Paleomagnetic study of Paleo to Mesoproterozoic geological units of the Amazonian Craton: implications for the paleogeography of the Columbia Supercontinent

• Grant number: 20/11819-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2021
• End date: March 12, 2023
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Carlos Henrique Grohmann de Carvalho
• Grantee: Fabiana Pereira Lasmar
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 16/06114-6 - The Neoproterozoic Earth System and the rise of biological complexity, AP.TEM

Abstract

Understanding the paleogeography of continents through time is crucial to constrain the geodynamics of the Earth. In this sense, the reconstruction of the Columbia supercontinent, its rupture and the subsequent formation of the Rodinia supercontinent are constantly debated. Despite the growing collection of paleomagnetic data for the possible constituent cratons of Columbia, the geodynamic processes that resulted in their formation and their longevity are still not well known. Information on the evolution of supercontinents comes from individual studies on cratons in different parts of the world. So the aim of this work is to define paleogeography and the evolution of Columbia, until the formation of Rodinia, based on new paleomagnetic and geochronological data obtained for the Amazonian Craton, between the Estaterian and Ectasian periods. The Estaterian units to be studied are represented by the Quarenta Ilhas Formation (AM), located in the Guianas Shield and the Vespor Intrusive Suite (MT) and the Colider Group (MT), located in the Central Brazil Shield. Geochronological dates indicate ages around 1780 Ma for these formations, whose studies will be important to test geological models proposed for Columbia, such as the SAMBA model (South America and BAltica) in which the Amazonian Craton appears together with the Baltic. It is also intended to study the mafic sill Mata-Matá located in the south of the Amazonas State, dated 1570 Ma, besides to more recent units, such as the Mafico-ultramafic complex Trincheira and the Canamã Intrusive Suite, this one with U-Pb age 1230 Ma, both located in the northwest of the State of Mato Grosso. The age of the Trincheira Complex is still uncertain, but it can be correlated to the Colorado Mafic Complex, dated in 1350 Ma and located in the State of Rondônia. Thus, it is intended to do the U-Pb dating of these samples and others that may be necessary. The study of magnetic mineralogy and field tests will support the paleomagnetic study for the definition of reference paleomagnetic reference poles, enabling the construction of the apparent polar wander for the Amazonian Craton, the paleogeographic reconstruction of the Columbia supercontinent, its subsequent breakdown and the formation of Rodinia in the Neoproterozoic. (AU)