Rift segment interaction in orthogonal and rotational extension experiments: Implications for the large-scale development of rift systems

Zwaan, Frank; Schreurs, Guido (2020). Rift segment interaction in orthogonal and rotational extension experiments: Implications for the large-scale development of rift systems. Journal of structural geology, 140(104119), p. 104119. Elsevier 10.1016/j.jsg.2020.104119

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During extension of the continental lithosphere, rift basins develop. These are often initially offset, and must interact and connect in order to create a continuous rift system that may ultimately achieve break-up. When simulating extensional tectonics and rift interaction structures, analogue and numerical modellers often apply a continuous extension rate along the strike of a rift or rift system. Yet in nature signi cant extension velocity variations occur along rifts and plate boundaries as a natural consequence of tectonic plates moving apart about a pole of rotation, resulting in rotational extension, and associated rift propagation and structural gradients. Here we present various analogue tectonic experiments to assess rift interaction structures forming in orthogonal extension settings versus rotational extension settings. Our modelling efforts show that rotational extension and orthogonal extension produce signi cantly different large-scale structures. Rotational extension can cause important variations in rift maturity between rift segments, delay rift interaction zone development, and make rift segments propagate in opposite directions. Still, local features in a rotational extension system can often be regarded as evolving in an orthogonal extension setting. Furthermore, we nd that various degrees of rift underlap produce three basic modes of rift linkage structures. Low underlap distance (high angle φ) experiments develop rift pass structures. With increasing underlap distance (φ = ca. 40◦), transfer zone basins develop. High degrees of underlap (φ ≤ 30◦) tend to result in en echelon sub-basins. Our results match with data from previous modelling efforts and natural examples. We furthermore propose a large-scale tectonic scenario for the East African Rift System based on rotational extension and associated rift propagation. These insights may also be applicable when studying other large-scale rift systems.

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:

0191-8141

Publisher:

Elsevier

Funders:

[4] Swiss National Science Foundation ; [126] Bern University Science Foundation

Projects:

[UNSPECIFIED] 4D Analogue modelling of oblique extension: from continental rifting to passive margin formation

Language:

English

Submitter:

Frank Zwaan

Date Deposited:

09 Sep 2020 09:09

Last Modified:

17 Sep 2020 08:09

Publisher DOI:

10.1016/j.jsg.2020.104119

BORIS DOI:

10.7892/boris.146427

URI:

https://boris.unibe.ch/id/eprint/146427

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