Steventon, MJ, Jackson, CA-L, Hodgson, DM orcid.org/0000-0003-3711-635X et al. (1 more author) (2019) Strain analysis of a seismically imaged mass‐transport complex, offshore Uruguay. Basin Research, 31 (3). pp. 600-620. ISSN 0950-091X
Abstract
Strain style, magnitude and distribution within mass‐transport complexes (MTCs) are important for understanding the process evolution of submarine mass flows and for estimating their runout distances. Structural restoration and quantification of strain in gravitationally driven passive margins have been shown to approximately balance between updip extensional and downdip contractional domains; such an exercise has not yet been attempted for MTCs. We here interpret and structurally restore a shallowly buried (c. 1,500 mbsf) and well‐imaged MTC, offshore Uruguay using a high‐resolution (12.5 m vertical and 15 × 12.5 m horizontal resolution) three‐dimensional seismic‐reflection survey. This allows us to characterise and quantify vertical and lateral strain distribution within the deposit. Detailed seismic mapping and attribute analysis shows that the MTC is characterised by a complicated array of kinematic indicators, which vary spatially in style and concentration. Seismic‐attribute extractions reveal several previously undocumented fabrics preserved in the MTC, including internal shearing in the form of sub‐orthogonal shear zones, and fold‐thrust systems within the basal shear zone beneath rafted‐blocks. These features suggest multiple transport directions and phases of flow during emplacement. The MTC is characterised by a broadly tripartite strain distribution, with extensional (e.g. normal faults), translational and contractional (e.g. folds and thrusts) domains, along with a radial frontally emergent zone. We also show how strain is preferentially concentrated around intra‐MTC rafted‐blocks due to their kinematic interactions with the underlying basal shear zone. Overall, and even when volume loss within the frontally emergent zone is included, a strain deficit between the extensional and contractional domains (c. 3%–14%) is calculated. We attribute this to a combination of distributed, sub‐seismic, ‘cryptic’ strain, likely related to de‐watering, grain‐scale deformation and related changes in bulk sediment volume. This work has implications for assessing MTCs strain distribution and provides a practical approach for evaluating structural interpretations within such deposits.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 The Authors. Basin Research © 2019 John Wiley & Sons Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists. This is the peer reviewed version of the following article: Steventon MJ, Jackson CA‐L, Hodgson DM, Johnson HD. Strain analysis of a seismically imaged mass‐transport complex, offshore Uruguay. Basin Res. 2019;00:1–21, which has been published in final form at https://doi.org/10.1111/bre.12337. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | deep‐water depositional systems; kinematic indicators; mass‐transport deposit (MTD); Oriential del Plata; Punta del Este; seismic geomorphology; submarine landslide |
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) |
Depositing User: | Symplectic Publications |
Date Deposited: | 09 Jan 2019 14:24 |
Last Modified: | 10 Jan 2020 01:39 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1111/bre.12337 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:140653 |