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| 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 |
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李凤业1,2, 史玉兰1,2, 何丽娟1,2, 陈福3,4, 朱笑青3,4
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1.中国科学院海洋研究所 青岛;266071;3.中国科学院地球化学研究所 贵阳;4.550002
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| 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2.10–8.50 cm/ka，晚更新世平均沉积速度为7.40–20.10 cm/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。 |
| 关键词: 冲绳海槽 沉积速率 古环境 |
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| 基金项目:国家自然科学基金资助项目，49376264号 |
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| RELATIONSHIP BETWEEN THE VARIATIONS IN SEDIMENTATION RATES AND SEDIMENTATION ENVIRONMENTS IN THE OKINAWA TROUGH SINCE THE LATE PLEISTOCENE |
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LI Feng-ye,SHI Yu-lan,HE Li-juan,CHEN Fu,ZHU Xiao-qing
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1.Institute of Oceanology, The Chinese Academy of Sciences,Qingdao, 266071;2.Institute of Geochemistry,The Chinese Academy of Sciences, Guiyang, 550002
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| Abstract: |
| Sediment cores were collected in June 1992, by the R/V Science 1 from the Okinawa Trough. Spectrometry of Th, 230Th, 232Th, U, 234U and 238U in six cores showed that, based on the 230Th/232Th activity ratio, the sedimentation rates ranged between 2.10 and 8.50 cm/ka during the Holocene and ranged between 7.40 and 20.10 cm/ka during the Pleistocene. Terrestrial materials from the East China Continental Shelf were largely transported to the Okinawa Trough during the glacial low sea-level period and the terrigenous material from the continent was sharply reduced during the Holocene. The Th, 232Th and Th/U ratio showed that variations in terrigenous material from the continental shelf were associated with sea level changes and the Warm Current fluctuations from the Pacific water masses. Most of the cores showed that 234U/238U ratio was <=1.13 during the Holocene and was bout >=1.13 during the Pleistocene; it seems to be true that salinity during the Pleistocene a (>=35) was higher than the Holocene (34.3–34.9). |
| Key words: Okinawa Trough, Sedimentation rates, Paleoenvironment |