南海ODP1148站33Ma以来的沉积矿物组成通量及其构造响应

IOCAS-IR > 海洋环流与波动重点实验室

	南海ODP1148站33Ma以来的沉积矿物组成通量及其构造响应
其他题名	The Composition and Fluxes of Sedimentary Minerals at ODP Site 1148 and Their Response to Tectonic Movements
	蒋恒毅
学位类型	博士
	2006-06-09
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	Odp1148 站陆源矿物组成沉积通量南海海底扩张青藏高原隆升构造响应
摘要	摘要矿物是沉积物的主要成分，其陆源组分经过地表径流或风带到海洋，直接或间接地沉积下来。海洋中陆源矿物的多寡反映了物源供给和输送动力的强弱，从长尺度看受构造活动和地貌演化所控制，因此大的构造运动必然在相邻边缘海沉积的陆源组分和通量变化中留下烙印。新生代南海海盆经历了两次扩张，第二次扩张发生在32～15.5 Ma，这次扩张使东北巴拉望地块向南漂移，形成了南海中央海盆。青藏高原的隆升具有分阶段不均匀性，目前研究认为渐新世以来青藏高原快速隆升的时代有25～17 Ma，13～8 Ma 和3.4 Ma～现今。为了探明青藏高原加速隆升和南海构造扩张在南海沉积中的响应，我们对ODP 184 航次在中国南海1148站取得的沉积物进行了矿物学分析。通过化学提纯分离方法获得陆源矿物，粘土矿物，长石矿物、石英的含量以及它们的通量；通过X射线衍射分析获得粘土矿物的组成并估算了各组分的沉积通量；用激光粒度仪分析了陆源物质的粒度。利用以上分析的结果和本航次的年代数据获得33 Ma以来的沉积矿物的含量、通量和陆源物质粒度随时间变化曲线。在此基础上讨论了33 Ma来南海陆源矿物含量和通量对南海构造扩张及青藏高原隆升的响应。结果发现南海28.5 Ma之前的沉积矿物组成与沉积通量同南海海底构造扩张的开始和脊跳跃有关；23.5 Ma之后的沉积受青藏高原隆升影响，青藏高原在25～17 Ma，13～8 Ma 和3.4～present的加速隆升南海沉积物中均有反映，尤其是3.4 Ma以来的快速隆升，在沉积矿物中的反映非常明显。从23.5 Ma开始，1148 站陆源矿物的源区从东南变到西北，这是因为随着南海海底扩张，南部物源远离沉积站位从而影响减弱；同时，青藏高原隆升导致地表剃度增加，河流转向与侵蚀加强并开始影响到南海。
其他摘要	Abstract Minerals are the main components of sediments, the terrigenous parts of which are carried into the ocean by rivers or winds and deposit directly or indirectly. The amount of the terrigenous minerals in marine sediments implies the supply of the source area and the strength of the transportation agency. It is strongly affected by tectonic movement and geomorphic evolution in long time scale. Therefore, the large tectonic movement must lead to the change of mineral components and fluxes marginal seas. South China Sea (SCS) basin experienced two tectonic expansion in Cenozoic and the second expansion occurred between 32~15.5 Ma. The second expansion formed the central basin, the Palawan block departed far away from the northern continent. The Tibet Plateau experienced three accelerated uplift at 25~17 Ma.B.P, 13~8 Ma.B.P and 3.4 Ma.B.P~present.. In order to determine the effective tectonic movement proxy indexes and find more evidence for the two large tectonic events in marginal sea sedimentary mineral composition and their fluxes were studied. Quartz, feldspar, clay minerals and terrigenous minerals were extracted from the sediments of site 1148 of ODP LEG 184 by chemical dissolve method, the contents and the mass accumulation rate (MAR) of which were calculated; the composition of clay minerals are obtained by XRD method, and the fluxes of smectite, illite, chlorite and kaolinite were identified and calculated half quantitatively; the grain size of terrigenous minerals were also analyzed by Laser Particle Analyzer. According to the chronology data in initial report of ODP LEG 184, vertical distribution of the terrigenous minerals and the clay minerals and their content and fluxes against age were established. Therefore, the respond of content and flux of terrigenous minerals and clay minerals to the expansion of South China Sea floor (SCS) and the uplift of Tibet Plateau were discussed. The results show that the highest terrigenous mineral components between 33~28.5 Ma was correlated with the start of SCS floor expansion and the ridge jump, while it was affected by the uplift of Tibet Plateau after 23.5 Ma. The accelerated uplift phases were very prominently revealed in the sediments, especially the rapid uplift since 3.4 Ma ago. The provenance of terrigenous mineral components changed from southeast to northwest at about 23.5 Ma as the southern source departed from the deposition site and the effects weakened with the expansion of the SCS floor, when the Tibet Plateau uplifted leaded to morphologic gradient increase, change of river direction and enhance of erosion.
页数	126
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/587
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	蒋恒毅. 南海ODP1148站33Ma以来的沉积矿物组成通量及其构造响应[D]. 海洋研究所. 中国科学院海洋研究所,2006.

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