Mineralization age and petrogenesis of associated intrusions in the Mingze-Chengba porphyry-skarn Mo-Cu deposit, Gangdese
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摘要:
冈底斯东南缘克鲁-冲木达矿带以发育渐新世斑岩-夕卡岩型Mo-W-Cu成矿作用而有别于冈底斯中新世斑岩-夕卡岩型Cu-Mo-Au矿带，但是对渐新世成矿岩石类型及成因以及渐新世与中新世斑岩成矿作用存在差异的原因尚不清楚，严重制约了该带矿产资源潜力评价。为此，本文选择矿带内程巴斑岩型Mo矿床及明则夕卡岩型Cu矿床开展了成岩与成矿年代学及含矿岩石成因研究。明则矿区与夕卡岩矿化有关的二长岩的结晶年龄为30.4±0.6Ma，表明夕卡岩矿化时代约30Ma，这与程巴斑岩型Mo矿床矿石中辉钼矿Re-Os同位素分析所揭示的约30Ma矿化时代一致。明则二长岩的SiO2含量为55%~57%，K2O含量为2.7%~5.0%，属于钾玄岩，具有较高的MgO含量(3.5%~6.9%)、Mg#值(57.6~67.2)以及相容元素含量(Cr=34×10-6~379×10-6；Ni为48×10-6~116×10-6)。而程巴花岗闪长岩的SiO2含量为65%~67%，K2O含量为3.2%~4.1%，属于高钾钙碱性岩，具有较低的MgO含量(1.7%~2.1%)、Mg#值(49.5~51.1)以及相容元素含量(Cr=20×10-6~39×10-6；Ni为16×10-6~25×10-6)。二长岩和花岗闪长岩均显示富集轻稀土元素与大离子亲石元素，亏损高场强元素，具有弱的Eu负异常，但二长岩的REE含量明显高于花岗闪长岩，且具有较低的Sr/Y比值(24~49)，后者Sr/Y比值为54~68。两种岩石均具有类似的Hf同位素组成，二长岩的εHf(t)值为+2.8~+6.8，花岗闪长岩εHf(t)值为+4.2~+6.1。综合分析表明，二长岩是受大洋板片流体交代的富集岩石圈地幔部分熔融的产物，而花岗闪长岩是增厚的新生下地壳部分熔融的产物，二者在形成过程中可能发生了幔源镁铁质岩浆与壳源长英质岩浆的混合作用，这种壳幔相互作用导致区域斑岩-夕卡岩型Cu-Mo矿化，但由于该区隆升剥蚀强烈，上部的斑岩型Cu矿体基本被剥蚀而没有保存下来，因此现今表现为斑岩型Mo矿床。
Abstract:The Kelu-Chongmuda metallogenic belt, different from the Gangdese Miocene porphyry-skarn Cu-Mo-Au belt, is characterized by Oligecene porphyry-skarn Mo-W-Cu mineralization. The types and petrogenesis of intrusions associated with Oligecene mineralization and the reason for the difference between the Kelu-Chongmuda and Gangdese mineralization remain topics of debate, which prevents the evaluation of resource potentiality. Therefore, we conducted the geochronological analysis and research on the petrogenesis of associated intrusions for the Chengba porphyry Mo deposit and Mingze skarn Cu deposit. The Mingze monzonlite associated with skarn mineralization has zircon SHRIMIP U-Pb age of 30.4±0.6Ma, indicating that the Mingze mineralization took place at ca. 30Ma, which is consistent with the mineralization age of the Chengba porphyry Mo deposit. The Mingze monzonlite are shoshonitie, with low SiO2 (55%~57%), high K2O (2.7%~5.0%), MgO (3.5%~6.9%), Mg# value (57.6~67.2), high abundances of compatible elements (e.g., Cr=34×10-6~379×10-6; Ni=48×10-6~116×10-6), and low Sr/Y ratios (24~49). The Chengba granodiorite, with the zircon SHRIMIP U-Pb age of 28.7±0.9Ma, are high-K calc-alkaline, with high SiO2 (65%~67%), high K2O (3.2%~4.1%), MgO (1.7%~2.1%), Mg# value (49.5~51.1), low abundances of compatible elements (e.g., Cr=20×10-6~39×10-6; Ni=16×10-6~25×10-6), and low Sr/Y ratios (53~76). Both the monzonlite and granodiorite display enriched LREE and LILE, depleted HSFE, marked negative Nb-Ta-Ti anomalies, and slightly negative Eu anomalies. However, the monzonlite have high abundances of REE than the granodiorite. They also have similar Hf isotopic compositions with εHf(t)=+2.8~+6.8 for the monzonlite and εHf(t)=+4.2~+6.1 for the granodiorite. Our new data, together with previously published work, lead us to suggest that the parental magmas of the Mingze monzonlite were most likely derived from enriched lithospheric mantle beneath southern Tibet and the Chengba granodiorites were derived from partial melting of a thickened juvenile lower crust. The magma mixing between the crust-derived and mantle-derived magmas is beneficial for the porphyry-skarn Cu-Mo mineralization in the Kelu-Chongmuda and Gangdese metallogenic belts. But due to the more intensive erosion in the Kelu-Chongmuda than in the Gangdese, the upper Cu bodies were not preserved and the lower Mo bodies were present in the Chengba porphyry Mo deposit.
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Key words:
- Porphyry and Skarn deposit /
- Kelu-Chongmuda metallogenic belt /
- Magma mixing /
- Petrogenesis /
- Oligecene /
- Gangdese
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图 1
青藏高原大地构造分区图(a, 据Zhu et al., 2011)和冈底斯东南缘泽当区域地质与矿床分布图(b, 据Harrison et al. 2000修改)
Figure 1.
Tectonic framework of the Tibetan Plateau (a, after Zhu et al., 2011) and regional geological map showing the localities of major deposits in the Zedong area, southeastern Gangdese (b, modified after Harrison et al. 2000)
图 3
程巴花岗闪长岩(CB-3)及明则二长岩(MZ-14)中锆石U-Pb年龄谐和图
Figure 3.
U-Pb concordia diagrams for zircons from Chengba granodiorite (CB-3) and Mingze monzonlite (MZ-14)
图 4
程巴矿床辉钼矿Re-Os等时线年龄图
Figure 4.
Re-Os isochron age diagram for molybdenite samples from the Chengba porphyry Mo deposit
图 5
程巴花岗闪长岩和明则二长岩主量及微量元素图解
Figure 5.
Discrimination diagrams for the Mingze monzonlite and Chengba granodiorite
图 6
明则二长岩与程巴花岗闪长岩稀土元素配分图(a)和微量元素蛛网图(b)(标准化值据Sun and McDonough, 1989)
Figure 6.
Chondrite-normalized rare earth element patterns (a) and primitive-mantle-normalized trace element patterns (b) for the Mingze monzonlite and Chengba granodiorite (normalization values after Sun and McDonough, 1989)
图 7
明则二长岩与程巴花岗闪长岩Sr/Y vs. Y图(a)和(La/Yb)N vs. YbN图(b)
Figure 7.
