冲绳海槽北部Rd－82和Rd－86孔氧同位素记录及其古环境分析  

OXYGEN ISOTOPE RECORDS AND PALEOENVIRON -MENT ANALYSIS IN CORE RD-82 AND CORE RD-86 IN THE NORTH OF THE OKINAWA TROUGH

作　　者：李铁钢[1] 阎军[1] 苍树溪[1] 

机构地区：[1]中国科学院海洋研究所

出　　处：《海洋地质与第四纪地质》1996年第2期57-64,共8页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金

摘　　要：本文对冲绳海槽北部Ｒｄ一８２孔浮游有孔虫Ｎ．ｄｕｔｅｒｔｒｅｉ和Ｒｄ一８６孔Ｎ．ｄｕｔｅｒｔｒｅｉ及Ｇ．ｓａｃｃｕｌｉｆｅｒ的氧同位素记录进行了分析。Ｒｄ一８２孔浮游有孔虫的氧同位素组成可清晰地划分氧同位素１一４期，跨越地质时代０一７１ｋａ；Ｒｄ一８６孔可划分氧同位素１一４期及５ａ－５ｃ亚期，跨越地质时代为０一１１０ｋａ。根据氧同位素变幅分析，末次冰期极盛时冲绳海槽北部可能有黄河和长江的淡水影响，其影响强度Ｒｄ一８２孔强于Ｒｄ一８６孔。晚更新世以来，黑潮流一直影响着本区，冰期时黑潮流主流线向东转折段向南偏移，根据现有资料至少南移０．３４个纬度。此外，在氧同位第２期，即末次冰期极盛期内发生一个短暂的气候回暖事件，该事件发生在２１一２０ｋａＢ，Ｐ，之间。Oxygen isotope records of planktoic foraminifera in Core Rd- 82(29°13.93'N,128°08.53'E)and Core d-86(28°53.29'N,128°40.28'E)taken from the north part of theOkinawa Trough have been analyzed.Based on the results,there are four oxygen isotopestages in Core Rd-82 and five oxygen isotope stages in Core Rd-86.According to theoxygen isotope geostratigraphic scale,sedimentation rates and fluxes were calculated foreach stage ,which shows that the sedimentation rates and fluxes in the last glaciationwere much higher than those in Holocene,High sedimentation rates and fluxes weremainly caused by the increase of terrigenous supply during the last glaciation(Core Rd-82)and by the fast accumulation of volcanic sediments during Late Pleistocene(CoreRd-86).On horizontal correlation,the terrigenous supply at Core Rd-82 position in thetrough bottom area is at least 4 times as much as that at Core Rd-86 position in the eastside of the trough;Analysis on the variation of oxygen isotope values shows that the north part of theOkinawa Trough may have been affected by freshwater from the Yellow River and theYangtze River during the last glaciation. And Core Rd-82 shows a greater influence ofthe freshwater than Core Rd-86.In addition,kuroshio current has influenced the northOkinawa Trough since Late Pleistocene,and the eastward turning section of the mainkuroshio path may have migrated southward at least 0.34 latitude degree. A fast warming event is recognized in the two cores within oxygen isotope stage 2.The presence of the event is between 21 and 20ka B. P.

关 键 词：氧同位素 古环境 回暖事件 冲绳海槽 

分 类 号：P597[天文地球—地球化学] P531[天文地球—地质学]