Assessing the robustness of carbonate-associated sulfate during hydrothermal dolomitization of the Latemar platform, Italy

Abstract

Carbonate-associated sulfate (CAS) is an important proxy for reconstructing marine sulfur cycling throughout Earth's history. In order to assess the impact of carbonate neomorphism on δ34SCAS data, a mineralogical-spatial transect from early diagenetic limestone into low-temperature hydrothermal dolostone was analyzed in the middle Triassic Latemar platform interior, northern Italy. This study addresses the yet unconstrained question whether hydrothermal dolostone preserves a marine δ34SCAS signature and, hence, might represent an archive for past seawater sulfate. In this study, δ34SCAS values were measured in low-temperature hydrothermal dolostone and compared with data from their corresponding precursor limestone. Results shown here reveal that δ34SCAS values for dolostone and precursor limestone are indistinguishable. This points to a rock-buffered middle Triassic marine δ34S signature not affected by hydrothermal alteration. Hence, hydrothermal dolostone represents, under favorable conditions, an archive for unraveling past marine sulfur cycling.