Late diapirism in granitic plutons? A case study in the Araçuaí belt

• Grant number: 19/24275-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2020
• End date: April 30, 2021
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Ricardo Ivan Ferreira da Trindade
• Grantee: Gelson Ferreira de Souza Junior
• 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

Plutons classically recognized as post-tectonic are erroneously associated with bodies free of any deformation and thus treated as isotropic. There are numerous mechanisms that are able to deform such rocks without involving tectonic efforts, such as the weight of the intrusive body itself that in certain circumstances may cause movement and consequently deformation, is imprinted on both the pluton and its wall rock. This aspect does not mischaracterize the post-tectonic classification, but raises questions about the "undeformed" terminology, which is generally linked to it. A deformed rock must have a preferential direction in its mineralogical fabric, even though subtle. In this regard, magnetic anisotropy has become increasingly a fundamental methodology in the determination of igneous rock petrotrama due to its extreme sensitivity, thus enabling the determination of the deformation axes (x, y and z), as they are analogous to the obtained axes with Anisotropy of Magnetic Susceptibility - AMS (k1, k2 and k3, respectively). Given these parameters it is known that, structurally, the plane that contemplates the x and z axes, given respectively by the maximum and minimum deformation, is the ideal section for kinematic analysis, especially using backscattered electron diffraction (EBSD-SEM) data. On the other hand, gravity modeling can, within certain limits, provide insight into the configuration and depth of the body studied and thus corroborate the interpretations of the other methods cited. Therefore, the objective of the present work is to generate a placement model for the Santa Angélica Intrusive Complex that can explain the causes of its deformation, widely recognized as a post-collisinal intrusion. (AU)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

SOUZA JUNIOR, Gelson Ferreira de. Magnetic anisotropy and gravimetry of the Santa Angélica Intrusive Complex, Araçuaí Belt. 2021. Master's Dissertation - Universidade de São Paulo (USP). Instituto Astronômico e Geofísico (IAG/SBD) São Paulo.