Journal article
Multiple migmatite events and cooling from granulite facies metamorphism within the Famatina arc margin of northwest Argentina
Tectonics, Vol.33(1), pp.1-25
01/2014
DOI: 10.1002/2013TC003398
Abstract
The Famatina margin records an orogenic cycle of convergence, metamorphism, magmatism, and extension related to the accretion of the allochthonous Precordillera terrane. New structural, petrologic, and geochronologic data from the Loma de Las Chacras region demonstrate two distinct episodes of lower crustal migmatization. The first event preserves a counterclockwise pressure‐temperature path in kyanite‐K‐feldspar pelitic migmatites that resulted in lower crustal migmatization via muscovite dehydration melting at ∼12 kbar and 868°C at 461 ±1.7 Ma. The shape of the pressure temperature path and timing of metamorphism are similar to those of regional midcrustal granulites and suggest pervasive Ordovician migmatization throughout the Famatina margin. One‐dimensional thermal modeling coupled with regional isotopic data suggests Ordovician melts remained at temperatures above their solidus for 20–30 Ma following peak granulite facies metamorphism, throughout a time period marked by regional oblique convergence. The onset of synconvergent extension occurred only after regional migmatites cooled beneath their solidus and was synchronous with the cessation of Precordillera terrane accretion at ∼436 Ma. The second migmatite event was regionally localized and occurred at ∼700°C and 12 kbar between 411 and 407 Ma via vapor saturated melting of muscovite. Migmatization was synchronous with extension, exhumation, and strike‐slip deformation that likely resulted from a change in the plate boundary configuration related to the convergence and collision of the Chilenia terrane. Key Points Two migmatite events are preserved in the middle‐lower crust Famatina margin Widespread melting did not result in orogenic collapse or extension Extension was driven by plate boundary processes
Details
- Title: Subtitle
- Multiple migmatite events and cooling from granulite facies metamorphism within the Famatina arc margin of northwest Argentina
- Creators
- Sean R Mulcahy - University of CaliforniaSarah M Roeske - University of CaliforniaWilliam C McClelland - University of IowaJoshua R Ellis - Kinross Gold CorporationFred Jourdan - Curtin UniversityPaul R Renne - Berkeley Geochronology CenterJeffrey D Vervoort - Washington State UniversityGraciela I Vujovich - University of Buenos Aires‐CONICET
- Resource Type
- Journal article
- Publication Details
- Tectonics, Vol.33(1), pp.1-25
- DOI
- 10.1002/2013TC003398
- ISSN
- 0278-7407
- eISSN
- 1944-9194
- Number of pages
- 25
- Language
- English
- Date published
- 01/2014
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983983658602771
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