Gas Hydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction.

Villar-Muñoz, Lucía, Vargas-Cordero, Iván , Bento, Joaquim P. , Tinivella, Umberta , Fernandoy, Francisco, Giustiniani, Michela , Behrmann, Jan H. and Calderon-Diaz, Sergio (2019) Gas Hydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction. Open Access Geosciences, 9 (28). DOI 10.3390/geosciences9010028.

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Large amounts of gas hydrate are present in marine sediments offshore Taitao Peninsula, near the Chile Triple Junction. Here, marine sediments on the forearc contain carbon that is converted to methane in a regime of very high heat flow and intense rock deformation above the downgoing oceanic spreading ridge separating the Nazca and Antarctic plates. This regime enables vigorous fluid migration. Here, we present an analysis of the spatial distribution, concentration, estimate of gas-phases (gas hydrate and free gas) and geothermal gradients in the accretionary prism, and forearc sediments offshore Taitao (45.5°–47° S). Velocity analysis of Seismic Profile RC2901-751 indicates gas hydrate concentration values <10% of the total rock volume and extremely high geothermal gradients (<190 °C·km−1). Gas hydrates are located in shallow sediments (90–280 m below the seafloor). The large amount of hydrate and free gas estimated (7.21 × 1011 m3 and 4.1 × 1010 m3; respectively), the high seismicity, the mechanically unstable nature of the sediments, and the anomalous conditions of the geothermal gradient set the stage for potentially massive releases of methane to the ocean, mainly through hydrate dissociation and/or migration directly to the seabed through faults. We conclude that the Chile Triple Junction is an important methane seepage area and should be the focus of novel geological, oceanographic, and ecological research.

Document Type: Article
Keywords: BSR; gas hydrate; methane; seepage; active margin; Chile Triple Junction; R/V Robert Conrad Cruise RC2902
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.3390/geosciences9010028
ISSN: 2076-3263
Projects: CONICYT
Date Deposited: 26 Nov 2018 10:19
Last Modified: 05 Jun 2019 09:33

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