地学前缘 ›› 2020, Vol. 27 ›› Issue (4): 272-281.DOI: 10.13745/j.esf.sf.2019.8.24

• 非主题来稿选登 • 上一篇    下一篇

藏南江孜侏罗系/白垩系界线时期古海洋环境分析

高莲凤1,2(), 李璞壮1, 张振国1,2,*(), 万晓樵3, 夏世强1, 董桂玉1, 王兆生1, 冷春鹏1, 张盈1, 姚纪明1, 张琳婷1, 于江涛1, 殷世艳1   

  1. 1.华北理工大学 矿业工程学院, 河北 唐山 063210
    2.辽宁工程技术大学 矿业学院, 辽宁 阜新 123000
    3.中国地质大学(北京) 生物地质与环境地质国家重点实验室, 北京 100083
  • 收稿日期:2018-11-21 修回日期:2019-06-05 出版日期:2020-07-25 发布日期:2020-07-25
  • 通讯作者: 张振国
  • 作者简介:高莲凤(1970—),女,博士,教授,主要从事古生物学与地层学、古海洋学等领域的教学与研究。E-mail: ytgaolf@163.com
  • 基金资助:
    国际地质联合会全球对比计划项目(IGCP679);国家自然科学基金项目(41972004);中国地质调查局地质调查项目(DD20190009);中国地质调查局地质调查项目(1212010711603);河北省自然科学基金项目(D2017209236);河北省自然科学基金项目(E2019209339)

Paleoceanographic environment in Gyangzê, South Tibet during the Jurassic-Cretaceous boundary interval

GAO Lianfeng1,2(), LI Puzhuang1, ZHANG Zhenguo1,2,*(), WAN Xiaoqiao3, XIA Shiqiang1, DONG Guiyu1, WANG Zhaosheng1, LENG Chunpeng1, ZHANG Ying1, YAO Jiming1, ZHANG Linting1, YU Jiangtao1, YIN Shiyan1   

  1. 1. College of Mining Engineering, North China University of Science and Technology, Tangshan 063210, China
    2. College of Mining Engineering, Liaoning Technical University, Fuxin 123000, China
    3. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences(Beijing), Beijing 100083, China
  • Received:2018-11-21 Revised:2019-06-05 Online:2020-07-25 Published:2020-07-25
  • Contact: ZHANG Zhenguo

摘要:

为了探讨西藏南部江孜一带侏罗系/白垩系界线时期海洋沉积环境的变化,本研究对采自藏南江孜甲不拉沟剖面的样品进行了常量、微量和稀土元素分析。Fe2O3+MgO与TiO2、Al2O3/SiO2关系判别图显示,从晚侏罗世维美组到早白垩世甲不拉组,研究区构造运动相对平静,基本上以大洋岛弧的构造演化为主,继承性明显。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,沉积条件从维美组浅海富氧、高盐、高沉积速率的环境演化为早白垩世甲不拉组深海、水体分层、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,即从维美组砂岩的浅海相沉积到甲不拉组下部的粉砂岩和上部的钙质泥岩、黑色页岩,水体经历了由浅到深的变化过程。

关键词: 侏罗系/白垩系界线, 地球化学特征, 古海洋环境, 江孜, 西藏南部

Abstract:

In order to investigate the evolution of marine sedimentary environments during the Jurassic-Cretaceous transition in the Gyangzê area, South Tibet, we collected samples from the Jiabulagou section, and performed major, trace and rare earth element analysis. The discrimination diagrams (Fe2O3+MgO vs. TiO2 or Al2O3/SiO2) showed that, from the Late Jurassic Weimei Formation to the Early Cretaceous Jiabula Formation, the tectonic setting in the study area is mainly oceanic island arc. The index elements of Mn, Fe, V, Co, Ni and REE, and U/Th, V/Cr, Sr/Ba, Lan/Ybn and V/(V+Ni) ratios showed that the deposition conditions evolved from the Weimei Formation environment, characterized by shallow sea, oxygen-enriched, high-salt and high deposition rate, to the Early Cretaceous Jiabula Formation environment, featuring deep sea, water stratification and decreasing sedimentation rate, with obvious characteristics of deep sea sedimentary environment. The geochemical data were consistent with tectonic discrimination diagram, i.e., shallow sea facies sediment, indicated by sandstone in the Weimei Formation, and siltstone in the lower and calcareous mudstone in the upper Jiabula Formation, experienced water changes from shallow to deep.

Key words: Jurassic-Cretaceous boundary, geochemical characteristics, paleoceanographic environment, Gyangzê aera, South Tibet

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