东沙群岛西南海区海底地震测线OBS2015-1揭示的深部地壳结构*

doi:10.11978/2016122

Abstract

Abstract:

To better understand deep reflectors in the multi-channel seismic profile D80 in the northern South China Sea, a coincident ocean bottom seismic survey line (OBS2015-1) with 15 OBSs was inversed. This OBS line extends ESE 300 km, from 800 m in the upper slope to 3760 m in the abyssal plain. OBS data processing includes position and time corrections, phase identification using Obstool software, and velocity inversion with FAST tomography software. The resultant velocity shows that Cenozoic strata has a velocity of 1.6-3.5 km·s^-1 and a depth of 2 km. Mesozoic velocity is 3.5-5.5 km·s^-1 with an average depth of 3 km. In the oceanic and continental transition zone (OCT), the sediment basement is greatly affected by Late Cenozoic magmatic activity. Obvious high velocity anomaly and isoline uplift (5 km) were detected in the upper crust of the upper slope, corresponding to chaotic reflection anticline structure in D80; and the overlying Late Cenozoic strata also presents as synchronous deformation, which may result from the Late Cenozoic magmatic intrusion. The crustal thickness decreases gradually from 23-20 km beneath the continental slope to 8 km in the oceanic basin. A high velocity (7.0-7.6 km·s^-1) layer was seen in the lower crust, which changes from 5 km in the upper slope to 2 km in the ocean basin. Because of the Late Cenozoic magmatic activity in the continental slope and OCT, we interpret that the high crustal velocity layer originated from magmatic intrusion after the cession of seafloor spreading.

Key words: southwestern Dongsha Island waters, ocean bottom seismograph (OBS), velocity tomography, high velocity layer, magmatic intrusion

Yaqing LI, Pin YAN, Yanlin WANG, Guangjian ZHONG. Deep crustal structure revealed by ocean bottom seismic profile OBS2015-1 in southwestern Dongsha waters[J].Journal of Tropical Oceanography, 2017, 36(5): 83-92.