Discrimination diagrams of Sr/Y ratios vs. Y contents (a) and (La/Yb)N ratios vs. YbN contents (b) for the Mingze monzonlite and Chengba granodiorite
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Aitchison JC, Zhu BD, Davis AM, Liu JB, Luo H, Malpas JG, McDeemind IRC, Wu HY, Ziabrev SV and Zhou MF. 2000. Remnants of a Cretaceous intra-oceanic subduction system within the Yarlung-Zangbu suture (southern Tibet). Earth and Planetary Science Letters, 183(1-2): 231-244
Blichert-Toft J and Albarède F. 1997. The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system. Earth and Planetary Science Letters, 148(1-2): 243-258
Bowden P, Batchelor RA, Chappell BW, Didier J and Lameyre J. 1984. Petrological, geochemical and source criteria for the classification of granitic rocks: A discussion. Physics of the Earth and Planetary Interiors, 35(1-3): 1-11
Chung SL, Liu DY, Ji JQ, Chu MF, Lee HY, Wen DJ, Lo CH, Lee TY, Qian Q and Zhang Q. 2003. Adakites from continental collision zones: Melting of thickened lower crust beneath southern Tibet. Geology, 31(11): 1021-1024
Chung SL, Chu MF, Ji JQ, O’Reilly SY, Pearson NJ, Liu DY, Lee TY and Lo CH. 2009. The nature and timing of crustal thickening in Southern Tibet: Geochemical and zircon Hf isotopic constraints from post collisional adakites. Tectonophysics, 477(1-2): 36-48
Deng J, Wang QF, Yang LQ, Wang YR, Gong QJ and Liu H. 2010. Delineation and explanation of geochemical anomalies using fractal models in the Heqing area, Yunnan Province, China. Journal of Geochemical Exploration, 105(3): 95-105
Deng J, Yang LQ, Ge LS, Yuan SS, Wang QF, Zhang J, Gong QJ and Wang CM. 2010. Character and post-ore changes, modifications and preservation of Cenozoic alkali-rich porphyry gold metallogenic system in western Yunnan, China. Acta Petrologica Sinica, 26(6): 1633-1645(in Chinese with English abstract)
Deng J, Yang LQ and Wang CM. 2011. Research advances of superimposed orogenesis and metallogenesis in the Sanjiang Tethys. Acta Petrologica Sinica, 27(9): 2501-2509 (in Chinese with English abstract)
Deng J, Wang CM and Li GJ. 2012. Style and process of the superimposed mineralization in the Sanjiang Tethys. Acta Petrologica Sinica, 28(5): 1349-1361 (in Chinese with English abstract)
Dong X, Zhang ZM and Santosh M. 2010. Zircon U-Pb chronology of the Nyingtri Group, southern Lhasa Terrane, Tibetan Plateau: Implications for Grenvillian and Pan-African provenance and Mesozoic-Cenozoic metamorphism. Journal of Geology, 118(6): 677-690
Du AD, Wu SQ, Sun DZ, Wang SX, Qu WQ, Markey R, Stain H, Morgan J and Malinovskiy D. 2004. Preparation and certification of Re-Os dating reference materials: Molybdenites HLP and JDC. Geostandards and Geoanalytical Research, 28(1): 41-52
Furman T and Graham D. 1999. Erosion of lithospheric mantle beneath the East African Rift system: Geochemical evidence from the Kivu volcanic province. Lithos, 48(1-4): 237-262
Gao YF, Hou ZQ, Kamber BS, Wei RH, Meng XJ and Zhao RS. 2007. Adakite-like porphyries from the southern Tibetan continental collision zones: Evidence for slab melt metasomatism. Contributions to Mineralogy and Petrology, 153(1): 105-120
Gao YF, Yang ZS, Santosh M, Hou ZQ, Wei RH and Tian SH. 2010. Adakitic rocks from slab melt-modified mantle sources in the continental collision zone of southern Tibet. Lithos, 119(3-4): 651-663
Griffin WL, Pearson NJ, Belousova E, Jackson SE, van Achterbergh E, O’Reilly SY and Shee SR. 2000. The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites. Geochimica et Cosmochimica Acta, 64(1): 133-147
