东昆仑造山带早古生代—早中生代构造演化的沉积地球化学记录

发布时间：2018-04-02 18:48

本文选题：东昆仑造山带　切入点：砂岩地球化学　出处：《现代地质》2017年04期

【摘要】：东昆仑地区发育一套显生宙碎屑岩地层,包括下寒武统沙松乌拉组、中—上奥陶统纳赤台群、上石炭统—下二叠统浩特洛哇组、下三叠统洪水川组、中三叠统希里科特组以及上三叠统八宝山组。研究区砂岩的CIA值反映沙松乌拉组砂岩源区化学风化程度较高,其余各组砂岩源区化学风化程度较低。主量和微量元素研究结果表明各组砂岩源区以长英质岩石为主,包含少量中性成分。La、Ce、Th、U、∑REE含量和La/Sc、Th/Sc、Sc/Cr、La/Y比值指示沙松乌拉组和纳赤台群砂岩沉积环境为大陆岛弧或活动大陆边缘,浩特洛哇组砂岩形成于被动大陆边缘环境,洪水川组砂岩沉积环境为活动大陆边缘,希里科特组砂岩的微量元素含量及其比值接近于活动大陆边缘和被动大陆边缘,八宝山组砂岩沉积环境为活动大陆边缘。综合分析认为沙松乌拉组和纳赤台群砂岩形成于原特提斯洋俯冲阶段,浩特洛哇组砂岩形成于古特提斯洋持续扩张阶段,洪水川组砂岩形成于古特提斯洋俯冲阶段,希里科特组砂岩形成于陆(弧)陆初始碰撞阶段,八宝山组砂岩形成于陆陆全面碰撞—碰撞后阶段。
[Abstract]:A set of Phanerozoic clastic strata developed in the East Kunlun area, including the Lower Cambrian Shasongwula formation, the Middle-Upper Ordovician Nachitai Group, the Upper Carboniferous and Lower Permian Holterlova formation, and the Lower Triassic Flooguan formation,Middle Triassic Shiri Kurt formation and Upper Triassic Babaoshan formation.The CIA value of sandstone in the study area shows that the chemical weathering degree of sandstone source area of Shasong Wula formation is higher, and the chemical weathering degree of other sandstones source area is lower.The sandstones of the Haoterova formation were formed in the passive continental margin environment, the sedimentary environment of the sandstones of the Hongchuan formation was the active continental margin, and the trace element contents and their ratios of the sandstones of the Shiri Kot formation were close to the active continental margin and the passive continental margin.The sandstone sedimentary environment of Babaoshan formation is active continental margin.It is considered that the sandstones of the Shasongwula formation and the Nachitai group were formed in the original Tethys ocean subduction stage, the Haoterlova sandstone formed in the paleoTethys ocean continuous expansion stage, and the flood formation sandstone formed in the paleoTethys ocean subduction stage.The sandstones of the Shiri Kurt formation were formed at the initial collision stage of the continental (arc) land, and the sandstone of the Babaoshan formation was formed at the stage of comprehensive collision and post-collision of the continental land.
【作者单位】：中国地质大学(北京)地球科学与资源学院;中国地质大学地质过程与矿产资源国家重点实验室;青海省地质调查院;
【基金】：国家自然科学基金项目(41572062,U1303292) 中央返还两权价款资金综合研究项目(Y15-1-LQ04) 青海省地质勘查基金项目(2016020003ky003)
【分类号】：P512.2;P548

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