| Summary: | WiscSIMS workshop High-Resolution Proxies of Paleoclimate (HiRes2017), 18-21 June 2017, Madison, Wisconsin Deep-sea or cold-water corals (CWCs) display cosmopolitan distribution over a wide range of depths in the ocean. Similar to their tropical counterparts, they provide continuous, high-resolution records of up to a century or more. Several CWC elemental and isotopic ratios have been proven or suggested as useful paleo-proxies. Our recent work focuses on relatively new and promising proxies for nutrients (P/Ca, Ba/Ca), carbonate system (U/Ca, B/Ca, B isotopes), and temperature (Mg/Li). Understanding the veracity of these proxies in our target archive, the solitary CWC Desmophyllum dianthus, requires high-resolution analysis of chemical distributions in the context of the meso-scale structure of the skeleton, on scales of 10's of microns. We are combining optical, LA-ICP-MS and micromilling-solution-ICP-MS approaches in the context of three major efforts: 1) Culturing studies using >150 live Desmophyllum currently growing at a range of pH and feeding conditions at the ICM (Barcelona) which we are using to calibrate proxies under a degree of control not possible in the open ocean; 2) Complementary calibration work using live-collected Desmophyllum from various ocean locations, in the context of the global ocean hydrographic database; and 3) exploitation of a new archive of fossil corals from waters around New Zealand, from which we plan to generate a paleo-record of Antarctic Intermediate water composition since the last Glacial period, important for testing hypotheses for mechanisms driving the transition out of the last Glacial period. We will discuss early laser ablation data that address the nature of intra-skeletal elemental variation with implications for efficiently extracting precise and accurate paleo-proxy signals from large archives of fossil corals. To advance rapid fossil coral dating, we have begun experimenting with highspatial resolution LA-MC-ICP-MS U-Th >speed-dating,> which has ...
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