冲绳海槽48ka以来的碳同位素记录及其环境指示意义  

CARBON ISOTOPE RECORD AND ITS ENVIRONMENT IMPLICATION IN THE OKINAWA TROUGH DURING THE LAST 48 KYS

作　　者：孙荣涛[1] 李铁刚[1] 张德玉[2] 李青[1] 江波[1] 

机构地区：[1]中国科学院海洋研究所 [2]国家海洋局第一海洋研究所,青岛266061

出　　处：《海洋与湖沼》2007年第4期314-321,共8页Oceanologia Et Limnologia Sinica

基　　金：国家自然科学基金重点基金项目;90411014;中国科学院知识创新工程项目;KZCX3-SW-233;国家自然科学基金;40506015;中法国际合作项目;40421150011号;科技部国际合作项目;2002DFG00034号联合资助

摘　　要：冲绳海槽是末次冰期以来东海唯一始终保持连续沉积的区域,保存了最为完整的古海洋古气候变动记录。为了研究末次冰期以来全球碳循环效应在这一区域的响应特征,对取自冲绳海槽北部CSH1孔的浮游有孔虫N.dutertrei和G.ruber壳体的δ13C记录进行了分析,并且与冲绳海槽中部DGKS9603孔的记录进行了详细对比。结果表明,48cal.kaB.P.以来在冲绳海槽共记录了4个典型的δ13C宽幅低值时期,其持续时间分别在44—38.5,36—30,25—18.5与14—10cal.kaB.P.之间。通过与开放太平洋及其他边缘海区的对比,并与陆地气候变动记录相互印证,证实了在这几个δ13C宽幅低值时期中冲绳海槽受到陆源冲淡水的显著影响。另外,西太平洋开放海区表层海水也影响海槽区。这两个主要影响因子在整个末次冰期呈现出此消彼涨的作用模式。To study local response in the Okinawa Trough to the event of global carbon cycle, along with local influence of regional environmental factors, a gravity piston core CSH1 that was retrieved in the northern Okinawa Trough was collected. The core contains environmental records of last 48ka. 142 samples were made in interval of 8-12 cm. Planktonic foraminifera coarser than 150μm were identified and counted. δ^18O and δ^13C measurements were performed on the shells of G. ruber and N. dutertrei respectively, using an IsoPrime mass spectrometer. The isotopic records of core CSH1 were compared with those of core DGKS9603 in the middle of Okinawa Trough. δ^13C records of the two cores were again compared with those of the South China Sea, the Sulu Sea, eastern equatorial Pacific, and western equatorial Pacific. Additionally, the δ^13C profile of G. ruber in Core CSH1 was contrasted to those of ice cores and loess. Four δ^13C depletion stages were recognized at 44-38.5, 36-30, 25-18.5, and 14-10 cal. kaB.P.. Disagreement in δ^18O gradient and SST gradient between the two cores indicated that large amount of terrestrial freshwater had invaded to the northern Okinawa Trough resulting in salinity reduction and δ^13C depletion, as freshwater carried low δ^13C terrestrial materials. Comparison among sediments of ocean, ice, and loess disclosed the correspondence between global environmental variations and these stages. Therefore, the δ^13C profile in the trough was the combination of global change in carbon stock and the local environmental factors. Warm surface water of open Pacific and global change in greenhouse gas concentration had clearly affected the Okinawa Trough in the last glaciation event.

关 键 词：冲绳海槽 δ^13C低值时期 陆源冲淡水 

分 类 号：P736.22[天文地球—海洋地质]