Sr, Nd and Li isotopes in carbonates of the Yangtze Platform and from Kazakhstan as tracers for the Ediacaran and Cambrian weathering history

扬子地台和哈萨克斯坦碳酸盐岩中的 Sr、Nd 和 Li 同位素作为埃迪卡拉纪和寒武纪风化历史的示踪剂

• 批准号: 45543845
• 负责人: Professor Dr. Harry Becker
• 金额: --
• 依托单位: Institut für Geologische Wissenschaften
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/45543845?language=en
• 关键词: Sr; Nd; Li; isotopes; carbonates

Understanding the rapid evolution of life at the Precambrian-Cambrian boundary requires a good understanding of its rapidly changing environment. The increase in oxygen content of the atmosphere and changes in seawater composition at around this time are often implicated as possible drivers of evolution; however, detailed causes, processes and feedbacks with the biosphere remain poorly constrained and reflects the incomplete record of geochemical tracer data of Ediacaran and Cambrian sediments. In this and some other projects of FOR 736, we intend to study several well-characterized stratigraphic sections from South China and Kazakhstan using a multi-proxy approach. In the present subproject, trace element abundances, strontium, neodymium and lithium isotopic compositions of Ediacaran and Cambrian marine carbonates will be studied. The data will be used to assess the diagenetic modification of the carbonates and to retrieve information on changes of seawater composition during this time interval. We will also test hypotheses, such as increased weathering rates as a possible cause of fluctuations in Sr isotopic composition, and evaluate similarities and differences between shallow- and deep-water proxy records.

要了解前寒武纪-寒武纪界线生命的快速演化，就需要很好地了解其快速变化的环境。大气中氧含量的增加和海水成分的变化在这个时候往往牵连作为可能的驱动程序的演变;然而，详细的原因，过程和反馈与生物圈仍然缺乏约束，并反映了不完整的地球化学示踪剂数据的埃迪卡拉纪和寒武纪沉积物的记录。在FOR 736的这个项目和其他一些项目中，我们打算使用多代理方法研究来自中国南方和哈萨克斯坦的几个具有良好特征的地层剖面。本次项目将研究埃迪卡拉纪和寒武纪海相碳酸盐岩的微量元素丰度、锶、钕和锂同位素组成。这些数据将用于评估碳酸盐岩的成岩改造，并检索这段时间内海水成分变化的信息。我们还将测试假设，如增加风化率作为锶同位素组成波动的可能原因，并评估浅水和深水代理记录之间的相似性和差异。