Co-precipitation of Elements and Stable Isotopes with Ca Carbonates

Our understanding of climate change and oceanographic variability through time is largely derived from knowledge of the partitioning of trace elements and isotopes between marine carbonates the ocean. This in turn links to geological processes, including the rate of mid-ocean ridge spreading, hydrothermal activity, volcanic activity, and continental weathering. Nevertheless, because most of these relationships are empirically derived, we know relatively little about the impacts of environmental parameters, such as growth rate, pH, and temperature, on the composition of skeletal carbonates in the absence of biological activity. Further, the general assumption that precipitation of carbonates typically occurs at chemical equilibrium is challenged by experimental results and studies of actual marine samples. In this work, I describe a series of aragonite and calcite precipitation experiments that have been performed under variable conditions (growth rate, pH, T) and the crystalline products analyzed to evaluate isotopic fractionation, element partition, and growth rate in order to better understand the role of precipitation environment on carbonate chemical and isotopic composition.