Guan Q, Zhu DC, Zhao ZD, Dong GC, Zhang LL, Li XW, Liu M, Mo XX, Liu YS and Yuan HL. 2012. Crustal thickening prior to 38Ma in southern Tibet: Evidence from lower crust-derived adakitic magmatism in the Gangdese Batholith. Gondwana Research, 21: 88-99
Guo ZF, Wilson M and Liu JQ. 2007. Post-collisional adakites in South Tibet: Products of partial melting of subduction-modified lower crust. Lithos, 96(1-2): 205-224
Han FJ. 2006. Geological characteristics and ore-searching directions of Mingze porphyry copper deposit, Sangri County, Tibet. Contributions to Geology and Mineral Resources Research, 21(Suppl.): 20-21(in Chinese with English abstract)
Harrison TM, Yin A, Grove M, Lovera OM, Ryerson FJ and Zhou XH. 2000. The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet. Journal of Geophysical Research, 105(B8): 19211-19230
Hofmann AW, Jochum KP, Seufert M and White WM. 1986. Nb and Pb in oceanic basalts: New constraints on mantle evolution. Earth and Planetary Science Letters, 79(1-2): 33-45
Hoskin PWO and Black LP. 2000. Metamorphic zircon formation by solid state recrystalliza-tion of protolith igneous zircon. Journal of Metamorphic Geology, 18(4): 423-439
Hou ZQ, Qu XM, Wang SX, Gao YF, Du AD and Huang W. 2003. Re-Os ages of molybdenite in the Gangdese porphyry copper belt in south Tibet: Duration of mineralization and application of the dynamic setting. Science in China (Series D), 33(7): 609-618 (in Chinese)
Hou ZQ, Gao YF, Qu XM, Rui ZY and Mo XX. 2004. Origin of adakitic intrusives generated during Mid-Miocene east-west extension in southern Tibet. Earth and Planetary Science Letters, 220(1-2): 139-155
Hou ZQ, Zheng YC, Yang ZM and Yang ZS. 2012. Metallogenesis of continental collision setting: Part Ⅰ. Gangdese Cenozoic porphyry Cu-Mo systems in Tibet. Mineral Deposits, 31(4): 647-670 (in Chinese with English abstract)
Jiang YH, Jiang SY, Zhao KD, Ni P, Ling HF and Liu DY. 2005. SHRIMP U-Pb zircon dating for lamprophyre from Liaodong Peninsula: Constraints on the initial time of Mesozoic lithosphere thinning beneath eastern China. Chinese Science Bulletin, 50(22): 2612-2620
Jiang YH, Jiang SY, Ling HF and Dai BZ. 2006. Low-degree melting of a metasomatized lithospheric mantle for the origin of Cenozoic Yulong monzogranite-porphyry, east Tibet: Geochemical and Sr-Nd-Pb-Hf isotopic constraints. Earth and Planetary Science Letters, 241(3-4): 617-633
Jiang YH, Jiang SY, Dai BZ and Ling HF. 2008. Origin of Ore-bearing Porphyries in the Yulong Porphyry Copper Deposit, East Tibet. Beijing: Geological Publishing House, 1-122(in Chinese)
Jiang ZQ, Wang Q, Wyman DA, Tang GJ, Jia XH, Yang YH and Yu HX. 2011. Origin of ~30Ma Chongmuda adakitic intrusive rocks in the southern Gangdese region, southern Tibet: Partial melting of the northward subducted Indian continent crust? Geochimica, 40(2): 126-146(in Chinese with English abstract)
Lee HY, Chung SL, Lo CH, Ji JQ, Lee TY, Qian Q and Zhang Q. 2009. Eocene Neotethyan slab breakoff in southern Tibet inferred from the Linzizong volcanic record. Tectonophysics, 477(1-2): 20-35
Li GM, Liu B, She HQ et al. 2006b. Early Himalayan mineralization on the southern margin of the Gangdise metallogenic belt, Tibet, China: Evidence from Re-Os ages of the Chongmuda skarn-type Cu-Au deposit. Geological Bulletin of China, 25(12): 1481-1486 (in Chinese with English abstract)
Ludwig KR. 1999. Using Isoplot/Ex, Version2.0: A geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication, 1a: 1-47
