Establishing the Magnesium Isotope Signature of Dolomites

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Magnesium is the 8th most abundant element in the continental crust and an important element in the hydrological and biological system and in the world’s oceans. Magnesium is the key element of dolomite and yet, published data on the magnesium-isotope signature of pene-contemporaneous and post-depositional dolomites and the impact of diagenesis on dolomite δ26Mg are at best scarce. This forms a strong motivation for an in depth magnesium-isotope study of various dolomite types using the state-of-the-art MC-ICP-MS facilities at the department of Sediment- and Isotope Geology at Bochum. The aims of this research proposal are (1) to test the hypothesis that specific dolomite types are characterized by specific δ26Mg signatures and (2) to assess the effects of increasing diagenetic alteration of pene-contemporaneous dolomite δ26Mg using the example of the Upper Triassic Hauptdolomit (Dolomia Principale) in the Alps. Depending on the outcome of the first two objectives, the compilation of a time-series δ26Mg stratigraphy of selected stratigraphic intervals is considered for the third project year. In the framework of this research, we intend to collaborate with expert colleagues from several institutions in order to obtain a broad selection of well-studied dolomite case examples including Precambrian and Phanerozoic material. The outcome of this work is of significance for those concerned with the dolomite problem in general and has the potential to represent a novel and independent approach for kinetic processes active during dolomite formation and stabilization.