Provenance of the Laga Formation at the Nixiong Area of the Western Lhasa Terrane: constraints from geochemistry of clastic rocks
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摘要: 拉萨地块西段缺失晚古生代岩浆岩，造成不能从岩浆岩角度探索其晚古生代地质演化，因此沉积岩的对比研究对理解拉萨地块晚古生代的差异演化过程至关重要。本文通过对尼雄地区上石炭统—下二叠统拉嘎组碎屑岩地球化学特征分析，试图揭示其物源特征及源区构造背景，提供拉萨地块晚古生代沉积岩对比分析的基础信息。尼雄地区拉嘎组一段和二段主量和微量元素特征略有差异，二段较一段CaO、Na2O含量更高，V、Cr、Ni、Co及轻稀土含量也更高，反映二者沉积源区有一定差异。拉嘎组物源区的构造背景兼具被动大陆边缘与活动大陆边缘特征，并且二段较一段显示更强的活动大陆边缘亲缘性。结合区域地质资料，认为拉嘎组碎屑岩主要来自成熟的大陆源区，为冈瓦纳大陆北缘基底岩石及早古生代沉积岩的再旋回沉积，二段源区的少量酸性及基性物质组分对应于冈瓦纳大陆北缘泛非期及寒武纪岩浆活动。Abstract: Owing to the lack of Late Paleozoic magmatic rocks in the western segment of Lhasa terrane, it is difficult to understand its Late Paleozoic tectonic evolution in terms of magmatism. Here we report the geochemical characteristics of the clastic rocks from Laga Formation in Nixiong area, in order to reveal its tectonic background and provenance. The contents of main and trace elementcs of the First and Second Members of Laga Formation in Nixiong areas are slightly different. The Second Member of Laga Formation show higher CaO, Na2O and V, Cr, Ni, Co contents, and light rare earth elements than the Second Member of Laga Formation, indicating their different sedimentary sources. The tectonic settings of the Laga Formation are characterized by passive continental margin and active continental margin, and the Second Member is with more features of active continental margin. The clastic rocks of the Laga Formation were mainly derived from the matural continental source areas, and the source materials were from recycling deposition of the basement rocks and the early Paleozoic sedimentary rocks in the northern margin of Gondwana land. The source rocks of the Second Member of Laga Formation comprised a few acid and basic components, which equated with magmatic activities during Pan-African period and Cambrian in the northern margin of Gondwanaland.
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Key words:
- Lhasa terrane /
- Nixiong area /
- the Laga Formation /
- geochemisty /
- provenance
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[1] 杨洋, 刘函, 崔浩杰, 等. 拉萨地块晚古生代沉积源区转变——来自措勤地区永珠组碎屑锆石的证据[J]. 地质通报, 2019, 38(6):1006-1017.
[2] 刘函, 李奋其, 周放, 等.拉萨地块西段尼雄地区晚古生代地震事件及其地质意义[J]. 地球科学. 2018, 43(8):2767-2779.
[3] Zhu D C, Zhao Z D, Niu Y L, et al., The origin and pre-Cenozoic evolution of the Tibetan Plateau[J]. Gondwana Research, 2013. 23(4):1429-1454.
[4] 李光明, 高大发, 黄志英. 西藏当雄纳龙晚古生代裂谷盆地的识别及其意义[J]. 沉积与特提斯地质, 2002, 22(1):83-87.
[5] 耿全如, 王立全, 潘桂棠, 等. 西藏冈底斯带石炭纪陆缘裂陷作用:火山岩和地层学证据[J]. 地质学报, 2007, 81(09):1259-1276.
[6] 冉明佳, 钟康惠, 罗明非, 等.西藏冈底斯带东段石炭纪构造环境讨论[J]. 地质评论, 2012, 58(2):250-258.
[7] 吴兴源, 王青, 朱弟成, 赵志丹, 等. 拉萨地体南缘早石炭世花岗岩类的起源及其对松多特提斯洋开启的意义[J]. 岩石学报, 2013, 29(11):3716-3730
[8] Dong X, Zhang Z M, Liu F, et al. Late Paleozoic intrusive rocks from the southeastern Lhasa terrane, Tibetan Plateau, and their Late Mesozoic metamorphism and tectonic implications[J]. Lithos, 2014, 198-199:249-262.
[9] Guo L, Zhang H F, Harris N, et al. Late Devonian-Early Carboniferous magmatism in the Lhasa terrane and its tectonic implications:Evidences from detrital zircons in the Nyingchi Complex. Lithos, 2016, 245:47-59.
[10] 解超明, 宋宇航, 王明, 等. 冈底斯中部松多岩组形成时代及物源:来自碎屑锆石U-Pb年代学证据[J]. 地球科学,2019,44(7):2224-2233.
[11] 马德胜, 熊兴国, 曾禹人, 等. 西藏塔惹增地区上石炭统-下二叠统拉嘎组火山岩夹层的发现及其地质意义[J]. 地质通报, 2015, 34(09):1636-1644.
[12] Zhu D C, Zhao Z D, Niu Y L, et al. Lhasa Terrane in Southern Tibet Came from Australia[J]. Geology, 2011, 39(8):727-730.
[13] Roser B P and Korsch R J. Provenance signatures of sandstones-mudstone suites determined using discriminate function analysis of major-element data. Chemical Geology[J], 1988, 67:119-139
[14] McLennan S m, Hemming S,McDanial D K, et al. Geochemical approaches to sedimentation, provenance, and tectonics[J]. Geological Society of American Special Paper, 1993, 284:21-40.
[15] Bhatia M R. Plate tectonics and geochemical composition of sandstones[J]. The Journal of Geology, 1983, 91(6):611-627.
