Progressive tilting of salt-bearing continental margins controls thin-skinned deformation

As a primary driving force, margin tilting is crucial for gravity-driven thin-skinned salt tectonics. We investigated how instant versus progressive margin tilting mechanisms influence salt tectonics using an analogue modeling setup where tilting rate could be controlled. Instant tilting resulted in...

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Bibliographic Details
Published in:Geology (Boulder) 2019-12, Vol.47 (12), p.1122-1126
Main Authors: Ge, Zhiyuan, Warsitzka, Michael, Rosenau, Matthias, Gawthorpe, Rob L
Format: Article
Language:English
Subjects:
analog simulation
continental margin
Continental margins
Coupling
Deactivation
Deformation
Deformation effects
experimental studies
Geology
global
Gravity
kinematics
laboratory studies
Mechanical properties
Overburden
passive margins
physical models
Plate tectonics
rates
salt tectonics
Salts
Structural geology
Tectonics
thin-skinned tectonics
tilt
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Summary:As a primary driving force, margin tilting is crucial for gravity-driven thin-skinned salt tectonics. We investigated how instant versus progressive margin tilting mechanisms influence salt tectonics using an analogue modeling setup where tilting rate could be controlled. Instant tilting resulted in initially high deformation rates, triggering widely distributed upslope extension and downslope contraction. Later, both the extensional and contractional domains migrated upslope as early extensional structures were successively deactivated, while deformation rates decreased exponentially. In contrast, progressive tilting led to downslope migration of the extensional domain by sequentially formed, long-lived normal faults. Contraction localized on a few, long-lived thrusts before migrating upslope. We attribute the distinct structural evolution of thin-skinned deformation, especially in the extensional domain, in the two tilting scenarios mainly to mechanical coupling between the brittle overburden and underlying viscous material. The coupling effect in turn is largely controlled by the deformation rate. By demonstrating the spatiotemporal variations of structural style and kinematic evolution associated with instant versus progressive tilting, we suggest that such variation is identifiable in nature and therefore can provide a new way to analyze margin tilting histories.
ISSN:0091-7613
1943-2682
DOI:10.1130/G46485.1