Publication: Mid- to Late Cambrian docking of the Rı´o de la Plata craton to southwestern
Gondwana: age constraints from U–Pb SHRIMP detrital zircon ages from Sierras
de Ambato and Velasco (Sierras Pampeanas, Argentina)
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Publication Date
2011
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Geological Society of London.
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Abstract
The Early Palaeozoic stratigraphy and tectonic history of the Eastern Sierras Pampeanas of central
Argentina are complicated by metamorphism and deformation resulting from the Pampean (545–510 Ma) and
Famatinian (490–440 Ma) orogenies. We report U–Pb sensitive high-resolution ion microprobe dating of
detrital zircons in two metasedimentary successions exposed at Quebrada de La Ce´bila (c. 28845’S, 66825’W):
the Ambato and the La Ce´bila metamorphic complexes. The Ambato zircons record age peaks corresponding
to Pampean (530 10 Ma), Brasiliano (c. 570 and c. 640 Ma), Grenville (c. 950 to c. 1025 Ma) and minor
Neoarchaean ages. Similar peaks are also apparent in the La Ce´bila sample but it additionally contains
Palaeoproterozoic zircons (c. 2.1 Ga) corresponding to the age of the Rio de la Plata craton, from which they
are considered to have been sourced. Our interpretation is that the protolith of the Ambato complex was
deposited prior to juxtaposition with the craton and is older than the Early Ordovician La Ce´bila metamorphic
complex. We infer that the craton reached its current relative position in the Mid- to Late Cambrian, after the
main Pampean tectonothermal event (530–520 Ma) and before deposition of the La Ce´bila protolith and the
Achavil Formation (Sierra de Famatina), which contain comparable detrital zircon populations.