Mao JW, Zhang JD and Guo CL. 2010. Porphyry Cu, epithermal Ag-Pb-Zn, distal hydrothermal Au deposits: A new model of mineral deposit: Taking the Dexing area as an example. Journal of Earth Sciences and Environment, 32(1): 1-14 (in Chinese with English abstract)
Middlmost EAK. 1994. Naming materials in the magma/igneous rock system. Earth-Science Reviews, 37(3-4): 215-224
Mo JH, Liang HY, Yu HX, Chen Y and Sun WD. 2008. Zircon U-Pb age of biotite hornblende monzonitic granite for Chongmuda Cu-Au (Mo) deposit in Gangdese belt, Xizang, China and its implications. Geochimica, 37(3): 207-212 (in Chinese with English abstract)
Mo XX, Niu YL, Dong GC, Zhao ZD, Hou ZQ, Zhou S and Ke S. 2008. Contribution of syncollisional felsic magmatism to continental crust growth: A case study of the Paleogene Linzizong volcanic succession in southern Tibet. Chemical Geology, 250(1-4): 49-67
Mungall JE. 2002. Roasting the mantle: Slab melting and the genesis of major Au and Au-rich Cu deposits. Geology, 30(10): 915-918
Oyarzun R, Márquez A, Lillo J, López I and Rivera S. 2001. Giant versus small porphyry copper deposits of Cenozoic age in northern Chile: Adakitic versus normal calc-alkaline magmatism. Mineralium Deposita, 36(8): 794-798
Pan GT, Mo XX, Hou ZQ, Zhu DC, Wang LQ, Li GM, Zhao ZD, Geng QR and Liao ZL. 2006. Spatial-temporal framework of the Gangdese Orogenic Belt and its evolution. Acta Petrologica Sinica, 22(3): 521-533 (in Chinese with English abstract)
Peccerillo R and Taylor SR. 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contributions to Mineralogy and Petrology, 58(1): 63-81
Qu XM, Hou ZQ and Li YG. 2004. Melt components derived from a subducted slab in late orogenic ore-bearing porphyries in the Gangdese copper belt, southern Tibetan Plateau. Lithos, 74(3-4): 131-148
Richards JP and Kerrich R. 2007. Adakite-like rocks: Their diverse origins and questionable role in metallogenesis. Economic Geology, 102(4): 537-576
Richards JP. 2009. Postsubduction porphyry Cu-Au and epithermal Au deposits: Products of remelting of subduction-modified lithosphere. Geology, 37(3): 247-250
Rogers NW, James D, Kelley SP and De Mulder M. 1998. The generation of potassic lavas from the eastern Virunga province, Rwanda. Journal of Petrology, 39(6): 1223-1247
Rudnick RL and Fountain DM. 1995. Nature and composition of the continental crust: A lower crustal perspective. Reviews of Geophysics, 33(3): 267-309
Rui ZY, Hou ZQ, Qu XM, Zhang LS, Wang LS and Liu YL. 2003. Metallogenetic epoch of Gangdese porphyry copper belt and uplift of Qinghai-Tibet Plateau. Mineral Deposits, 22(30): 217-225(in Chinese with English abstract)
Sderlund U, Patchett PJ, Vervoort JD and Isachsen CE. 2004. The 176Lu decay constant determined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusions. Earth and Planetary Science Letters, 219(3-4): 311-324
Stern CR and Kilian R. 1996. Role of the subducted slab, mantle wedge and continental crust in the generation of adakites from the Andean Austral Volcanic Zone. Contributions to Mineralogy and Petrology, 123(3): 263-281
Sun SS and McDonough WF. 1989. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. In: Saunders AD and Norry MJ (eds.). Magmatism in the Ocean Basins. Geological Society, London, Special Publication, 42(1): 313-345
Sun X, Deng J, Zhao ZY, Zhao ZH, Wang QF, Yang LQ, Gong QJ and Wang CM. 2010. Geochronology, petrogenesis and tectonic implications of granites from the Fuxin area, western Liaoning, NE China. Gondwana Research, 17(4): 642-652
