, J.F., Gao, J.J., Ye, H.S., Li, Y.F., Guo, B.J., 2011. Mesozoic molyb-denum deposits in the East Qinling-Dabie Orogenic belt: characteristics and tectonicsettings. Ore Geol. Rev. 43, 264–293.

Mao, J.W., Pirajno, F., Lehmann, B., Luo, J., Beraina, A., 2014. Distribution of porphyry de-posits in the Eurasian continent and their corresponding tectonic settings. Journalof Asian Earth Science 79, 576–585.

Meng, X.J., Hou, Z.Q., Gao, Y.F., Huang, W., Qu, X.M., Qu, W.J., 2003. Re–Os dating for mo-lybdenite from Qulong porphyry copper deposit in Gangdese metallogenic belt, Xi-zang and its metallogenic significance. Geological Review 49 (6), 660–666 (inChinese with English abstract).

Meng, Y., Xu, Z., Santosh, M., Ma, X., Chen, X., Guo, G., Liu, F., 2016. Late Triassic crustalgrowth in southern Tibet: evidence from the Gangdese magmatic belt. GondwanaRes. 37, 449–464.

Mo, X.X., Zhao, Z.D., Deng, J.F., Dong, G.C., Zhou, S., Guo, T.Y., Zhang, S.Q., Wang, L.L., 2003.Response of volcanism to the India–Asian collision. Geosci. Front. 10, 135–148 (inChinese with English abstract).

Mo, X.X., Hou, Z.Q., Niu, Y.L., Dong, G.C., Qu, X.M., Zhao, Z.D., Yang, Z.M., 2007. Mantle con-tributions to crustal thickening in south Tibet in response to the India–Asia collision.Lithos 96, 225–242.

Mo, X.X., Niu, Y.L., Dong, G.C., Dong, G.C., Zhao, Z.D., Hou, Z.Q., Ke, S., 2008. Contribution ofsyncollisional felsic magmatism to continental crust growth: a case study of the Pa-leogene Linzizong volcanic succession in southern Tibet. Chem. Geol. 250, 49–67.

Murphy, J.B., 2013. Appinite suites: a record of the role of water in the genesis, transport,emplacement and crystallization of magma. Earth Sci. Rev. 119, 35–59.

Pan, G.T., Ding, J., Yao, D.S., Wang, L.Q., 2004. Geological Map of the Qinghai-Xizang(Tibet) Plateau and Adjacent Areas: China. Chengdu Cartographic Publishing House.

Pan, G.T., Wang, L.Q., Li, R.S., Yuan, S.H., Ji, W.H., Yin, F.G., Zhang, W.P., Wang, B.D., 2012.Tectonic evolution of the Qinghai-Tibet Plateau. J. Asian Earth Sci. 53, 3–14.

Patiño Douce, A.E., Johnston, A.D., 1991. Phase equilibria and melt productivity in thePeliticSystem: implications for the origin of peraluminous granitoids and aluminousgranulites. Contribution to Mineralogy and Petrology 107, 202–218.

Pearce, J.A., 1982. Trace element characteristics of lavas from destructive plate bound-aries. Andesites 8, 525–548.

Pearce, J.A., 1983. Role of the sub-continental lithosphere inmagma genesis at active con-tinental margins. In: Hawkesworth, C.J., Norry, M.J. (Eds.), Continental Basalts andMantleXenoliths. Shiva Publishing, Nantwich, pp. 158–185.

Pearce, J.A., Peate, D.W., 1995. Tectonic implications of the composition of volcanic arcmagmas. Annu. Rev. Earth Planet. Sci. 23, 251e285.

Pearce, J.A., Thirlwall, M.F., Ingram, G., Murton, B.J., Arculus, R.J., Van der Laan, S.R., 1992.Isotopic evidence for the origin of boninites and related rocks drilled in the Izu-Bonin(Ogasawara) forearc, Leg 1251. Proc. Ocean Drilling Program. Scientific Results. vol.125, pp. 237–261.

