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On the formation of hydrothermal vents and cold seeps in the Guaymas Basin, Gulf of California

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Geilert Sonja, Hensen Christian, Schmidt Mark, Liebetrau Volker, Scholz Florian, Doll Mechthild, Deng Longhui, Fiskal Annika, Lever Mark A., Su Chih-Chieh, Schloemer Stefan, Sarkar Sudipta, Thiel Volker, Berndt Christian,
Project Swiss participation in the International Ocean Discovery Program (IODP) through membership in the European Consortium for Ocean Research Drilling (ECORD)
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Original article (peer-reviewed)

Journal Biogeosciences
Volume (Issue) 15(18)
Page(s) 5715 - 5731
Title of proceedings Biogeosciences
DOI 10.5194/bg-15-5715-2018

Open Access

URL http://doi.org/10.5194/bg-15-5715-2018
Type of Open Access Publisher (Gold Open Access)

Abstract

Abstract. Magmatic sill intrusions into organic-rich sediments cause the release of thermogenic CH 4 and CO 2 . Pore fluids from the Guaymas Basin (Gulf of California), a sedimentary basin with recent magmatic activity, were investigated to constrain the link between sill intrusions and fluid seepage as well as the timing of sill-induced hydrothermal activity. Sampling sites were close to a hydrothermal vent field at the northern rift axis and at cold seeps located up to 30 km away from the rift. Pore fluids close to the active hydrothermal vent field showed a slight imprint by hydrothermal fluids and indicated a shallow circulation system transporting seawater to the hydrothermal catchment area. Geochemical data of pore fluids at cold seeps showed a mainly ambient diagenetic fluid composition without any imprint related to high temperature processes at greater depth. Seep communities at the seafloor were mainly sustained by microbial methane, which rose along pathways formed earlier by hydrothermal activity, driving the anaerobic oxidation of methane (AOM) and the formation of authigenic carbonates. Overall, our data from the cold seep sites suggest that at present, sill-induced hydrothermalism is not active away from the ridge axis, and the vigorous venting of hydrothermal fluids is restricted to the ridge axis. Using the sediment thickness above extinct conduits and carbonate dating, we calculated that deep fluid and thermogenic gas flow ceased 28 to 7 kyr ago. These findings imply a short lifetime of hydrothermal systems, limiting the time of unhindered carbon release as suggested in previous modeling studies. Consequently, activation and deactivation mechanisms of these systems need to be better constrained for the use in climate modeling approaches.
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