Textural variation and tin mineralization in granites from the main range province of the Southeast Asian Tin Belt

Pitfield, P.E.J.; Teoh, L. H.; Cobbing, E. J.

doi:10.1002/gj.3350250324

Cited by 24 publications

(10 citation statements)

References 7 publications

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“…The topaz granite matrix rock at Pitinga has many petrographic features in common with rocks described by Pitfield et al (1990). However, the hypothesis considered by these authors for the textural evolution is that the primary phases were consolidated prior to disruption, which is at variance with the petrographic features observed at Pitinga, such as gradational transition and absence of absorption of primary phases.…”

Section: Discussion Of the Textural Featuresmentioning

confidence: 88%

“…This material is commonly described texturally as granite porphyry or porphyritic granite, but the significance of the texture is commonly overlooked. Cobbing et al (1986) and Pitfield et al (1990) described a sequence of texturally and geochemically evolved granites from the Main Range Province (Malaysia) in which the texturally heterogeneous granites were defined as "two-phase variants". They considered that the two-phase texture is formed when a residual magma undergoes a sudden pressure release, resulting in fluidization and invasion of earlier crystallized coarsergrained granite.…”

Section: Introductionmentioning

confidence: 99%

“…The aim of this contribution is to describe the petrographic characteristics of the texture, herein termed "matrix rock", and its relationship to the evolution of the Pitinga granites and their associated mineralization. The texture is referred to as "matrix rock" because the proposed origin is slightly different of the hypothesis considered by Pitfield et al (1990).…”

Section: Introductionmentioning

confidence: 99%

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Matrix Rock Texture in the Oitinga Topaz Granite, Amazonas, Brazil

Lenharo

Pollard

Born

2000

RBG

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The porphyritic topaz granite of the Água Boa batholith at the Pitinga Mine contains rounded quartz and rectangular white and pink feldspar phenocrysts. The fine-grained groundmass is composed of quartz, white and pink feldspar, micas (biotite and Li-siderophylite) and topaz. Accessory minerals include zircon, fluorite, Fe-Ti oxides, RE-minerals, thorite, columbite-tantalite, cassiterite, xenotime and sulphides. The topaz granite is peraluminous, similar to low P 2 O 5 topaz granites, shows some features resulting from post-magmatic metassomatic processes and is considered as a likely source of tin mineralizing fluids in the Água Boa Granite. Three subtypes of topaz granite have been identified, based on modal composition and petrographic features: 1) end-member with around 20% angular phenocrysts; 2) intermediate member with approximately 36% phenocrysts exhibiting dendritic margins; and 3) matrix rock containing around 68% phenocrysts and phenocryst aggregates with irregular and dendritic margins. The estimated amount of K-feldspar phenocrysts decreases at the expense of quartz and plagioclase phenocrysts from the matrix rock to the end-member type. Petrographically, the matrix rock contains relict quartz, Kfeldspar and plagioclase aggregates of the older, medium-to coarse-grained granite facies. These aggregates are surrounded by irregular and anastomosing films of topaz granite displaying magmatic flow textures. Individual phenocrysts of quartz show evidence of partial absorption and subsequent dendritic growth. The model for the formation of the matrix rock at the Pitinga Mine considers that the partially crystallized, earlier facies were intruded by the more evolved topaz granite crystal mush, which underwent decompression during emplacement, causing compositional desequilibrium and later re-equilibration at low pressure associated with late fluid stage separation.

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Section: Discussion Of the Textural Featuresmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Matrix Rock Texture in the Oitinga Topaz Granite, Amazonas, Brazil

Lenharo

Pollard

Born

2000

RBG

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“…The chemical and petrographic evidence suggests that the Tai Lam pluton is a composite intrusive body: the fine-to medium-grained granite hosting an earlier coarse-grained central core. In the fine-to medium-grained lithologies, textural variation forms a continuum from primary texture granite (Pitfield et al 1990) through transitional xenocrystic types, to equigranular microcrystic granite with an entirely derived texture. Such derivative porphyritic granites have been termed two-phase variants in Peninsular Malaysia (Cobbing et al 1986) and are thought to represent a late, high-level pervasive emplacement of highly differentiated residual magma into a partly crystalline coarser-grained granite host.…”

