A calibration of the oxygen isotope paleothermometer of coral aragonite from porites

International audienceThe oxygen isotopic composition (•18Oaragonite)of coral aragonite is dependent upon two parameters, temperature and water oxygen isotopic composition. This tracer allows temperature reconstruction in tropical zones. Different published b•80:temperature relationships show a slope derived from the regression •80 against T(øC) which varies between-0.16 and-0.23 for Porites genus. This implies greater uncertainty for paleoclimatic reconstruction. The calibrations were generated differently. They were obtained from several colonies, collected in different locations or the formula was derived from the same coral head following seasonal variations of temperature. The relationships took into account of •5•SOsw fluctuation or •5•SOsw were estimated from salinity or were not considered. We show by using isotopic data from Weber and Woodhead (1972) and assessing the •5•SOsw value by two different methods that a thermodynamically significant formula is generated