南海海槽增生楔沉积物环境磁学研究

发布时间：2019-06-27 12:53

【摘要】：俯冲带区域地震释放的能量占全球地震活动释放能量的90%(Lay,2005),而地震活动产生的地震和海啸,对人口稠密地区存在灾难性的影响。因此,对俯冲带区域的研究,成为地球科学研究的热点。为了更好地理解俯冲带的演化规律及其引发地震的原因,国际大洋钻探计划(IODP)在日本西南外海执行多航次的南海海槽发震带实验,研究俯冲带地区的岩石、沉积物和流体的基本特征(Margins Steering Committee,2004)。IODP316航次C0004和C0008站位位于俯冲带区域增生楔八字形非序列逆冲断层的浅部,其目标是为了探究俯冲带不同构造位置沉积物的差异,进而为南海海槽构造和环境演化提供信息。本文对南海海槽316航次C0004和C0008站位岩芯样品进行了系统的环境磁学研究。研究结果显示C0004,C0008站位沉积物岩芯中的磁性矿物主要为铁硫化物(黄铁矿,胶黄铁矿,磁黄铁矿)及粗粒的磁铁矿,沉积物可能经历了后期的还原成岩作用。利用磁学参数识别了硫酸盐-甲烷转换界面深度：C0004钻孔硫酸盐-甲烷转换界面顶界在,-2m CSF,底界在-20m CSF; C0008A钻孔硫酸盐-甲烷转换过渡带在3-15m CSF。对比发现,钻孔的磁学特征对增生楔的构造演化有很好的响应,并且受流体影响,C0004钻孔沉积物黄铁矿矿化完全。
[Abstract]:The energy of the subduction zone seismic release is 90% of the energy released by the global seismic activity (Lay,2005), and the earthquake and tsunami produced by the seismic activity have a disastrous effect on the densely populated area. Therefore, the research on the subduction zone has become the focus of the earth science research. In order to better understand the evolution of the subduction zone and the cause of the earthquake, the International Ocean Drilling Program (IODP), in the south-west coast of Japan, carried out a multi-voyage in the South China Sea Trough to study the basic characteristics of rock, sediment and fluid in the subduction zone (Margins Steering Committee,2004). The IODP316 flight C0004 and C0008 are located in the shallow part of the subduction zone and the regional hyperplastic wedge-shaped non-sequence thrust fault, and the aim is to explore the difference of the sediment in different tectonic positions of the subduction zone and to provide the information for the structure and the environmental evolution of the South China Sea. In this paper, the environmental magnetism of the core samples of the C0004 and C0008 stations in the sea trough of the South China Sea is studied in this paper. The results show that the magnetic minerals in the core of the deposit of C0004 and C0008 are mainly iron sulfide (pyrite, pyrites, pyrrhotite) and coarse-grained magnetite, and the sediments may undergo the later-stage reduction and diagenesis. The depth of the sulfate-methane conversion interface is identified by using magnetic parameters: the top boundary of the C0004 borehole sulfate-methane conversion interface is at, -2m CSF, and the bottom boundary is -20m CSF; the C0008A drilling sulfate-methane conversion transition zone is between 3 and 15 m CS F. It is found that the magnetic character of the borehole has a good response to the structural evolution of the accretive wedge and is affected by the fluid.
【学位授予单位】：中国地质大学（北京）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P738.3;P736.21

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