Skip to Main Content
GEOREF RECORD

Characteristics and generation mechanism of gullies and mega-pockmarks in the Zhongjiannan Basin, western South China Sea

Geng Minghui, Song Haibin, Guan Yongxian, Chen Jiangxin and Bai Yang
Characteristics and generation mechanism of gullies and mega-pockmarks in the Zhongjiannan Basin, western South China Sea
Interpretation (Tulsa) (May 2017) 5 (3): SM49-SM59

Abstract

The paleoceanography and deep-water circulation process of the South China Sea (SCS) is still poorly understood. We have evaluated multibeam bathymetry and multichannel seismic reflection data acquired by Guangzhou Marine Geological Survey in recent years, and we investigate the characteristics, distribution, and generation mechanism of submarine seabed gullies and mega-pockmarks in the northern Zhongjiannan Basin of the SCS. Our data reveal that there are northwest-southeast-trending gullies and randomly or linearly arraying mega-pockmarks in the northern depression of the Zhongjiannan Basin. Gullies are 1 km or more in width and tens of kilometers in length. The long-axis diameter for the largest mega-pockmarks can reach up to 4293 m. The mega-pockmarks found in the west block of the northern depression are the manifestation of focused fluid flow migrating along shallow inclined faults induced by slumps that reached the seabed. Gullies are trending southeast and perpendicular to the contours of the continental slope, suggesting that gravity flows have played an important role in the evolution of gullies. Our data demonstrate that the gullies have a close relationship with mega-pockmarks, and that they were formed through the interaction of intense focused fluid flow and gravity flows. The pockmarks formed first, subsequently growing in size and number under the effect of subsurface fluid flows. The southeastward moving gravity flow caused discrete pockmarks to coalesce and form immature gullies. After being fully converged, gullies finally become smooth-bottomed and matured. Because gullies and mega-pockmarks are the manifestation of the geologic process of fluid escape at the seabed, they should be taken into account when assessing the potential for gas hydrates and seafloor instability.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 5
Serial Issue: 3
Title: Characteristics and generation mechanism of gullies and mega-pockmarks in the Zhongjiannan Basin, western South China Sea
Affiliation: Tongji University, School of Ocean and Earth Science, China
Pages: SM49-SM59
Published: 201705
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
Accession Number: 2017-085802
Categories: Geomorphology
Document Type: Serial
Bibliographic Level: Analytic
N00°00'00" - N25°00'00", E99°10'00" - E122°00'00"
Secondary Affiliation: Guangzhou Marine Geological Survey, CHN, ChinaChinese Geological Survey, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201745
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal