Morpho-acoustic variability of cold seeps on the continental slope offshore Nicaragua: result of fluid flow interaction with sedimentary processes.

Bürk, Dietmar, Klaucke, Ingo, Sahling, Heiko and Weinrebe, Reimer Wilhelm (2010) Morpho-acoustic variability of cold seeps on the continental slope offshore Nicaragua: result of fluid flow interaction with sedimentary processes. Marine Geology, 275 . pp. 53-65. DOI 10.1016/j.margeo.2010.04.007.

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Abstract

Based on multibeam bathymetry, high-resolution deep-towed sidescan sonar and Chirp subbottom profiling 32 cold seep sites, already identified in Sahling et al. (2008a), have been studied in an approximately 1000 km2 large area ranging from 800 to 2600 m water depth along the middle slope of the active continental margin offshore Nicaragua. Ground truthing is available from towed camera surveys and coring on seven of the structures. The seeps occur in different settings on the slope: upslope and along the headwall of large submarine slides, as isolated eroded massifs, and forming linear ridges between deeply incised canyons. The seep sites show a wide range regarding their size and morphology, their backscatter intensity patterns, their structure in subbottom profiles, and their fluid venting activity inferred from seafloor observations. Surface extension of the seep sites ranges from less than 200 to more than 1500 m in diameter, and relief height varies between no relief and 180 m. Indications of extruded materials such as mud flows are not observed in the area of the seep sites. Instead the seeps are characterized by high proportions of authigenic carbonates. The carbonates occur as crusts, detritus, or single layers embedded in the seafloor sediments. They appear as high backscatter intensities on sidescan sonar images. On some seep sites living vent fauna indicative of active seepage is observed, but gas bubbles have not been observed. To explain the high morphological variability of the features, we propose a generic model including the interaction of several processes: (1) episodic fluid venting and associated authigenic carbonate formation; (2) background sedimentation and subsidence; (3) linear erosion along canyons and denudation on the slope surface.

Document Type: Article
Keywords: Meeresgeologie; Sedimentology; Biogeochemistry; Mound structures; cold seeps; fluid venting; sedimentation; erosion; sidescan sonar; Nicaragua; Costa Rica
Research affiliation: OceanRep > SFB 574 > A1
OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.margeo.2010.04.007
ISSN: 0025-3227
Projects: sfb574
Contribution Number:
ProjectNumber
SFB 574190
Expeditions/Models/Experiments:
Date Deposited: 13 Jul 2010 13:54
Last Modified: 07 Aug 2017 13:36
URI: http://oceanrep.geomar.de/id/eprint/8647

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