Metallogenetic systems associated with granitoid magmatism in the Amazonian Craton: An overview of the present level of understanding and exploration significance

Abstract

The Amazonian Craton hosts world-class metallogenic provinces with a wide range of styles of primary precious, rare, base metal, and placer deposits. This paper provides a synthesis of the geological database with regard to granitoid magmatic suites, spatio temporal distribution, tectonic settings, and the nature of selected mineral deposits. The Archean Caraj as Mineral Province comprises greenstone belts (3.04 e2.97 Ga), metavolcanic-sedimentary units (2.76e2.74 Ga), granitoids (3.07e2.84 Ga) formed in a magmatic arc and syn-collisional setting, post-orogenic A 2-type granites as well as gabbros (ca. 2.74 Ga), and anorogenic granites (1.88 Ga). Archean iron oxide-Cu-Au (IOCG) deposits were synchronous or later than bimodal magmatism (2.74e2.70 Ga). Paleoproterozoic IOCG deposits, emplaced at shallow-crustal levels, are enriched with NbeYeSneBeeU. The latter, as well as SneW and Au-EGP deposits are coeval with ca. 1.88 Ga A 2-type granites. The Tapaj os Mineral Province includes a low-grade meta-volcano-sedimentary sequence (2.01 Ga), tonalites to granites (2.0e1.87 Ga), two calc-alkaline volcanic sequences (2.0e1.95 Ga to 1.89e1.87 Ga) and A-type rhyolites and granites (1.88 Ga). The calc-alkaline volcanic rocks host epithermal Au and base metal mineralization, whereas CueAu and CueMo ± Au porphyry-type mineralization is associated with sub-volcanic felsic rocks, formed in two continental magmatic arcs related to an accretionary event, resulting from an Andean-type northwards subduction. The Alta Floresta Gold Province consists of Paleoproterozoic plutono-volcanic sequences (1.98e1.75 Ga), generated in oceaneocean orogenies. Disseminated and vein-type Au ± Cu and Au þ base metal deposits are hosted by calc-alkaline I-type granitic intrusions (1.98 Ga, 1.90 Ga, and 1.87 Ga) and quartz-feldspar porphyries (ca. 1.77 Ga). Timing of the gold deposits has been constrained between 1.78 Ga and 1.77 Ga and linked to post-collisional Juruena arc felsic magmatism (e.g., Colíder and Teles Pires suites). The Transamazonas Province corresponds to a NeS-trending orogenic belt, consolidated during the Transamazonian cycle (2.26e1.95 Ga), comprising the Lourenço, Amap a, Carecuru, Bacaj a, and Santana do Araguaia tectonic domains. They show a protracted tectonic evolution, and are host to the pre-, syn-, and post-orogenic to anorogenic granitic magmatism. Gold mineralization associated with magmatic events is still unclear. Greisen and pegmatite SneNbeTa deposits are related to 1.84 to 1.75 Ga late-orogenic to anorogenic A-type granites. The Pitinga Tin Province includes the Madeira SneNbeTaeF deposit, Sngreisens and Sn-episyenites. These are associated with A-type granites of the Madeira Suite (1.84 e1.82 Ga), which occur within a cauldron complex (Iricoum e Group). The A-type magmatism evolved from a post-collisional extension, towards a within-plate setting. The hydrothermal processes (400 C e100 C) resulted in albitization and formation of disseminated cryolite, pyrochlore columbitization, and formation of a massive cryolit...

Bismuth‐melt trails trapped in cassiterite–quartz veins

“…Our samples come from the Santa Bárbara deposit in the Rondônia tin province (RTP), northern Brazil, characterized by A‐type, metaluminous to peraluminous granitic rocks of the 0.99‐Ga Santa Bárbara batholith (Bettencourt et al., ).…”

Granito Aragão — Suíte intrusiva Nhandú — um granito oxidado, tipo A2, de 1967 a 1964 Ma na Província Aurífera Alta Floresta — Cráton Amazônico

“…De modo geral, a PAAF é constituída por sequências pluto-vulcânicas paleoproterozoicas que exibem idades de cristalização de 1,75 a 2,03 Ga, idades modelo Nd (TDM) entre 2,76 e 2,15 Ga, além de valores e Nd(t) entre -7,62 e 3,09 (Moura, 1998;Santos et al, 2000;Souza et al, 2005; Paes de Barros, 2007;Silva e Abram, 2008;Assis et al, 2014;Assis, 2015;Bettencourt et al, 2016). Esses dados são coerentes com os demais domínios acrescionários do Cráton, visto que indicam magmatismo de fonte arqueana a dominantemente paleoproterozoica, em ambiente de arco juvenil, porém, com variada contribuição crustal.…”

Estudo de inclusões fluidas em quartzo do garimpo do Papagaio, um sistema magmático-hidrotermal, Província Aurífera de Alta Floresta (MT), Cráton Amazônico

“…Nesse conceito, ao final dos anos 1990, iniciou-se uma série de pesquisas relacionadas à origem dos depósitos da província. Desde então, dados de isótopos estáveis e microtermométricos em inclusões fluidas têm evidenciado fluidos magmáticos como importantes contribuintes para as gêneses dos depósitos auríferos da PAAF (e.g., Moura, 1998;Botelho e Moura, 1998;Moura et al, 2006;Silva e Abram, 2008;Biondi, 2009;Rodrigues, 2012;Dias, 2012;Rambo, 2014;Serrato, 2014;Assis, 2015;Trevisan, 2015;Bettencourt et al, 2016).…”

“…Os grupos 3 e 4, no entanto, por estarem hospedados em subvulcânicas, vulcanossedimentares e granitos alcalinos epizonais oxidados (granitos tipo A 2 ), exibem atributos geológicos compatíveis com os sistemas epitermais de low a intermediate sulfidation (Assis et al, 2014;Bettencourt et al, 2016).…”

“…Todas essas características são, portanto, similares àquelas descritas para depósitos profundos gerados em arco magmático, como sistemas do tipo pór-firo, a exemplo das reportadas por Sinclair (2007);Taylor (2007); Sillitoe (2010), Pirajno (1992) e Sun et al (2015 ou mesmo intrusion-related gold systems (IRGS) (e.g., Hart e Goldfarb, 2005;Hart, 2005Hart, , 2007. De acordo com a profundidade da fonte dos fluidos e da preservação do nível crustal, sistemas magmático-hidrotermais semelhantes (e.g., pórfiros de Au ± Cu, epitermal high-intermediate e low sulfidation) vêm sendo sugeridos para as mineralizações associadas ao magmatismo ácido no sul do Cráton Amazônico (Juliani et al, 2005;Paes de Barros, 2007;Xavier et al, 2011;Assis et al, 2014;Assis, 2015;Bettencourt et al, 2016).…”