Section: Lion Rock Suitementioning

confidence: 99%

Geochemistry and Rb–Sr geochronology of Mesozoic granites from Hong Kong

Sewell¹,

Darbyshire²,

Langford³

et al. 1992

Geological Society of America Special Papers

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The granites of Hong Kong comprise a variety of assemblages dominated by chemically evolved compositions. They are divided into two suites based on petrographic, geochemical, and age criteria. The oldest and most primitive intrusive units are deformed biotite-hornblende granodiorites and monzogranites of the Lamma Suite. These rocks are characterised by high CaO (1-4-2-7%), and low Nb and Y contents. The Lion Rock Suite (LRS) is dominated by relatively undeformed monzogranite with subordinate quartz syenite and comprises three subgroups. Granites of subgroup I are separated into coarse-and fine-to medium-grained lithologies. The fine-to medium-grained granites are predominantly fluoritebearing with silica contents ranging from 75-5-78%. They are characterised by high total REE, Ga, F, Rb, Nb, and Y contents and yield a Rb-Sr whole-rock isochron age of 155 ± 6 Ma with an initial 87 Sr/ 86 Sr ratio of 0-7101 ± 0-0060 (MSWD = 4-6). Granites of subgroup II comprise a diverse range of compositions (Si0 2 = 63-77%) and are characterised by highly variable trace element abundances. Coarse-grained granites yield an age of 148 ± 9 Ma with an initial 87 Sr/ 86 Sr ratio of 0-7060 ± 0-0006 (MSWD = 0-1). Granites of subgroup III are moderately to highly evolved (Si0 2 = 72-5-77-9%) and the silica-rich compositions are marked by enrichment in Y, Nb, Rb and depletion in Ba and Sr. Rb-Sr whole-rock isochron ages for individual plutons vary from 138 ± 1 to 136 ± 1 and corresponding initial 87 Sr/ 86 Sr ratios are 0-7080 ± 0-0002 (MSWD = 1-2) and 0-7092 ± 0-0006 (MSWD = 0-4). Granites of the Lamma Suite and coarse-grained granites of LRS subgroup I are interpreted as synorogenic I-types, whereas those of LRS subgroups II and III are interpreted as late-orogenic to postorogenic, fractionated I-types. Fineto medium-grained granites of LRS subgroup I have distinctive A-type affinities and together with their association with quartz syenite indicate a transition from compressional to tensional tectonics.

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“…wolframita -(Fe,Mn)WO4, cassiterita -SnO2, molibdenita -MoS2 e columbita-tantalita -(Fe,Mn)(Nb,Ta)2O6). Estes normalmente estão hospedados em cavidades miarolíticas e corpos pegmatíticos nas zonas de cúpula das intrusões graníticas (Suwimonprecha et al, 1995;Pollard, 1995), assim como em zonas hidrotermalizadas (e.g., greisen) e sistemas de veios nas bordas das intrusões e em suas rochas encaixantes (Derre et al, 1986;Pitfield et al, 1990;Haapala, 1995;Moura et al, 2007).…”

Section: Capítulo I I1 Introduçãounclassified

O leucogranito Inhandjara: um exemplo de diferenciação magmato-hidrotermal na província Granítica Itu, SP (Brasil)

Araujo¹

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Deixo aqui meus sinceros agradecimentos a todas as pessoas e entidades que tornaram este trabalho possível, me apoiando, ajudando e incentivando das formas mais sutis e diretas de qual modo fosse necessário. Agradeço à Universidade de São Paulo e ao Instituto de Geociências por ter me recebido de forma acolhedora ao longo da graduação e mestrado. E por toda infraestrutura que tive acesso para desenvolver minha pesquisa. Ao CNPq pela bolsa de mestrado (149342/2016-0) que possibilitou minha dedicação exclusiva ao projeto e à FAPESP (2015/01817-6) pelo auxílio financeiro relativo aos custos analíticos da pesquisa. Também agradeço ao Programa de Mineralogia e Petrologia e seus coordenadores (Prof. Renato Moraes e Profa. Eliane Del Lama) por todo suporte dado. À Profa. Lucelene Martins tenho muito a agradecer, pela paciência que teve e por compartilhar seus conhecimentos comigo. Com sua ajuda me iniciei na pesquisa acadêmica e cresci muito como pessoa ao longo dos 6 anos que convivemos. A partir dos seus ensinamentos sobre as geociências, acho que consegui desenvolver uma pesquisa interessante e de qualidade. Aos Profs. Valdecir Janasi e Adriana Alves pelas aulas de petrologia, dentro e fora das salas, pelas conversas que me iluminaram e por compartilharem seus trabalhos e dados comigo. Isto também vale para a Giovanna Pereira, que me acompanhou no mundo dos granitos de Itu e me ajudou durante todo o mestrado.

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Textural variation and tin mineralization in granites from the main range province of the Southeast Asian Tin Belt

Cited by 24 publications

References 7 publications

Matrix Rock Texture in the Oitinga Topaz Granite, Amazonas, Brazil

Matrix Rock Texture in the Oitinga Topaz Granite, Amazonas, Brazil

Geochemistry and Rb–Sr geochronology of Mesozoic granites from Hong Kong

O leucogranito Inhandjara: um exemplo de diferenciação magmato-hidrotermal na província Granítica Itu, SP (Brasil)

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