Geoquímica da intrusão Mutum, Complexo Alcalino de Planalto da Serra, Mato Grosso

Abstract

This work was carried out in the area of the Complexo Alcalino Planalto da Serra, located about 250 km from Cuiabá in the municipality of Planalto da Serra, state of Mato Grosso. The rocks of this complex are intruded in the metasediments of the Cuiabá Group and are characterized by a great lithological diversity of ultramafic-alkaline nature belonging to three distinct series of magmatic differentiation, whose evolution involved fractional crystallization and/or immiscibility of liquids generated from a primitive magma. Ultramafic series comprising peridotites and pyroxenites; Carbonatitic Series that includes the carbonatites and Phoscorite Series, represented only by the apatitites. Phenites (phlogopitites, phyllites and phenitized diamictites) generated by contact metamorphism of magma with the host, hornfels and carbonatite breccias typical of volcanic conduits were also identified (Ormond 2006). The rocks of the complex constitute six main associations arranged parallel to the direction of regional structures in a N60-80E trend (Neder et al. 2005), extending for approximately 45 km called intrusions from east to west of Chibata, Denizar, Chibata II, Mutum , Big Valley and Lau-Massao. Preliminary geochemical data suggest for the rocks of this complex, an association of ultramaficalkaline rocks, associated with carbonatites and enriched in incompatible elements. The results obtained during the research in the area enabled the elaboration of an article called Geochemistry of the Intrusion Mutum Alkaline Complex Planalto da Serra, Mato Grosso, which was submitted to Revista Brasileira de Geociências, which corresponds to chapter two of this volume.