用接收函数方法研究华南大陆东部地壳上地幔结构
发布时间：2018-10-19 20:24
【摘要】：华南大陆东部地区地处欧亚板块和太平洋板块的交汇区域,长期受到印度洋板块、太平洋板块和菲律宾海板块的俯冲影响,是欧亚大陆东部边缘构造框架极其重要的一部分,也是研究板块相互作用的最佳天然实验室之一。本文简要介绍了华南大陆东部地区的地质概况和近年来华南大陆东部地区地壳上地幔结构的研究成果,采用华南大陆东部赣闽地区35台三分量宽频流动台站于2012年6月至2014年6月期间记录的远震数据,以及赣闽地区58台固定台站于2011年1月至2012年12月期间记录的远震数据,提取了6784条P波接收函数,利用H-κ扫描叠加方法,得到了华南大陆东部赣闽地区地壳厚度和波速比结构的分布；通过接收函数的CCP叠加方法得到了华南大陆东部由内陆到沿海地区的莫霍面形态,以及深部410 km和660 km界面的形态,结合其它地质地球物理资料讨论了华南大陆东部地区的地壳及上地幔结构特征,并对其动力学模式进行了初步探讨。本文研究表明：(1)华南大陆东部地区地壳厚度范围在28—34 km之间,由内陆向沿海有起伏的逐渐减薄,江西西北部和沿海地区地壳较薄,江西东南部和福建西北部地壳较厚。波速比值在1.61—1.83之间,相应的泊松比值在0.21-0.28之间,波速比值(泊松比值)由内陆向沿海增加。研究区地壳主要以中、酸性岩石为主,部分地区受到地幔物质强烈上涌影响,地壳岩石中镁铁成分明显增加从而导致泊松比升高。沿海地区福州、漳州等地泊松比值较高,可能在深部存在部分熔融(2)沿江西九江—福建宁化剖面走向,地壳的平均波速比值在1.65-1.75之间,相对应的地壳平均泊松比值介于0.21-0.26之间,反映了华南大陆东部内陆的泊松比结构。泊松比值显示,研究区地壳岩石以长英质占优,表明研究区地壳结构相对比较稳定,壳幔垂向物质交换活动较弱。沿萍乡—广丰断裂带的波速比值明显高于两侧,其原因可能是受深部残存新元古代蛇绿混杂岩带的影响,这个结果进一步证明了该断裂是赣北地区两块体的汇聚边界,为江绍断裂的自然西延。(3)华南大陆东部地区上地幔主要速度间断面4101km和660 km在横向上未发现明显突变或起伏,上地幔转换带厚度与全球平均值基本一致,暗示了华南大陆东部地区上地幔转换带温度保持正常状态,表明华南大陆东部地区的上地幔转换带未受到欧亚大陆板块与菲律宾板块碰撞的明显影响。
[Abstract]:The eastern part of South China is located in the intersection area of Eurasian plate and Pacific plate, and has long been affected by subduction of the Indian Ocean plate, Pacific plate and Philippine sea plate, which is an extremely important part of the tectonic framework of the eastern margin of Eurasia. It is also one of the best natural laboratories for studying plate interaction. This paper briefly introduces the geological situation of the eastern part of the South China continent and the research results of the crustal and upper mantle structures in the eastern part of the South China continent in recent years. The remote seismic data recorded by 35 three-component wideband mobile stations from June 2012 to June 2014 and by 58 fixed stations from January 2011 to December 2012 in the eastern part of southern China are used. 6784 P-wave reception functions were extracted and the distribution of crustal thickness and wave-velocity ratio structure in the eastern Jiangxi and Fujian regions of South China were obtained by using H- 魏 scan superposition method. By means of the CCP superposition method of the reception function, the Moho surface morphology from the interior to the coastal area in the eastern part of the South China continent and the morphology of the deep 410 km and 660 km interfaces are obtained. Based on other geophysical data, the crustal and upper mantle structures in the eastern part of South China are discussed, and their dynamic models are preliminarily discussed. The results show that: (1) the crustal thickness ranges from 28 to 34 km in the eastern part of South China continent, and gradually decreases from inland to coastal, the crust of northwest Jiangxi and coastal areas is thin, and the crust of southeast Jiangxi and northwestern Fujian is thicker. The wave velocity ratio is between 1.61-1.83 and the corresponding Poisson ratio is between 0.21-0.28. The wave velocity ratio (Poisson ratio) increases from inland to coastal. In the study area, the crust is mainly intermediate and acidic rocks, and some areas are strongly affected by the upwelling of mantle material, and the composition of magnesium-iron in crustal rocks increases obviously, which leads to the increase of Poisson's ratio. In the coastal areas of Fuzhou and Zhangzhou, the Poisson ratio is relatively high, and there may be partial melting in the deep part. (2) along the Jiujiang-Ninghua section of Jiangxi Province, the average wave velocity ratio of the crust is between 1.65-1.75, and the corresponding average Poisson ratio of the crust is between 0.21-0.26. It reflects the Poisson's ratio structure in the eastern part of South China continent. Poisson's ratio shows that felsic rocks dominate the crustal rocks in the study area, indicating that the crustal structure in the study area is relatively stable and the vertical material exchange activity of crust and mantle is relatively weak. The ratio of wave velocity along Pingxiang-Guangfeng fault zone is obviously higher than that along both sides, which may be due to the deep residual Neoproterozoic ophiolite melange, which further proves that the fault is the convergence boundary of two blocks in north Jiangxi. It is a natural westward extension of the Jiangshao fault. (3) there are no obvious abrupt changes or fluctuations in the main intervelocity-velocity sections 4101km and 660 km of the upper mantle in the eastern part of the South China continent, and the thickness of the transition zone of the upper mantle is basically consistent with the global average. It is suggested that the temperature of the upper mantle transition zone in the eastern part of the South China continent remains normal, indicating that the upper mantle transition zone in the eastern part of the South China continent is not significantly affected by the collision between the Eurasian plate and the Philippine plate.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2
