冈底斯中段早侏罗世辉长岩-花岗岩杂岩体成因及其对新特提斯构造演化的启示:以日喀则东嘎岩体为例
Petrogenesis of the Early Jurassic gabbro-granite complex in the middle segment of the Gangdese belt and its implications for tectonic evolution of Neo-Tethys: A case study of the Dongga pluton in Xi'gaze
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摘要: 以冈底斯中段日喀则东嘎出露的早侏罗世辉长岩-花岗岩杂岩体为对象,进行了锆石U-Pb年龄和Hf同位素,以及全岩元素地球化学组成的系统测定,据此探讨了岩石的成因及其对新特提斯构造演化的启示。该杂岩体中辉长岩主要由角闪石和钙质斜长石组成,缺乏辉石;花岗岩主要为英云闪长岩、花岗闪长岩等构成的TTG岩石组合;花岗岩中普遍发育呈塑变形态的镁铁质包体。锆石LA-ICP-MS U-Pb定年结果显示,英云闪长岩和镁铁质包体的成岩年龄十分接近,且与辉长岩的年龄基本一致,均为177~180Ma。化学组成上,辉长岩低硅、富铝、贫碱,富轻稀土和大离子亲石元素,贫高场强元素,相似于高铝玄武岩。英云闪长岩贫碱、准铝、富钠,属钙碱性I型花岗岩。镁铁质包体具有与寄主岩相似的矿物组成和微量元素分布模式,二者均具有显著亏损的锆石Hf同位素组成,εHf(t)值分别为+11.4~+15.0和+14.4~+18.6。综合分析表明,早侏罗世冈底斯南缘应处于新特提斯洋板片俯冲的构造背景,其中辉长质侵入体为遭受俯冲板片析出流体交代作用的亏损地幔部分熔融的产物,花岗质岩石起源于初生地壳的部分熔融,镁铁质包体为辉长质岩浆与花岗质岩浆二者经混合作用的产物。结合对区内其它辉长质侵入体及相关镁铁质包体资料的全面分析,表明在新特提斯洋板片的整个俯冲过程中(>205~40Ma),冈底斯南缘应存在多次的基性岩浆底侵及其诱发的壳幔岩浆混合作用。
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关键词:
- 辉长岩-花岗岩杂岩体 /
- 岩石成因 /
- 岩浆混合作用 /
- 新特提斯洋俯冲 /
- 日喀则东嘎
Abstract: The gabbro-granite complexes developed in convergent plate margins provide an excellent opportunity to investigate the genetic relationships between acid and basic magmas, and their interactions within the intrusive environment. Such complexes are widely outcropped in the southern margin of the Gangdese magmatic belt. In this paper, we take the Early Jurassic gabbro-granite complex in Dongga near Xi'gaze as an example, and conduct an integrated study including petrology, elemental geochemistry and zircon Hf isotopes, with the aims of understanding their petrogenesis and the implications for Neotethyan evolution. Lithologically, gabbroic rocks in the Dongga complex consist mainly of amphiboles and calcic plagioclases, and pyroxenes are rarely observed. Granitoids are a set of TTG association composed mainly of tonalites and granodiorites. Mafic enclaves with various plastic shapes are widely dispersed in the granitoids. Zircon LA-ICP-MS U-Pb dating demonstrates that the tonalites and the mafic enclaves share similar ages of 177~180Ma with the gabbros. Chemically, the gabbros have low SiO2 and K2O+Na2O, but high Al2O3 contents, and are enriched in LREEs and LILEs, depleted in HFSEs, showing similar chemical features with the high-alumina basalts. The tonalites exhibit sub-alkaline, metaluminous, and Na-rich signatures, and are genetically of calc-alkaline I-type granites. The mafic enclaves share similar mineral assemblages and trace element distribution patterns with the host granitoids. Both the granitoids and the mafic enclaves have highly depleted zircon Hf isotopic compositions, with εHf(t) values of +11.4~+15.0 and +14.4~+18.6, respectively. The integrated petrology and elemental and isotopic compositions suggest that during the Early Jurassic, the southern margin of the Gangdese belt was under the Neotethyan subduction setting. The gabbros were generated by the hydrous partial melting of depleted mantle metasomatized by fluids released from subducted oceanic