冲绳海槽晚更新世以来沉积速率的变化与沉积环境的关系  

RELATIONSHIP BETWEEN THE VARIATIONS IN SEDIMENTATION RATES AND SEDIMENTATION ENVIRONMENTS IN THE OKINAWA TROUGH SINCE THE LATE PLEISTOCENE

作　　者：李凤业[1] 史玉兰[1] 何丽娟[1] 陈福[2] 朱笑青[2] 

机构地区：[1]中国科学院海洋研究所,青岛266071 [2]中国科学院地球化学研究所,贵阳550002

出　　处：《海洋与湖沼》1999年第5期540-545,共6页Oceanologia Et Limnologia Sinica

基　　金：国家自然科学基金!49376264

摘　　要：1992年6月对冲绳海槽进行了热水活动和底质调查。从所采岩芯中挑选有代表性的岩芯6个，对样品进行了放射性同位素Th、230Th、232Th、U、234U、238U的测定。结果表明，冲绳海槽全新世期间沉积物沉积速率比晚更新世期间低，全新世平均沉积速率为2．10—8．50cm／ka，晚更新世平均沉积速度为7．40－20．10cm／ka。这揭示了晚更新世低海平面期间大量的陆源物质和火山碎屑输入到冲绳海槽，而全新世海平面抬升，输入到海槽的陆源物质相对减少。Sediment cores were collected in Jume, 1992, by the R/ V Science l from the OkinawaTrough. Spectrometry of Th,232Th, 230Th, U, 234Uand238U in six cores showed that based on the230Th /232Th activity ratio, the sedimentation rates ranged between 2.10 and 8.50 cm / ka during theHolocene and ranged between 7.40 and 20. 10cm / ka during the Pleistocene. Terrestrial materials.from the East China Continental Shelf were largely stransported to the Okinawa Trough during theglacial low sea-level period and the terrigenous materiaI from the conhnent was sharply reducedduring the Holocene. The Th,232Th and Th / U ratio showed that variations in terrigenous materialfrom the continental shelf were associated with sea level changes and the Warm Current fluctuationsfrom the Pacific water masses. Most of the cores showed that234U /238U ratio was≤1.13 during theHolocene and was bout≥. 13 during the Pleistocene; it seems to be true that salinity during thePleistocene a (≥35) was higher than the Holocene (34.3-34.9).

关 键 词：冲绳海槽 沉积速率 古环境 沉积环境 

分 类 号：P736.213[天文地球—海洋地质] P736.14[天文地球—海洋科学]