Sulfate and dolomitization - constraints for precipitation and alteration

碳酸盐伴生硫酸盐是我们探索地球演化的重要代表，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，详细了解碳酸盐缔合硫酸盐的形成和成岩作用是成功进行地球系统科学研究的关键前提。尽管硫酸盐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什么、如何、在哪里以及有多少硫酸盐被纳入，并在成岩作用期间保留下来，仍然存在不确定性。对于代表前寒武纪关键岩性的白云岩和多变的白云化石灰岩来说，全面了解硫酸盐融入碳酸盐(以及成岩作用期间的变化)特别重要，但也存在许多显生界的例子。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细菌的活动密切相关。然而，详细的情况才刚刚浮出水面。这项研究旨在通过地球历史阐明硫酸盐和白云石化之间的密切联系。它集中在原生特征和次生成岩特征之间的明显区别。对选定的岩石序列进行分析，从太古宙到现在，将导致对碳酸盐岩中测得的与碳酸盐有关的硫酸盐丰度(以及同位素组成)如何(特别是)与周围海水硫酸盐浓度(和同位素组成)的关系有一个定量的了解。

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).