Identification:
Title:
Stress orientation in gas hydrate-bearing sediments near Hydrate Ridge; evidence from borehole breakouts observed from logging-while-drilling resistivity images
Year:
2005
Source:
In: Trehu, Anne M., Bohrmann, Gerhard, Torres, Marta E., Rack, Frank R., Bangs, Nathan L., Barr, Samantha R., Borowski, Walter S., Claypool, George E., Collett, Timothy S., Delwiche, Mark E., Dickens, Gerald R., Goldberg, David S., Gracia, Eulalia, Guerin, Gilles, Holland, Melanie, Johnson, Joel E., Lee, Young-Joo, Liu, Char-Shine, Long, Philip E., Milkov, Alexei V., Riedel, Michael, Schultheiss, Peter, Su Xin, Teichert, Barbara, Tomaru, Hitoshi, Vanneste, Maarten, Watanabe, Mahito, Weinberger, Jill L., Boetius, Antje, Brockman, Fred J., Deyhle, Annette, Fehn, Udo, Flemings, Peter B., Girguis, Peter R., Heesemann, Martin, Joye, Samantha B., Lorenson, Thomas D., Mills, Christopher T., Musgrave, Robert J., Popa, Radu, Ussler, Bill, Wilkes, Heinz, Winckler, Gisela, Winters, William J., Proceedings of the Ocean Drilling Program; scientific results; drilling gas hydrates on Hydrate Ridge, Cascadia continental margin; covering Leg 204 of the cruises of the drilling vessel JOIDES Resolution; Victoria, British Columbia, Canada, to Victoria, British Columbia, Canada; Sites 1244-1252; 7 July-2 September 2002
Publisher:
Texas A&M University, Ocean Drilling Program, College Station, TX, United States
Volume:
204
Issue:
Pages:
Abstract:
We report new observations of borehole breakouts at three sites drilled during Ocean Drilling Program (ODP) Leg 204 in gas hydrate- bearing sediments near Hydrate Ridge on the Cascadia margin. Breakouts are stress-induced features expressed as elongations in the crosssectional shape of the borehole, caused by compressive failure of the formation under differential horizontal stresses that exceed the formation's in situ strength. Borehole breakouts were detected using an electrical resistivity logging-while-drilling tool (resistivity-at-the-bit tool) in images of the borehole wall, and they occur at two ODP sites located close to the summit of the ridge (Sites 1244 and 1245) and at one site at a greater distance east of the ridge (Site 1251). Based on the orientation of the breakouts, the direction of the in situ maximum horizontal stress (SHmax) was determined at all three sites. We observe SHmax orientations to correspond to localized stresses in the vicinity of Hydrate Ridge (north-northwest-south-southeast at Site 1244 and northeast-southwest at Site 1245), whereas at Site 1251 SHmax appears to roughly correspond to the regional east-west component of the subduction direction.
Language:
English
Genre:
Serial
Rights:
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