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日本南海海槽IODP C0004C岩芯样品热释光信号特征及其对古气候变化的响应

Thermoluminescent signal of the core C0004C from Nankai Troughand its response to the paleoclimate change

  • 摘要: 海洋沉积物的天然热释光强度的变化特征和冰期、间冰期的旋回有良好的对应关系,表明海洋沉积物的天然热释光强度可以指示古海洋气侯的变化.本研究取自日本南海海槽增生楔的1ODP00004C岩芯样品由更新统和下中上新统沉积物组成.样品的热释光测量结果与生物壳体碳酸钙含量、重结晶方解石含量对比后发现,热释光强度与生物壳体碳酸钙含量变化呈负相关,与重结晶方解石含量变化呈正相关,天然热释光强度的高值区与间冰期对应,低值区与冰期对应,根据岩芯样品热释光特征,在岩芯中划分出三个间冰期和三个冰期.根据热释光与磁化率的对比分析,结合岩性观察,推测岩芯中IIA段的角砾岩为陆源物质.鉴于样品物质组成、来源的差异性及热释光信号的敏感性,建议在利用海洋沉积物的天然热释光进行古气侯和古沉积环境研究时,应选取地质作用过程比较简单、沉积环境相对稳定的地区

     

    Abstract: Natural thermoluminescence(NTL)from ocean sediments is a good indicator for the paleoclimate evolution becausethe vanation of NTLis correponding to theglacial change.Sedimentary age of the core IODPC004Cin Nankai Trough is early late Pleistocene and early-middle Pliocene.NTL of 120 samples from the core were meas-ured.The result shows NTL has a negative correlation with the content of CaCO,and has positive corelation with the content of calcite.The high and low NTL corespond to the interglacial and glacial stages,respectively.Three interglacial and 3 glacial stages were divided according to the feature of NTL of the core.The breccia in IIA of the core is supposed to be terigenous sediment according to comparison of NTL with magnetic susceptibility.It is sug-gested that when NTL of sediments is used to study paleoclimate,the areas with relatively simple geological processand stable sedimentary environment should be chosen firstly.

     

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