[16] Bhatia M R and Crook K A W. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins[J]. Contributions to Mineralogy and Petrology, 1986, 92(2):181-193.
[17] 林宝玉. 西藏申扎地区古生代地层[C]. 青藏高原地质文集[A]. 1983:1-13.
[18] 尹集祥, 郭师曾.珠穆朗玛峰北坡冈瓦纳相地层的发现[J]. 地质科学. 1976, 4:291-322.
[19] 蔺吉庆. 西藏罗仓地区下石炭统永珠组划分及相分析[D]. 成都:成都理工大学, 2014.
[20] 饶世成, 杨晨梦. 西藏罗仓地区晚石炭世拉嘎组物源及构造环境[J]. 四川地质学报. 2018, 38(4):531-535.
[21] 牛旭宁, 丁枫, 霍艳, 庞艳春, 等. 西藏罗仓地区昂杰组碎屑岩地球化学特征及物源[J]. 四川地质学报. 2016, 36(3):465-471.
[22] Pettijohn F J, Potter P E, Siever R. 1972. Sand and sandstone[M]. Berlin:Springer-Verlag, 62.
[23] Zhang J, Nozaki Y. Rare earth elements and yttrium in seawater:ICP-MS determinations in the East Caroline, Coral Sea, and South Fiji basins of the western South Pacific Ocean.Geochinica at Cosmochinica Acta, 1996,60(23):4631-4644.
[24] Rudnick R L and Gao S. Composition of the Continental Crust//Rudnick R L. The Crust Treaties on Geochemistry 3[M]. Oxford:Elsevier Pergamon, 2003. 1-64.
[25] Crook K A W. Lithogennesis and geltectonics:The significance of compositioin in flysch arenites (gray wackes) Dott R H, Shaver R H. Modren and ancient geosynclinal sedimentation[J]. Tulsa:SEPM Spec. Publ., 1974, 19:304-310.
[26] Schwab F L. Sedimentary signatures of foreland basin assemblages:Real or counterfect? Foreland basin[J]. Spec. Publ. Int. Ass. Sediment, 1986, 8:395-410.
[27] 李双应, 李任伟, 岳书仓, 等.安徽肥西中生代碎屑岩地球化学特征及其对物源制约[J]. 岩石学报, 2004, 202(3):667-676.
[28] Roser B P, Korsch R J. Determinatioin of tectonic setting of sandstone mudstone suites using SiO2 content and K2O/Na2O ratio[J]. J. Geol., 1986, 94(5):635-650.
[29] 孙高远, 胡修棉.仲巴地体的板块亲缘性:来自碎屑锆石U-Pb年代学和Hf同位素的证据[J]. 岩石学报, 2012, 28(05):1635-1646.
[30] 范建军, 李才, 王明, 等. 青藏高原羌塘南部冈玛错地区展金组的沉积环境分析及碎屑锆石U-Pb定年[J]. 地质学报, 2014, 88(10):1820-1831.
[31] 计文化, 陈守建, 赵振明, 等. 西藏冈底斯构造带申扎一带寒武系火山岩的发现及其地质意义[J]. 地质通报, 2009, 28(9):1350-1354.
[32] Zhu D C, Zhao Z D, Niu Y L, et al. Cambrian bimodal volcanism in the Lhasa Terrane, southern Tibet:Record of an early Paleozoic Andean-type magmatic arc in the Australian proto-Tethyan margin[J]. Chemical Geology, 2012,328:290-308.
[33] Hu P Y, Li C, Wang M, et al. Cambrian volcanism in the Lhasa terrane, southern Tibet:Record of an early Paleozoic Andean-type magmatic arc along the Gondwana proto-Tethyan margin[J]. Journal of Asian Earth Sciences, 2013, 77(0):91-107.
[34] Zhang Z M, Dong X, Liu F, et al. The making of Gondwana:Discovery of 650Ma HP granulites from the North Lhasa, Tibet[J]. Precambrian Research, 2012. 212-213(0):107-116.
[35] 王立全, 朱同兴. 青藏高原及邻区地质图说明书(1:1500000)[M], 北京:地质出版社, 2013. 1-282.
[36] 郭安臣, 王彦, 李广铁. 西藏申扎地区下古生界扎扛组的重新厘定及时代讨论[J]. 世界地质, 2014, 33(01):246.
[37] 纪占胜, 姚建新, 高联达, 等. 藏北申扎地区下石炭统永珠组下部孢子组合的特征及意义[J]. 古生物学报, 2006, 45(3):399-409.
[38] 朱同兴, 潘桂棠, 冯心涛, 等.藏南喜马拉雅北坡色龙地区二叠系基性火山岩的发现及其构造意义[J]. 地质通报, 2002, 21(11):717-722.
[39] Zhai Q G, Jahn B M, Su L, et al. SHRIMP zircon U-Pb Geochronology, Geochemistry and Sr-Nd-Hf Isotopic Compositions of a Mafic Dyke Swarm in the Qiangtang Terrane, northern Tibet and Geodynamic Implications[J]. Lithos, 2012, doi:10.1016/j.lithos.2012.10.018.
[37] 胡道功, 吴珍汉,江万, 等. 西藏念青唐古拉岩群HRIMP锆石U-Pb年龄和Nd同位素研究[J]. 中国科学(D辑:地球科学), 2005, 35(01):29-37.
[38] Hu P Y, Zhai Q G, Wang J, et al. Precambrian origin of the North Lhasa terrane, Tibetan Plateau:Constraint from early Cryogenian back-arc magmatism[J]. Precambrian Research, 2018, 313:51-67.
[39] 王明, 曾孝文, 李才, 等. 藏北羌塘南部埃迪卡拉系达布热组的建立及其地质意义[J]. 地质通报, 2018, 37(8):1379-1386.
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