Sulfate and dolomitization - constraints for precipitation and alteration

碳酸盐相关的硫酸盐是我们探索地球演化的一个重要代表，特别是在氧化还原及其与生物硫和碳循环的联系方面。因此，详细了解碳酸盐伴生硫酸盐的形成和成岩作用是地球系统科学研究成功的关键先决条件。尽管它在以前的研究中得到了广泛的应用，但在碳酸盐沉淀过程中为何、如何、在哪里以及有多少硫酸盐被掺入以及在成岩作用过程中被保留仍然存在不确定性。对硫酸盐掺入碳酸盐（以及成岩作用期间的变化）的全面机械理解对于代表前寒武纪关键岩性的碳酸盐岩和碳酸盐化石灰岩特别重要，但也存在许多碳酸盐岩的例子。更重要的是，白云石的形成与环境中硫酸盐的存在和硫酸盐还原菌的活性密切相关。然而，一个细节只是出现。本研究的目的是通过地球历史阐明硫酸盐与石化作用之间的密切联系。它的中心是原生特征和次生成岩特征之间的明显区别。分析选定的岩石继承，年龄从太古代到现在，将导致定量的了解如何（特别是）测量碳酸盐相关的硫酸盐丰度（以及同位素组成）在碳酸盐岩与周围海水硫酸盐浓度（和同位素组成）。

Carbonate-associated sulfate is an important proxy in our quest for unraveling Earth evolution, specifically in respect to redox and its link to biological sulfur and carbon cycling. Consequently, a detailed understanding of the formation and diagenesis of carbonateassociated sulfate is a key prerequisite for successful research in Earth System Science. Despite its wide application in previous studies, uncertainties why, how, where and how much sulfate is incorporated during carbonate precipitation and retained during diagenesis still exist. A full mechanistic understanding of sulfate incorporation into carbonate (and changes during diagenesis) is particularly important for dolomites and variably dolomitized limestones that represent key lithologies in the Precambrian, yet numerous Phanerozoic examples exist as well. Even more so, as dolomite formation is intimately linked to the presence of sulfate in the environment and the activity of sulfate-reducing bacteria. Yet, a detailed is only emerging. This study aims at elucidating the intimate link between sulfate and dolomitization through Earth history. It centers on a clear differentiation between primary signatures and secondary, diagenetic features. Analysis of selected rock successions, ranging in age from the Archean to the present, will lead to a quantitative understanding how (in particular) the measured carbonate-associated sulfate abundance (but also the isotopic composition) in a carbonate rock relates back to ambient seawater sulfate concentration (and isotopic composition).