Plank, T., 2014. The chemical composition of subducting sediments[M]. Elsevier.Polat, A., Hofmann, A.W., Rosing, M.T., 2002. Boninite-like volcanic rocks in the 3.7–3.8 Ga

Isua greenstone belt, West Greenland: geochemical evidence for intra-oceanic sub-duction zone processes in the early earth. Chem. Geol. 184, 231–254.

Qiu, J.T., Qiu, L., 2016. Geochronology and magma oxygen fugacity of Ehu S-type graniticpluton in Zhe-Gan-Wan region, SE China. Chemie der Erde - Geochemistry - Interdis-ciplinary Journal for Chemical Problems of the Geosciences and Geoecology 76 (3),441–448.

Qu, X.M., Hou, Z.Q., Zaw, K., Li, Y.G., 2007. Characteristics and genesis ofGangdeseporphyry copper deposits in the southern Tibetan plateau: preliminarygeochemical and geochronological results. Ore Geol. Rev. 31, 205–223.

Rapp, R.P., Watson, E.B., 1995. Dehydration melting of metabasalt at 8–32 kbar: implica-tions for continental growth and crust-mantle recycling. J. Petrol. 36, 891–931.

Richards, J.P., 2003. Tectono-magmatic precursors for porphyry Cu-(Mo-Au) deposit for-mation. Econ. Geol. 98, 1515–1533.

Richards, J.P., 2011. High-Sr/Y arc magmas and porphyry Cu ± Mo ± Au deposits: justadd water. Econ. Geol. 106, 1075–1081.

Richards, J.P., Kerrich, R., 2007. Special paper: adakite-like rocks: their diverse origins andquestionable role in metallogenesis. Econ. Geol. 102 (4), 537–576.

Rudnick, R.L., Fountain, D.M., 1995. Nature and composition of the continental crust: alower crustal perspective. Rev. Geophys. 33 (3), 267–309.

Rudnick, R.L., Gao, S., 2003. Composition of the continental crust. Treatise on geochemis-try 3, 659.

Sciunnach, D., Garzanti, E., 2012. Subsidence history of the Tethys Himalaya. Earth-Sci.Rev. 111, 179–198.

Shui, X.F., He, Z.Y., Klemd, R., Zhang, Z.M., Lu, T.Y., Yan, L.L., 2018. Early Jurassic adakiticrocks in the southern Lhasa sub-terrane, southern Tibet: petrogenesis andgeodynamic implications. Geol. Mag. 155 (1), 132–148.

Sillitoe, R.H., 2010. Porphyry copper system. Econ. Geol. 105, 3–41.Sisson, T.W., Grove, T.L., 1993. Experimental investigations of the role of H2O in calc-

alkaline differentiation and subduction zone magmatism. Contrib. Mineral. Petrol.113 (2), 143–166.

Sisson, T.W., Ratajeski, K., Hankins, W.B., Glazner, A.F., 2005. Voluminous granitic magmasfrom common basaltic sources. Contribution to Mineralogy and Petrology 148,635–661.

Song, S.W., Liu, Z., Zhu, D.C., Wang, Q., Zhang, L.X., Zhang, L.L., Zhao, Z.D., 2014. Zircon U-Pb chronology and Hf isotope of the Late Triassic andesitic magmatism in Dajiacuo,Tibet. Acta Petrologica Sinica 30 (10), 3100–3112 (in Chinese with English abstract).

Stein, H.J., Markey, R.J., Morgan, J.W., Hannah, J.L., Schersten, A., 2001. The remarkable Re–Os chronometer in molybdenite: how and why it works. Terra Nova 13, 479–486.

Streck, M.J., Leeman,W.P., Chesley, J., 2007. High-magnesian andesite fromMount Shasta:a product of magmamixing and contamination, not a primitive mantle melt. Geology35, 351–354.

Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalt:implications for mantle compositions and processes. Geol. Soc. Lond., Spec. Publ. 42,313–345.

Sun, X., Zheng, Y.Y., Wu, S., Z.M., Wu, X., Li, M., Zhou, T.C., Dong, J., 2013. Mineralizationage and petrogenesis of associated intrusions in the Mingze-Chengba porphyry–skarnMo–Cu deposit, Gangdese. Acta Petrol. Sin. 29, 1392–1406 (in Chinese with En-glish abstract).

