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Involvement of the Argentine Precordillera terrane in the Famatinian mobile belt: U-Pb SHRIMP and metamorphic evidence from the Sierra de Pie de Palo

Casquet, C.; Baldo, E.; Pankhurst, R.J.; Rapela, C.W.; Galindo, C.; Fanning, C.M.; Saavedra, J.. 2001 Involvement of the Argentine Precordillera terrane in the Famatinian mobile belt: U-Pb SHRIMP and metamorphic evidence from the Sierra de Pie de Palo. Geology, 29 (8). 703-706. 10.1130/0091-7613(2001)029<0703:IOTAPT>2.0.CO;2

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Abstract/Summary

New data suggest that the eastern margin of the Argentine Precordillera terrane comprises Grenvillian basement and a sedimentary cover derived from it that were together affected by Middle Ordovician deformation and metamorphism during accretion to the Gondwana margin. The basement first underwent low pressure/temperature (P/T) type metamorphism, reaching high-grade migmatitic conditions in places (686 ± 40 MPa, 790 ± 17 °C), comparable to the Grenvillian M2 metamorphism of the supposed Laurentian counterpart of the terrane. The second metamorphism, recognized in the cover sequence, is of Famatinian age and took place under higher P/T conditions, following a clockwise P-T path (baric peak: 1300 ± 100 Mpa, 600 ± 50 °C). Low-U zircon overgrew detrital Grenvillian cores as pressure fell from its peak, and yields U-Pb SHRIMP ages of ca. 460 Ma. This is interpreted as the age of ductile thrusting coincident with early uplift; initial accretion to Gondwana must have occurred before this. The absence of late Neoproterozoic detrital zircons is consistent with a Laurentian origin of the Argentine Precordillera terrane.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1130/0091-7613(2001)029<0703:IOTAPT>2.0.CO;2
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Antarctica in the Dynamic Global Plate System
ISSN: 0091-7613
Additional Keywords: Argentina, Ordovician, continent collision, metamorphism, SHRIMP zircon dating
Date made live: 28 Jun 2012 07:33
URI: http://nora.nerc.ac.uk/id/eprint/18505

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