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Comparison of fold-thrust belts driven by plate convergence and gravitational failure

Comparison of fold-thrust belts driven by plate convergence and gravitational failure
Comparison of fold-thrust belts driven by plate convergence and gravitational failure
Deepwater fold-thrust belts (FTBs) are predominantly formed by the deformation of sedimentary sequences as a result of subduction of oceanic plates at active margins, gravitational failure at passive margins, or a combination of these two driving mechanisms at both types of margin. A key question is: Is the FTB driven by gravitational failure basically the same as the FTB driven by plate convergence or are there fundamental differences? To address this, we reviewed FTB examples from different tectonic settings (end members and hybrid systems) in terms of geometry, structure, deformation, shortening rate, and tectonic process. The energy source in gravity-driven systems lies within the sedimentary material itself that is being deformed by updip extension and downdip contraction, whereas in the plate convergence-driven systems, it lies outside the local sediment pile and within the broader undeformed crust and lithosphere. The energy in gravity-driven systems is resupplied by sediment input from large river deltas and therefore deformation tends to be episodic, linked to episodes of major sediment input; whereas in a system driven by plate motions, the energy is resupplied by movement of a boundary upon which force is acting, and tends to be stable and less episodic. Therefore the sedimentation plays an important role in the gravity-driven deformation, but a less important role in the plate convergence-driven deformation. In gravity-driven systems, it promotes upward propagation of normal faulting at upslope by increasing maximum principal stress but hinders upward propagation of thrusting (i.e. mostly buried structures) by increasing minimum principal stress at downslope; while in plate convergence systems, thrusts and folds tend to deform sea floor as a result of large compression, with less effect from sedimentation. Despite the varying basal strength, the observed thrust faults in both systems are mostly basinward-verging, in slight contrast to the theoretical model predication (with homogeneous material), implicating the control of likely variability of stratigraphic strength on thrust vergence. The shortening rate across plate convergence-driven systems is high (several tens mm/yr), and continuous on a long timescale; whereas across the gravity-driven fold-thrust belts, it is generally slow (several mm/yr) and more variable or even catastrophic through time. Despite overall seaward younging of thrusting, fault activity differs slightly among different systems. Focused activity at the frontal structures of FTBs is more common at the plate convergence system while activity focused in the rear to middle of FTBs is more common in the gravity-driven system. Plate convergence-driven system is primarily limited by rate of plate motion, i.e. the rate at which the plate is fed into the FTB, whereas in gravity-driven system, the movement is limited (resisted) by the strength of sediments and detachment.
0012-8252
Yang, Xiaodong
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Peel, Frank J.
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Mcneill, Lisa
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Sanderson, David
5653bc11-b905-4985-8c16-c655b2170ba9
Yang, Xiaodong
0c44aab1-3c52-4e2a-925e-565a34967c57
Peel, Frank J.
ccbb86f8-56a0-4b59-b664-e772a9c4015f
Mcneill, Lisa
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Sanderson, David
5653bc11-b905-4985-8c16-c655b2170ba9

Yang, Xiaodong, Peel, Frank J., Mcneill, Lisa and Sanderson, David (2020) Comparison of fold-thrust belts driven by plate convergence and gravitational failure. Earth-Science Reviews, 203, [103136]. (doi:10.1016/j.earscirev.2020.103136).

Record type: Article

Abstract

Deepwater fold-thrust belts (FTBs) are predominantly formed by the deformation of sedimentary sequences as a result of subduction of oceanic plates at active margins, gravitational failure at passive margins, or a combination of these two driving mechanisms at both types of margin. A key question is: Is the FTB driven by gravitational failure basically the same as the FTB driven by plate convergence or are there fundamental differences? To address this, we reviewed FTB examples from different tectonic settings (end members and hybrid systems) in terms of geometry, structure, deformation, shortening rate, and tectonic process. The energy source in gravity-driven systems lies within the sedimentary material itself that is being deformed by updip extension and downdip contraction, whereas in the plate convergence-driven systems, it lies outside the local sediment pile and within the broader undeformed crust and lithosphere. The energy in gravity-driven systems is resupplied by sediment input from large river deltas and therefore deformation tends to be episodic, linked to episodes of major sediment input; whereas in a system driven by plate motions, the energy is resupplied by movement of a boundary upon which force is acting, and tends to be stable and less episodic. Therefore the sedimentation plays an important role in the gravity-driven deformation, but a less important role in the plate convergence-driven deformation. In gravity-driven systems, it promotes upward propagation of normal faulting at upslope by increasing maximum principal stress but hinders upward propagation of thrusting (i.e. mostly buried structures) by increasing minimum principal stress at downslope; while in plate convergence systems, thrusts and folds tend to deform sea floor as a result of large compression, with less effect from sedimentation. Despite the varying basal strength, the observed thrust faults in both systems are mostly basinward-verging, in slight contrast to the theoretical model predication (with homogeneous material), implicating the control of likely variability of stratigraphic strength on thrust vergence. The shortening rate across plate convergence-driven systems is high (several tens mm/yr), and continuous on a long timescale; whereas across the gravity-driven fold-thrust belts, it is generally slow (several mm/yr) and more variable or even catastrophic through time. Despite overall seaward younging of thrusting, fault activity differs slightly among different systems. Focused activity at the frontal structures of FTBs is more common at the plate convergence system while activity focused in the rear to middle of FTBs is more common in the gravity-driven system. Plate convergence-driven system is primarily limited by rate of plate motion, i.e. the rate at which the plate is fed into the FTB, whereas in gravity-driven system, the movement is limited (resisted) by the strength of sediments and detachment.

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Comparison of Fold-Thrust Belts - Proof
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Accepted/In Press date: 14 February 2020
e-pub ahead of print date: 19 February 2020
Published date: April 2020

Identifiers

Local EPrints ID: 439223
URI: http://eprints.soton.ac.uk/id/eprint/439223
ISSN: 0012-8252
PURE UUID: e29d8751-7b55-4ea9-bb6a-632ba6344054
ORCID for David Sanderson: ORCID iD orcid.org/0000-0002-2144-3527

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Date deposited: 07 Apr 2020 16:30
Last modified: 19 Feb 2021 05:01

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