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Datación U-Pb SHRIMP de circones detríticos en paranfibolitas neoproterozoicas de las secuencia Difunta Correa (Sierras Pampeanas Occidentales, Argentina)

Rapela, Carlos W. and Pankhurst, R.J. and Casquet, César and Fanning, C.M. and Galindo Francisco, Mª del Carmen and Baldo, Edgardo G. (2005) Datación U-Pb SHRIMP de circones detríticos en paranfibolitas neoproterozoicas de las secuencia Difunta Correa (Sierras Pampeanas Occidentales, Argentina). Geogaceta, 38 . pp. 227-230. ISSN 0213-683X

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Abstract

The Neoproterozoic Difunta Correa meta-sedimentary sequence (DCSS) of Western Sierras Pampeanas is
a cover to a rejuvenated Grenvillian basement. The Western Sierras Pampeanas are allegedly part of the
exotic Precordillera Terrane, which was accreted to the proto-Andean margin of Gondwana in lower
Palaeozoic times. A para-amphibolite from this sedimentary sequence contains abundant zircons mostly
consisting of detrital igneous cores with a metamorphic overgrowth. The latter formed at 439±34 Ma,
i.e., during the Famatinian orogeny, although mantles are also found with mixed Grenvillian - Ordovician
ages due to Pb-loss. Ages of igneous cores are ~ 625 Ma , 1050-1150 Ma and 1200-1500 Ma with a peak
at c. 1.4 Ga. The ~ 625 Ma group zircon is of Gondwanan provenance and this age is an upper value for
the age of the host amphibolite. An age between 580 Ma and 620 Ma is inferred for the DCSS. The
provenance of zircons between 1.05 Ga and c. 1.2 Ga probably lies in the underlying Grenvillian basement.
However zircons older than 1.2 Ga were derived from an unexposed area: palaeogeographical considerations
suggest that this area could be either in Laurentia (trans-Laurentia belt) or in southern Amazonia (Rondonia-
San Ignacio belt), both 1.3-1.5 Ga in age.

Item Type:Article
Uncontrolled Keywords:SHRIMP zircon dating, Neoproterozoic, Sierras Pampeanas, Argentina
Subjects:Sciences > Geology > Geochemistry
ID Code:11460
Deposited On:04 Nov 2010 12:32
Last Modified:06 Feb 2014 09:04

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