Bitumen veins and Eocene transpression, Neuquén Basin, Argentina

In the northwestern part of the petroleum-rich Neuquén Basin, veins of solid hydrocarbon (bitumen) have been reported from over 150 localities. The bitumen veins are mostly steeply-dipping and show intrusive relationships with their wall rocks. The largest are some 8 m wide, 8 km long and probably s...

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Autores principales: Cobbold, P.R., Diraison, M., Rossello, E.A.
Formato: JOUR
Materias:
Argentina
Bitumen veins
Eocene transpression
Neuquén Basin
bitumen
Eocene
tectonics
transpression
vein (geology)
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00401951_v314_n4_p423_Cobbold
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00401951_v314_n4_p423_Cobbold
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spelling todo:paper_00401951_v314_n4_p423_Cobbold2023-10-03T14:50:08Z Bitumen veins and Eocene transpression, Neuquén Basin, Argentina Cobbold, P.R. Diraison, M. Rossello, E.A. Argentina Bitumen veins Eocene transpression Neuquén Basin bitumen Eocene tectonics transpression vein (geology) Argentina In the northwestern part of the petroleum-rich Neuquén Basin, veins of solid hydrocarbon (bitumen) have been reported from over 150 localities. The bitumen veins are mostly steeply-dipping and show intrusive relationships with their wall rocks. The largest are some 8 m wide, 8 km long and probably several kilometres deep. The bitumen probably formed in the earliest stages of thermal maturation of organically-rich source rocks. The most likely source rocks for the bitumen, as well as for most of the oil and gas in the Neuquén Basin, are black marine shales of the Vaca Muerta and Agrio formations. These were deposited in a rift setting during the late Jurassic and Early Cretaceous. According to subsidence models, the source rocks should have reached thermal maturity in the latest Cretaceous or Paleocene and should have remained in the oil window ever since. Although the bitumen has not been dated directly, the veins probably formed soon after maturation of the source rocks, in other words, in the Paleocene or Eocene. The wall rocks of the veins are mostly the source rocks themselves. Other veins have been emplaced into overlying strata of Early Cretaceous to Paleocene ages or into underlying sediments of Jurassic age. The bitumen veins have preferred orientations. The dominant trend is 060° and subsidiary trends are either 000° to 020° or 100°. As in other basins worldwide, the majority of bitumen veins in the Neuquén Basin probably formed by tensile failure, in orientations perpendicular to the least compressive stress, under the combined effects of regional tectonics and fluid overpressures. The orientations of the veins are compatible with the direction of oblique convergence between continental South America and the oceanic Nazca plate in the Eocene. Many major structures in the Neuquén Basin are also of Eocene age and may have formed under right-lateral transpression. © 1999 Elsevier Science B.V. All rights reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00401951_v314_n4_p423_Cobbold
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Argentina
Bitumen veins
Eocene transpression
Neuquén Basin
bitumen
Eocene
tectonics
transpression
vein (geology)
Argentina
spellingShingle Argentina
Bitumen veins
Eocene transpression
Neuquén Basin
bitumen
Eocene
tectonics
transpression
vein (geology)
Argentina
Cobbold, P.R.
Diraison, M.
Rossello, E.A.
Bitumen veins and Eocene transpression, Neuquén Basin, Argentina
topic_facet Argentina
Bitumen veins
Eocene transpression
Neuquén Basin
bitumen
Eocene
tectonics
transpression
vein (geology)
Argentina
description In the northwestern part of the petroleum-rich Neuquén Basin, veins of solid hydrocarbon (bitumen) have been reported from over 150 localities. The bitumen veins are mostly steeply-dipping and show intrusive relationships with their wall rocks. The largest are some 8 m wide, 8 km long and probably several kilometres deep. The bitumen probably formed in the earliest stages of thermal maturation of organically-rich source rocks. The most likely source rocks for the bitumen, as well as for most of the oil and gas in the Neuquén Basin, are black marine shales of the Vaca Muerta and Agrio formations. These were deposited in a rift setting during the late Jurassic and Early Cretaceous. According to subsidence models, the source rocks should have reached thermal maturity in the latest Cretaceous or Paleocene and should have remained in the oil window ever since. Although the bitumen has not been dated directly, the veins probably formed soon after maturation of the source rocks, in other words, in the Paleocene or Eocene. The wall rocks of the veins are mostly the source rocks themselves. Other veins have been emplaced into overlying strata of Early Cretaceous to Paleocene ages or into underlying sediments of Jurassic age. The bitumen veins have preferred orientations. The dominant trend is 060° and subsidiary trends are either 000° to 020° or 100°. As in other basins worldwide, the majority of bitumen veins in the Neuquén Basin probably formed by tensile failure, in orientations perpendicular to the least compressive stress, under the combined effects of regional tectonics and fluid overpressures. The orientations of the veins are compatible with the direction of oblique convergence between continental South America and the oceanic Nazca plate in the Eocene. Many major structures in the Neuquén Basin are also of Eocene age and may have formed under right-lateral transpression. © 1999 Elsevier Science B.V. All rights reserved.
format JOUR
author Cobbold, P.R.
Diraison, M.
Rossello, E.A.
author_facet Cobbold, P.R.
Diraison, M.
Rossello, E.A.
author_sort Cobbold, P.R.
title Bitumen veins and Eocene transpression, Neuquén Basin, Argentina
title_short Bitumen veins and Eocene transpression, Neuquén Basin, Argentina
title_full Bitumen veins and Eocene transpression, Neuquén Basin, Argentina
title_fullStr Bitumen veins and Eocene transpression, Neuquén Basin, Argentina
title_full_unstemmed Bitumen veins and Eocene transpression, Neuquén Basin, Argentina
title_sort bitumen veins and eocene transpression, neuquén basin, argentina
url http://hdl.handle.net/20.500.12110/paper_00401951_v314_n4_p423_Cobbold
work_keys_str_mv AT cobboldpr bitumenveinsandeocenetranspressionneuquenbasinargentina
AT diraisonm bitumenveinsandeocenetranspressionneuquenbasinargentina
AT rosselloea bitumenveinsandeocenetranspressionneuquenbasinargentina
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