藏南贡嘎晚侏罗世—早白垩世海相地层地球化学特征与古海洋环境演化

发布时间：2018-07-02 08:47

本文选题：晚侏罗世 + 早白垩世　；参考：《地学前缘》2017年01期

【摘要】：西藏南部有出露良好的海相侏罗纪—白垩纪地层。本研究针对采自藏南贡嘎东拉剖面的样品进行了常量、微量和稀土元素分析,探讨晚侏罗世—早白垩世海洋沉积环境的演化。Fe_2O_3+MgO与TiO_2、Al_2O_3/SiO_2关系判别图显示,从晚侏罗世维美组到早白垩世桑秀组,研究区经历了从大陆岛弧到大洋岛弧的构造演化。Mn、Fe、V、Co、Ni、REE等指标元素,和U/Th、V/Cr、Sr/Ba、Lan/Ybn、V/(V+Ni)等比值结合显示:沉积条件也从维美组浅海富氧、低盐、高沉积速率的环境演化为早白垩世桑秀组深海、水体分层、盐度升高、沉积速率降低,具有明显深海沉积特征的环境。地化数据分析结果总体上与岩性成因分析相一致,即维美组砂岩所指示的浅海相沉积,桑秀组从下部的粉砂岩到上部钙质泥岩,经历了水体由浅到深的变化过程。
[Abstract]:There are good marine Jurassic-Cretaceous strata in southern Tibet. In this study, the samples collected from Gonggadongla section, southern Tibet, were analyzed by constant, trace and rare earth elements, and the evolution of marine sedimentary environment of late Jurassic-early Cretaceous was discussed. The relationship between Fe2O3MgO and TiO2Al2O3SiOS2 shows that the relationship between Fe _ 2O _ 2O _ 3MgO and Tio _ 2S _ 2O _ 2O _ 2O _ 3 / Sio _ 2O _ 2 can be determined. From the late Jurassic Weimei formation to the early Cretaceous Sangxiu formation, the study area experienced tectonic evolution from continental island arc to oceanic island arc. The index elements, I. e. The environment with high deposition rate evolved into the deep sea of the early Cretaceous Sangxiu formation with stratified water bodies, higher salinity and lower deposition rate, which had obvious deep-sea sedimentary characteristics. The results of geochemical data analysis are consistent with the lithologic genetic analysis on the whole, that is, the shallow marine sediments indicated by the Weimei sandstone, and the Sangxiu formation from the siltstone in the lower part to the calcareous mudstone in the upper part, experienced the process of water body changing from shallow to deep.
【作者单位】：华北理工大学地层古生物研究中心;华北理工大学矿业工程学院;中国地质大学生物地质与环境地质国家重点实验室;
【基金】：国家重点基础研究发展计划“973”项目(2012CB822000) 国家自然科学基金项目(41172015,41302008) 中国地质调查局项目(1212010711603) 现代古生物学与地层学国家重点实验室开放基金项目(113108) 河北省自然科学基金项目(D2015209075,D2012209045) 河北省教育厅自然科学基金重点项目(ZD2016077) 华北理工大学省自然科学基金培育项目(SP201501)
【分类号】：P534.5

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