Evolução geológica do depósito de óxido de ferro-cobre-ouro (IOCG) Igarapé Cinzento (GT-46), Província Carajás

Volcanogenic features of IOCG deposits of North Carajás, Brazil, and related constraining evidence

“…They return robust depositional ages, for instance, U-Pb from zircons of volcanic rocks of 2.73 to 2.76 Ga (Vasquez et al 2008). The metamorphism, to which some authors have related the mineralization (Winter 1994;Toledo 2017), is poorly constrained in terms of age. Available ages are limited and include 2.73 Ga and 2.76 Ga for the Pojuca and Salobo deposits, respectively (Machado et al 1991).…”

“…Similarly, Tavares et al (2018) indicated a prolonged complex structural history for the northeast sector of the Carajás domain. This aspect seems to have been taken into consideration in the interpretation of geochronological signatures shown by some of the stratabound deposits of north Carajás (Melo et al 2017;Toledo et al 2017Toledo et al , 2019Trunfull et al 2020).…”

“…12): (1) Part of the deposit hosted in the Neoarchean volcanicsedimentary Grão Pará Group with the coeval Igarapé Gelado granite possibly accounting for the sustained heat source required for the development of robust volcanogenic hydrothermal systems. (2) Reference to regional Ca-Na hastingsite-albite alteration of mafic volcanic rocks (Toledo 2017), which is roughly remindful of semi-conformable alteration products of reservoir zone of widespread distribution underneath VMS deposits (Franklin et al 2005;Santaguida et al 2002;Paradis et al 2002). (3) Ore host rocks including biotite amphibolite, amphibole-biotite schist, garnetbiotite-amphibole-quartz-magnetite schist with interlayered grunerite-quartz-magnetite banded iron-formation, and almandine-sillimanite-rich schist and gneiss, this configuring a host package similar to that of the Furnas deposit, and commonly found in metamorphosed volcanogenic deposits.…”

“…12). ( 2) Toledo (2017) and Toledo et al (2019) in contrastanalysing recrystallized quartz from a mineralized quartzgarnet-amphibole schist (1st main mineralization stage) and quartz from a coarse-grained garnet-biotite-chalcopyrite rock representing a late, second stage of alteration and mineralization (Appendix 6.1) -presenting a large spectrum 1 stage (principal, disseminated, strata-bound, ca. 2720 Ma, next item) as indicative of leaching of sulfur from the country rock, an interpretation with a particular appeal for a syngenetic origin for part of the mineralization of Ig.…”