Fluid seepage and mound formation offshore Costa Rica revealed by deep-towed sidescan sonar and sub-bottom profiler data.

Petersen, Carl Jörg, Klaucke, Ingo, Weinrebe, Reimer Wilhelm and Ranero, Cesar (2009) Fluid seepage and mound formation offshore Costa Rica revealed by deep-towed sidescan sonar and sub-bottom profiler data. Marine Geology, 266 (1-4). pp. 172-181. DOI 10.1016/j.margeo.2009.08.004.

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Abstract

Our analysis of geoacoustic data from the Middle American margin provides an insight into the formation and evolution mechanisms of mound structures observed on the continental slope offshore Costa Rica. Based on high-resolution deep-towed sidescan sonar and sub-bottom profiler (SBP) data six different mound and fluid seepage structures at the Hongo mound field are characterized in detail. The Hongo mound field is located on the lower continental slope offshore Nicoya peninsula in the prolongation of the subducting Nicoya fracture zone. The mounds have oval to circular shapes with diameters of 500-1600 m and relief heights of 60-100 m. High backscatter anomalies near the mound summits indicate carbonate precipitation and focused fluid seepage activity within the last 10 ka. The data do not show evidence for mud extrusions and the structures were probably formed by a combination of carbonate precipitation and mud diapirism. Based on seismic stratigraphy analysis, mud diapirism is at least active since 42.5-57 ka and average vertical growth rates vary between 6-24 cm/ka. However, if diapirism represents the dominant mound evolution mechanism, mound heights of 80 m point to much older mound ages of 330-1330 ka. (C) 2009 Elsevier B.V. All rights reserved.

Document Type: Article
Keywords: fluid seepage, deep-towed side-scan sonar, sub-bottom profiler, carbonate, mound, mud diapir
Research affiliation: OceanRep > SFB 574 > A1
OceanRep > SFB 574
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.margeo.2009.08.004
ISSN: 0025-3227
Projects: Future Ocean, SFB574
Contribution Number:
ProjectNumber
SFB 574179
Expeditions/Models/Experiments:
Date Deposited: 05 Jan 2010 09:02
Last Modified: 04 Aug 2017 12:11
URI: http://oceanrep.geomar.de/id/eprint/1198

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