Tang JX, Chen YC, Wang DH, Wang CH, Xu YP, Qu WJ, Wang W and Huang Y. 2009. Re-Os dating of molybdenite from the Sharang porphyry molybdenum deposit in Gongbo’gyamda County, Tibet and its geological significance. Acta Geologica Sinica, 85(5): 698-704 (in Chinese with English abstract)
Tang JX, Li FJ, Li ZJ, Zhang L, Tang XQ, Deng Q, Lang XH, Huang Y, Yao XF and Wang Y. 2010. Time limit for formation of main geological bodies in Xiongcun copper-gold deposit, Xietongmen County, Tibet: Evidence from zircon U-Pb ages and Re-Os age of molybdenite. Mineral Deposits, 29(3): 461-475(in Chinese with English abstract)
Turner S, Arnaud N, Liu J, Rogers N, Hawkesworth C, Harris N, Kelley S, Van Calsteren P and Deng W. 1996. Post-collision, shoshonitic volcanism on the Tibetan Plateau: Implications for convective thinning of the lithosphere and the source of ocean island basalts. Journal of Petrology, 37(1): 45-71
Wang YW, Wang JB, Long LL, Zou T, Tang PZ and Wang LJ. 2012. Type, indicator, mechanism, model and relationship with mineralization of magma mixing: A case study in North Xinjiang. Acta Petrologica Sinica, 28(8): 2317-2330 (in Chinese with English abstract)
Wen DR, Chung SL, Song B, Iizuka Y, Yang HJ, Ji JQ, Liu DY and Gallet S. 2008. Late Cretaceous Gangdese intrusions of adakitic geochemical characteristics, SE Tibet: Petrogenesis and tectonic implications. Lithos, 105(1-2): 1-11
Williams IS. 1998. U-Th-Pb geochronology by ion microprobe. In: McKibben MA, Shanks WC Ⅲ and Ridley WI (eds.). Applications of Microanalytical Techniques to Understanding Mineralizing Processes. Reviews in Economic Geology, 1-35
Wyllie PJ and Sekine T. 1982. The formation of mantle phlogopite in subduction zone hybridization. Contributions to Mineralogy And Petrology, 79(4): 375-380
Yan XY, Huang SF and Du AD. 2010. Re-Os ages of large tungsten, copper and molybdenum deposit in the Zetang orefield, Gangdise and marginal strike-slip transforming metallogenesis. Acta Geologica Sinica, 84(3): 398-406 (in Chinese with English abstract)
Yang LQ, Liu HT, Zhang C, Wang QF, Ge LS, Wang ZL, Zhang J and Gong QJ. 2010. Superimposed orogenesis and metallogenesis: An example from the orogenic gold deposits in Ailaoshan gold belt, Southwest China. Acta Petrologica Sinica, 26(6): 1723-1739 (in Chinese with English abstract)
Yang ZM, Hou ZQ, Song YC, Li ZQ, Xia DX and Pan FC. 2008. Qulong superlarge porphyry Cu deposit in Tibet: Geology, alteration and mineralization. Mineral Deposits, 27(3): 279-318 (in Chinese with English abstract)
Yuan HL, Gao S, Dai MN, Zong CL, Günther D, Fontaine GH, Liu XM and Diwu CR. 2008. Simultaneous determinations of U-Pb age, Hf isotopes and trace element compositions of zircon by excimer laser-ablation quadrupole and multiple-collector ICP-MS. Chemical Geology, 247(1-2): 100-118
Zheng YY, Xue YX, Cheng LJ, Fan ZH and Gao SB. 2004. Finding, characteristics and significances of Qulong superlarge porphyry copper (molybdenum) deposit, Tibet. Earth Science, 29(1): 103-108(in Chinese with English abstract)
Zhu DC, Zhao ZD, Pan GT, Lee HY, Kang ZQ, Liao ZL, Wang LQ, Li GM, Dong GC and Liu B. 2009. Early cretaceous subduction-related adakite-like rocks of the Gangdese Belt, southern Tibet: Products of slab melting and subsequent melt-peridotite interaction? Journal of Asian Earth Sciences, 34(3): 298-309
Zhu DC, Zhao ZD, Niu YL, Mo XX, Chung SL, Hou ZQ, Wang LQ and Wu FY. 2011. The Lhasa Terrane: Record of a microcontinent and its histories of drift and growth. Earth and Planetary Science Letters, 301(1-2): 241-255
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