Bi-modal deformation styles in confined mass-transport deposits: examples from a salt minibasin in SE Brazil

Gamboa, Davide and Alves, Tiago Marcos ORCID: https://orcid.org/0000-0002-2765-3760 2016. Bi-modal deformation styles in confined mass-transport deposits: examples from a salt minibasin in SE Brazil. Marine Geology 379 , pp. 176-193. 10.1016/j.margeo.2016.06.003

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Abstract

High-quality 3D seismic data reveal bi-modal deformation styles in mass-transport deposits filling a salt minibasin in SE Brazil (Espírito Santo Basin). We analyse three mass-transport deposits within the same Miocene stratigraphic interval, and four others in Holocene strata. Our interpretation reveals that deformation in the mass-transport deposits relates to their long-axis orientation. As a result, they are divided into two types: a) Type 1 have long axes parallel to the direction of movement and show significant internal deformation; b) Type 2 have long axes perpendicular to the direction of movement, are highly heterogeneous and include large undeformed slabs. The long axes of Type 2 mass-transport deposits are parallel to the strike of bounding faults and salt structures. The majority of mass-transport deposits show intense deformation at their headwalls, and relative short remobilisation distances are inferred for both Types 1 and 2. In the study area, the timing of emplacement of mass-transport deposits was controlled by the growth of adjacent salt ridges. Earlier halokinesis in the northern axial areas of the minibasin shifted southwards in a second stage. Holocene mass-transport deposits suggest alternating growth of the eastern and western salt ridges. Our results show that detailed seismic-stratigraphic analyses are a key to understanding the timings and magnitude of deformation of mass-transport deposits in salt minibasins. The classification proposed can be applied to MTDs on continental margins and in lacustrine settings.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Publisher:	Elsevier
ISSN:	0025-3227
Date of First Compliant Deposit:	20 September 2016
Date of Acceptance:	5 June 2016
Last Modified:	02 Dec 2024 22:45
URI:	https://orca.cardiff.ac.uk/id/eprint/92016

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