Paired stable oxygen isotope and Mg/Ca analyses in calcite tests of the mixed-layer-dwelling planktic foraminifer Globigerinoides ruber has been used to reconstruct equatorial Indian Oceanδ18O of seawater （δ 18Osw ...Paired stable oxygen isotope and Mg/Ca analyses in calcite tests of the mixed-layer-dwelling planktic foraminifer Globigerinoides ruber has been used to reconstruct equatorial Indian Oceanδ18O of seawater （δ 18Osw ） over the last ~137 thousand years. On the basis of ice-volume-correctedδ18Osw （δ18Osw-ivc ）, relative changes in sea surface salinity （SSS） have been estimated. The SSS estimates suggest three episodes of higher SSS （131-113 thousand years before present （kyr BP）, 62-58 kyr BP, and 30-24 kyr BP） within the last glacial period as compared with the present. SSS comparison between interglacial episodes reveals that the surface seawater over the core site was significantly saltier during the penultimate interglacial than the Holocene. We suggest that the evolution of a seasonal insolation gradient between the Indian monsoon areas and the equator over the investigated time interval was instrumental in shaping the strength of the Indian winter and summer monsoons that left their imprints on the equatorial Indian Ocean SSS via freshwater input and wind-induced mixing. The study shows that the insolation difference between northern latitudes and the equator during winter affects monsoon strength in the Indian region, especially during cold intervals.展开更多
为了分析南海北部上陆坡东沙隆起西侧海域海底稳定性,对A和B两个岩芯进行了AMS14C测年、浮游有孔虫氧同位素分析、粉色红拟抱球虫Globigerinoides ruber鉴定、粒度分析等工作。综合研究表明,A、B岩芯分别发育了距今920 ka BP、960 ka B...为了分析南海北部上陆坡东沙隆起西侧海域海底稳定性,对A和B两个岩芯进行了AMS14C测年、浮游有孔虫氧同位素分析、粉色红拟抱球虫Globigerinoides ruber鉴定、粒度分析等工作。综合研究表明,A、B岩芯分别发育了距今920 ka BP、960 ka BP以来的更新世、全新世地层。A岩芯3.3~14.08 m层位地层发生了倒转,这与3.3m、6.12~6.18 m发育的两个浊积层有关。在71.5~71.63 m(冰期370 ka BP左右)也发育一浊积层。B岩芯在9.2 m、25.2~28.6 m等层位发育了浊积层。同样位于陆坡坡折,水深较大的A岩芯,由于滑坡导致的浊流活动略强一些。展开更多
基金the DAAD,Germany,Council of Scientific and Industrial Research,Indiathe the Department of Science and Technology, India forproviding financial support
文摘Paired stable oxygen isotope and Mg/Ca analyses in calcite tests of the mixed-layer-dwelling planktic foraminifer Globigerinoides ruber has been used to reconstruct equatorial Indian Oceanδ18O of seawater （δ 18Osw ） over the last ~137 thousand years. On the basis of ice-volume-correctedδ18Osw （δ18Osw-ivc ）, relative changes in sea surface salinity （SSS） have been estimated. The SSS estimates suggest three episodes of higher SSS （131-113 thousand years before present （kyr BP）, 62-58 kyr BP, and 30-24 kyr BP） within the last glacial period as compared with the present. SSS comparison between interglacial episodes reveals that the surface seawater over the core site was significantly saltier during the penultimate interglacial than the Holocene. We suggest that the evolution of a seasonal insolation gradient between the Indian monsoon areas and the equator over the investigated time interval was instrumental in shaping the strength of the Indian winter and summer monsoons that left their imprints on the equatorial Indian Ocean SSS via freshwater input and wind-induced mixing. The study shows that the insolation difference between northern latitudes and the equator during winter affects monsoon strength in the Indian region, especially during cold intervals.
文摘为了分析南海北部上陆坡东沙隆起西侧海域海底稳定性,对A和B两个岩芯进行了AMS14C测年、浮游有孔虫氧同位素分析、粉色红拟抱球虫Globigerinoides ruber鉴定、粒度分析等工作。综合研究表明,A、B岩芯分别发育了距今920 ka BP、960 ka BP以来的更新世、全新世地层。A岩芯3.3~14.08 m层位地层发生了倒转,这与3.3m、6.12~6.18 m发育的两个浊积层有关。在71.5~71.63 m(冰期370 ka BP左右)也发育一浊积层。B岩芯在9.2 m、25.2~28.6 m等层位发育了浊积层。同样位于陆坡坡折,水深较大的A岩芯,由于滑坡导致的浊流活动略强一些。
