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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

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Casquet, César and Baldo, Edgardo G. and Pankhurst, R.J. and Rapela, Carlos W. and Galindo Francisco, Mª del Carmen and Fanning, C.M. and Saavedra, Julio (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). pp. 703-706. ISSN 0091-7613 (print) / 1943-2682 (web

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Official URL: http://www.geology/article/29/8/703/192086/involvement-of-the-argentine-precordillera-terrane


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Abstract

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 6 40 MPa, 790 6 17 8C), 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 6 100 Mpa, 600 6 50 8C). 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:Article
Uncontrolled Keywords:Argentina, Ordovician, Continent collision, Metamorphism, SHRIMP zircon dating
Subjects:Sciences > Geology > Geodynamics
Sciences > Geology > Petrology
ID Code:44767
Deposited On:25 Sep 2017 07:24
Last Modified:25 Sep 2017 14:16

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