Sun, W.D., Huang, R.F., Li, H., Hu, Y.B., Zhang, C.C., Sun, S.J., Zhang, L.P., Ding, X., Li, C.Y.,Zartman, R.E., Ling, M.X., 2014. Porphyry deposits and oxidized magmas. Ore Geol.Rev. 65, 97–131.

Tafti, M.A., Hameedy, M.A., Baghal, N.M., 2009. Dyslexia, a deficit or a difference: compar-ing the creativity andmemory skills of dyslexic and nondyslexic students in Iran. Soc.Behav. Personal. Int. J. 37 (8), 1009–1016.

Tang, J.X., Lang, X.H., Xie, F.W., Gao, Y.M., Li, Z.J., Huang, Y., Ding, F., Yang, H.H., Zhang, L.,Wang, Q., Zhou, Y., 2015. Geological characteristics and genesis of the Jurassic no.Iporphyry Cu–Au deposit in the Xiongcun district, Gangdese porphyry copper belt,Tibet. Ore Geological Review 70, 438–456.

Tapponnier, P., Xu, Z., Roger, F., Meyer, B., Arnaud, N., Wittlinger, G., Yang, J.S., 2001.Oblique stepwise rise and growth of the Tibet Plateau. Science 23 (5547), 1671–1677.

Thorpe, R.S., Francis, P.W., O'Callaghan, L., 1984. Relative roles of source composition, frac-tional crystallization and crustal contamination in the petrogenesis of Andean volca-nic rocks. Philosophical Transactions of the Royal Society of London. Series A,Mathematical and Physical Sciences 310 (1514), 675–692.

Tiepolo, M., Tribuzio, R., 2008. Petrology and U–Pb zircon geochronology of amphibole-rich cumulates with sanukitic affinity from Husky Ridge (Northern Victoria Land,Antarctica): insights into the role of amphibole in the petrogenesis of subduction-related magmas. J. Petrol. 49 (5), 937–970.

Trail, D., Watson, E.B., Tailby, N.D., 2011. The oxidation state of Hadean magmas and im-plications for early Earth’s atmosphere. Nature 480, 79–82.

Trail, D., Watson, E.B., Tailby, N.D., 2012. Ce and Eu anomalies in zircon as proxies for theoxidation state of magmas. Geochim. Cosmochim. Acta 97, 70–87.

Turner, S., Hawkesworth, G., Liu, J., Rogers, N., Kelley, S., Calsteren, P.V., 1993. Timing ofTibetan uplift constrained by analysis of volcanic rocks. Nature 364, 50–54.

Wang, L.L., Mo, X.X., Li, B., Dong, G.C., Zhao, Z.D., 2006. Geochronology and geochemistryof the ore-bearing porphyry in Qulong Cu (Mo) ore deposit, Tibet. Acta Petrol. Sin. 22(4), 1001–1008 (in Chinese with English abstract).

Wang, Q., Wyman, D.A., Xu, J.F., Jian, P., Zhao, Z.H., Li, C., Xu, W., Ma, J.L., He, B., 2007. EarlyCretaceous adakitic granites in the Northern Dabie Complex, central China: implica-tions for partial melting and delamination of thickened lower crust. Geochim.Cosmochim. Acta 71, 2609–2636.

Wang, B.D., Xu, J.F., Chen, J.L., Zhang, X.G., Wang, L.Q., Xia, B.B., 2010. Petrogenesis andgeochronology of the ore–bearing porphyritic rocks in Tangbula porphyrymolybdenum–copper deposit in the eastern segment of the Gangdesemetallogenicbelt. Acta Petrol. Sin. 26 (6), 1820–1832 (in Chinese with Englishabstract).

Wang, C., Dai, J., Zhao, X., Li, Y., Graham, S., He, D., Ran, B., Meng, J., 2014. Outward-growthof the Tibetan Plateau during the Cenozoic: a review. Tectonophysics 621, 1–43.

