MULTI-PROXY APPROACH TO INFER THE ATMOSPHERIC RESPONSE TO THE MIOCENE CLIMATE OPTIMUM AND MID-MIOCENE CLIMATE TRANSITION,, TASMAN SEA, IODP SITE U1510

The Miocene Climate Optimum (MCO; 16.9–14.7 Ma) was a period of warming due at least in part to CO2 release during the eruption of the Columbia River Flood Basalts. This event was followed by the mid-Miocene Climate Transition (MMCT; 14.7–13.8 Ma) which was a major cooling event associated with the expansion of Antarctic ice sheets. The MCO is used as an analogue time period for how Earth system processes will behave under >1.5–2°C of anthropogenic warming. In particular, the oceanic mid-latitude response to increased warming is still poorly understood. We used sediments that span both the MCO and MMCT from IODP Expedition 371, Site U1510, located at 36°S, 164°E in the Tasman Sea to investigate surface to deep ocean processes across both climate events, including XRF, ICP-OES, and carbon content analysis. Additionally, we discuss ways to improve methods for isolating organic carbon from carbonate-rich deep-sea sediments. PCA analyses applied to the XRF data indicate increased export productivity during the MCO associated with periods of increased abundances of elements associated with terrestrial input over the site. PCA across the MMCT indicates decreased terrestrial input over the site associated with productivity. We link these results to expansion and contraction of the Hadley Cell during the MCO and MMCT, respectively. Preliminary data indicates that the acid fumigation method may be best for determining total carbon, whereas aqua regia digestion was likely incomplete for many elements. Future work in this area includes opportunities for improving the organic and total carbon data sets by improving digestion methods. In addition, analyzing a wider set of samples with XRF and ICP-OES will allow us to determine the accuracy of the findings we have already discovered.