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Structural styles of Albian rafts in the Espírito Santo Basin (SE Brazil): Evidence for late raft compartmentalisation on a ‘passive’ continental margin

Piedade, Aldina and Alves, Tiago Marcos 2017. Structural styles of Albian rafts in the Espírito Santo Basin (SE Brazil): Evidence for late raft compartmentalisation on a ‘passive’ continental margin. Marine and Petroleum Geology 79 , pp. 201-221. 10.1016/j.marpetgeo.2016.10.023

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Abstract

In recent years, hydrocarbon exploration offshore SE Brazil has been focusing on Lower Cretaceous strata deformed by gravity gliding above Aptian salt. A three-dimensional (3D) seismic volume from the Espírito Santo Basin, SE Brazil is here used to: a) test the parameters considered to control raft tectonics on a margin tectonically reactivated in the Cenozoic, and b) investigate the impact of prolonged halokinesis on raft deformation. Offshore Espírito Santo, the combined effects of halokinesis and multiple (Andean) tectonic phases are expressed by local collapse, fault reactivation and late segmentation of Albian rafts. As a result of this deformation we observe four main raft geometries: a) rolled-over rafts, b) tabular rafts, c) collapsed rafts, and d) folded and tilted rafts on the flanks of salt rollers. This work shows that salt rollers formed buttresses to moving Albian-Cenomanian rafts, with withdrawal of salt from underneath some of the rafts leading to their collapse and welding onto pre-salt strata. This process occurred in the studied part of the Espírito Santo Basin with minimum control of post-raft overburden thickness on raft compartmentalisation. Salt withdrawal from underneath the rafts is an important phenomenon as it enhanced connectivity between pre-salt and post-salt units, potentially promoting the migration of hydrocarbons from syn-rift source units into post-salt reservoirs.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Publisher: Elsevier
ISSN: 0264-817
Funders: Fundacao para a Ciencia e Tecnologia, Portugal
Date of First Compliant Deposit: 19 February 2018
Date of Acceptance: 21 October 2016
Last Modified: 05 Aug 2019 13:49
URI: http://orca.cf.ac.uk/id/eprint/70617

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