Ortiz-Karpf, A, Hodgson, DM orcid.org/0000-0003-3711-635X and McCaffrey, WD orcid.org/0000-0003-2895-3973 (2015) The role of mass-transport complexes in controlling channel avulsion and the subsequent sediment dispersal patterns on an active margin: The Magdalena Fan, offshore Colombia. Marine and Petroleum Geology, 64. pp. 58-75. ISSN 0264-8172
Abstract
Submarine channel avulsion is a fundamental process in the evolution of submarine fans that records abrupt changes in the sediment dispersal patterns, and the development of sand-rich splay deposits. On passive margins, changing flow conditions have been invoked to explain the location and timing of channel avulsion. On tectonically active basin margins, processes such as seismic activity, seabed faulting and folding and emplacement of mass-transport complexes (MTCs) are additional triggers. This study is based on the detailed mapping and interpretation of the first 1000 m below seabed of a 1900 km2 3D seismic volume in the southern Magdalena Fan, offshore Colombia, a tectonically-active margin. The emplacement of a large MTC deposit (>400 km2 in area and 200 m in thickness) is interpreted to have controlled the avulsion node of a major channel-levee complex-set and influenced the evolution of the subsequent avulsion lobe complex-set. The basal surface of the MTC is highly erosional resulting in net degradation of the seascape. Substrate entrainment by the MTC left behind a narrow erosional remnant ridge that formed a bathymetric anomaly upon which a channel-levee complex-set developed. The irregular levee geometries above the remnant ridge led to instability and levee collapse prior to channel avulsion. Map view geometries and seismic amplitude extractions suggest that the initial avulsion lobes were mud-prone and relatively erratically distributed, and evolved to form well-defined sand-prone lobes. The distribution, morphology and evolution of the avulsion lobe complexes were strongly influenced by the bathymetric anomalies on the MTC top surface which, are generally coincident with protruding megaclasts.
The role of MTC emplacement in triggering submarine channel avulsion and the development of sand-prone deposits in proximal locations has important implications for hydrocarbon exploration and production. This study serves as a high-resolution, shallow-subsurface analogue for less well-imaged avulsion cycles on tectonically-active basin margins that are prone to MTCs.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Keywords: | Submarine channel complexes;; Avulsion lobes;; Frontal splays; Mass-transport complexes (MTC); Magdalena Fan |
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: | 07 May 2015 12:30 |
Last Modified: | 29 Oct 2020 17:16 |
Published Version: | http://dx.doi.org/10.1016/j.marpetgeo.2015.01.005 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.marpetgeo.2015.01.005 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:84306 |