High Gas Hydrate and Free Gas Concentrations: An Explanation for Seeps Offshore South Mocha Island.

Vargas-Cordero, Ivan, Tinivella, Umberta, Villar-Muñoz, Lucía and Bento, Joaquim P. (2018) High Gas Hydrate and Free Gas Concentrations: An Explanation for Seeps Offshore South Mocha Island. Open Access Energies, 11 (Article 3062). DOI 10.3390/en11113062 .

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Supplementary data:

Abstract

Recent studies have reported shallow and deep seep areas offshore Mocha island. Gas hydrate occurrences along the Chilean margin could explain seeps presence. Gas phases (gas hydrate and free gas) and geothermal gradients were estimated analysing two seismic sections. Close to Mocha island (up to 20 km) were detected high (up to 1900 m/s) and low (1260 m/s) velocities associated with high gas hydrate (up to 20 % of total volume) and free gas (up to 1.1% of total volume) concentrations respectively. These values are in agreement with a variable and high geothermal gradient (65 to 110 °C/km) related to high supply deep fluids canalised by faults and fractures. Faraway from Mocha island (more than 60 km), free gas concentrations decrease to 0.3 % of total volume and low geothermal gradient (from 35 to 60 °C/km) are associated with low fluids supply. Finally, we propose gas hydrate dissociation processes as the main supply source for seeps in the vicinity of Mocha island. These processes can be triggered by ancient sliding reported in literature.

Document Type: Article
Keywords: Gas hydrate; BSR; Mocha Island
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.3390/en11113062
ISSN: 1996-1073
Related URLs:
Date Deposited: 27 Aug 2018 15:25
Last Modified: 01 Feb 2019 15:06
URI: http://oceanrep.geomar.de/id/eprint/44063

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