Paleogeography in the Ediacaran-Cambrian: case study of the Araçuaí orogen

Abstract

The latitudinal distribution of continental masses and mountain chains is a key element in the paleoenvironmental reconstruction of the Ediacaran-Cambrian times. However, there is a scant paleomagnetic database for this time interval, and the few poles available for the same age shows high dispersion between them, and overall cannot be correlated. Besides the unconstrained latitude of the blocks, the age and evolution of the mountain chains are also undetermined along most of the Brasiliano-Panafrican belts. In this project, we intend to better define the position and evolution of part of the Araçuai Orogen (AO) by combining paleomagnetic data in the post-collisional intrusions, SIG-based paleogeographic reconstructions and a compilation of geochronological and thermochronological data from SE Brazil. The study is focused on Cambrian granitic bodies (~ 500 Ma) pluton Santa Angelica, pluton Conceição de Muqui and Chanockito Padre Paraiso. For the definition of the emplacement model, structural study of anisotropy of magnetic susceptibility (AMS) was already performed for Santa Angélica pluton and Conceição de Muqui pluton and will be performed for Padre Paraíso charnockite. In this project, we intend to better define the position and evolution of the AO combining paleomagnetic data in the post-collisional intrusions, and a compilation of geochronological and thermochronological data from AO. For this, reference Neoproterozoic paleomagnetic poles of these targets will be performed using rock magnetic techniques such as alternating field demagnetization (AF) and thermal demagnetization (TD) to successfully discriminate the most reliable magnetization directions. The paleogeographic reconstruction will be performed on the GIS-based GPlates platform in order to create a continuous-time model from Ediacaran to Cambrian with tectonophysical links. There are four alternative paleogeographic scenarios for the AO. Such models do not consider paleomagnetic data as input. The reconstruction from this work will be used to test these existing primary models for the evolution of the araçuaí orogen. This project is part of the Fapesp Thematic Project 2016/06114-6.