Table of Contents
Journal of Geological Research
Volume 2011 (2011), Article ID 359597, 8 pages
http://dx.doi.org/10.1155/2011/359597
Research Article

Geophysical Indicators of Gas Hydrate in the Northern Continental Margin, South China Sea

1Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
2Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology, Ministry of Land and Resources, Qingdao 266071, China
3Guangzhou Marine Geological Survey, MLR, Guangzhou 510760, China

Received 7 April 2011; Revised 11 August 2011; Accepted 11 August 2011

Academic Editor: Umberta Tinivella

Copyright © 2011 Xiujuan Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Gas hydrate drilling results show that gas hydrate has a close relationship with strong bottom-simulating reflectors (BSRs) identified from seismic data in the Baiyun sag, South China Sea. The BSRs observed on seismic profiles at the crests of submarine canyons indicate the likely existence of gas hydrate. We calculate the acoustic impedance using constrained sparse spike inversion (CSSI), the interval velocity, and the seismic reflection characteristics such as reflection strength, instantaneous frequency, blanking, and enhanced reflection to demonstrate the presence of gas hydrate. Higher acoustic impedance and P-wave velocity were identified above the BSR. A remarkable low impedance, low frequency, and acoustic blanking indicated the presence of gas below gas hydrate stability zone. The occurrence of gas hydrate at the crests of canyons suggests that the abundance of gas hydrate in Baiyun sag may be due to the migrating submarine canyons providing the structural reliefs and the topographic ridges.