Geochemical and gamma-spectrometry data on the evaluation of the potential of brasiliano igneous bodies to generate for rare earth elements ion adsorption clay concentration (Apiai-Guaxupé Terrain, Minas Gerais and São Paulo states, Brazil)

Abstract

The rare earth elements are of increasing importance in the world economy, mainly due to their applications in the technology industry, which leads to the interest in prospecting mineral sources for these elements. In this context, a particular model of mineralization known in China stands out as the main source of heavy rare earth elements (Eu to Lu) and yttrium (Y), less common than light rare earth elements (La to Sm). This deposit type, called ion adsorption clay, consists of weathering profiles developed from biotite and/or muscovite granites, where the exogenous concentration of rare earth elements is given by the adsorption of these elements by neoformed kaolinitic clays by the weathering process. Several characteristics affect the genesis of these mineralizations, where the presence of rare earth elements minerals very susceptible to weathering and developmental characteristics of the exogenous alteration are of great importance for this type of rare earth elements enrichment. The Apiaí-Guaxupe Terrain, with a diversity of igneous bodies and Cenozoic weathering process, is an example of area with prospective potential to this deposit type. There are no descriptive information about rare earth elements (fluor)carbonate minerals, very susceptible to weathering and primordial to the genesis of these deposits, in these igneous bodies. Thus, the use of chemical informations and descriptions over accessory minerals and hydrothermal alteration to define the possibility of rare earth elements formation is necessary. In this work, the investigation of the potential enrichment of ion adsorption clay-type rare earth elements for this terrain was based on the use of published information of 16 syn-, tardi- and post-orogenic, Brasiliano igneous bodies,encompassing geologic, chemical (228 samples) and mineralogical data. The comparative analysis among this data and the bodies that generate these ion adsorption clay-type rare earth elements mineralization show similarities of five granitoids with Chinese granites that gave rise to these concentrations. Gamma-spectrometry data corroborate the presence of weathering profiles in these five bodies, indicating potential to advancing the research on this model of rare earth elements mineralization.