Low-K Calc-Alkaline Granitic Series of Southeastern Tocantins State: Chemical Evidence for Two Sources for the Granite-Gneissic Complexes in the Paleoproterozoic Almas-Dianópolis Terrane

Cruz, Emílio Lenine Carvalho Catunda Da; Kuyumjian, Raul Minas; Boaventura, Géraldo Resende

doi:10.25249/0375-7536.2003332125136

Cited by 20 publications

(11 citation statements)

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“…Cruz & Kuyumjian (1998, Cruz et al (2003), Kuyumjian et al, (2012), Gorayeb (1988) e Costa (1985 são os principais responsáveis pelos projetos desenvolvidos no embasamento do extremo norte da faixa. Seus trabalhos são importantes não só pela caracterização geológica, mas também por apresentarem as primeiras datações feitas na região.…”

Section: Justificativa Do Projetounclassified

Geologia, geocronologia e geoquímica do embasamento granítico paleoproterozóico em natividade, Faixa Brasília Norte

Sousa¹

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Section: Justificativa Do Projetounclassified

Geologia, geocronologia e geoquímica do embasamento granítico paleoproterozóico em natividade, Faixa Brasília Norte

Sousa¹

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“…Segundo, respectivamente, Silva et al (1990) (Thomsen & Kuyumjian 1994b, Cruz & Kuyumjian 1998, Cruz et al 2003. Segundo Thomsen & Kuyumjian (1994a), a formação ferrífera bandada da região de Conceição do Tocantins apresenta composição química semelhante à obtida por Graf (1978) para formações ferríferas paleoproterozoicas.…”

Section: Litoquímica E Ambiente Geotectônicounclassified

Geologia e ocorrências de ouro do Terreno Granito-Greenstone do Tocantins, TO: síntese do conhecimento e parâmetros para exploração mineral

Kuyumjian

Cruz²,

Filho

et al. 2012

RBG

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Resumo O Terreno Granito-Greenstone do Tocantins é composto por domos granito-gnáissicos e estreitas faixas de greenstone, formados em ambiente de subducção no Paleoproterozoico. As ocorrências de ouro nesse terreno são hospedadas em quartzo de veios associados a produtos de alteração hidrotermal de anfi bolito, formação ferrífera bandada e rochas graníticas em zonas de cisalhamento. Sugere-se que as ocorrências e depósitos de ouro do Terreno Granito-Greenstone do Tocantins formaram-se durante a orogênese Brasiliana, com a participação de fl uidos hidrotermais de origem metamórfi ca, com contribuição granítica. Os dados obtidos até o presente revelam critérios de exploração mineral para ouro no Terreno Granito-Greenstone do Tocantins.Palavras-chave: Tocantins, greenstone, ouro, exploração mineral. Abstract Geology of and gold occurrences in the Granite-Greenstone Terrane of Tocantins, Central Brazil: state of the art and guide lines for mineral exploration programs.The Paleoproterozoic Tocantins GraniteGreenstone Terrane is composed of granite-gneissic domes and narrow intervening greenstone belts. Tholeiitic metabasalts and calc-alkaline metatonalites have chemical composition characteristic of subduction tectonic environment. The main gold concentrations occur in iron-rich amphibolite, banded iron formation and granitic rocks. It is suggested that the Tocantins Granite-Greenstone Terrane gold occurrences and deposits were formed by dominantly metamorphic hydrothermal fl uids during the Brasiliano Orogeny, with granitic contribution. Guide lines for mineral exploration programs for gold in the Tocantins Granite-Greenstone Terrane are presented.

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“…This probably suggests that some sort of assimilation with and/or partial melting of evolved crustal rocks were operative during the evolution of these rocks (e.g. 'Suite 2' TTGs in Almas-Dianopolis Terrane, Central Brazil; Cruz et al 2003). The patchy microcline replacing sodic plagioclase in some Bilgi granodiorites (Fig.…”

Section: Petrogenesismentioning

confidence: 99%

Geochemistry of granitoids of Bilgi area, northern part of eastern Dharwar craton, southern India — Example of transitional TTGs derived from depleted source

Dey

Chaki

2009

J Geol Soc India

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Mildly deformed granitoids exposed around Bilgi in the northernmost part of the eastern Dharwar craton are divided into two groups viz. granodiorites and monzogranites. The granodiorites contain microgranular enclaves and amphibolite xenoliths, and show low-Al TTG affinity with high SiO 2 (71-74 %), Na 2 O, Y and Sr/Y, moderate to moderately high Mg#, Cr and Ni, low to moderate LILE, and low Nb and Ta. However, compared to similar TTGs from different cratons the Bilgi granodiorites have distinctly higher K 2 O, K 2 O/Na 2 O, Rb and lower REE and Th. The amphibolite xenoliths are characterized by variable enrichment of K 2 O, Rb, Ba and Th and depletion of Ti, Zr and P compared to MORB. The microgranular enclaves are quartz diorite to granodiorite in composition with high Mg, Ni and Cr, and compared to MORB, are enriched in LILE and depleted in Ti and Y. The monzogranites, compared to the granodiorites, display higher SiO 2 , K 2 O and Rb with lower Mg#, although still maintaining the high Na 2 O, Ni and Cr and low REE character.The Bilgi granodiorites are explained as transitional TTGs late synkinematic with respect to regional deformation. Geochemical signatures and regional geological set up suggest that they are probably derived from partial melting of a highly depleted slab material (metabasalt) followed by variable contamination or assimilation of intermediate crustal rocks in a subduction zone set up. Late stage fluid activity on the granodioritic magma is probably responsible for the generation of monzogranites. The amphibolite xenoliths predate the granodiorites and possibly represent fragments of a schist belt carried away by the granitic magma. They are probably island arc basalt derived from mantle source that has been metasomatized by slab-derived fluids. The microgranular enclaves are coeval with the Bilgi granodiorites and also likely to be island arc magmas derived from mantle variably enriched in slab-derived and within-plate components.

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Low-K Calc-Alkaline Granitic Series of Southeastern Tocantins State: Chemical Evidence for Two Sources for the Granite-Gneissic Complexes in the Paleoproterozoic Almas-Dianópolis Terrane

Cited by 20 publications

References 0 publications

Geologia, geocronologia e geoquímica do embasamento granítico paleoproterozóico em natividade, Faixa Brasília Norte

Geologia, geocronologia e geoquímica do embasamento granítico paleoproterozóico em natividade, Faixa Brasília Norte

Geologia e ocorrências de ouro do Terreno Granito-Greenstone do Tocantins, TO: síntese do conhecimento e parâmetros para exploração mineral

Geochemistry of granitoids of Bilgi area, northern part of eastern Dharwar craton, southern India — Example of transitional TTGs derived from depleted source

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