Preprints
https://doi.org/10.5194/hess-2018-362
https://doi.org/10.5194/hess-2018-362

  29 Aug 2018

29 Aug 2018

Review status: this preprint has been withdrawn by the authors.

Pore-water in marine sediments associated to gas hydrate dissociation offshore Lebu, Chile

Carolina Cárcamo1,2, Iván Vargas-Cordero1, Francisco Fernandoy1, Umberta Tinivella3, Diego López-Acevedo4, Joaquim P. Bento5, Lucía Villar-Muñoz6, Nicole Foucher1, Marion San Juan1, and Alessandra Rivero1 Carolina Cárcamo et al.
  • 1Universidad Andres Bello, Facultad de Ingeniería, Quillota 980, Viña del Mar, Chile
  • 2Centro de Investigación Marina Quintay. CIMARQ. Facultad de Ciencias de la Vida. Universida Andres Bello, Viña del Mar, Chile
  • 3OGS Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Borgo Grotta Gigante 42/C, 34010, Sgonico, Italy
  • 4Universidad de Concepción, Departamento de Oceanografía, Programa COPAS Sur-Austral, Campus Concepción Víctor Lamas 1290, P.O. Box 160-C, Concepción, Chile
  • 5Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Av. Altamirano 1480, 2360007 Valparaíso, Chile
  • 6GEOMAR Helmholtz Centre for Ocean Research, Wischhofstr. 1–3, 24148 Kiel, Germany

Abstract. Gas hydrate occurrences along the Chilean margin has been documented, but the processes associated to fluid escapes originated by gas hydrate dissociation yet are unknown. Here, we report morphologies growing related to fluid migration in the continental shelf offshore western Lebu (37 °S) by analysing mainly geochemical features. In this study oxygen and deuterium stable water isotopes in pore water were measured. Knowledge was completed by analysing bathymetric data, biological and sedimentological data. From bathymetric interpretation a positive relief at 127 m below sea level was recognised; it is oriented N55 °E and characterised by five peaks. Moreover, enrichment values for δ18O (from 0.0 to 1.8 ‰) and δD (from 0.0 to 5.6 ‰) were obtained. These are typical values related to hydrate melting during coring and post-sampling. The evident orientation of positive relief could be associated with faults and fractures reported by others authors, in which these structures constitute pathways for fluid migration from deep to shallow zones. Finally, benthic foraminifera observed in the core sample can be associated to seep areas. On the basis of theoretical modelling, we conclude that the positive relief correspond to mud growing processes related to gas hydrates dissociation and represent a key area to investigate fluid migration processes.

This preprint has been withdrawn.

Carolina Cárcamo et al.

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Carolina Cárcamo et al.

Carolina Cárcamo et al.

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