Rise of the base of the gas hydrate zone since the last glacial recorded by rock magnetism

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doi: 10.1130/G22008.1
Author(s): Musgrave, Robert J.; Bangs, Nathan L.; Larrasoaña, Juan Cruz; Gràcia, Eulàlia; Hollamby, Jennifer A.; Vega, Marta E.
Author Affiliation(s): Primary:
Monash University, School of Geosciences, Clayton, Victoria, Australia
University of Texas, United States
Universitat de Barcelona, Spain
Centre Mediterrani d'Investigacions Marines i Ambientals, Spain
La Trobe University, Australia
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 34(2), p.117-120. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. With GSA Data Repository Item 2006025. 30 refs.; illus., incl. sketch map
Summary: Gas hydrate, a clathrate of methane and water widespread on continental margins, has been implicated as a trigger of climate change and submarine slides as a result of methane release when the base of its stability zone moves upward rapidly. Direct tests of these hypotheses are made difficult by the ephemeral record of gas hydrate in sediment. In places, a seismic reflector (double bottom simulating reflector, BSR) appears to mark the old base of the gas hydrate layer, but the occurrence of this feature is patchy and its interpretation is controversial. Microbial activity is stimulated in the presence of gas hydrate, and results in the production of magnetic iron sulfides; the base of the gas hydrate interval is marked by a sharp reduction in the magnetic hysteresis parameter DJH. At Hydrate Ridge on the Cascadia margin, sampled during Ocean Drilling Program Leg 204, this signature occurs between 20 and 65 m below the present-day base of the gas hydrate zone, at a depth consistent with predictions for the base of gas hydrate stability given water depths and bottom-water temperatures appropriate for the last glacial maximum. Seismic evidence for a double BSR over part of Hydrate Ridge corroborates the rock magnetic interpretation.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Aliphatic hydrocarbons; Alkanes; Applications; Bottom-simulating reflectors; Cenozoic; Climate change; Continental margin; Depth; East Pacific; Gas hydrates; Geophysical methods; Geophysical profiles; Geophysical surveys; Glacial environment; Glaciomarine environment; High-resolution methods; Hydrate Ridge; Hydrocarbons; Last glacial maximum; Leg 204; Magnetic hysteresis; Marine environment; Marine sediments; Methane; North Pacific; Northeast Pacific; Ocean Drilling Program; Organic compounds; Pacific Ocean; Paleoclimatology; Paleomagnetism; Porosity; Quaternary; Sediments; Seismic methods; Seismic profiles; Surveys; Techniques; Upper Quaternary
Coordinates: N443300 N443600 W1250600 W1251000
Record ID: 2006021474
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States