Reconstruction of deglacial sea surface temperatures in the tropical Pacific from selective analysis of a fossil coral

Abstract

The Sr/Ca of coral skeletons demonstrates potential as an indicator of sea surface temperatures (SSTs). However, the glacial-interglacial SST ranges predicted from Sr/Ca of fossil corals are usually higher than from other marine proxies. We observed infilling of secondary aragonite, characterised by high Sr/Ca ratios, along intraskeletal pores of a fossil coral from Papua New Guinea that grew during the penultimate deglaciation (130 ± 2 ka). Selective microanalysis of unaltered areas of the fossil coral indicates that SSTs at ∼130 ka were ≤1°C cooler than at present in contrast with bulk measurements (combining infilled and unaltered areas) which indicate a difference of 6-7°C. The analysis of unaltered areas of fossil skeletons by microprobe techniques may offer a route to more accurate reconstruction of past SSTs. Copyright 2005 by the American Geophysical Union.