Subduction initiation without magmatism: The case of the missing Alpine magmatic arc

Anders McCarthy*, Cyril Chelle-Michou, Othmar Müntener, Richard J Arculus, Jon Blundy

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

13 Citations (Scopus)
283 Downloads (Pure)

Abstract

Models of orogens identify subduction of oceanic crust as the key mechanism leading to continental collision. Such models, based inter alia on thermobarometric and geochronological evidence preserved in high-pressure metamorphic rocks and subduction-related magmatism, have been used to explain the convergence of Europe and Adria in the Cretaceous-Cenozoic and the subsequent Alpine orogen. Here, we review the metamorphic, igneous, and sedimentary record of the past 300 Ma of the Alpine orogen to show that there is no evidence of igneous activity during subduction initiation and prograde high-pressure metamorphism, leading to an ~50 Ma hiatus in magmatism, or "arc gap." The closure of rift basins forming the Piemont-Liguria ocean did not follow a classical Wadati-Benioff-type subduction. Instead, subduction initiation at passive margins allowed for the accretion of the hydrated portion of the subducting plate within an orogenic wedge as subduction of dry subcontinental lithosphere inhibited magmatism during subduction initiation and ocean closure.

Original languageEnglish
Pages (from-to)1059-1062
Number of pages4
JournalGeology
Volume46
Issue number12
Early online date23 Oct 2018
DOIs
Publication statusPublished - Dec 2018

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