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Carbon Geochemistry of Cold Seeps: Methane Fluxes and Transformation in Sediments from Kazan Mud Volcano, Eastern Mediterranean Sea

Created 16/10/2025

Updated 16/10/2025

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Despite growing concerns about potential enhancement of global warming and slope failure by methane produced by gas hydrate dissociation, much uncertainty surrounds estimates of gas hydrate reservoir sizes, as well as methane fluxes and oxidation rates at the sea floor. For cold seep sediments of the eastern Mediterranean Sea, depth-dependent methane concentrations and rates of anaerobic oxidation of methane (AOM) are constrained by modeling the measured pore-water sulfate profile. The calculated dissolved methane distribution and flux are sensitive to the advective flow velocity, which is estimated from the depth distributions of conservative pore-water constituents (Na, B). Near-complete anaerobic oxidation of the upward methane flux is supported by the depth distributions of indicative biomarkers, and the carbon isotopic compositions of organic matter and dissolved inorganic carbon. Pore-water and solid-phase data are consistent with a narrow depth interval of AOM, 14-18 cm below the sediment-water interface. Based on an isotopic mass balance, the biomass of the microbial population carrying out oxidation of methane coupled to sulfate reduction at the given methane flux represents about 20% of the total organic carbon, which is a significant pool of in situ formed organic matter. Model results indicate that the asymptotic methane concentration is reached a few meters below the sediment surface. The predicted asymptotic concentration is close to the in situ saturation value with respect to gas hydrate, suggesting that the rate of shallow gas hydrate formation is controlled by the ascending methane flux. The proposed model approach can be used to predict the formation of gas hydrate, and to quantify methane fluxes plus transformation rates in surface sediments where fluid advection is an important transport mechanism.

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Title Carbon Geochemistry of Cold Seeps: Methane Fluxes and Transformation in Sediments from Kazan Mud Volcano, Eastern Mediterranean Sea
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/29536cbd-d79a-47b0-8fd6-193ede8a7f7f
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 22/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
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Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Carbon Geochemistry of Cold Seeps: Methane Fluxes and Transformation in Sediments from Kazan Mud Volcano, Eastern Mediterranean Sea". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/carbon-geochemistry-of-cold-seeps-methane-fluxes-and-transformation-in-sediments-from-kazan-mud