Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

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

Lucía Villar-Muñoz
* ,
Iván Vargas-Cordero
* ORCID logo ,
Joaquim P. Bento
ORCID logo ,
Umberta Tinivella
ORCID logo ,
Francisco Fernandoy
ORCID logo ,
Michela Giustiniani
ORCID logo ,
Jan H. Behrmann
,
Sergio Calderon-Diaz
Version 1 : Received: 25 October 2018 / Approved: 26 October 2018 / Online: 26 October 2018 (06:18:51 CEST)

A peer-reviewed article of this Preprint also exists.

Villar-Muñoz, L.; Vargas-Cordero, I.; Bento, J.P.; Tinivella, U.; Fernandoy, F.; Giustiniani, M.; Behrmann, J.H.; Calderón-Díaz, S. Gas Type of the Paperhydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction. Geosciences 2019, 9, 28. Villar-Muñoz, L.; Vargas-Cordero, I.; Bento, J.P.; Tinivella, U.; Fernandoy, F.; Giustiniani, M.; Behrmann, J.H.; Calderón-Díaz, S. Gas Type of the Paperhydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction. Geosciences 2019, 9, 28.

Abstract

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 zone 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 °Ckm-1). Gas hydrates are located in shallow sediments (90-280 meters below the seafloor). The large amount of hydrate and free gas estimated (7.21x1011 m3 and 4.1x1010 m3, respectively), the high seismicity, the mechanically unstable nature of the sediments, and the anomalous geothermal conditions, set the stage for potential 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 and ecological research.

Keywords

BSR; gas hydrate; methane; seepage; active margin; Chile Triple Junction

Subject

Environmental and Earth Sciences, Geophysics and Geology

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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