The Mesoproterozoic to early Neoproterozoic passive margin Lajeado Group and Apiai Gabbro, Southeastern Brazil

Autor(es)

Campanha, G. A. C. ^[1] ; Basei, M. S. ^[1] ; Faleiros, F. M. ^[1] ; Nutman, A. P. ^{[2, 3]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Geociencias, BR-05508 Sao Paulo - Brazil

^[2] Univ Wollongong, Sch Earth & Environm Sci, Wollongong, NSW 2500 - Australia

^[3] Chinese Acad Geol Sci, Beijing SHRIMP Ctr, 26 Baiwzhuang Rd, Beijing 100037 - Peoples R China

• Tipo de documento: Artigo Científico
• Fonte: GEOSCIENCE FRONTIERS; v. 7, n. 4, p. 683-694, JUL 2016.
• Citações Web of Science: 6

Resumo

The Lajeado Group in the Ribeira Belt, southeastern Brazil, corresponds to an open-sea carbonate platform, comprised of seven overlapping siliciclastic and carbonatic formations, intruded in its upper portion by the Apiai Gabbro. These rocks have a Neoproterozoic tectonometamorphic overprint related to arc magmatism and the Brasiliano collisional orogeny. Geochronological constraints are given by new U-Pb SHRIMP and LA-ICP-MS data for Lajeado Group detrital zircons and for magmatic zircons from the Apiai Gabbro. The youngest detrital zircons in the Lajeado Group are 1400-1200 Ma, and constrain its maximum age of deposition to be <1200 Ma, whereas the 877 +/- 8 Ma age for magmatic zircons in the Apiai Gabbro give the minimum age. Detritus source areas are mainly Paleoproterozoic (2200-1800 Ma) with some Archean and Mesoproterozoic contribution (1500-1200 Ma), with distal or tectonic stable cratonic character. The Lajeado Group should be a Stenian-Tonian carbonate platform passive margin of a continent at this time, namely the Columbia/Nuna or the Rodinia. The Apiai Gabbro displays similar age to other intrusive basic rocks in the Lajeado and Itaiacoca groups and represents tholeiitic MORB-like magmatism that we relate to the initial break-up of a Mesoproterozoic continent and the formation of the Brasiliano oceans. (C) 2015, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. (AU)

• Processo FAPESP: 01/13457-1 - Caracterização isotópica de rochas dos subgrupos Ribeira e Lajeado na região de Iporanga, SP
• Beneficiário: Ginaldo Ademar da Cruz Campanha
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 06/01327-0 - Caracterizacao metamorfica, estrutural e geocronologica de terrenos pre-cambrianos no sul do estado de sao paulo.
• Beneficiário: Ginaldo Ademar da Cruz Campanha
• Modalidade de apoio: Auxílio à Pesquisa - Regular