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Fast sediment underplating and essentially coeval juvenile magmatism in the Ordovician margin of Gondwana, Western Sierras Pampeanas, Argentina

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Casquet, César and Rapela, Carlos W. and Pankhurst, R.J. and Baldo, Edgardo G. and Galindo Francisco, Mª del Carmen and Fanning, C.M. and Dahlquist, Juan A. (2012) Fast sediment underplating and essentially coeval juvenile magmatism in the Ordovician margin of Gondwana, Western Sierras Pampeanas, Argentina. Gondwana research, 22 . pp. 664-673. ISSN 1342-937X

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Official URL: http://www.journals.elsevier.com/gondwana-research



Abstract

Metasedimentary high-pressure upper amphibolite facies gneisses (1.2±0.1 GPa and 780±45 °C) at Las
Chacras, Sierra de Valle Fértil, are tectonically juxtaposed to thewesternmost parts (outboard) of the Famatinian
(Early Ordovician) magmatic arc, which underwent syn-plutonic middle crust high-grade metamorphism at
lower pressure. U–Pb SHRIMP zircon data suggest that the gneisses contain Famatinian igneous detritus, so
that their sedimentary protoliths were probably deposited in a forearc basin and then rapidly underthrust and
accreted to the lower crust of the arc, essentially coevallywith arc magmatismat 468±4 Ma. Chemically and isotopically
juvenile garnetiferous amphibolites within the gneisses are recognised as representing themost primitive
magmas so far observed in this belt, which has often been considered to be a continental arc derived from
isotopically mature sources. This is consistent with the idea that at least part of the dominant Famatinian
magmatism originated in depleted mantle but was heavily contaminated by crustal components.


Item Type:Article
Uncontrolled Keywords:Famatinian magmatic arc, Juvenile magmatism, U–Pb SHRIMP , Zircon geochronology, Gondwana, Sierras Pampeanas
Subjects:Sciences > Geology > Petrology
ID Code:21750
Deposited On:10 Jun 2013 09:09
Last Modified:01 Jul 2014 23:01

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