Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kennett, J. P. Articles by Fackler-Adams, B. N. Search for Related Content GeoRef GeoRef Citation

Relationship of clathrate instability to sediment deformation in the upper Neogene of California

¹ Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara, California 93106, USA

Widespread soft-sediment deformation (SSD) in upper-bathyal continental-margin sediments has been explained by compaction-related dewatering and related physical processes that can destabilize margin sediments. We present the hypothesis that SSD in such facies resulted in part from instability of gas hydrates (clathrates), leading to overpressurization in sediments and resulting fluid flow and brecciation. Clathrate-related deformation must be widespread in upper-bathyal continental-margin methanogenic sequences at depths where clathrates are destabilized by changes in bottom-water temperatures and sea level. A close association exists between an array of SSD features with clathrate-hosting sediments in ocean drill cores. Similar features are conspicuous in the partly laminated, upper Neogene upper bathyal sediments of the Sisquoc Formation in southern California, suggesting that clathrates may have been responsible for abundant and well-developed SSD in these units. The lithology, methane-producing organic content, and depositional environment of the Sisquoc Formation are similar to those features in modern clathrate-hosting settings. These characteristics, in conjunction with the upper bathyal paleobathymetry of the unit, the geothermal gradient of the region, and ¹³C values of benthic foraminifera and dolomite concretions suggest the occurrence of clathrates in the shallow subsurface of these sediments. We suggest that the analyzed parts of the Sisquoc Formation represent an exhumed zone of SSD resulting from clathrate instability in the shallow subsurface of the continental margin. Sedimentary rocks exhibiting an association of SSD features that resulted from clathrate formation and dissociation are named clathrites.

Key Words: soft-sediment deformation • gas hydrates • Sisquoc • clathrates • Neogene sediments

This article has been cited by other articles:

				B. M.A. Teichert, N. Gussone, A. Eisenhauer, and G. Bohrmann Clathrites: Archives of near-seafloor pore-fluid evolution ({delta}44/40Ca, {delta}13C, {delta}18O) in gas hydrate environments Geology, March 1, 2005; 33(3): 213 - 216. [Abstract] [Full Text] [PDF]

				A. J. Maltman and A. Bolton How sediments become mobilized Geological Society, London, Special Publications, January 1, 2003; 216(1): 9 - 20. [Abstract] [PDF]

				K. H. Freeman and K. H. Freeman Isotopic Biogeochemistry of Marine Organic Carbon Reviews in Mineralogy and Geochemistry, January 1, 2001; 43(1): 579 - 605. [Full Text] [PDF]