Dalton, TJS, Paton, DA, Oldfield, SJ orcid.org/0000-0002-7947-9901 et al. (2 more authors) (2017) The Importance of missing strain in Deep Water Fold and Thrust Belts. Marine and Petroleum Geology, 82. pp. 163-177. ISSN 0264-8172
Abstract
Deep water fold and thrust belts (DWFTBs) are sedimentary wedges that accommodate plate-scale deformation on both active and passive continental margins. Internally, these wedges consist of individual structures that strongly influence sediment dispersal, bathymetry and fluid migration. Most DWFTB studies investigate basin- and intra-wedge- scale processes using seismic reflection profiles, yet are inherently limited by seismic resolution. Of critical importance is strain distribution and its accommodation on discrete faults compared to distributed deformation. Recent studies have considered strain distribution by investigating regional reflection DWFTBs profiles within coupled systems, which contain down-dip compression and up-dip extension. There is broad agreement of a mis-balance in compression versus extension, with ∼5% excess in the latter associated with horizontal compaction, yet this remains unproven. Using two exceptionally well exposed outcrops in the Spanish Pyrenees we consider deformation of DWFTB at a scale comparable to, and beyond, seismic resolution for the first time. By coupling outcrop observations (decametre to hectometre scale) with a re-evaluation of seismic profiles from the Orange Basin, South Africa, which contains one of the best imaged DWFTBs globally, we provide a unique insight into the deformation from metre to margin scale. Our observations reveal hitherto unrecognised second order structures that account for the majority of the previously recognised missing strain. This re-evaluation implies that ∼5% missing strain should be accounted for in all DWFTBs, therefore existing studies using restorations of the sediment wedge will have underestimated crustal shortening in active margins, or sedimentary shortening in gravity driven systems by this amount. In contrast to previous studies, our observations imply that the majority of this strain is accommodated on discrete fault surfaces and this can explain the occurrence and location of a range of intra-wedge processes that are intimately linked to structures including sediment dispersal, fluid migration pathways and reservoir compartmentalisation.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Elsevier Ltd. This is an author produced version of a paper published in Marine and Petroleum Geology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Deep water fold thrust belts; Orange basin; Pyrenee's: Sesimic interpretation; Restorations: Gravity driven collapse |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Funding Information: | Funder Grant number EON E&P UK Ltd No External Ref |
Depositing User: | Symplectic Publications |
Date Deposited: | 17 Jan 2017 12:15 |
Last Modified: | 19 Jan 2018 01:38 |
Published Version: | https://doi.org/10.1016/j.marpetgeo.2017.01.013 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.marpetgeo.2017.01.013 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:110641 |