Gas emissions and ROV survey tracks of the Regab pockmark (Northern Congo Fan)


Autoria(s): Marcon, Yann; Ondreas, H; Sahling, Heiko; Bohrmann, Gerhard; Olu, Karine
Cobertura

LATITUDE: -5.796660 * LONGITUDE: 9.710000 * MINIMUM ELEVATION: -3160.0 m * MAXIMUM ELEVATION: -3160.0 m

Data(s)

17/04/2014

Resumo

Pockmarks are seafloor depressions commonly associated with fluid escape from the seabed and are believed to contribute noticeably to the transfer of methane into the ocean and ultimately into the atmosphere. They occur in many different areas and geological contexts, and vary greatly in size and shape. Nevertheless, the mechanisms of pockmark growth are still largely unclear. Still, seabed methane emissions contribute to the global carbon budget, and understanding such processes is critical to constrain future quantifications of seabed methane release at local and global scales. The giant Regab pockmark (9°42.6' E, 5°47.8' S), located at 3160 m water depth near the Congo deep-sea channel (offshore southwestern Africa), was investigated with state-of-the-art mapping devices mounted on IFREMER's (French Research Institute for Exploitation of the Sea) remotely operated vehicle (ROV) Victor 6000. ROV-borne micro-bathymetry and backscatter data of the entire structure, a high-resolution photo-mosaic covering 105,000 m2 of the most active area, sidescan mapping of gas emissions, and maps of faunal distribution as well as of carbonate crust occurrence are combined to provide an unprecedented detailed view of a giant pockmark. All data sets suggest that the pockmark is composed of two very distinctive zones in terms of seepage intensity. We postulate that these zones are the surface expression of two fluid flow regimes in the subsurface: focused flow through a fractured medium and diffuse flow through a porous medium. We conclude that the growth of giant pockmarks is controlled by self-sealing processes and lateral spreading of rising fluids. In particular, partial redirection of fluids through fractures in the sediments can drive the pockmark growth in preferential directions.

Formato

text/tab-separated-values, 8 data points

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.831989

doi:10.1594/PANGAEA.831989

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Marcon, Yann; Ondreas, H; Sahling, Heiko; Bohrmann, Gerhard; Olu, Karine (2014): Fluid flow regimes and growth of a giant pockmark. Geology, 42(1), 63-66, doi:10.1130/G34801.1

Palavras-Chave #File format; File name; File size; off southwest Africa; Pourquoi Pas ?; Regab_pockmark; Uniform resource locator/link to file; VICTOR; Victor6000 ROV; WACS
Tipo

Dataset