Corrente Canoa pluton: A less-evolved portion of the Statherian Borrachudos Suite (Guanhães basement inlier, Araçuaí orogen)

Abstract

We bring new geophysical, geochemical, petrographic and geochronological data for the Corrente Canoa pluton, an igneous body within the Guanhães basement inlier, Araçuaí orogen. Our results demonstrate that this unit was crystallized in 1703.1 ± 4.3 Ma (U–Pb, LA-ICP-MS, zircons) and is part of the anorogenic Borrachudos Suite, integrating the Statherian Silicic Large Igneous Province emplaced at the São Francisco-Congo Paleocontinent in the context of an extensive rifting event. The Corrente Canoa pluton presents a distinctive geophysical and geochemical signature, which sets it apart from the other plutons in the suite. In airborne gammaspectrometry maps, its area of occurrence is depleted in Th and U. Geochemically, it presents a negative correlation between SiO2 and TiO2. Al2O3, MgO, CaO e FOt, which suggests fractionation of plagioclase, pyroxene, amphibole, biotite and Fe–Ti oxides along the crystallization process. K-feldspar and pyroxene controlled the fractional crystallization, and the latter is increased in the Corrente Canoa pluton, indicating that it is less-evolved. The difference between Eu/Eu × of the Corrente Canoa pluton (1.01 av.) and the rest of the Borrachudos Suite (0.32 av.) also attest its lower degree of fractionation. Zr saturation thermometry indicates an average crystallization temperature for the Corrente Canoa pluton of 888 °C, a result higher than the average for the rest of the Borrachudos Suite (846 °C). Altogether, these results suggest that the Corrente Canoa pluton was crystallized in a deeper portion of the crust. Based on this evidence, we argue that the genesis of the Corrente Canoa pluton and their differences to the other plutons of the Borrachudos Suite are better explained by fractional crystallization processes rather than the metasomatism suggested by previous studies. Fractional crystallization not only clarifies the distinctions between these plutons but also enhances the understanding of the entire differentiation process within the Borrachudos Suite. Additionally, we discuss possible explanations for the juxtaposition of the Current Canoa and Morro do Urubu plutons, based on their differences in age and petrogenesis. The distinct characteristics of the Corrente Canoa pluton points to the need of a thorough cartographic review in the Guanhães block, because at least part of what is now mapped as basement units might be in fact rocks of the Borrachudos Suite, but with a different geophysical and geochemical signature than usual for this suite.