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Article

Ridge Jumps and Mantle Exhumation in Back-Arc Basins

1
The Centre for Earth Evolution and Dynamics (CEED), Department of Geosciences, University of Oslo, 0371 Oslo, Norway
2
Department of Earth and Environmental Science, New Mexico Tech, Socorro, NM 87801, USA
3
Barcelona Center for Subsurface Imaging, Institut de Ciències del Mar (ICM), CSIC, 08003 Barcelona, Spain
4
School of Earth & Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD 4001, Australia
*
Author to whom correspondence should be addressed.
Academic Editors: Olivier Lacombe and Jesus Martinez-Frias
Geosciences 2021, 11(11), 475; https://doi.org/10.3390/geosciences11110475
Received: 29 September 2021 / Revised: 12 November 2021 / Accepted: 16 November 2021 / Published: 19 November 2021
(This article belongs to the Special Issue Tectonics and Morphology of Back-Arc Basins)
Back-arc basins in continental settings can develop into oceanic basins, when extension lasts long enough to break up the continental lithosphere and allow mantle melting that generates new oceanic crust. Often, the basement of these basins is not only composed of oceanic crust, but also of exhumed mantle, fragments of continental crust, intrusive magmatic bodies, and a complex mid-ocean ridge system characterised by distinct relocations of the spreading centre. To better understand the dynamics that lead to these characteristic structures in back-arc basins, we performed 2D numerical models of continental extension with asymmetric and time-dependent boundary conditions that simulate episodic trench retreat. We find that, in all models, episodic extension leads to rift and/or ridge jumps. In our parameter space, the length of the jump ranges between 1 and 65 km and the timing necessary to produce a new spreading ridge varies between 0.4 and 7 Myr. With the shortest duration of the first extensional phase, we observe a strong asymmetry in the margins of the basin, with the margin further from trench being characterised by outcropping lithospheric mantle and a long section of thinned continental crust. In other cases, ridge jump creates two consecutive oceanic basins, leaving a continental fragment and exhumed mantle in between the two basins. Finally, when the first extensional phase is long enough to form a well-developed oceanic basin (>35 km long), we observe a very short intra-oceanic ridge jump. Our models are able to reproduce many of the structures observed in back-arc basins today, showing that the transient nature of trench retreat that leads to episodes of fast and slow extension is the cause of ridge jumps, mantle exhumation, and continental fragments formation. View Full-Text
Keywords: back-arc basins; mid-ocean ridge jumps; continental lithospheric extension; mantle exhumation; continental fragments formation; subduction zones; back-arc magmatism; numerical models back-arc basins; mid-ocean ridge jumps; continental lithospheric extension; mantle exhumation; continental fragments formation; subduction zones; back-arc magmatism; numerical models
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MDPI and ACS Style

Magni, V.; Naliboff, J.; Prada, M.; Gaina, C. Ridge Jumps and Mantle Exhumation in Back-Arc Basins. Geosciences 2021, 11, 475. https://doi.org/10.3390/geosciences11110475

AMA Style

Magni V, Naliboff J, Prada M, Gaina C. Ridge Jumps and Mantle Exhumation in Back-Arc Basins. Geosciences. 2021; 11(11):475. https://doi.org/10.3390/geosciences11110475

Chicago/Turabian Style

Magni, Valentina, John Naliboff, Manel Prada, and Carmen Gaina. 2021. "Ridge Jumps and Mantle Exhumation in Back-Arc Basins" Geosciences 11, no. 11: 475. https://doi.org/10.3390/geosciences11110475

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