OBS survey and crustal structure of the Southwest Sub-basin and Nansha Block, South China Sea

doi:10.3969/j.issn.0001-5733.2011.12.012

	OBS survey and crustal structure of the Southwest Sub-basin and Nansha Block, South China Sea
	Qiu Xue-Lin 1; Zhao Ming-Hui 1; Ao Wei 1; Lu Chuan-Chuan 2; Hao Tian-Yao 2; You Qing-Yu 2; Ruan Ai-Guo 3; Li Jia-Biao 3
刊名	CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
	2011-12-01
卷号	54 期号:12 页码:3117-3128
关键词	Southwest Sub-basin Nansha Block Ocean Bottom Seismometer (OBS) Crustal structure Conjugate continental margins
ISSN号	0001-5733
DOI	10.3969/j.issn.0001-5733.2011.12.012
文献子类	Article
英文摘要	OBS973-1 is a wide angle reflection and refraction deep seismic line using Ocean Bottom Seismometers (OBS), deployed for the first time in the southern part of South China Sea. The line crosses the southern margin of the Southwest Sub-basin and the middle part of Nansha Block. By seismic phase analysis and travel time fitting, a 2D P-wave velocity model along the line is constructed. The modeling results show that the surface sedimentary layer has a velocity of 2. 5 similar to 4. 5 km/s and a thickness of 1000 similar to 3000m, with locally rough basement interface. The crystalline basement has a velocity of 4. 5 similar to 5. 5 km/s on the top, increasing to 6. 8 similar to 6. 9 km/s near the bottom of the crust. In the middle crust there is a small velocity discontinuity (0. 1 similar to 0. 2 km/s), while the Moho at the bottom of crust has a large velocity contrast (1. 2 km/s). On the top mantle the velocity is 8. 0 similar to 8. 1 km/s. The Moho depth and the crustal thickness have much difference between the northern and southern segments along the line. The northern segment is in the deep sea basin, where the Moho is 11 km deep and the crystalline crust is only 5 similar to 6 km thick, which are typical characteristics of oceanic crust. In contrast, the southern segment is on the continental block, where the Moho has a maximum depth of 24 km and the crust has a corresponding thickness of 20 km, which are representative characteristics of thinned continental crust. From the deep sea basin to the continental block, the Moho depth and the crustal thickness increase rapidly. In the continental area, the upper crust and lower crust have similar thickness and variation. No High Velocity Layer (HVL) is seen in the lower crust. These may imply that pure-shear extension and uniform thinning are dominating inside the crust, and magma underplating is not developed in the lower crust. Comparing with the structure models of OBS973-2 and OBS973-3, it is inferred that the middle and eastern parts of Nansha Block have similar tectonic characters, and the two sides of Southwest Sub-basin are a pair of non-volcanic asymmetric conjugate continental margins.
WOS关键词	CONTINENTAL-MARGIN ; CONSTRAINTS ; TECTONICS ; ANOMALIES ; ASIA
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	SCIENCE PRESS
WOS记录号	WOS:000298906400012
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/74258]
专题	中国科学院地质与地球物理研究所
通讯作者	Qiu Xue-Lin
作者单位	1.Chinese Acad Sci, S China Sea Inst Oceanol, Key Lab Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China 2.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Petr Resources Res, Beijing 100029, Peoples R China 3.State Ocean Adm, Inst Oceanog 2, Key Lab Submarine Geosci, Hangzhou 310012, Zhejiang, Peoples R China
推荐引用方式 GB/T 7714	Qiu Xue-Lin,Zhao Ming-Hui,Ao Wei,et al. OBS survey and crustal structure of the Southwest Sub-basin and Nansha Block, South China Sea[J]. CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,2011,54(12):3117-3128.
APA	Qiu Xue-Lin.,Zhao Ming-Hui.,Ao Wei.,Lu Chuan-Chuan.,Hao Tian-Yao.,...&Li Jia-Biao.(2011).OBS survey and crustal structure of the Southwest Sub-basin and Nansha Block, South China Sea.CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,54(12),3117-3128.
MLA	Qiu Xue-Lin,et al."OBS survey and crustal structure of the Southwest Sub-basin and Nansha Block, South China Sea".CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION 54.12(2011):3117-3128.