Stable isotope record, organic geochemistry and sea surface temperature estimation of ODP Hole 117-721B (Table 1)

Late Pleistocene sea surface water temperatures (SST) offshore Oman were calculated from the UK'37 ratio measured in sediment extracts from ODP holes drilled on the Oman Margin (723B, 728B) and on the Owen Ridge (721B, 731A). The data revealed a complex history of SST variations with a temperature range of 18°/19°C-27°/28°C, which is in accord with the present-day SST range in the western Arabian Sea. We found that, notably, in the glacial periods of isotopic stages 3 and 8 the SST was lower than during the interglacials. The lowest SST values occurred during isotopic stage 3. A mechanism involving a strong influence of cold northeasterly winds during glacial periods, with the southwestern monsoon being less effective at the same time, explains cold SST during glacial periods. However, further research is necessary to approve or disapprove this mechanism, because in the present study not all glacial periods were clearly marked by low SST values.

本研究通过对阿曼陆坡（723B、728B孔）与欧文海岭（721B、731A孔）的大洋钻探计划（Ocean Drilling Program，ODP）沉积物抽提物中测得的UK'37比值进行分析，计算得到阿曼近海晚更新世海水表层温度（sea surface water temperatures, SST）。研究数据揭示了SST变化的复杂演化历史，其温度区间为18~19℃至27~28℃，与现今阿拉伯海西部的SST区间相符。值得注意的是，氧同位素阶段3与8的冰期内，SST显著低于间冰期；其中最低SST值出现在氧同位素阶段3。冰期时寒冷东北风的强烈影响，加之同期西南季风作用减弱，这一机制可解释冰期SST偏低的成因。但由于本研究中并非所有冰期均表现出明确的低温SST特征，因此仍需开展进一步研究以验证该机制的合理性。