Complex rift patterns, a result of interacting crustal and mantle weaknesses, or multiphase rifting? Insights from analogue models

Zwaan, Frank; Chenin, Pauline; Erratt, Duncan; Manatschal, Gianreto; Schreurs, Guido (2021). Complex rift patterns, a result of interacting crustal and mantle weaknesses, or multiphase rifting? Insights from analogue models. Solid Earth, 12(7), pp. 1473-1495. Copernicus Publications 10.5194/se-12-1473-2021

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During lithospheric extension, localization of deformation often occurs along structural weaknesses inherited from previous tectonic phases. Such weaknesses may occur in both the crust and mantle, but the combined effects of these weaknesses on rift evolution remain poorly understood. Here we present a series of 3D brittle–viscous analogue models to test the interaction between differently oriented weaknesses located in the brittle upper crust and/or upper mantle. We find that crustal weaknesses usually express first at the surface, with the formation of grabens parallel to their orientation; then, structures parallel to the mantle weakness overprint them and often become dominant. Furthermore, the direction of extension exerts minimal control on rift trends when inherited weaknesses are present, which implies that present-day rift orientations are not always indicative of past extension directions. We also suggest that multiphase extension is not required to explain different structural orientations in natural rift systems. The degree of coupling between the mantle and upper crust affects the relative influence of the crustal and mantle weaknesses: low coupling enhances the influence of crustal weaknesses, whereas high coupling enhances the influence of mantle weaknesses. Such coupling may vary over time due to progressive thinning of the lower crustal layer, as well as due to variations in extension velocity. These findings provide a strong incentive to reassess the tectonic history of various natural examples.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Tectonics

UniBE Contributor:

Zwaan, Frank and Schreurs, Guido

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1869-9510

Publisher:

Copernicus Publications

Funders:

[4] Swiss National Science Foundation

Projects:

Projects 178731 not found.

Language:

English

Submitter:

Frank Zwaan

Date Deposited:

05 Jul 2021 08:33

Last Modified:

05 Jul 2021 08:33

Publisher DOI:

10.5194/se-12-1473-2021

BORIS DOI:

10.48350/157310

URI:

https://boris.unibe.ch/id/eprint/157310

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