Figures/Tables 9

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References 29

[1]	郝沪军, 林鹤鸣, 杨梦雄, 等, 2001. 潮汕坳陷中生界——油气勘探的新领域[J]. 中国海上油气(地质), 15(3): 157-163.
	HAO HUJUN, LIN HEMING, YANG MENGXIONG, et al, 2001. The Mesozoic in Chaoshan Depression: A new domain of petroleum exploration[J]. China Offshore Oil and Gas (Geology), 15(3): 157-163 (in Chinese).
[2]	吕修亚, 阎贫, 陈洁, 等, 2009. 折射方法在南海北部潮汕坳陷中生界地层研究中的应用[J]. 热带海洋学报, 28(1): 43-47.
	LÜ XIUYA, YAN PIN, CEHN JIE, et al, 2009. Application of refraction velocity in studing Mesozoic strata in Chaoshan Depression on northern margin of South China Sea[J]. Journal of Tropical Oceanography, 28(1): 43-47 (in Chinese).
[3]	邱燕, 王立飞, 黄文凯, 等, 2016. 中国海域中新生代沉积盆地[M]. 北京: 地质出版社: 114.
[4]	邵磊, 尤洪庆, 郝沪军, 等, 2007. 南海东北部中生界岩石学特征及沉积环境[J]. 地质论评, 53(2): 164-169.
	SHAO LEI, YOU HONGQING, HAO HUJUN, et al, 2007. Petrology and depositional environments of Mesozoic strata in the Northeastern South China Sea[J]. Geological Review, 53(2): 164-169 (in Chinese).
[5]	吴振利, 李家彪, 阮爱国, 等, 2011. 南海西北次海盆地壳结构: 海底广角地震实验结果[J]. 中国科学: 地球科学, 41(10): 1463-1476.
	WU ZHENLI, LI JIABIAO, RUAN AIGUO, et al, 2012. Crustal structure of the northwestern sub-basin, South China Sea: Results from a wide-angle seismic experiment[J]. Science China Earth Sciences, 55(1): 159-172.
[6]	姚伯初, 曾维军, 陈艺中, 等, 1995. 南海北部陆缘东部中生代沉积的地震反射特征[J]. 海洋地质与第四纪, 15(1): 81-90.
	YAO BOCHU, ZENG WEIJUN, CHEN YIZHONG, et al, 1995. Seismic reflective characteristics of Mesozoic sediments on the eastern continental margin in the North of the South China Sea[J]. Marine Geology & Quaternary Geology, 15(1): 81-90 (in Chinese).
[7]	张莉, 张光学, 王嘹亮, 等, 2014. 南海北部中生界分布及油气资源前景[M]. 北京: 地质出版社: 208-211.
[8]	周蒂, 王万银, 庞雄, 等, 2006. 地球物理资料所揭示的南海东北部中生代俯冲增生带[J]. 中国科学 D辑: 地球科学, 36(3): 209-218.
	ZHOU DI, WANG WANYIN, PANG XIONG, et al, 2006. Mesozoic subduction-accretion zone in northeastern South China Sea inferred from geophysical interpretations[J]. Science in China: Series D Earth Sciences, 49(5): 471-482.
[9]	BOILLOT G, RECQ M, WINTERER E L, et al, 1987. Tectonic denudation of the upper mantle along passive margins: a model based on drilling results (ODP Leg 103, western Galicia margin, Spain)[J]. Tectonophysics, 132(4): 335-342.
[10]	ČERVENÝ V, MOLOTKOV J A, PSENCIK I, 1977. Ray Method in Seismology[M]. Prague: Charles University Press.
[11]	CHRISTESON G, 1998. OBSTOOL: Software for Processing UTIG OBS Data[M]. Austin: Institute for Geophysics, University of Texas.
[12]	FRANKE D, 2013. Rifting, lithosphere breakup and volcanism: comparison of magma-poor and volcanic rifted margins[J]. Marine and Petroleum Geology, 43: 63-87.
[13]	GERNIGON L, RINGENBACH J C, PLANKE S, et al, 2004. Deep structures and breakup along volcanic rifted margins: insights from integrated studies along the outer Vøring Basin (Norway)[J]. Marine and Petroleum Geology, 21(3): 363-372.
[14]	HAO HUJUN, ZHANG XIANGTAO, YOU HONGQING, et al, 2009. Characteristics and hydrocarbon potential of Mesozoic strata in eastern Pearl River Mouth Basin, Northern South China Sea[J]. Journal of Earth Science, 20(1): 117-123.
[15]	MJELDE R, KASAHARA J, SHIMAMURA H, et al, 2002. Lower crustal seismic velocity-anomalies; magmatic underplating or serpentinised peridotite? Evidence from the Vøring Margin, NE Atlantic[J]. Marine Geophysical Researches, 23: 169-183.
[16]	NIRRENGARTEN M, GERNIGON L, MANATSCHAL G, 2014. Lower crustal bodies in the Møre volcanic rifted margin: Geophysical determination and geological implications[J]. Tectonophysics, 636: 143-157.
[17]	NISSEN S S, HAYES D E, BUHL P, et al, 1995. Deep penetration seismic soundings across the northern margin of the South China Sea[J]. Journal of Geophysical Research, 100(B11): 22407-22433.
[18]	RESTON T J, 2009. The structure, evolution and symmetry of the magma-poor rifted margins of the North and Central Atlantic: A synthesis[J]. Tectonophysics, 468(1-4): 6-27.
[19]	SAWYER D S, WHITMARSH R B, KLAUS A, 1994. Explanatory notes[C]//Proceedings of the Ocean Drilling Program, Initial Reports. College Station, TX: Ocean Drilling Program: 1-25.
[20]	TAYLOR B, HAYES D E, 1983. Origin and history of the South China Sea basin[M]//HAYES D E. The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands: Part 2. Washington, DC: American Geophysical Union, 27: 23-56.
[21]	WANG T K, CHEN MINGKAI, LEE C S, et al, 2006. Seismic imaging of the transitional crust across the northeastern margin of the South China Sea[J]. Tectonophysics, 412(3-4): 237-254.
[22]	WHITE R, MCKENZIE D, 1989. Magmatism at rift zones: the generation of volcanic continental margins and flood basalts[J]. Journal of Geophysical Research, 94(B6): 7685-7729.
[23]	WHITMARSH R B, BESLIER M O, WALLACE P J, 1998. Return to Iberia[C]//Proceedings of the Ocean Drilling Program, Initial Reports, 173. College Station, TX: Ocean Drilling Program: 1-30.
[24]	WU JINMIN, 1994. Evaluation and models of Cenozoic sedimentation in the South China Sea[J]. Tectonophysics, 235(1-2): 77-98.
[25]	YAN PIN, WANG LIAOLIANG, WANG YANLI, 2014. Late Mesozoic compressional folds in Dongsha waters, the northern margin of the South China Sea[J]. Tectonophysics, 615-616: 213-223.
[26]	YAN PIN, ZHOU DI, LIU ZHAOSHU, 2001. A crustal structure profile across the northern continental margin of the South China Sea[J]. Tectonophysics, 338(1): 1-21.
[27]	ZELT C A, BARTON P J, 1998. Three-dimensional seismic refraction tomography: A comparison of two methods applied to data from the Faeroe Basin[J]. Journal of Geophysical Research, 103(B4): 7187-7210.
[28]	ZELT C A, SMITH R B, 1992. Seismic traveltime inversion for 2-D crustal velocity structure[J]. Geophysical Journal International, 108(1): 16-34.
[29]	ZHAO MINGHUI, QIU XUELIN, XIA SHAOHONG, et al, 2010. Seismic structure in the northeastern South China Sea: S-wave velocity and Vp/Vs ratios derived from three-component OBS data[J]. Tectonophysics, 480(1-4): 183-197.

Deep crustal structure revealed by ocean bottom seismic profile OBS2015-1 in southwestern Dongsha waters

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