Carbon isotopes, sulfur isotopes, and trace elements of the dolomites from the Dengying Formation in Zhenba area, southern Shaanxi: Implications for shallow water redox conditions during the terminal Ediacaran
Carbon isotopes, sulfur isotopes, and trace elements of the dolomites from the Dengying Formation in Zhenba area, southern Shaanxi: Implications for shallow water redox conditions during the terminal Ediacaran
复制标题
陕南镇巴地区灯影组白云岩碳同位素、硫同位素及微量元素对埃迪卡拉末期浅水氧化还原条件的影响
DOI：
10.1007/s11430-015-5071-0
复制
发表时间：
2015-04
影响因子：
5.7
通讯作者：
Zhai MingGuo
中科院分区：
文献类型：
--
作者：
Chen YaLi;Chu XueLei;Zhang XingLiang;Zhai MingGuo
对陕南两河口剖面灯影组碳酸盐岩进行了碳同位素、硫同位素和微量元素（包括稀土元素，REE）分析，重建了扬子地台西北缘埃迪卡拉末期浅水环境。两河口段北湾段中部50 m样品表现为低ΣREE浓度、无mree富集分布模式、高Ce/Ce*值接近1、氧化还原敏感元素富集的特征，而下部30 m和上部10 m样品表现为高ΣREE浓度、无mree富集分布模式、低Ce/Ce*值约0.6、无氧化还原敏感元素富集的特征。表明扬子地台西北缘浅水确实发生过氧合作用，浅水氧化还原条件由相对氧合到缺氧再回到氧合。我们认为北湾期中期出现的缺氧可能与缺氧上升水有关。一方面，上升流带来了丰富的营养物质，刺激了光合固碳，增加了缺氧条件下的有机碳埋藏，使γ - 13c峰值达到3.6‰；另一方面，由于缺氧上升水取代了缺氧浅水，加上水柱中有机质的增加，细菌硫酸盐还原作用增强，从而迅速降低硫酸盐浓度，最终导致γ - 34s升高至50‰。然而，随着上升流逐渐消失，γ13C和γ 34scas值在北湾晚期也有所下降，表明浅水再次回到缺氧或缺氧状态。
Carbon isotope, sulfur isotope, and trace element (including Rare Earth Elements, REE) analyses were conducted on the carbonates of the Dengying Formation at Lianghekou section in southern Shaanxi to reconstruct the terminal Ediacaran shallow-water environment on the northwestern margin of the Yangtze Platform. At Lianghekou section, samples in the middle 50-m of the Beiwan Member show characteristics of low ΣREE concentrations, no MREE-enriched REE distribution patterns, high Ce/Ce* values close to 1, and enriched redox-sensitive elements, whereas samples in the lower 30-m and upper 10-m show opposite characteristics of high ΣREE concentrations, MREE-enriched REE distribution patterns, low Ce/Ce* values around 0.6, and no redox-sensitive elements enriched, indicating that oxygenation did occur in the shallow water on the northwestern margin of the Yangtze Platform and redox conditions of the shallow water fluctuated from relatively oxygenated to anoxic and then back to oxygenated again. We propose that the anoxia appeared in middle of the Beiwan time may associate with the anoxic upwelled water. On one hand, abundant nutrients were brought in by this upwelling event, which stimulated the photosynthetic carbon fixation and increased the organic carbon burial under this anoxic condition, causing a peak of 3.6‰ inγ13C. On the other hand, because the anoxic upwelled water replaced the oxic shallow water, together with the increasing organic matter in the water column, bacterial sulfate reduction was enhanced and therefore quickly reduced the sulfate concentration, which eventually causedγ34S increasing to 50‰. However, as the upwelling gradually disappeared,γ13C andγ34SCASvalues decreased as well in the late Beiwan time, indicating the shallow water went back to suboxic or oxic again.
登录
查看更多内容
华南新元古代浅至深碳酸盐岩中捕获的马里诺冰川消融的硫同位素特征
影响因子：
3.8
作者：
Tao Sun;Lianjun Feng;Qirui Zhang;Huajin Chang
通讯作者：
Huajin Chang
华南陡山沱组稀土元素和碳同位素地球化学：对中埃迪卡拉系浅海氧化还原条件的启示
影响因子：
--
作者：
Jiang ShaoYong;Xiao ShuHai;Chen Zhe;Yuan XunLai
通讯作者：
Yuan XunLai
影响因子：
5
作者：
G. Webb;B. Kamber
通讯作者：
G. Webb;B. Kamber
影响因子：
3.8
作者：
Yang Jiedong;Sun Weiguo;Wang Zongzhe;Xue Yaosong;Tao Xiancong
通讯作者：
Yang Jiedong;Sun Weiguo;Wang Zongzhe;Xue Yaosong;Tao Xiancong
DOI：
10.1016/j.palaeo.2007.03.016
发表时间：
2007-10-08
影响因子：
3
作者：
Guo, Qingjun;Shields, Graham A.;Yang, Xinglian
通讯作者：
Yang, Xinglian