slab. The granitoids were originated from partial melting of juvenile crustal materials. The mafic enclaves were produced by binary mixing between the gabbroic and granitic magmas. In combination with a comprehensively synthesis of the other gabbros and related mafic enclaves along the southern margin of the Gangdese belt, we propose that multiple underplating of mafic magmas and the induced magma mixing were occurred during the whole duration (>205~40Ma) of the Neotethyan subduction.-
Key words:
- Gabbro-granite complex /
- Petrogenesis /
- Magma mixing /
- Neotethyan subduction /
- Dongga, Xi'gaze
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[1] Ayers J. 1998. Trace element modeling of aqueous fluid-peridotite interaction in the mantle wedge of subduction zones. Contributions to Mineralogy and Petrology, 132(4): 390-404
[2] Beard JS. 1986. Characteristic mineralogy of arc-related cumulate gabbros: Implications for the tectonic setting of gabbroic plutons and for andesite genesis. Geology, 14(10): 848-851
[3] 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
[4] Boynton WV. 1984. Geochemistry of the rare earth elements: Meteorite studies. In: Henderson P (ed.). Rare Earth Elements Geochemistry. Amsterdam: Elservier, 63-144
[5] Chu MF, Chung SL, Song B, Liu DY, O'Reilly SY, Pearson NJ, Ji JQ and Wen D. 2006. Zircon U-Pb and Hf isotope constraints on the Mesozoic tectonics and crustal evolution of Southern Tibet. Geology, 34(9): 745-748
[6] Connelly JN. 2001. Degree of preservation of igneous zonation in zircon as a signpost for concordancy in U/Pb geochronology. Chemical Geology, 172(1-2): 25-39
[7] Corfu F, Hanchar JM, Hoskin PWO and Kinny P. 2003. Altas of zircon textures. Reviews in Mineralogy and Geochemistry, 53(1): 469-500
[8] Dong GC, Mo XX, Zhao ZD, Zhu DC, Wang LL, Chen T and Li B. 2006. Magma mixing in middle part of Gangdese magma belt: Evidences from granitoid complex. Acta Petrologica Sinica, 22(4): 835-844 (in Chinese with English abstract)
[9] Dong GC, Mo XX, Zhao ZD, Zhu DC, Song YT and Wang L. 2008. Gabbros from southern Gangdese: Implication for mass exchange between mantle and crust. Acta Petrologica Sinica, 24(2): 203-210 (in Chinese with English abstract)
[10] Fernandez AN and Barbarin B. 1991. Relative rheology of coeval mafic and felsic magmas: Nature of resulting interaction processes and shape and mineral fabrics of mafic microgranular enclaves. In: Dider J and Barbarin B (eds.). Enclaves and Granite Petrology. Amsterdam: Elsevier, 263-276
[11] Gao JF, Lu JJ, Lai MY, Lin YP and Pu W. 2003. Analysis of trace elements in rock samples using HR-ICPMS. Journal of Nanjing University (Natural Sciences), 39(6): 844-850 (in Chinese with English abstract)
[12] Griffin WL, Wang X, Jackson SE, Pearson NJ, O'Reilly SY, Xu XS and Zhou XM. 2002. Zircon chemistry and magma mixing, SE China: In-situ analysis of Hf isotopes, Tonglu and Pingtan Igneous complexes. Lithos, 61(3-4): 237-269
