Rifting under steam-How rift magmatism triggers methane venting from sedimentary basins

C. Berndt, C. Hensen, C. Mortera-Gutierrez, S. Sarkar, S. Geilert, M. Schmidt, V. Liebetrau, R. Kipfer, F. Scholz, M. Doll, S. Muff, J. Karstens, S. Planke, S. Petersen, C. Böttner, W. C. Chi, M. Moser, R. Behrendt, A. Fiskal, M. A. LeverC. C. Su, L. Deng, M. S. Brennwald, D. Lizarralde

Research output: Contribution to journalArticleAcademicpeer-review

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.

Original languageEnglish
Pages (from-to)767-770
Number of pages4
JournalGeology
Volume44
Issue number9
DOIs
Publication statusPublished - 1 Sept 2016

Bibliographical note

Funding Information:
This work is being funded by the German Ministry of Science and Education (BMBF) through the MAKS project. We thank Nick Schofield and two anonymous reviewers for valuable input to this paper. We thank the master and the crew of the R/V Sonne for their relentless support during cruise SO

Publisher Copyright:
© 2016 Geological Society of America.

Funding

This work is being funded by the German Ministry of Science and Education (BMBF) through the MAKS project. We thank Nick Schofield and two anonymous reviewers for valuable input to this paper. We thank the master and the crew of the R/V Sonne for their relentless support during cruise SO

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