Amanda J. Waite
MGG
Education:
2003 B.A. in Geology, Hamilton College 2005 M.S. in Oceanography, Univ. of Delaware College of Marine Studies
Research Interests: My research focuses on the geochemical analysis of various forms of biomineralization, as it relates to the reconstruction of paleoclimatic and paleoenvironmental conditions in the world’s oceans. In particular, this includes the trace element and stable isotopic compositions of biogenically produced carbonates, which capture snap shots of local environmental conditions through time and preserve them in the geologic record.
Current Project: Within the Stable Isotope Laboratory at RSMAS, I am presently examining stable isotope (δ13C and δ180) and trace metal (ie. Sr/Ca) signatures in the skeletons of both corals and sclerosponges from the Caribbean as proxies for reconstructing the temperature and salinity of the region over the last few centuries. The project is being conducted under the guidance of Dr. P. Swart and capitalizes on a series of coral cores (Montastraea faveolata and Siderastrea sidereal) collected from the Lesser Antilles by the CASE Cruise in 2002. The objective of the CASE project is to examine the interaction between salinity, water, and temperature in the Atlantic and the Caribbean and the goals of my research follow in a similar vain. Additionally, the CASE suite is supplemented by an approximately 400 year old sclerosponge, Ceraptorella nicholsoni, collected from Lee Stocking Island in the Bahamas.
My research takes a multi-proxy approach to reconstructing regional climate, water mass flow, and riverine inputs in the Caribbean region. Assuming, based on instrumental records, that water temperature variations are similar across the specimen collection sites, then differences in the oxygen isotopic signatures of the corals/sclerosponge at the individual localities should principally reflect salinity anomalies in the region. To this extent, early findings from specimens collected at Bequia, Union Island, Guadaloupe, and St. Croix display distinct differences in oxygen isotope composition, with the specimens originating from the more southerly islands exhibiting oxygen isotopic values which are more negative than their northern counterparts. This suggests that the southern portion of the Caribbean is influenced by lower salinity waters originating from the input of the Amazon and Orinoco Rivers, and ITCZ associated precipitation. On a local scale some corals demonstrate less pronounced cyclicity in oxygen isotopes, while maintaining a clear annual carbon cycle. This seems to suggest that run off from land may both amplify the carbon and mask the oxygen isotopic signatures.
A portion of my study will also be devoted to a review and assessment of the methods we use to sample and analyze carbonate skeleton geochemistry. Preliminary investigation suggests that fine tuning both age control and sample drilling techniques can eliminate some of the observed ambiguity and highlights the need for more refined practices for the analysis of skeletal records. Additionally, it is also a goal of this work to experiment with and implement methods for the analysis of coral and sclerosponge skeleton slabs within the XRF Core Scanner recently acquired by Dr. L. Peterson.