Abiotic methane from ultraslow-spreading ridges can charge Arctic gas hydrates

Biotic gas generation from the degradation of organic carbon in marine sediments supplies and maintains gas hydrates throughout the world’s oceans. In nascent, ultraslow-spreading ocean basins, methane generation can also be abiotic, occurring during the high-temperature (>200 °C) serpentinizatio...

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Bibliographic Details
Published in:Geology
Main Authors: Johnson, Joel E., Mienert, Jurgen, Plaza-Faverola, Andreia, Vadakkepuliyambatta, Sunil, Knies, Jochen, Bunz, Stefan, Andreassen, Karin, Ferre, Benedicte
Format: Text
Language:unknown
Published: University of New Hampshire Scholars' Repository 2015
Subjects:
geophysical methods
marine sediments
sea-floor spreading
sediments
Arctic region
Arctic Ocean
Fram Strait
Arctic
Greenland
Molloy
Svalbard
Methane hydrate
North Atlantic
Online Access:https://scholars.unh.edu/faculty_pubs/547
https://doi.org/10.1130/G36440.1
Description
Summary:Biotic gas generation from the degradation of organic carbon in marine sediments supplies and maintains gas hydrates throughout the world’s oceans. In nascent, ultraslow-spreading ocean basins, methane generation can also be abiotic, occurring during the high-temperature (>200 °C) serpentinization of ultramafic rocks. Here, we report on the evolution of a growing Arctic gas- and gas hydrate–charged sediment drift on oceanic crust in eastern Fram Strait, a tectonically controlled, deep-water gateway between the subpolar North Atlantic and Arctic Oceans. Ultraslow-spreading ridges between northwest Svalbard and northeast Greenland permit the sustained interaction of a mid-ocean ridge transform fault and developing sediment drift, on both young (<10 Ma) and old (>10 Ma) oceanic crust, since the late Miocene. Geophysical data image the gas-charged drift and crustal structure and constrain the timing of a major 30 km lateral displacement of the drift across the Molloy transform fault. We describe the buildup of a 2 m.y., long-lived gas hydrate– and free gas–charged drift system on young oceanic crust that may be fed and maintained by a dominantly abiotic methane source. Ultraslow-spreading, sedimented ridge flanks represent a previously unrecognized carbon reservoir for abiotic methane that could supply and maintain deep-water methane hydrate systems throughout the Arctic.

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