Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 15 (2014): 867-885, doi:10.1002/2013GC005108.
Description:
During the Irish National Seabed Survey (INSS) in 2003, a gas related pockmark field was discovered and extensively mapped in the Malin Shelf region (NW Ireland). In summer 2006, additional complementary data involving core sample analysis, multibeam and single-beam backscatter classification, and a marine controlled-source electromagnetic survey were obtained in specific locations.This multidisciplinary approach allowed us to map the upper 20 m of the seabed in an unprecedented way and to correlate the main geophysical parameters with the geological properties of the seabed. The EM data provide us with information about sediment conductivity, which can be used as a proxy for porosity and also to identify the presence of fluid and fluid migration pathways. We conclude that, as a whole, the central part of the Malin basin is characterized by higher conductivities, which we interpret as a lithological change. Within the basin several areas are characterized by conductive anomalies associated with fluid flow processes and potentially the presence of microbial activity, as suggested by previous work. Pockmark structures show a characteristic electrical signature, with high-conductivity anomalies on the edges and less conductive, homogeneous interiors with several high-conductivity anomalies, potentially associated with gas-driven microbial activity.
Description:
We wished to thank the Geological
Survey of Ireland, the Integrated
Mapping for the Sustainable Development
of Ireland’s Marine Resources
(INFOMAR) program, the Petroleum
Affairs Division (PAD), and the Dublin
Institute for Advanced Studies for
funding this study. This work is
also supported by a research grant
from the Spanish Ministry of Science
and Innovation (CTM2011-30400-C02-
02).
Description:
2014-10-02
Keywords:
Electromagnetism
;
Subbottom profiler
;
Gas
;
Sediments
;
Malin Sea
;
Microbial activity
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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