[13] Guan Q, Zhu DC, Zhao ZD, Dong GC, Mo XX, Liu YS, Hu ZC and Yuan HL. 2011. Zircon U-Pb chronology, geochemistry of the Late Cretaceous mafic magmatism in the southern Lhasa Terrane and its implications. Acta Petrologica Sinica, 27(7): 2083-2094 (in Chinese with English abstract)
[14] Ji WQ, Wu FY, Liu CZ and Chung SL. 2009. Geochronology and petrogenesis of granitic rocks in Gangdese batholith, southern Tibet. Science in China (Series D), 52(9): 1240-1261
[15] Kelemen PB, Johnson KTM, Kinzler RJ and Irving AJ. 1990. High-field-strength element depletions in arc basalts due to mantle-magma interaction. Nature, 345(6275): 521-524
[16] Leake BE. 1990. Granite magmas: Their sources, initiation and consequences of emplacement. Journal of the Geological Society, 147(4): 579-589
[17] Li Z, Qiu JS and Xu XS. 2012. Geochronological, geochemical and Sr-Nd-Hf isotopic constraints on petrogenesis of Late Mesozoic gabbro-granite complexes on the southeast coast of Fujian, South China: Insights into a depleted mantle source region and crust-mantle interactions. Geological Magazine, 149(3): 459-482
[18] Liu YS, Gao S, Hu ZC, Gao CG, Zong KQ and Wang DB. 2010. Continental and oceanic crust recycling-induced melt-peridotite interactions in the Trans-North China Orogen: U-Pb dating, Hf isotopes and trace elements in zircons of mantle xenoliths. Journal of Petrology, 51(1-2): 537-571
[19] Luhr JF and Haldar D. 2006. Barren Island Volcano (NE Indian Ocean): Island-arc high-alumina basalts produced by troctolite contamination. Journal of Volcanology and Geothermal Research, 149(3-4): 177-212
[20] Ma L, Wang Q, Li ZX, Wyman DA, Jiang ZQ, Yang JH, Gou GN and Guo HF. 2013. Early Late Cretaceous (ca. 93Ma) norites and hornblendites in the Milin area, eastern Gangdese: Lithosphere-asthenosphere interaction during slab roll-back and an insight into early Late Cretaceous (ca. 100~80Ma) magmatic ‘flare-up’ in southern Lhasa (Tibet). Lithos, 172-173: 17-30
[21] McDonough WF and Sun SS. 1995. The composition of the Earth. Chemical Geology, 120(3-4): 223-253
[22] Middlemost EAK. 1994. Naming materials in the magma/igneous rock system. Earth-Science Reviews, 37(3-4): 215-224
[23] Peccerillo A and Taylor SR. 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contributions to Mineralogy and Petrology, 58(1): 63-91
[24] Pitcher WS, Atherton MP, Cobbing EJ and Beckinsale RD. 1985. Magmatism at a Plate Edge: The Peruvian Andes. Glasgow: Springer, 1-328
[25] Plank T and Langmuir CH. 1998. The chemical composition of subducting sediment and its consequences for the crust and mantle. Chemical Geology, 145(3-4): 325-394
[26] Renna MR, Tribuzio R and Tiepolo M. 2007. Origin and timing of the post-Variscan gabbro-granite complex of Porto (Western Corsica). Contributions to Mineralogy and Petrology, 154(5): 493-517
[27] Scherer E, Münker C and Mezger K. 2001. Calibration of the lutetium-hafnium clock. Science, 293(5530): 683-687
[28] Shinjoe H. 1997. Origin of the granodiorite in the forearc region of Southwest Japan: Melting of the Shimanto accretionary prism. Chemical Geology, 134(4): 237-255
[29] Sisson TW and Grove TL. 1993. Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism. Contributions to Mineralogy and Petrology, 113(2): 143-166
[30] Sisson TW, Grove TL and Coleman DS. 1996. Hornblende gabbro sill complex at Onion Valley, California, and a mixing origin for the Sierra Nevada batholith. Contributions to Mineralogy and Petrology, 126(1-2): 81-108
[31] Tan CC. 2012. The age and tectonic evolution of the Dongga instrusive of Gangdese in north of Shigatse. Master Degree Thesis. Beijing: China University of Geosciences, 1-73 (in Chinese with English summary)
[32] Vervoort JD and Blichert-Toft J. 1999. Evolution of the depleted mantle: Hf isotope evidence from juvenile rocks through time. Geochimica et Cosmochimica Acta, 63(3-4): 533-556
[33] Wang YJ, Zhang AM, Fan WM, Zhang YH and Zhang YZ. 2013. Origin of paleosubduction-modified mantle for Silurian gabbro in the Cathaysia Block: Geochronological and geochemical evidence. Lithos, 160-161: 37-54
[34] Weaver BL. 1991. The origin of ocean island basalt end-member compositions: Trace element and isotopic constraints. Earth and Planetary Science Letters, 104(2-4): 381-397
[35] Wu YB and Zheng YF. 2004. Genesis of zircon and its constraints on interpretation of U-Pb age. Chinese Science Bulletin, 49(15): 1554-1569
[36] 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
[37] Zhang SH, Zhao Y, Kröner A, Liu XM, Xie LW and Chen FK. 2009. Early Permian plutons from the northern North China Block: Constraints on continental arc evolution and convergent margin magmatism related to the Central Asian Orogenic Belt. International Journal of Earth Sciences, 98(6): 1441-1467
[38] Zhi XC. 1990. Trace element geochemistry and petrogenesis of Cenozoic alkalic basalts from the Penglai and Lingju areas, Shandong Province, Geological Review, 36(5): 385-393 (in Chinese with English abstract)
[39] Zhou XR. 1994. Hybridization in the genesis of granitoids. Earth Science Frontiers, 1(1-2): 87-97 (in Chinese with English abstract)
[40] Zhu DC, Mo XX, Zhao ZD, Niu YL, Pan GT, Wang LQ and Liao ZL. 2009. Permian and Early Cretaceous tectonomagmatism in southern Tibet and Tethyan evolution: New perspective. Earth Science Frontiers, 16(2): 1-20 (in Chinese with English abstract)
[41] 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
[42] 董国臣, 莫宣学, 赵志丹, 朱弟成, 王亮亮, 陈涛, 李冰. 2006. 冈底斯岩浆岩带中段岩浆混合作用: 来自花岗杂岩的证据. 岩石学报, 22(4): 835-844
[43] 董国臣, 莫宣学, 赵志丹, 朱弟成, 宋云涛, 王磊. 2008. 西藏冈底斯南带辉长岩及其所反映的壳幔作用信息. 岩石学报, 24(2): 203-210
[44] 高剑峰, 陆建军, 赖鸣远, 林雨萍, 濮巍. 2003. 岩石样品中微量元素的高分辨率等离子质谱分析. 南京大学学报(自然科学), 39(6): 844-850
[45] 管琪, 朱弟成, 赵志丹, 董国臣, 莫宣学, 刘勇胜, 胡兆初, 袁洪林. 2011. 西藏拉萨地块南缘晚白垩世镁铁质岩浆作用的年代学、地球化学及意义. 岩石学报, 27(7): 2083-2094
[46] 谭陈诚. 2012. 日喀则东嘎乡冈底斯岩体的形成年代及成因. 硕士学位论文. 北京:中国地质大学, 1-73
[47] 支霞臣. 1990. 山东蓬莱、临朐新生代碱性玄武岩的痕量元素和岩石成因. 地质论评, 36(5): 385-393
[48] 周珣若. 1994. 花岗岩混合作用. 地学前缘, 1(1-2): 87-97
[49] 朱弟成, 莫宣学, 赵志丹, 牛耀龄, 潘桂棠, 王立全, 廖忠礼. 2009. 西藏南部二叠纪和早白垩世构造岩浆作用与特提斯演化: 新观点. 地学前缘, 16(2): 1-20
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