Pre-salt rift morphology controls salt tectonics in the Campos Basin, offshore SE Brazil

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Authors

Francyne Bochi do Amarante, Christopher A-L Jackson , Leonardo Muniz Pichel , Claiton Marlon dos Santos Scherer , Juliano Kuchle 

Abstract

Classic models of gravity-driven salt tectonics commonly depict kinematically linked zones of overburden deformation, characterised by updip extension and downdip contraction, separated by a weakly deformed zone associated with downdip translation above a relatively smooth base-salt surface. We use 2D and 3D seismic reflection and borehole data from the south-central Campos Basin to show that these models fail to adequately capture the complex range of structural styles forming during salt-detached gravity-driven deformation above a rugose base-salt surface. In the Campos Basin the base-salt is defined by broadly NE-trending, margin-parallel, generally seaward-dipping ramps with up to 2 km of structural relief. We define three domains of overburden deformation: an updip extensional domain, an intermediate multiphase domain, and a downdip contractional domain. The multiphase domain is defined by large, partly fault-bounded, ramp-syncline basins, the stratigraphic record of which suggest c. 35 km of seaward (horizontal) gravity-driven translation of salt and its overburden since the Albian. We also identify three main types of salt structures in the multiphase domain: (i) contractional anticlines that were subjected to later extension and normal faulting; (ii) passive-to-active diapirs that were later extended and widened, and which are bound on their landward margins by landward-dipping, salt-detached normal faults; and (iii) reactive (extensional) diapirs that was subsequently squeezed. We argue that this multiphase, hybrid-style of deformation occurs as a consequence of basinward translation of salt and its overburden over complex base-salt relief, consistent with the predictions of physical models and several other 3D seismic reflection data-based studies. Critically, these local strains overprint margin-scale patterns of deformation producing kinematically-variable and multiphase salt-related deformation.

DOI

https://doi.org/10.31223/X5XW3W

Subjects

Physical Sciences and Mathematics

Keywords

base-salt relief, passive margin, rift basin, ramp syncline basins, rift basin, passive margin, South Atlantic basins, ramp syncline basins, gravity‚Äźdriven deformation, salt translation., South Atlantic basins, gravity‚Äźdriven deformation, salt translation

Dates

Published: 2021-03-15 01:56

Last Updated: 2021-03-15 08:56

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
The seismic and well data supporting this study were made available by ANP (Brazilian Agency of Petroleum, Natural Gas and Biofuels). The authors are not allowed to share the data, which were used under license for this study.

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