期刊
SCIENCE CHINA-EARTH SCIENCES
卷 58, 期 7, 页码 1107-1122出版社
SCIENCE PRESS
DOI: 10.1007/s11430-015-5071-0
关键词
Yangtze Platform; southern Shaanxi; Ediacaran; trace elements; carbon isotopes; sulfur isotopes
资金
- National Basic Research Program of China [2011CB808805]
- MOST Special Fund from the State Key Laboratory of Continental Dynamics, Northwest University
- National Natural Science Foundation of China [41172029]
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 Sigma REE 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 Sigma REE 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 parts per thousand in delta C-13. 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 caused delta S-34 increasing to 50 parts per thousand. However, as the upwelling gradually disappeared, delta C-13 and delta S-34(CAS) values decreased as well in the late Beiwan time, indicating the shallow water went back to suboxic or oxic again.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据