本文编号：2282261
[Abstract]:The eastern part of South China is located in the intersection area of Eurasian plate and Pacific plate, and has long been affected by subduction of the Indian Ocean plate, Pacific plate and Philippine sea plate, which is an extremely important part of the tectonic framework of the eastern margin of Eurasia. It is also one of the best natural laboratories for studying plate interaction. This paper briefly introduces the geological situation of the eastern part of the South China continent and the research results of the crustal and upper mantle structures in the eastern part of the South China continent in recent years. The remote seismic data recorded by 35 three-component wideband mobile stations from June 2012 to June 2014 and by 58 fixed stations from January 2011 to December 2012 in the eastern part of southern China are used. 6784 P-wave reception functions were extracted and the distribution of crustal thickness and wave-velocity ratio structure in the eastern Jiangxi and Fujian regions of South China were obtained by using H- 魏 scan superposition method. By means of the CCP superposition method of the reception function, the Moho surface morphology from the interior to the coastal area in the eastern part of the South China continent and the morphology of the deep 410 km and 660 km interfaces are obtained. Based on other geophysical data, the crustal and upper mantle structures in the eastern part of South China are discussed, and their dynamic models are preliminarily discussed. The results show that: (1) the crustal thickness ranges from 28 to 34 km in the eastern part of South China continent, and gradually decreases from inland to coastal, the crust of northwest Jiangxi and coastal areas is thin, and the crust of southeast Jiangxi and northwestern Fujian is thicker. The wave velocity ratio is between 1.61-1.83 and the corresponding Poisson ratio is between 0.21-0.28. The wave velocity ratio (Poisson ratio) increases from inland to coastal. In the study area, the crust is mainly intermediate and acidic rocks, and some areas are strongly affected by the upwelling of mantle material, and the composition of magnesium-iron in crustal rocks increases obviously, which leads to the increase of Poisson's ratio. In the coastal areas of Fuzhou and Zhangzhou, the Poisson ratio is relatively high, and there may be partial melting in the deep part. (2) along the Jiujiang-Ninghua section of Jiangxi Province, the average wave velocity ratio of the crust is between 1.65-1.75, and the corresponding average Poisson ratio of the crust is between 0.21-0.26. It reflects the Poisson's ratio structure in the eastern part of South China continent. Poisson's ratio shows that felsic rocks dominate the crustal rocks in the study area, indicating that the crustal structure in the study area is relatively stable and the vertical material exchange activity of crust and mantle is relatively weak. The ratio of wave velocity along Pingxiang-Guangfeng fault zone is obviously higher than that along both sides, which may be due to the deep residual Neoproterozoic ophiolite melange, which further proves that the fault is the convergence boundary of two blocks in north Jiangxi. It is a natural westward extension of the Jiangshao fault. (3) there are no obvious abrupt changes or fluctuations in the main intervelocity-velocity sections 4101km and 660 km of the upper mantle in the eastern part of the South China continent, and the thickness of the transition zone of the upper mantle is basically consistent with the global average. It is suggested that the temperature of the upper mantle transition zone in the eastern part of the South China continent remains normal, indicating that the upper mantle transition zone in the eastern part of the South China continent is not significantly affected by the collision between the Eurasian plate and the Philippine plate.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2
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