Abstract
Magmatic sill intrusions into organic-rich sediments cause the release of thermogenic CH4 and CO2. 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.
Original language | English |
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Pages (from-to) | 5715-5731 |
Number of pages | 17 |
Journal | Biogeosciences |
Volume | 15 |
Issue number | 18 |
DOIs | |
Publication status | Published - 27 Sept 2018 |
Bibliographical note
Funding Information:Acknowledgements. This work was undertaken within the MAKS project funded by the German Ministry of Science and Education (BMBF). We thank the master and crew of the R/V Sonne for their support during the SO241 cruise. Further thanks goes to Regina Surberg, Bettina Domeyer, and Anke Bleyer for analytical support during the cruise and on shore. We greatly appreciate the support from Ana Kolevica, Tyler Goepfert, Sebastian Fessler, Andrea Bodenbinder, Yan Shen, and Jutta Heinze for onshore analyses. Additional support of this work was provided by EU-COST Action ES1301 “FLOWS” (https://www.flows-cost.eu, last access: 25 September 2018). We would also like to thank the editor Helge Niemann and two anonymous reviewers for their comments and constructive reviews.
Publisher Copyright:
© Author(s) 2018.
Funding
Acknowledgements. This work was undertaken within the MAKS project funded by the German Ministry of Science and Education (BMBF). We thank the master and crew of the R/V Sonne for their support during the SO241 cruise. Further thanks goes to Regina Surberg, Bettina Domeyer, and Anke Bleyer for analytical support during the cruise and on shore. We greatly appreciate the support from Ana Kolevica, Tyler Goepfert, Sebastian Fessler, Andrea Bodenbinder, Yan Shen, and Jutta Heinze for onshore analyses. Additional support of this work was provided by EU-COST Action ES1301 “FLOWS” (https://www.flows-cost.eu, last access: 25 September 2018). We would also like to thank the editor Helge Niemann and two anonymous reviewers for their comments and constructive reviews.