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Crustal structure in an onshore-offshore transitional zone near Hong Kong, northern South China Sea
Xia, SH; Zhao, MH; Qiu, XL; Xu, HL; Shi, XB;;
AbstractTo study the crustal structure beneath the onshore-offshore transitional zone, a wide-angle onshore-offshore seismic experiment was carried out in northern South China Sea near Hong Kong, using large volume airgun sources at sea and seismic stations on land. The crustal velocity model constructed from traveltime fitting shows that the sedimentary thickness abruptly increases seaward of the Dangan Islands based on the characteristics of Pg and Multiple Pg, and the crustal structure beneath the sedimentary layer is relatively simple. The Moho depth is about 25-28 km along the profile and the P-wave velocity increases gradually with depth. The velocities in the upper crust range from 5.5 to 6.4 km/s, while that in the lower crust is 6.4-6.9 km/s. It also reveals a low velocity zone with a width of more than 10 km crossing the crust at about 75-90 km distance, which suggests that the Littoral Fault Zone (LFZ) exists beneath the onshore-offshore transitional zone. The magnetism anomalies, bouguer gravity anomalies and active seismic zone along the coastline imply the LFZ is a main tectonic fault in the onshore-offshore area. Combined with two previously published profiles in the continental South China (L-G profile) and in the northern margin of South China Sea (OBS1993) respectively, we constructed a land-sea super cross-section about 1000 km long. The results show the onshore-offshore transitional zone is a border separating the unstretched and the stretched continental crust. The low velocity layer (LVL) in the middle crust was imaged along L-G profile. However, the high velocity layer (HVL) in the lower crust was detected along OBS 1993. By analyzing the mechanisms of the LVL in the middle crust and HVL in the base of crust, we believe the crustal structures had distinctly different attributes in the continental South China and in the northern SCS, which indicates that the LFZ could be the boundary fault between them. (C) 2009 Elsevier Ltd. All rights reserved.
Department[Xia, Shaohong; Zhao, Minghui; Qiu, Xuelin; Xu, Huilong; Shi, Xiaobin] Chinese Acad Sci, CAS Key Lab Marginal Sea Geol, S China Sea Inst Oceanol, Guangzhou 510301, Guangdong, Peoples R China; [Xia, Shaohong] Chinese Acad Sci, Grad Univ, Beijing 100039, Peoples R China
KeywordCrustal Structure Littoral Fault Zone Onshore-offshore Transitional Zone Onshore-offshore Seismic Experiment The South China Sea Continental South China
Subject AreaGeosciences, Multidisciplinary
Indexed Bysci
Funding Project海洋地质
WOS IDWOS:000275289700006
Citation statistics
Cited Times:26[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Recommended Citation
GB/T 7714
Xia, SH,Zhao, MH,Qiu, XL,et al. Crustal structure in an onshore-offshore transitional zone near Hong Kong, northern South China Sea[J]. JOURNAL OF ASIAN EARTH SCIENCES,2010,37(40669):460-472.
APA Xia, SH.,Zhao, MH.,Qiu, XL.,Xu, HL.,Shi, XB.,...& structure in an onshore-offshore transitional zone near Hong Kong, northern South China Sea.JOURNAL OF ASIAN EARTH SCIENCES,37(40669),460-472.
MLA Xia, SH,et al."Crustal structure in an onshore-offshore transitional zone near Hong Kong, northern South China Sea".JOURNAL OF ASIAN EARTH SCIENCES 37.40669(2010):460-472.
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