Deciphering the source of multiple U–Pb ages and complex Hf isotope composition in zircon from post-collisional charnockite-granite associations from the Araçuaí orogen (southeastern Brazil)

The role of Ediacaran synkinematic anatectic rocks and the late-orogenic charnockitic rocks in the development of the hot Araçuaí belt

“…We find no evidence in the literature supporting that Carlos Chagas rocks were first emplaced in upper crustal levels before 570 Ma, and subsequently buried and metamorphosed at 570-550 Ma, as suggested by Melo et al (2017a, b). Efficient melt migration from the source to emplacement at upper crustal levels would likely produce vertical lineation and foliation, as observed for example in the Central tonalitic domain west of the CCD (Region 2 in Figure 6 of Mondou et al, 2012). Furthermore, efficient melt migration needed to form isolated granitic bodies at upper crustal levels is strongly controlled by tectonic settings, in which weak or permeable structures, such as shear zones, facilitate vertical magma flow (e.g., Solar et al, 1998;De Saint Blanquat et al, 2011;Cavalcante et al, 2016).…”

“…The occurrence of charnockitic bodies, part of the Padre Paraíso unit, has been attributed to a late (520-480 Ma) post-collisional event in the Araçuaí orogen (Pedrosa-Soares et al, 2011 and references therein). U-Pb dating in zircon produced an age of 504 ± 5 Ma, interpreted to date crystallization of the charnockite that intruded the central portion of the CCD (sample 470 in Gradim et al, 2014), while Melo et al (2020) recorded a range of dates between 510-498 Ma for the Barra de São Francisco body.…”

“…Based on their age and their geochemical characteristics, charnockites have been interpreted as part of the post-collisional (520-480 Ma;Pedrosa-Soares et al, 2011) magmatism of the Araçuaí orogen. The emplacement ages for the BSF rocks range between 508-498 Ma (Gradim et al, 2014;Melo et al, 2020). The geochemistry of the BSF body shows a ferroan, metaluminous signature (Figs.…”

“…Several studies conducted over the last three decades have produced a large body of structural, geochronological, geochemical and petrological data that provides important constraints on the tectonic setting and orogenic processes of the hot Araçuaí belt (e.g. Trompette et al, 1993;Vauchez et al, 1994Vauchez et al, , 2007Vauchez et al, , 2019Trompette, 1997;Pedrosa-Soares et al, 2001;Martins et al, 2004;Alkmim et al, 2006;Petitgirard et al, 2009;Mondou et al, 2012;Cavalcante et al, 2013Cavalcante et al, , 2014Cavalcante et al, , 2018Richter et al, 2016;Melo et al, 2017a, b;Angelo et al, 2020). However, key questions, especially those related to the geodynamic implications of the formation of a large migmatitic-anatectic area with evidence of being partially molten for a long time period (e.g., Cavalcante et al, 2018;Vauchez et al, 2019), have not received due attention.…”

Anisotropia magnética e gravimetria do Complexo Intrusivo Santa Angélica, Faixa Araçuaí

“…O método da geotermobarometria tem sido amplamente utilizado nos plútons póscolisionais para investigar as suas condições de colocação. Segundo alguns autores (Aranda et al, 2020;Medeiros et al, 2001;Melo et al, 2020;Mendes et al, 1999;Mendes & De Campos, 2012;Wiedemann et al, 2002) os plútons G5 do sul do Orógeno Araçuaí (AO) intrudiram a pressões correspondentes aos níveis de crosta média a inferior (~19 -30 km). É importante ressaltar que os dados geofísicos apresentados por Assumpção et al (2013) apontam que a porção sul do orógeno Araçuaí possui uma crosta de aproximadamente 40 km de espessura.…”