Petrology and textural evolution of granites associated with tin and rare-metals mineralization at the Pitinga mine, Amazonas, Brazil

Lenharo, S L R; Pollard, P. J.; Born, Helmut

doi:10.1016/s0024-4937(02)00201-3

Cited by 77 publications

(42 citation statements)

References 22 publications

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“…The mineralized granitoids of Madeira Suite were emplaced at around 1.83 Ga ago in an entirely anorogenic setting, and represent an outstanding Sn and Nb-Ta ore producers (Horbe et al 1991, Lenharo 1998, Costi et al 2000, Lenharo et al 2003. Mafic to intermediate tholeiitic rocks of the Quarenta Ilhas Formation have ∼1.78 Ga and consist of subvolcanic bodies emplaced throughout pre-existing ring structures (Veiga Jr. et al 1979, Santos et al 2002.…”

Section: Local Geologymentioning

confidence: 99%

Paleoproterozoic (~1.88Ga) felsic volcanism of the Iricoumé Group in the Pitinga Mining District area, Amazonian Craton, Brazil: insights in ancient volcanic processes from field and petrologic data

Pierosan

Lima

Nardi

et al. 2011

An. Acad. Bras. Ciênc.

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The Iricoumé Group correspond to the most expressive Paleoproterozoic volcanism in the Guyana Shield, Amazonian craton. The volcanics are coeval with Mapuera granitoids, and belong to the Uatumã magmatism. They have U-Pb ages around 1880 Ma, and geochemical signatures of A-type magmas. Iricoumé volcanics consist of porphyritic trachyte to rhyolite, associated to crystal-rich ignimbrites and co-ignimbritic fall tuffs and surges. The amount and morphology of phenocrysts can be useful to distinguish lava (flow and dome) from hypabyssal units. The morphology of ignimbrite crystals allows the distinction between effusive units and ignimbrite, when pyroclasts are obliterated. Co-ignimbritic tuffs are massive, and some show stratifications that suggest deposition by current traction flow. Zircon and apatite saturation temperatures vary from 799 • C to 980 • C, are in agreement with most temperatures of A-type melts and can be interpreted as minimum liquidus temperature. The viscosities estimation for rhyolitic and trachytic compositions yield values close to experimentally determined melts, and show a typical exponential decay with water addition. The emplacement of Iricoumé volcanics and part of Mapuera granitoids was controlled by ring-faults in an intracratonic environment. A genesis related to the caldera complex setting can be assumed for the Iricoumé-Mapuera volcano-plutonic association in the Pitinga Mining District.

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Section: Local Geologymentioning

confidence: 99%

Paleoproterozoic (~1.88Ga) felsic volcanism of the Iricoumé Group in the Pitinga Mining District area, Amazonian Craton, Brazil: insights in ancient volcanic processes from field and petrologic data

Pierosan

Lima

Nardi

et al. 2011

An. Acad. Bras. Ciênc.

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“…This is more than in the A-type granites from the Erzgebirge (32-47 ppm Ga, Al/1000Ga = 1.5-2.3; this paper) or in the highly fractionated A-type Madeira Complex in Brazil (max. 59 ppm Ga, Al/1000Ga = 2.2; Lenharo et al 2003). Differences in the ionic potentials of Al and Ga are particularly manifested in water-and F-rich residual melts where a distinct relative enrichment with Ga occurs, regardless of the geochemical type of parental magma.…”

Section: Changes In Al/ga and Si/ge Values During Pluton Evolutionmentioning

confidence: 95%

Gallium and germanium geochemistry during magmatic fractionation and post-magmatic alteration in different types of granitoids: a case study from the Bohemian Massif (Czech Republic)

Breiter¹,

Gardenová²,

Kanický³

et al. 2013

Geologica Carpathica

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Abstract:Contents of Ga and Ge in granites, rhyolites, orthogneisses and greisens of different geochemical types from the Bohemian Massif were studied using inductively coupled plasma mass spectrometry analysis of typical whole-rock samples. The contents of both elements generally increase during fractionation of granitic melts: Ga from 16 to 77 ppm and Ge from 1 to 5 ppm. The differences in Ge and Ga contents between strongly peraluminous (S-type) and slightly peraluminous (A-type) granites were negligible. The elemental ratios of Si/1000Ge and Al/1000Ga significantly decreased during magmatic fraction: from ca. 320 to 62 and from 4.6 to 1.2, respectively. During greisenization, Ge is enriched and hosted in newly formed hydrothermal topaz, while Ga is dispersed into fluid. The graph Al/Ga vs. Y/Ho seems to be useful tool for geochemical interpretation of highly evolved granitoids.

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“…Microcline and quartz phenocrysts contain frequent inclusions of albite laths arranged in a discontinuously rounded pattern. This textural feature is typically magmatic and is indicative of their crystallization from the late stage residual and highly fractionated granitic melts (Stemprok 1991, Schwartz 1992, Zhu et al 2001, Lenharo et al 2003.…”

Section: Local Geological Settingmentioning

confidence: 99%

Mineralogy, stable isotopes (δ18O and δ34S) and 40Ar-39Ar geochronology studies on the hydrothermal carapace of the Igarapé Manteiga W-Sn Deposit, Rondônia

Nascimento

Souza

2017

Braz. J. Geol.

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ABSTRACT:The Igarapé Manteiga W-Sn deposit is formed by a granite stock that intrudes in the Paleoproterozoic basement. The mineralization is encapsulated in an alumino-siliceous hydrothermal carapace formed by greisen, vein-veinlets and breccia, developed in the apex zone of a granite stock. At this site, wolframite, cassiterite and sulfides-minerals, as well as siderite, monazite, xenotime, hematite and others, are spread out or in massive clusters associated with quartz, topaz, zinnwaldite and fluorite. Wolframite is not zoned and relatively rich in Fe, and poor in Nb and Ta. Cassiterite exhibits growth-zones with light-yellow to dark-orange colors, and is rich in Ta, and poor in Ti, W, Mn and U. Oxygen and sulfur (δ 18 O and δ 34 S) isotope data on the ore-and sulfide-minerals indicates that it is a magmatic source, with closing temperatures from 230°C to 480°C. The hydrothermal phase was cyclical and protractedly active, promoting greisenization and hydrofracturing. The lowering of temperature and the change in the composition of fluids (from oxidized to reduced) controlled the precipitation of the hydrothermal mineral assemblage. The 40 Ar-39 Ar analyses reveal a plateau age of 988 Ma, interpreted as the closure time for the hydrothermal processes responsible for mineralization, which is linked to the final magmatic evolution of the Rondônia Intrusive Suite (995-991 Ma). . KEYWORDS:

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Petrology and textural evolution of granites associated with tin and rare-metals mineralization at the Pitinga mine, Amazonas, Brazil

Cited by 77 publications

References 22 publications

Paleoproterozoic (~1.88Ga) felsic volcanism of the Iricoumé Group in the Pitinga Mining District area, Amazonian Craton, Brazil: insights in ancient volcanic processes from field and petrologic data

Paleoproterozoic (~1.88Ga) felsic volcanism of the Iricoumé Group in the Pitinga Mining District area, Amazonian Craton, Brazil: insights in ancient volcanic processes from field and petrologic data

Gallium and germanium geochemistry during magmatic fractionation and post-magmatic alteration in different types of granitoids: a case study from the Bohemian Massif (Czech Republic)

Mineralogy, stable isotopes (δ18O and δ34S) and 40Ar-39Ar geochronology studies on the hydrothermal carapace of the Igarapé Manteiga W-Sn Deposit, Rondônia

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