Grenvillian massif-type
anorthosites in the Sierras
Pampeanas
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Publication date
2004
Authors
Pankhurst, R.J.
Rapela, Carlos W.
Dahlquist, Juan A.
Baldo, Edgardo G.
Saavedra, Julio
González Casado, José Manuel
Fanning, C.M.
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Publisher
Geological Society of London.
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Abstract
We report the discovery of massif-type anorthosites
in the Andean basement of the Western
Sierras Pampeanas of Argentina. U–Pb zircon
dating (by sensitive high-resolution ion
microprobe) of a cogenetic gabbronorite dyke yields ages of
1070 ± 41 Ma for igneous emplacement and 431 ± 40 Ma for
metamorphism. These anorthosites are petrologically and
geochemically comparable with those of the Grenville province
of Laurentia. Palaeogeographical reconstructions of
Rodinia at 1.0–1.1 Ga suggest that the Sierras Pampeanas
anorthosites were part of a large anorthosite province in the
late Mesoproterozoic.