RECONSTRUCTING PAST ENVIRONMENTAL CHANGES WITH OSTRACOD GEOCHEMISTRY

It has recently been suggested that the amount of trace elements taken from ostracods can provide insight on paleoclimatic conditions. This hypothesis has been tested using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), a system specifically designed for studying variations in trace elements. In this study, certain elements were chosen and measured via laser-ablation. These elements include ¹¹B, ²⁵Mg, ²⁷Al, ²⁹Si, ⁴³Ca, ²³⁸U, ⁸⁶Sr and most of the lanthanide elements. Two standards were also used as controls: NIST612, glass containing trace elements, and USGS MACS-3, made of pure calcium carbonate and crucial when ablating ostracods or any other carbonate organisms. When ablated, and with the added uncertainties, the standards fell under the correct reference values. Ablation of ostracods, collected as a bulk sample from the same region and sample horizon in a hypersaline lake on Big Darby Island, Bahamas, yielded similar trace elements with small variations in concentrations of a few (namely, Mg and Sr). This data, yielding an overall similarity in the ostracods’ geochemistry with small fluctuations in certain trace element concentrations, suggest that ostracod carapaces do indeed record environmental conditions and can help in understanding the environmental changes that occurred in the past.