Geological study of São Miguel do Tapuio meteorite impact structure, Piauí - Brazil

• Grant number: 19/00320-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2019
• End date: February 29, 2020
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Alvaro Penteado Crósta
• Grantee: Najlah Zeitoum de Souza
• Host Institution: Instituto de Geociências (IG). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The São Miguel do Tapuio structure is located in the eastern portion of the Parnaíba Basin, in the State of Piaui, Brazil. It is a circular feature of about 20 km in diameter, which exhibits a raised outer rim, concentric inner rings and a central elevated core, formed in sedimentary rocks of the Serra Grande and Canindé Groups. The origin of this feature has been under debate for several decades and recent preliminary data obtained by the supervisor of this proposal indicated an impact cratering origin. Pending the confirmation of these data, São Miguel do Tapuio structure becomes the second largest impact crater known in Brazil and South America. Evidence for this origin consists of micro-deformation characteristics of high-pressure regimes, such as planar fractures, feather features, and planar deformation features in quartz grains. However, such evidence results from a preliminary investigation of a small number of samples. The main purpose of this project is to analyze rock samples already collected in the field and their respective thin sections, seeking a more detailed characterization of the deformation features, which are diagnostic of the extremely high pressures that crustal rocks go through during meteoritic impacts. The aim of this project is to contribute to the knowledge of the genesis of the São Miguel do Tapuio structure, updating the record of large meteoritic impacts in Brazil and the World.