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Analyses of bottom simulating reflections offshore Arauco and Coyhaique (Chile)

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Abstract

Two seismic sections offshore Arauco and Coyhaique, Chile, have been analysed to better define the seismic character of hydrate-bearing sediments. The velocity analysis was used to estimate the gas-phase concentration, which can serve to correlate hydrate presence to the geological features. The velocity model allowed us to recognise the hydrate layer above the bottom simulating reflector (BSR), and the free gas layer below it. The velocity field is affected by strong lateral variation, showing maximum (above the BSR) and minimum (below the BSR) values in the southern sector. Here, highest gas hydrate and free gas concentrations were calculated (15% and 2.7% of total volume respectively). The estimated geothermal gradient ranges from 35 to 95°C/km. In the northern sector, the highest gas hydrate and free gas concentrations are 15% and 0.2% of total volume respectively, and the geothermal gradient is uniform and equal to about 30°C/km.

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Acknowledgments

The authors are very grateful to Joyce Alsop and Volkmar Damm for seismic data provided by the Lamont Doherty Earth Laboratory (LDEO), USA and the Federal Institute for Geosciences and Natural Resources (BGR), Germany respectively. We thank Ernest Ohene Asare and Frank Calixto Mory for useful English revision. This work was partially supported by The International Centre for Theoretical Physics (Trieste).

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Authors and Affiliations

  1. Dipartimento di Scienze Geologiche, Ambientale e Marine, Università degli Studi di Trieste, C. San Giovanni, Via E. Weiss 2, Trieste, 34100, Italy

    Ivan de la Cruz Vargas Cordero & Francesco Fanucci

  2. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta 42C, Trieste, Italy

    Ivan de la Cruz Vargas Cordero, Umberta Tinivella, Flavio Accaino & Maria Filomena Loreto

  3. International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy

    Ivan de la Cruz Vargas Cordero

  4. Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655, Hannover, Germany

    Christian Reichert

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  1. Ivan de la Cruz Vargas Cordero
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  2. Umberta Tinivella
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  3. Flavio Accaino
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  4. Maria Filomena Loreto
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  5. Francesco Fanucci
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  6. Christian Reichert
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Correspondence to Ivan de la Cruz Vargas Cordero.

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Vargas Cordero, I., Tinivella, U., Accaino, F. et al. Analyses of bottom simulating reflections offshore Arauco and Coyhaique (Chile). Geo-Mar Lett 30, 271–281 (2010). https://doi.org/10.1007/s00367-009-0171-5

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  • DOI: https://doi.org/10.1007/s00367-009-0171-5

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