Paleoproterozoic source contributions to the São Roque Group sedimentation: LA-MC-ICPMS U-Pb dating and Sm-Nd systematics of clasts from metaconglomerates of the Boturuna Formation

Authors

  • Renato Henrique-Pinto Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Valdecir de Assis Janasi Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Antonio Simonetti University of Notre Dame; Department of Civil Engineering and Geological Sciences
  • Colombo Celso Gaeta Tassinari Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Larry Michael Heaman University of Alberta; Department of Earth & Atmospheric Sciences

DOI:

https://doi.org/10.5327/Z1519-874X2012000300002

Keywords:

São Roque Group, Metaconglomerates, U-Pb dating, Sm-Nd data, Provenance

Abstract

The São Roque Group is characterized by volcano-sedimentary sequences, in which deposition probably started in the late Paleoproterozoic. U-Pb dating by LA-MC-ICPMS of zircons extracted from predominantly equigranular monzogranites clasts from Morro Doce and Morro do Polvilho regions, yield paleoproterozoic ages of 2199 ± 8.5 Ma and 2247 ± 13 Ma, respectively. These represent the ages for the main source of granite for the metaconglomerates from the Boturuna Formation (basal unit of São Roque Group). Its polycyclic history is reinforced by the presence of inherited Archean zircons (2694 ± 29 Ma) found within the clasts. Moreover, these clasts have also been affected by the Neoproterozoic overprinting event as indicated by their lower intercept Concordia ages. Sm-Nd isotope data for the main clast varieties from the Morro Doce metaconglomerates yield T DM ages of 2.6 to 2.7 Ga, demonstrating that these granites are the recycling products of an Archean crustal component. The metaconglomerate arkosean framework yields slightly lower εNd(t) values than those for the clasts, indicating that a younger and/or more primitive source also contributed to the Boturuna Formation.

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Published

2012-12-01

Issue

Vol. 12 No. 3 (2012)

Section

Articles

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How to Cite

Henrique-Pinto, R., Janasi, V. de A., Simonetti, A., Tassinari, C. C. G., & Heaman, L. M. (2012). Paleoproterozoic source contributions to the São Roque Group sedimentation: LA-MC-ICPMS U-Pb dating and Sm-Nd systematics of clasts from metaconglomerates of the Boturuna Formation . Geologia USP. Série Científica, 12(3), 21-32. https://doi.org/10.5327/Z1519-874X2012000300002