Outcrop analogues of pockmarks and associated methane-seep carbonates: A case study from the Lower Cretaceous (Albian) of the Basque-Cantabrian Basin, western Pyrenees
2013 | journal article. A publication with affiliation to the University of Göttingen.
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Outcrop analogues of pockmarks and associated methane-seep carbonates: A case study from the Lower Cretaceous (Albian) of the Basque-Cantabrian Basin, western Pyrenees
Agirrezabala, L. M.; Kiel, S.; Blumenberg, M. ; Schaefer, N. & Reitner, J. (2013)
Palaeogeography Palaeoclimatology Palaeoecology, 390 pp. 94-115. DOI: https://doi.org/10.1016/j.palaeo.2012.11.020
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- Authors
- Agirrezabala, Luis M.; Kiel, Steffen; Blumenberg, Martin ; Schaefer, Nadine ; Reitner, Joachim
- Abstract
- Late Albian deep-water sediments of the Black Flysch Group in the Basque-Cantabrian Basin (western Pyrenees) preserve a fossil pockmark field including methane seep carbonates and associated macrofauna. The geometry of the pockmarks is reconstructed from repeated lens-shaped turbidite deposits with centrally located carbonate bodies. Early diagenetic carbonate phases such as clotted micrite and yellow calcite with delta C-13 values as low as -41.6%, and hydrocarbon biomarkers (e.g. 2,6,10,15,19-pentamethylicosane) with strong depletions in C-13 indicate that the carbonates precipitated due to anaerobic oxidation of methane. The pockmarks probably formed due to subsidence induced by dewatering and degassing of the gas-charged seabed perhaps enhanced by the weight of the carbonate bodies. The macrofauna resembles that of other late Mesozoic deep-water methane-seeps world-wide, and is dominated by large lucinid and Caspiconcha bivalves, and hokkaidoconchid gastropods. During late diagenesis the carbonate delta O-18 values were reset to a narrow range of -12 to -10%., the remaining pore spaces and fissures were filled with pyrobitumen, and additional carbonate phases precipitated, potentially due to thermochemical sulfate reduction processes. (C) 2012 Elsevier B.V. All rights reserved.
- Issue Date
- 2013
- Journal
- Palaeogeography Palaeoclimatology Palaeoecology
- ISSN
- 1872-616X; 0031-0182