| Holocene tephra deposits in the northern Okinawa Trough |
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| 作者姓名： | LIU Yanguang OLE Bjφrslev Nielsen ZHANG Deyu DU Dewen JAN Heinemeier WU Yonghua |
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| 作者单位： | Department of Earth Sciences University of Aarhus Aarhus C DK-8000 Denmark，AMS 14C Laboratory University of Aarhus Aarhus C DK-8000 Denmark |
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| 摘 要： | 1 Introduction Volcanic activities have played an important role in the process of global climatic changes. Being good stratigraphic markers, widespread tephra layers in ma- rine sediments can provide reliable evidences for the regional paleoceanographic …
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| 关 键 词： | 冲绳岛 全新世 沉积物 火山灰 |
| 收稿时间： | 2005-08-27 |
| 修稿时间： | 2005-11-18 |
Holocene tephra deposits in the northern Okinawa Trough |
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| LIU Yanguang,OLE Bjφrslev Nielsen,ZHANG Deyu,DU Dewen,JAN Heinemeier,WU Yonghua.Holocene tephra deposits in the northern Okinawa Trough[J].Acta Oceanologica Sinica,2006,25(1):78-89. |
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| Authors: | LIU Yanguang OLE Bjφrslev Nielsen ZHANG Deyu DU Dewen JAN Heinemeier WU Yonghua |
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| Institution: | 1.College of Marine Geosciences, Ocean University of China, Qingdao 266003, China;KeyLaboratoryofMarine Sedimentologyand Environmental Geology, First Institute ofOceanography, State Oceanic Administration, Qingdao 266061, China;Department of Earth Sciences, University of Aarhus2.Department of Earth Sciences, University of Aarhus3.KeyLaboratoryofMarine Sedimentologyand Environmental Geology, First Institute ofOceanography, State Oceanic Administration, Qingdao 266061, China |
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| Abstract: | The mineralogical and geochemical characteristics of sediments of Core CSH1, which was collected from the northern Okinawa Trough, indicate that large amounts of volcanic materials have deposited in the northern Okinawa Trough during the Holocene. On the basis of down-core variations in mineral and element contents of sediments, two layers in the uppermost section of Core CSH1 characterized by high quartz, Na2O, MnO, K2O, uranium contents and low contents of clay minerals, volatiles, Fe2O3, MgO, CaO and strontium, have been identified as the tephra deposits. Systematic grain-size measurements also suggest that sediments from the northern Okinawa Trough are made up of terrigenous materials and volcanic ashes with different proportion during the Holocene. The sediments of tephra layers in Core CSH1 show bi-modal patterns in grain-size distribution with modal grain-sizes of 74.3 and 7.81 μm,respectively. According to the radiocarbon dating on shells of zooplankton foraminifera, two tephra layers in Core CSH1, formed at 7 250 and 10 870 a BP (cal), approximately correspond to the K-Ah tephra 7 300 a BP (cal)] and the eruption of Kuju Volcano (12～10 ka BP), respectively. |
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| Keywords: | Okinawa Trough Holocene tephra deposits |
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