USING ARCHAEA BIOMARKER INDEX TEX₈₆ AS A PALEO-SEA SURFACE TEMPERATURE PROXY

TEX₈₆ index is a relatively new paleo-sea surface temperature (SST) proxy, based on the ratio of a newly discovered group of biomarkers, glycerol dialkyl glycerol tetraethers(GDGTs),which are produced by marine archaea Crenarchaeota. Results based on laboratory culture and analyses of both particulate organic matter and surface sediments from the global oceans all indicate that SST is the main environmental control on the TEX₈₆ index; while salinity, nutrient concentration and other factors have no obvious influences on it. However, terrestrial materials also contain low contents of GDGTs, so large errors can occur when the TEX₈₆ index is applied to coastal and shallow marine environments. But simultaneous use of both the TEX₈₆ index and another biomarker index BIT can ensure the accurate reconstruction of shallow water SST. In contrast to the commonly used U₃₇^K' index, the TEX₈₆ index can be applied to warm water regions with SST higher than 29℃, and this index has been successfully applied to the reconstruction of warmer period SSTs in the past.Thus,the TEX₈₆ has great potential for SST reconstructions of the western Pacific which includes the western Pacific Warm Pool and many marginal seas.