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An Acad Bras Cienc. 2015 Sep;87(3):1611-22. doi: 10.1590/0001-3765201520130222. Epub 2015 Aug 25.

Zircon ages delimit the provenance of a sand extrudite from the Botucatu Formation in the Paraná volcanic province, Iraí, Brazil.

Author information

1
Universidade Federal de Pelotas, Pelotas, RS, BR.
2
Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, BR.
3
Centre for Exploration Targeting, The University of Western Australia, Crawley, WA, AU.
4
John de Laeter Centre of Mass Spectrometry, Curtin University of Technology, Bentley, WA, AU.

Abstract

Ion microprobe age determinations of 102 detrital zircon crystals from a sand extrudite, Cretaceous Paraná volcanic province, set limits on the origin of the numerous sand layers present in this major flood basalt province. The zircon U-Pb ages reflect four main orogenic cycles: Mesoproterozoic (1155-962 Ma), latest Proterozoic-early Cambrian (808-500 Ma) and two Palaeozoic (Ordovician- 480 to 450 Ma, and Permian to Lower Triassic- 296 to 250 Ma). Two additional small concentrations are present in the Neoarchean (2.8 to 2.6 Ga) and Paleoproterozoic (2.0 to 1.7 Ga). Zircon age peaks closely match the several pulses of igneous activity in the Precambrian Brazilian Shield and active orogeny in Argentina. A main delimitation of the origin of the sand is the absence of zircon ages from the underlying Cretaceous basalts, thus supporting an injectite origin of the sand as an extrudite that emanated from the paleoerg that constitutes the Botucatu Formation.

PMID:
26312429
DOI:
10.1590/0001-3765201520130222
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