Chromium isotope fractionation between modern seawater and biogenic carbonates from the Great Barrier Reef, Australia: Implications for the paleo-seawater δ53Cr reconstruction

Finally, our compilation of δ53Cr data from recent marine biogenic carbonates originating from the main oceanic provinces (South/North Pacific, South/North Atlantic, Caribbean, Mediterranean Sea) confirms that marine carbonates tend to be systematically enriched in light Cr isotopes relative to local ocean waters. Trace element constraints, however, indicate that some of these shifts to lower δ53Cr values (i.e., approaching −0.1 per mil) are related to a presence of lithogenic Cr in the shells, causing a diagenetic overprint of the primary marine δ53Cr signal.