Wang, C., Ding, L., Zhang, L.Y., Kapp, P., Pullen, A., Yue, Y.H., 2016. Petrogenesis of Middle–Late Triassic volcanic rocks from the Gangdese belt, southern Lhasa terrane: implica-tions for early subduction of Neo-Tethyan oceanic lithosphere. Lithos 262, 320–333.

Wang, R., Weinberg, R.F., Collins, W.J., Richards, J.P., Zhu, D.C., 2018. Origin ofpostcollisional magmas and formation of porphyry Cu deposits in southern Tibet.Earth Sci. Rev. 181, 122–143.

Wang, X.H., Lang, X.H., Tang, J.X., Deng, Y.L., Cui, Z.W., 2019. Early–Middle Jurassic(182–170 Ma) Ruocuo adakitic porphyries, southern margin of the Lhasa terrane,Tibet: implications for geodynamic setting and porphyry Cu–Au mineralization.J. Asian Earth Sci. 173, 336–351.

Watson, E.B., Wark, D.A., Thomas, J.B., 2006. Crystallization thermometers for zircon andrutile. Contributions to Mineralogy and Petrology 151 (4), 413–433.

Williams, Q., Hemley, R.J., 2001. Hydrogen in the deep Earth. Annu. Rev. Earth Planet. Sci.29 (1), 365–418.













https://doi.org/10.1029/2018JB017106
























































































































































Wood, D.A., Joron, J.L., Treuil, M., 1979. A re-appraisal of the use of trace elements to clas-sify and discriminate between magma series erupted in different tectonic settings.Earth Planet. Sci. Lett. 45, 326–336.

Woodhead, J.D., Eggins, S.M., Johnson, R.W., 1998. Magma genesis in the New Britain is-land arc: further insights into melting and mass transfer processes. Journal of Petrol-ogy 39, 1641–1668.

Wu, Y.B., Zheng, Y.F., 2004. Genesis of zircon and its constraints on interpretation of U-Pbage. Chin. Sci. Bull. 49, 1554–1569.

Wu, S., Zheng, Y.Y., Sun, X., 2016. Subduction metasomatism and collision-related meta-morphic dehydration controls on the fertility of porphyry copper ore-forming highSr/Y magma in Tibet. Ore Geol. Rev. 73, 83–103.

Xu, W.C., Zhang, H.F., Guo, L., Yuan, H.L., 2010. Miocene high Sr/Y magmatism, southTibet: product of partial melting of subducted Indian continental crust and its tec-tonic implication. Lithos 114 (3–4), 293–306.

Xu, B., Hou, Z., Zheng, Y., Zhou, Y., Zhou, L., Yang, Y., Han, Y., Zheng, G., Wu, C., 2017. Juras-sic hornblende gabbros in Dongga, eastern Gangdese, Tibet: partial melting of mantlewedge and implications for crustal growth. Acta Geologica Sinica-English Edition 91(2), 545–564.

Yan, X.Y., Huang, S.F., Du, A.D., 2010. Re–Os ages of large tungsten, copper and molybde-num deposit in the Zetang orefield, Gangdise and marginal strike–slip transformingmetallogenesis. Geol. Sin. 84 (3), 398–406 (In Chinese with English abstract).

Yang, Z.M., Hou, Z.Q., Jiang, Y.F., Zhang, H.R., Song, Y.C., 2011. Sr–Nd–Pb and zircon Hf iso-topic constraints on petrogenesis of the Late Jurassic granitic porphyry at Qulong,Tibet. Acta Petrol. Sin. 27, 2003–2010 (In Chinese with English abstract).

Yang, Z.M., Lu, Y.J., Hou, Z.Q., Chang, Z.S., 2015. High-Mg diorite from Qulong in southernTibet: implications for the genesis of Adakite-like intrusions and associated porphyryCu deposits in collisional orogens. J. Petrol. 56, 227–254.

Yin, A., Harrison, T.M., 2000. Geologic evolution of the Himalayan-Tibetan orogen. AnnualReviews in Earth and Planetary Science 28, 211–280.

