Ridge Jumps and Mantle Exhumation in 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...

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Autores principales:	Valentina Magni, John Naliboff, Manel Prada, Carmen Gaina
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	back-arc basins mid-ocean ridge jumps continental lithospheric extension mantle exhumation continental fragments formation subduction zones Geology QE1-996.5
Acceso en línea:	https://doaj.org/article/f392366f3acc4ca19e5154eb76dda9a2
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id	oai:doaj.org-article:f392366f3acc4ca19e5154eb76dda9a2
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spelling	oai:doaj.org-article:f392366f3acc4ca19e5154eb76dda9a22021-11-25T17:43:15ZRidge Jumps and Mantle Exhumation in Back-Arc Basins10.3390/geosciences111104752076-3263https://doaj.org/article/f392366f3acc4ca19e5154eb76dda9a22021-11-01T00:00:00Zhttps://www.mdpi.com/2076-3263/11/11/475https://doaj.org/toc/2076-3263Back-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.Valentina MagniJohn NaliboffManel PradaCarmen GainaMDPI AGarticleback-arc basinsmid-ocean ridge jumpscontinental lithospheric extensionmantle exhumationcontinental fragments formationsubduction zonesGeologyQE1-996.5ENGeosciences, Vol 11, Iss 475, p 475 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	back-arc basins mid-ocean ridge jumps continental lithospheric extension mantle exhumation continental fragments formation subduction zones Geology QE1-996.5
spellingShingle	back-arc basins mid-ocean ridge jumps continental lithospheric extension mantle exhumation continental fragments formation subduction zones Geology QE1-996.5 Valentina Magni John Naliboff Manel Prada Carmen Gaina Ridge Jumps and Mantle Exhumation in Back-Arc Basins
description	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.
format	article
author	Valentina Magni John Naliboff Manel Prada Carmen Gaina
author_facet	Valentina Magni John Naliboff Manel Prada Carmen Gaina
author_sort	Valentina Magni
title	Ridge Jumps and Mantle Exhumation in Back-Arc Basins
title_short	Ridge Jumps and Mantle Exhumation in Back-Arc Basins
title_full	Ridge Jumps and Mantle Exhumation in Back-Arc Basins
title_fullStr	Ridge Jumps and Mantle Exhumation in Back-Arc Basins
title_full_unstemmed	Ridge Jumps and Mantle Exhumation in Back-Arc Basins
title_sort	ridge jumps and mantle exhumation in back-arc basins
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/f392366f3acc4ca19e5154eb76dda9a2
work_keys_str_mv	AT valentinamagni ridgejumpsandmantleexhumationinbackarcbasins AT johnnaliboff ridgejumpsandmantleexhumationinbackarcbasins AT manelprada ridgejumpsandmantleexhumationinbackarcbasins AT carmengaina ridgejumpsandmantleexhumationinbackarcbasins
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Ridge Jumps and Mantle Exhumation in Back-Arc Basins

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