Chronostratigraphic revision of the Dom João local stage in some interior basins of the Brazilian Northeast

• Grant number: 19/02600-1
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2019
• End date: January 31, 2022
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Giancarlo Scardia
• Grantee: Giancarlo Scardia
• Host Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil
• Associated researchers: Ana Maria Pimentel Mizusaki ; Claudio Riccomini ; Daniel Paul Miggins ; Eleonora Maria Gouvêa Vasconcellos ; Gerson Fauth ; Marcos Antonio Batista dos Santos Filho ; Mario Luis Assine

Abstract

Recent Rb-Sr datings of sedimentary rocks from the Recôncavo and Sergipe-Alagoas basins and referred to the Dom João Brazilian local stage provided absolute ages around 230-220 Ma, i.e. Late Triassic. Based on 40Ar/39Ar geochronology, mafic volcanic rocks of the Lavras de Mangabeira basin are associated at the same time interval and correlated with the magmatism of the Central Atlantic Ocean tectonic phase. The implication of these new datings in the Northeast of Brazil has a major impact on our understanding of the tempo and mode of evolution of the South Atlantic Ocean rift. They support a synchrony between the opening of the Central Atlantic Ocean and the subsidence produced during the Dom João stage, already considered pre-rift in most of the previous tectono-stratigraphic schemes.The aim of this proposal is to solve the problem of the chronostratigraphic position of the Dom João stage, in view of its tectonic significance in the context of the break of Gondwana. Representative sections from the Lavras de Mangabeira, Araripe, Recôncavo/Tucano, and Iguatu basins will be studied by means of paleomagnetism, practically never applied in the context of the Brazilian Northeast geology, supported by new biostratigraphic analyses on ostracodes, new 40Ar/39Ar and Rb-Sr datings, and a detailed petrographic and geochemical characterization of volcanic rocks of Lavras. (AU)