Sulfate and dolomitization - constraints for precipitation and alteration

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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).