Sea surface temperature reconstruction for the middle Okinawa Trough during the last glacial–interglacial cycle using C37 unsaturated alkenones

C37 unsaturated alkenones were analyzed on a core retrieved from the middle Okinawa Trough. The calculated U37K′ displays a trend generally parallel with those of the oxygen isotopic compositions of two planktonic foraminiferal species, Neogloboquadrina dutertrei and Globigerinoides sacculifer, suggesting that in this region, SST has varied in phase with global ice volume change since the last glacial–interglacial cycle. The U37K′-derived SST ranged from ca. 24.0 to 27.5 °C, with the highest value 27.5 °C occurring in marine isotope stage 5 and the lowest ∼ 24.0 °C in marine isotope stage 2. This trend is consistent with the continental records from the East Asian monsoon domain and the marine records from the Equatorial Pacific. The deglacial increase of the U37K′-derived SST is ∼ 2.4 °C from the Last Glacial Maximum to the Holocene.