RV SONNE 241 Cruise Report / Fahrtbericht, Manzanillo, 23.6.2015 – Guayaquil, 24.7.2015 : SO241 - MAKS: Magmatism induced carbon escape from marine sediments as a climate driver – Guaymas Basin, Gulf of California

Berndt, Christian (2015) RV SONNE 241 Cruise Report / Fahrtbericht, Manzanillo, 23.6.2015 – Guayaquil, 24.7.2015 : SO241 - MAKS: Magmatism induced carbon escape from marine sediments as a climate driver – Guaymas Basin, Gulf of California GEOMAR Helmholtz Centre for Ocean Research Kiel. DOI 10.3289/CR_S241.

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Abstract

SO241 set out to test the hypothesis that rift-related magmatism is able to increase carbon emissions from sedimentary basins to the extent that they can actively force climate. To this end we investigated a study area in the Guaymas Basin in the Gulf of California which is one of very few geological settings where rift-related magmatism presently leads to magmatic intrusions into a sediment basin. During the cruise we collected 1100 km of 2D seismic lines to image the extent and volume of magmatic intrusions as well as the extent of metamorphic overprinting of the surrounding sediments and associated subsurface sediment mobilization. We selected three typical seep sites above magmatic intrusions for detailed geochemical studies using gravity corers, multicorers and TV grab. With these samples we will be able to determine the pore water composition to assess the amount and composition of hydrocarbon compounds that are released from these systems. Detailed ocean bottom seismometer measurements at a seep site in the center of the Guaymas Basin will provide further insights into effects of magmatic intrusions on carbon release and diagenetic
overprinting of the sediments. It will be possible to reconstruct its long-term seepage history from big carbonate blocks that we have collected with a TV-grab. The northeastern margin of the Guaymas Basin is known for the presence of gas hydrates. During the cruise we collected several seismic lines, which show a clear but unusually shallow BSR indicating high heat flow in the region. Using the seismic data we discovered a previously unknown geological structure on the flank of the northern rift segment: a large mound that seems to consist entirely of black smoker deposits. It seems to be the result of a recent intrusion into the underlying sediments and changes the view how such systems function. The structure was investigated with a comprehensive geochemical, geothermal, and video surveying program which revealed at least seven vents that are active simultaneously. These vents inject methane and helium-rich vent fluids several hundred meters up into the water column. These findings suggest that large-scale magmatism, for example during the opening of an ocean basin under the influence of a hot spot, can be an effective way of liberating large amounts of carbon high up into the water column. The data collected during SO241 will allow us to constrain the amount of carbon that can escape into the atmosphere during LIP emplacement and their relevance on a global scale can be assessed. In addition to reaching the main objectives of the project we discovered a large landslide complex that was probably associated with a tsunami.

Document Type: Report (Cruise Report)
Keywords: FS SONNE ; Cruise report ; SO241 ; MAKS ; Hydrothermal Systems Guaymas Basin
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
DOI etc.: 10.3289/CR_S241
Projects: MAKS
Expeditions/Models:
Date Deposited: 27 Nov 2015 10:52
Last Modified: 27 Nov 2015 11:15
URI: http://eprints.uni-kiel.de/id/eprint/30382

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