d super(18)O of a shallow water benthic foraminifer Marginopora and paleotemperature calibration

Research in chemical proxies of past ocean water temperatures, as preserved in skeletal carbonates of marine organisms, has witnessed a phenomenal growth in recent years. Oxygen isotopic composition (expressed as ae super(18)O) of the foraminiferal carbonates is the principal proxy used for paleoclimate reconstruction. It is known that inorganic equilibrium precipitation is not valid for biogenic carbonates and therefore, species specific calibrations are emphasized for paleoceanographic and paleoclimate studies. Planktonic and deep water benthic foraminifera are commonly analyzed to estimate temperatures of sea surface and bottom waters to reconstruct ocean water circulation. There are, however, very few studies on ae super(18)O of shallow water, symbiont-bearing, benthic foraminifera, popularly known as larger foraminifera. These foraminifera are important contributors to modern reef sediments and have been the most abundant constituent of shallow water carbonates of the Cenozoic times. It necessitates developing a paleotemperature scale based on shallow water benthic foraminifera. In the present, work we analyze ae super(18)O of seasonally collected, symbiont-bearing benthic foraminifer, Marginopora, from Akajima (Okinawa), Japan. The specimens were picked live from the reef flat (depth < 2 m) and the analysis was carried on: 1) whole-test and 2) outer-most chambers.