Paper No. 74-13
Presentation Time: 9:00 AM-5:30 PM
MIDDLE HOLOCENE SST RECORD (6,200 +/- 80 TO 4,760 +/- 90 YR B.P.) BASED ON CORALS FROM CAÑADA HONDA, DOMINICAN REPUBLIC
The Holocene was initially considered to have a relative stable climate; however, significant climate variations have been observed in several paleoclimate records studies. Fossil corals provide access to study past climates. One of the limitations of this method is the high potential for diagenesis of scleractinian corals that lead to uncertainties in the climate reconstructions. As a consequence of diagenesis, finding pristine fossil corals can be challenging. The subaerial exposure of the Cañada Honda fossil coral reef located in the Enriquillo Valley in the Dominican Republic, provide remarkable well-preserved corals that lived in a shallow water reef environment providing the opportunity to study Holocene paleoclimate. A high-resolution archive of past climate is present in the geochemistry of the skeleton in the scleractinian coral. Significant marine environment parameters during coral growth are reflected in the δ18O isotopic values and trace element ratios. This project will measure δ18O isotopic values and Sr/Ca trace elemental ratios that will be integrated to the chronology of skeletons. With this information sea surface temperature (SST) values and sea surface salinity (SSS) variations will be approximated. Previous studies have shown that coral proxy records can provide past archives of paleoclimate variations. This investigation is going to be conducted in the Cañada Honda Reef exposure located at the Enriquillo Valley, in the western part of the Dominican Republic. An important feature of Cañada Honda is that 63% of the corals along the reef exposure are in growth position. Coral samples are cut into 5mm slabs to be X-rayed to create maps of the growth bands based on image density variations. Micromilling of the coral skeleton is performed in the coral slab to perform the geochemical analyses. The Orbicella spp. will be the main focus of this project since previous works are available for these species. δ18O isotopic values and Sr/Ca trace elemental concentrations in the coral skeletons will be used as proxy’s records for temperatures (SST) and (SSS) variations. The SST and SSS measurements will be presented within a chronologic context based on sclerochronology and coral colony dating (U/Th). Local changes in SST and SSS will be compared to modern data and available data for the same time interval.