Título:	U-pb dating of Barra Velha carbonates reveals the influence of Santos basin sedimentary and tectonothermal history on pre-salt carbonate ages
Autor(es):	Brito, João Pedro Santos de Santos, Roberto Ventura Gonçalves, Guilherme de Oliveira Barbosa, Paola Ferreira Cruz, C. E. Souza Ushirobira, C. A. Souza, Valmir da Silva Richter, Fabiana Abreu, C. J.
ORCID:	https://orcid.org/0000-0003-1556-6376 https://orcid.org/0000-0001-7661-455X https://orcid.org/0000-0002-4957-5951 https://orcid.org/0000-0001-6990-3679
Afiliação do autor:	University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology University of Brasilia, Institute of Geosciences, Graduate Program in Geology
Assunto:	Datação U-Pb Carbonatos pré-sal Formação Barra Velha Interação fluido-rocha
Data de publicação:	Out-2024
Editora:	Elsevier BV
Referência:	BRITO, J. P. S.; SANTOS, R. V.; GONÇALVES, G.O.; BARBOSA, P. F.; SOUZA CRUZ, C. E.; USHIROBIRA, C. A.; SOUZA, V. S.; RICHTER, F.; ABREU, C. J. U-pb dating of Barra Velha carbonates reveals the influence of Santos basin sedimentary and tectonothermal history on pre-salt carbonate ages. Marine and Petroleum Geology, [S. l.], v. 168, 107035, 2024. DOI: https://doi.org/10.1016/j.marpetgeo.2024.107035. Disponível em: https://www.sciencedirect.com/science/article/pii/S0264817224003477?via%3Dihub.
Abstract:	The depositional age and diagenetic history of the Upper Barra Velha carbonates are poorly understood. To clarify the geochronology of these events and the behavior of the U-Pb isotopic system in carbonates, we conducted an integrated petrographic, QEMSCAN imaging, and in situ U-Pb dating study of calcites and dolomites from the Barra Velha Formation, in the central Santos Basin (SE Brazil). Our results span three geochronological intervals, which are ∼125 Ma, ∼116-114 Ma, and ∼105-100 Ma. The U-Pb isotopic system of calcite allochems was disturbed, yielding ages of ∼115 Ma and ∼105-100 Ma. These ages coincide with magmatic and hydrothermal events in the pre-salt. Dolomites showed that geochronological disturbance of carbonate components may not be pervasive but rather related to fluid-rock interactions and properties of rocks and their constituents such as mineralogy, porosity and permeability. This is evidenced by the U-Pb system of non-porous, non-permeable, and less reactive dolomitic aggregates remaining undisturbed. Eodiagenetic microcrystalline and fine dolomite rhombs provided evidence of Barremian ages, challenging the belief that the Upper Barra Velha deposits are Aptian. Other eodiagenetic dolomites occur as ∼117 Ma eodiagenetic lamellar dolomites, as pseudomorphic dolomites that underwent U-Pb alteration at ∼100 Ma, and as ∼112 Ma pervasive rhombohedral dolomites associated with Mg-rich fluids percolation in the Upper Barra Velha carbonates. Blocky dolomite and saddle dolomite cements have ages of ∼100 Ma, with saddle dolomite constraining the latest silicification event as > 100 Ma. This research elucidates significant geological events, processes, and factors (including magmatic activity, hydrothermal alteration, fluid-rock interactions, and petrographic and mineralogical controls) that influenced the ages of the Upper Barra Velha carbonates. Moreover, it aids in reconstructing the depositional and diagenetic history of the Barra Velha Formation and enhances the understanding of the Santos Basin tectonothermal evolution.
Unidade Acadêmica:	Instituto de Geociências (IG)
Programa de pós-graduação:	Programa de Pós-Graduação em Geologia
DOI:	https://doi.org/10.1016/j.marpetgeo.2024.107035
Versão da editora:	https://www.sciencedirect.com/science/article/pii/S0264817224003477?via%3Dihub
Aparece nas coleções:	Artigos publicados em periódicos e afins

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