Zhang, L.L., Liu, C.Z., Wu, F.Y., Ji, W.Q., Wang, J.G., 2014. Zedong terrane revisited: an intra-oceanic arc within Neo-Tethys or a part of the Asian active continental margin?J. Asian Earth Sci. 80, 34–55.

Zhang, C.C., Sun, W.D., Wang, J.T., Zhang, L.P., Sun, S.J., Wu, K., 2017. Oxygen fugacity andporphyry mineralization: a zircon perspective of Dexing porphyry Cu deposit, China.Geochim. Cosmochim. Acta 206, 343–363.

Zhang, Y.H., Cao, H.W., Hollis, S.P., Tang, L., Xu, M., Jiang, J.S., Wang, Y.S., 2019. Geochronol-ogy, geochemistry and Sr-Nd-Pb-Hf isotopes of the Early Paleogene gabbro and gran-ite from Central Lhasa, southern Tibet: petrogenesis and tectonic implications. Int.Geol. Rev. 61 (7), 868–894.

Zhao, J.X., Qin, K.Z., Li, G.M., Li, J.X., Xiao, B., Chen, L., Yang, Y.H., Li, C., Liu, Y.S., 2014.Collision-related genesis of the Sharang porphyry molybdenum deposit, Tibet: evi-dence from zircon U–Pb ages, Re–Os ages and Lu–Hf isotopes. Ore Geology Reviews56, 312–326.

Zhao, X.Y., Yang, Z.S., Zheng, Y.C., Liu, Y.C., Tian, S.H., Fu, Q., 2014. Geology and genesis ofthe post-collisional porphyry–skarn deposit at Bangpu, Tibet. Ore Geol. Rev. 70,486–509.

Zheng, Y.Y., Zhang, G.Y., Xu, R.K., Gao, S.B., Pang, Y.C., Cao, L., Du, A., Shi, Y.R., 2007. Geo-chronological constraints on magmatic intrusions and mineralization of the Zhunuoporphyry copper deposit in Gangdese, Tibet. Chin. Sci. Bull. 52 (22), 3139–3147.

Zheng, Y.Y., Sun, X., Gao, S.B., Wang, C.M., Zhao, Z.Y.,Wu, S., Li, J.D., Wu, X., 2014a. Analysisof stream sediment data for exploring the Zhunuo porphyry Cu deposit, southernTibet. J. Geochem. Explor. 143, 19–30.

Zheng, Y.Y., Sun, X., Gao, S.B., Zhao, Z.D., Zhang, G.Y., Wu, S., You, Z.M., Li, J.D., 2014b. Mul-tiplemineralization events at the Jiru porphyry copper deposit, southern Tibet: impli-cations for Eocene and Miocenemagma sources and resource potential. Journal ofAsian Earth Science 79, 842–857.

Zheng, Y.Y., Sun, X., Gao, S.B., Wu, S., Xu, J., Jiang, J.S., Chen, X., Zhao, Z.Y., Liu, Y., 2015.Metallogenesis and the minerogenetic series in the Gangdese polymetallic copperbelt. Journal of Asian Earth Science 103, 23–39.

Zhu, D.C., Pan, G.T., Chung, S.L., Liao, Z.L., Wang, L.Q., Li, G.M., 2008. SHRIMP zircon age andgeochemical constraints on the origin of Lower Jurassic volcanic rocks from the YebaFormation, southern Gangdese, South Tibet. Int. Geol. Rev. 50 (5), 442–471.

Zhu, D.C., Zhao, Z.D., Niu, Y., Mo, X.X., Chung, S.L., Hou, Z.Q., Wang, L.Q., Wu, F.-Y., 2011.The Lhasa Terrane: record of a microcontinent and its histories of drift and growth.Earth and Planetary Science Letters 301, 241–255.

Zhu, D.C., Zhao, Z.D., Niu, Y., Dilek, Y., Hou, Z.Q., Mo, X.X., 2013. The origin and pre-Cenozoic evolution of the Tibetan Plateau. Gondwana Res. 23, 1429–1454.

































































Ages and petrogenesis of the late Triassic andesitic rocks at ...

Documents