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首页> 外文期刊>Journal of Asian earth sciences >High-frequency redox variations of the Eocene cyclic lacustrine sediments in the Yingxi area, western Qaidam Basin, China
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High-frequency redox variations of the Eocene cyclic lacustrine sediments in the Yingxi area, western Qaidam Basin, China

机译：柴达木盆地西部营西地区始新世环状湖相沉积物的高频氧化还原变化

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摘要

The mineral assemblages of lacustrine mixed sediments have vital significance for reconstructing paleo-lake environments, and typical lacustrine mixed sediments deposited during the Eocene are distributed throughout the Yingxi area in the western Qaidam Basin. Accordingly, the framboid size distributions and sulfur isotope (delta(34)(py)) characteristics of pyrite in addition to the carbon isotope (delta C-13(carb)) characteristics and redox-sensitive element ratios (Th/U, V/(V + Ni) and V/Cr) of authigenic carbonates were investigated to reconstruct the high frequency redox variations in cyclic lacustrine sediments.Corresponding to different redox conditions, three types of mixed sediments developed during transgression and regression stages within the saline basin in the Yingxi area during the Eocene: mixed terrigenous clasts formed in oxic-dysoxic water column conditions during lake transgression, mixed carbonates formed in anoxic water column conditions during early-stages lake regression, and mixed evaporites formed in anoxic-sulfidic water column conditions during middle-late-stage lake regression. The redox proxies correlate well with the water salinity, exhibit little or no correlation with the water temperature, and show an incongruity with the water depth, suggesting that the redox conditions were predominantly controlled by the water salinity rather than the water depth or temperature. Therefore, based on the water redox condition variations and the salinity, three dynamic formation models of the high-frequency sedimentary cycles in a saline basin are established: a deep-water, low-salinity, oxic-dysoxic model (Model I, a medium-water, medium-salinity, anoxic model (Model II) and a shallow-water, high-salinity, anoxic-sulfidic model (Model III). Because the climate gradually turned dry and hot from lake transgression to regression, the continued closure of the basin enhanced evaporation and salinization. In addition, mixed terrigenous clasts, mixed carbonates and mixed evaporites deposited successively. Correspondingly, salinity stratification gradually developed within the lake water, increasing the extent of bacterial sulfate reduction in the bottom water.
机译：湖相混合沉积物的矿物组合对于重建古湖环境具有重要意义，始新世期间沉积的典型湖相混合沉积物分布在柴达木盆地西部的莺溪地区。因此，除了碳同位素（δC-13（carb））特性和氧化还原敏感元素比率（Th / U，V /）之外，黄铁矿的磁石尺寸分布和硫同位素（delta（34）（py））特性研究了自生碳酸盐的（V + Ni）和V / Cr）来重建环状湖沉积物中的高频氧化还原变化。对应于不同的氧化还原条件，在盐碱盆地海侵和回归阶段形成了三种混合沉积物。始新世的迎溪地区：湖侵过程中在有氧-低氧水柱条件下形成的混合陆源碎屑，在早期湖泊退化期间在无氧水柱条件下形成的混合碳酸盐，以及在中期的缺氧-硫水柱条件下形成的混合蒸发物。后期湖泊消退。氧化还原代理与水的盐度有很好的相关性，与水的温度几乎没有或没有相关性，并且与水的深度没有一致性，这表明氧化还原条件主要由水的盐度而不是水的深度或温度控制。因此，根据水的氧化还原条件变化和盐度，建立了一个盐盆地高频沉积循环的三个动态形成模型：深水，低盐度，有氧-低氧模型（模型I，中等水，中盐度，缺氧模型（模型II）和浅水，高盐度，缺氧硫化物模型（模型III）。由于气候从湖泊的海侵转变为回归，逐渐变得干热。此外，陆相碎屑，碳酸盐和蒸发物相继沉积，湖水内盐分分层逐渐发展，增加了底水中细菌硫酸盐还原的程度。

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  • 来源
    《Journal of Asian earth sciences》 |2019年第1期|135-151|共17页
  • 作者

    Jiang Qicai; Ma Yongsheng; Shen Yingchu; Guo Rongtao; Gao Xiaoqiao; Liu Bo; Cui Jun; Wu Kunyu;

  • 作者单位

    Peking Univ, Sch Earth & Space Sci, Oil & Gas Inst, Beijing 100871, Peoples R China;

    Peking Univ, Sch Earth & Space Sci, Oil & Gas Inst, Beijing 100871, Peoples R China|SINOPEC, Beijing 100728, Peoples R China;

    Peking Univ, Sch Earth & Space Sci, Oil & Gas Inst, Beijing 100871, Peoples R China;

    Peking Univ, Sch Earth & Space Sci, Oil & Gas Inst, Beijing 100871, Peoples R China;

    China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China;

    Peking Univ, Sch Earth & Space Sci, Oil & Gas Inst, Beijing 100871, Peoples R China;

    PetroChina Qinghai Oilfield Co, Res Inst Explorat & Dev, Dunhuang 736202, Peoples R China;

    PetroChina Qinghai Oilfield Co, Res Inst Explorat & Dev, Dunhuang 736202, Peoples R China;

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  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    Mixed sediments; Redox conditions; Salinity; Dynamic formation model; Saline basin;

    机译：混合沉积物氧化还原条件盐度动态形成模型盐盆;

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