Marine redox variations during the Ediacaran–Cambrian transition on the Yangtze Platform, South China
Marine redox variations during the Ediacaran–Cambrian transition on the Yangtze Platform, South China
复制标题
DOI：
10.1002/gj.2878
复制
发表时间：
2018
影响因子：
1.8
通讯作者：
Lina Zhai;Chaodong Wu;Y. Ye;Shuichang Zhang;Zhengze An
中科院分区：
文献类型：
--
作者：
Lina Zhai;Chaodong Wu;Y. Ye;Shuichang Zhang;Zhengze An
扬子地台广泛发育的黑色页岩记录了埃迪卡拉纪—寒武纪过渡时期的古海洋环境信息。本文描述了对华南贵州省东北部道托埃迪卡拉系-寒武系黑色页岩中稀土元素（REE）、氧化还原敏感微量元素（RSTE）和总有机碳（TOC）含量的综合地球化学研究。来自道托地区的综合 RSTE 数据，结合之前发表的来自另外 6 个剖面（沙滩、九龙湾、中岭、杨家坪、龙鼻嘴和五河）的铁形态和钼基代理数据，表明了埃迪卡拉纪-寒武纪过渡期间的三个主要水环境。在此条件下，有机质和 RSTE 在黑色页岩中经历了不同程度的富集，特别是在九门冲组下部。鉴于Mo-U共变模式，金属羟基氧化物颗粒梭可能在道沱陡山沱组（II级）黑色页岩沉积过程中起作用。值得注意的是，根据六岔坡组和基底九门冲组的REE、RSTE数据和沉积学特征，表明上坡水在最早的寒武纪时期是含氧-缺氧的。边马冲组黑色页岩（寒武系 2，第 3 阶段结束）中 RSTE 浓度普遍较低，表明上坡环境中存在持续的含氧水柱。海洋氧合与生态系统发展之间的一致性可能表明埃迪卡拉纪-寒武纪过渡期间氧气和生物元素含量增加对动物群的刺激作用。版权所有 © 2016 约翰·威利父子有限公司
The widely developed black shales on the Yangtze Platform recorded palaeoceanographic environment information during the Ediacaran–Cambrian transition. This paper describes an integrated geochemical study of rare earth elements (REEs), redox‐sensitive trace elements (RSTEs), and total organic carbon (TOC) contents in Ediacaran–Cambrian black shales at Daotuo, northeastern Guizhou Province, South China. Integrated RSTE data from the Daotuo area, in combination with previously published Fe speciation and Mo‐based proxies from another six sections (Shatan, Jiulongwan, Zhongling, Yangjiaping, Longbizui and Wuhe), suggest three major periods of water euxinia during the Ediacaran–Cambrian transition. Under these conditions, organic matter and RSTEs experienced various levels of enrichment in the black shales, especially in the lower Jiumenchong Formation. Given the patterns of Mo‐U covariations, metal‐oxyhydroxide particulate shuttles may have operated during the black shale deposition of the Doushantuo Formation (Member II) at Daotuo. Conspicuously, the upper slope water was oxic‐dysoxic during the earliest Cambrian, as determined by the REE, RSTE data and sedimentological characteristics of the Liuchapo Formation and the basal Jiumenchong Formation. The generally low RSTE concentrations in the Bianmachong Formation black shales (Cambrian Series 2, end of Stage 3) suggest a persistently oxic water column in upper slope settings. The coincidence between the marine oxygenation and the development of the ecosystem likely indicates the galvanizing effects of enhanced oxygen and biological element content on the fauna during the Ediacaran–Cambrian transition. Copyright © 2016 John Wiley & Sons, Ltd.