Three-dimensional fault meshes and multi-layer shear in mass-transport blocks: Implications for fluid flow on continental margins

Gamboa, Davide A. ORCID: https://orcid.org/0000-0003-3323-4172 and Alves, Tiago Marcos ORCID: https://orcid.org/0000-0002-2765-3760 2015. Three-dimensional fault meshes and multi-layer shear in mass-transport blocks: Implications for fluid flow on continental margins. Tectonophysics 647 , pp. 21-32. 10.1016/j.tecto.2015.02.007

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Abstract

Submarine mass-transport deposits (MTDs) frequently include blocks of strata with variable deformation styles. In this paper, a 3D seismic volume from SE Brazil is compared with outcrop information from SE Crete to investigate multi-scale deformation patterns within mass-transport blocks. Block morphology relates closely to the orientation of internal faults and fractures, with wide chasms separating block fragments that opened along these planar features. Two families of sub-perpendicular faults associated with intra-block extension are observed on both scales. On seismic data, we show new evidence of intra-block horizontal shear and thrust faulting. At outcrop, downslope verging folds, load casts and injectites are observed along poorly consolidated sand-prone beds that are less than 1 m thick. Documented orientations and cross-cutting geometries suggest a syn-kinematic origin for these structures. By integrating the observations made at different scales we suggest the development of 3D meshes in MTD blocks, which are characterised by the intersection of faults and fractures with bed-parallel shear planes. These meshes greatly increase the relative permeability of individual blocks. The results in this work have implications for the analysis of fluid flow paths on continental margins, and show that mass-transport blocks can comprise important fluid bypass points when buried in low permeability strata.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0040-1951/ (accessed 24/2/15) Available online 18 February 2015
Publisher:	Elsevier
ISSN:	0040-1951
Related URLs:	Publisher
Date of First Compliant Deposit:	30 March 2016
Date of Acceptance:	10 February 2015
Last Modified:	20 Nov 2024 21:30
URI:	https://orca.cardiff.ac.uk/id/eprint/70864

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