The evolution of triple junctions: from failure to success

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Authors

Hany Mohamed Khalil, Fabio Capitanio, Alexander R. Cruden 

Abstract

Divergent triple junctions are stable plate margins where three spreading ridges meet. Although it is accepted that this configuration is inherited from an earlier phase of continental rifting, how post-breakup triple junctions emerge from the separation of two plates remains unclear. By documenting the strain rate history recorded in the three rift-arms of several modern and ancient triple junctions, we show that deformation is episodic and localized in only one or two rifts at any given time. We further investigate this behavior in three-dimensional (3D) analog experiments of rifting, under a range of kinematic boundary conditions and containing a variety of pre-existing lithospheric heterogeneities. Deformation in the experiments is characterized by strain jumps and rift abandonment, comparable to natural observations. Boundary rotation during extension induces oblique stretching directions, along-strike strain gradients and forces significant strain jump to reduce the number of rifts segments active. Models that comprise lithospheres ranging from homogenous to containing a triple junction-like pre-existing heterogeneities, never developed a three-armed rift, where all rift segments are active at same time, at any stage. Our experimental results indicate that, unlike mature, successful, and stable oceanic triple junctions, early-stage continental rifting progresses through unstable “double-junctions” characterized by repeated strain jumps and rift failures and reactivations.

DOI

https://doi.org/10.31223/X5FK7Z

Subjects

Physical Sciences and Mathematics

Keywords

Triple junction, Rotational extension, Failed rifts

Dates

Published: 2021-09-20 13:22

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
All the data available within the manuscript and its supplementary information and references within

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