Zircon and whole-rock Nd-Pb isotopic provenance of Middle and Upper Ordovician siliciclastic rocks, Argentine Precordillera

GLEASON, J.D.; FINNEY, STANLEY C.; PERALTA, SILVIO H.; GEHRELS, G.E.; MARSAGLIA, K.

SEDIMENTOLOGY

Blackwell Scientific Publications

Lugar: London; Año: 2007 vol. 54 p. 107 - 136

0037-0746

Graptolite-bearing Middle and Upper Ordovician siliciclastic facies of the Argentine Precordillera fold-thrust belt record the disintegration of a longlived Cambro-Mid Ordovician carbonate platform into a series of tectonically partitioned basins. A combination of stratigraphic, petrographic, U-Pb detrital zircon, and Nd-Pb whole-rock isotopic data provide evidence for a variety of clastic sediment sources. Four Upper Ordovician quartzo-lithic sandstones collected in the eastern and central Precordillera yield complex U-Pb zircon age spectra dominated by 1Æ05?1Æ10 Ga zircons, secondary populations of 1Æ22, 1Æ30, and 1Æ46 Ga, rare 2Æ2 and 1Æ8 Ga zircons, and a minor population (