English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/132729
logo share SHARE   Add this article to your Mendeley library MendeleyBASE
Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL | DATACITE
Exportar a otros formatos:


Mega-pockmarks surrounding IODP Site U1414: Insights from the CRISP 3D seismic survey

AuthorsNale, Stephanie M.; Kluesner, Jared W.; Silver, Eli A.; Bangs, Nathan L.; McIntosh, Kirk D.; Ranero, César R. CSIC ORCID
Issue Date9-Dec-2013
PublisherAmerican Geophysical Union
CitationAGU Fall Meeting: T31F-2574 (2013)
AbstractVisualization of neural network meta-attribute analyses reveals fluid migration pathways associated with mega-pockmarks within the CRISP 3D seismic volume offshore southern Costa Rica, near site U1414 of IODP Expedition 344. A 245km2 field of mega-pockmarks was imaged on the Cocos Ridge using EM122 multibeam bathymetry, backscatter and 3D seismic reflection aboard R/V Marcus G. Langseth during the 2011 CRISP seismic survey. We utilize the OpendTect software package to calculate supervised neural network meta-attributes within the 3D seismic volume, in order to detect and visualize probable faults and fluid-migration pathways within the sedimentary section of the incoming Cocos plate [see Kluesner et al., this meeting]. Pockmarks imaged within the 3D volume near the trench commonly show a two-tier structure with upper pockmarks located above the steep walls of deeper, older pockmarks. The latter appear to truncate surrounding strata, including widespread high-amplitude reverse polarity reflectors (RPRs), interpreted as trapping horizons. In addition, RPRs are also truncated by positive polarity crosscutting reflections (CCRs), most of which form the base and sides of lens-like structures below the RPRs that are frequently located next to imaged pockmarks. Site U1414 intersects one of these lens-like structures and this appears to correlate to a sharp density and porosity swing observed at ~255 mbsf. In addition, preliminary geochemical analyses from site U1414 show evidence of lateral fluid flow through sediments below the RPR [Expedition 344 Scientists, 2013]. Thus, we interpret the 3D lens-like structures to be pockets of trapped gas and/or over-pressured fluid. Based on 3D imaging we propose a 3-stage pockmark evolution: (1) Overpressure and blowout along RPRs, resulting in pockmark formation, (2) sustained seepage along pockmark walls, resulting in preferential deposition near the center of the pockmark, and (3) rapid burial as pockmarks near the trench axis. On the seafloor, small high-backscatter mounds are found near the walls of a subset of pockmarks, suggesting recent or active seafloor seepage. Further geochemical analyses are needed to determine the source of fluid/gas migration associated with the pockmark structures.
DescriptionAmerican Geophysical Union (AGU) Fall Meeting, 9-13 December 2013, San Francisco
Publisher version (URL)http://fallmeeting.agu.org/2013/scientific-program-2/
Appears in Collections:(ICM) Comunicaciones congresos
Files in This Item:
There are no files associated with this item.
Show full item record
Review this work

WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.