Rifting under steam-How rift magmatism triggers methane venting from sedimentary basins
Journal
Geology
Journal Volume
44
Journal Issue
9
Pages
767-770
Date Issued
2016
Author(s)
Hensen, C.
Mortera-Gutierrez, C.
Sarkar, S.
Geilert, S.
Schmidt, M.
Liebetrau, V.
Kipfer, R.
Scholz, F.
Doll, M.
Muff, S.
Karstens, J.
Planke, S.
Petersen, S.
B\\i??ttner, C.
Chi, W.-C.
Moser, M.
Behrendt, R.
Fiskal, A.
Lever, M.A.
Deng, L.
Brennwald, M.S.
Lizarralde, D.
Abstract
During opening of a new ocean, magma intrudes into the surrounding sedimentary basins. Heat provided by the intrusions matures the host rock, creating metamorphic aureoles potentially releasing large amounts of hydrocarbons. These hydrocarbons may migrate to the seafloor in hydrothermal vent complexes in sufficient volumes to trigger global warming, e.g., during the Paleocene-Eocene Thermal Maximum (PETM). Mound structures at the top of buried hydrothermal vent complexes observed in seismic data offNorway were previously interpreted as sediment volcanoes, and the amount of released hydrocarbon was estimated based on this interpretation. Here, we present new geophysical and geochemical data from the Gulf of California suggesting that such mound structures could in fact be edifices constructed by the growth of black smoker-type chimneys rather than sediment volcanoes. We have evidence for two buried and one active hydrothermal vent systems outside the rift axis. The active vent releases fluids of several hundred degrees Celsius containing abundant methane, mid-ocean ridge basalt-type helium, and precipitating solids up to 300 m high into the water column. Our observations challenge the idea that methane is emitted slowly from rift-related vents. The association of large amounts of methane with hydrothermal fluids that enter the water column at high pressure and temperature provides an efficient mechanism to transport hydrocarbons into the water column and atmosphere, lending support to the hypothesis that rapid climate change such as during the PETM can be triggered by magmatic intrusions into organic-rich sedimentary basins. © 2016 Geological Society of America.
Other Subjects
Global warming; Hot springs; Hydrothermal synthesis; Metamorphic rocks; Methane; Sedimentology; Seismology; Settling tanks; Tectonics; Volcanoes; Gulf of California; High-pressure and temperatures; Hydrothermal fluids; Magmatic intrusions; Mid ocean ridge basalts; Paleocene-eocene thermal maximums; Rapid climate change; Sedimentary basin; Transport properties; hydrocarbon migration; hydrothermal fluid; hydrothermal vent; magma; magmatism; methane; mid-ocean ridge basalt; rifting; sedimentary basin; Gulf of California; Norway; Pacific Ocean
Type
journal article