Integrated carbon, sulfur, and nitrogen isotope chemostratigraphy of the Ediacaran Lantian Formation in South China: Spatial gradient, ocean redox oscillation, and fossil distribution

作者：Wei Wang, Chengguo Guan, Chuanming Zhou, Yongbo Peng, Lisa M. Pratt, X. Chen, L. Chen, Z. Chen, Xunlai Yuan, Shuhai Xiao · 发表于：Geobiology · 年份：2017 · DOI：10.1111/gbi.12226 · 被引用次数：100 · 研究领域：Paleontology and Stratigraphy of Fossils、Methane Hydrates and Related Phenomena、Geology and Paleoclimatology Research

Abstract The Ediacaran Doushantuo Formation in South China is a prime target for geobiological investigation because it offers opportunities to integrate chemostratigraphic and paleobiological data. Previous studies were mostly focused on successions in shallow‐water shelf facies, but data from deep‐water successions are needed to fully understand basinal redox structures. Here, we report δ13Ccarb, δ13Corg, δ34Spyr, δ34SCAS, and δ15Nsed data from a drill core of the fossiliferous Lantian Formation, which is a deep‐water equivalent of the Doushantuo Formation. Our data confirm a large (>10‰) spatial gradient in δ13Ccarb in the lower Doushantuo/Lantian formations, but this gradient is probably due to the greater sensitivity of carbonate‐poor deep‐water sediments to isotopic mixing with 13C‐depleted carbonate cements. A pronounced negative δ13Ccarb excursion (EN3) in the upper Doushantuo/Lantian formations, however, is spatially consistent and may be an equivalent of the Shuram excursion. δ34Spyr is more negative in deeper‐water facies than in shallow‐water facies, particularly in the lower Doushantuo/Lantian formations, and this spatial pattern is interpreted as evidence for ocean redox stratification: Pyrite precipitated in euxinic deep waters has lower δ34Spyr than that formed within shallow‐water sediments. The Lantian Formation was probably deposited in oscillating oxic and euxinic conditions. Euxinic black shales have higher TOC and TN contents, but lower δ34Spyr and δ15Ns...