Evolution in accessory mineral paragenesis, during metasomatic alteration of granites in eastern Transbaykalia massifs

Сырицо, Л. Ф.; Chernik, L.N.

doi:10.1080/00206816709474517

Cited by 5 publications

(7 citation statements)

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“…The model most commonly proposed (Beus and Zalashkova 1964;Syritso and Chernik 1967;Hu et al 1984) envisages ore formation to result from the upward migration of postmagmatic fluids through the consolidated granite. These fluids produce zoned and overprinting alteration assemblages, leach metals from the lower zones, and deposit them in the upper zones.…”

Section: Discussionmentioning

confidence: 98%

“…3). Although known principally as a tin-tungsten province (Kozlov et al 1974;Ivankin and Kulagashev 1980), granites associated with TaNb-Li-Be mineralization are also reported (Boguslavskiy et al 1966;Syritso and Chernik 1967). The rare-metal granites are associated with Mesozoic granites of possible Jurassie age which intrude Palaeozoic metasediments (Syritso and Chernik 1967;Navilkin 1973).…”

Section: Eastem Transbaikaimentioning

confidence: 93%

“…In detail, the alteration patterns developed may be much more complicated than the simplified models suggest. For example, Beus et al (1962) and Syritso and Chernik (1967) recognize several generations of a1bitization and microclinization in rare-metal granite cupolas in eastern Siberia. In these tantalum-bearing granites, the green microcline variety amazonite is a common alteration mineral (Beus et al 1962;Zalashkova and Gerasimovskii 1974).…”

Section: Postmagmatic Alterationmentioning

confidence: 97%

“…The most common feldspathic alterations observed are the replacement ofplagioclase by microcline and microcline by albite. These are accompanied by replacement of original biotite by muscovite and Li-micas (Syritso and Chernik 1967), or of sodic amphibole by varieties richer in Iithium (Kinnaird et al 1985a). In detail, the alteration patterns developed may be much more complicated than the simplified models suggest.…”

Section: Postmagmatic Alterationmentioning

confidence: 98%

“…These fluid-rock interaction processes can result in trends towards increasing Al20 3 , N a20 and F with decreasing Si0 2 in progressively more albitized zones towards the roof ofthe pluton. K 2 0 frequently decreases during albitization, but may increase substantially in association with the development of amazonite-albite granites in the a pical zones of some intrusions (Beus et al 1962;Syritso and Chernik 1967).…”

Section: Postmagmade Trendsmentioning

confidence: 98%

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Geochemistry of Granites Associated with Tantalum and Niobium Mineralization

Pollard

1989

Lanthanides, Tantalum and Niobium

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Tantalum and niobium mineralization is often assoeiated with geoehemieally speeialized granites whieh are eharaeterized by enriehment in fluorine, and by the development ofpervasive, postmagmatie alteration. Three major varieties of granite ean be reeognized:1. Alkaligranites eontaining alkali pyroxenes and/or amphiboles whieh are eharaeterized by high Fe, F, Nb, Zr, Rb, Sn and REE, and by low CaO, Ba, Sr and Ta/Nb. Thesegranites oeeur prineipally in anorogenie settings, and are assoeiated mainly with niobium mineralization.2. Biotite and/or museovite granitesoften eontaining Fe-Li mieas whieh are eharaeterized by high F, Rb and Sn, and by low CaO, Ba, Sr and Eu. Thesegranites oeeur in both anorogenie and pastaragenie settings, and are assoeiated prineipally with Nb-Ta( -Sn) mineralization.3. Lepidolite-albite granitesoften eontaining topaz whieh are eharaeterized by high Al20 3 , F, Li, Rb, Sn, Ta and Ta/Nb, and by low Ba, Sr, Eu, Zr and REE. These granites oeeur prineipally in pastaragenie settings, but also form marginal facies varieties ofbiotite and/or museovite granites in both anorogenie and pastaragenie settings. Lepidolite-albite granites are generally assoeiated with Ta(-Nb-Sn) mineralization.Many granites assoeiated with tantalum and niobium mineralization are zoned vertieally, with the finer-grained porphyritie, granophyrie, pegmatitie and/or miarolitie roeks whieh oeeur insmall eupolas grading downwards into medium-and eoarse-grained granite. This vertieal textural zonation indieates an important eoneentration ofvolatile and ore elements in the roof ofthe plutons from the earliest stages of erystallization.The mineralogieal and geoehemieal features of rare-metal granites refleet features of their souree roek eompositions, as well as magmatie fraetionation and postmagmatie alteration proeesses. Trends towards inereasing Al 2 0 3 , Na 2 0, Fand a variety ofrare metals in the most evolved roeks may refleet erystal and/or liquid fraetionation during magma evolution and/or postmagmatie alteration by interaetion with fluorine-rieh hydrothermal fluids.Detailed petrographie and mineralogieal study of a variety of examples is required before geoehemieal and isotopie modeHing ofthese rare-meta! granites ean advanee beyond the preliminary stage.

show abstract

Section: Discussionmentioning

confidence: 98%

Section: Eastem Transbaikaimentioning

confidence: 93%

Section: Postmagmatic Alterationmentioning

confidence: 97%

Section: Postmagmatic Alterationmentioning

confidence: 98%

Section: Postmagmade Trendsmentioning

confidence: 98%

See 3 more Smart Citations

Geochemistry of Granites Associated with Tantalum and Niobium Mineralization

Pollard

1989

Lanthanides, Tantalum and Niobium

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Genetic Modelling of Greisen-Style Tin Systems

Pollard¹,

Taylor²,

Cuff

1988

Geology of Tin Deposits in Asia and the Pacific

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Geologic Characteristics and Genetic Problems Associated with the Development of Granite-Hosted Deposits of Tantalum and Niobium

Pollard

1989

Lanthanides, Tantalum and Niobium

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Granite-hosted deposits of tantalum and niobium form massive or sheetlike zones of disseminated mineralization in the upper portions of some geochemically specialized granite plutons. Such mineralization usually reaches a maximum in association with albite and ftuorite ( ±lithium)-rich zones in small, late-stage intrusions. These zones are formed in some cases by crystallization of ftuorine-rich magmas, and in other cases may result from postmagmatic alteration.The detailed texturaland timing information required to assess the inftuence of magmatic and postmagmatic processes in the development of these deposits is lacking in many cases. Two major genetic models for mineralization envisage metal accumulation to result either from enrichment within the upper portion of a zoned magma chamber at the magmatic stage, or by leaching from lower levels of the granite with precipitation in the upper levels at the postmagmatic stage. Further detailed mineralogical, textural, geochemical and isotopic studies are required before the relative importance of these alternatives can be fully assessed.

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Evolution in accessory mineral paragenesis, during metasomatic alteration of granites in eastern Transbaykalia massifs

Cited by 5 publications

References 0 publications

Geochemistry of Granites Associated with Tantalum and Niobium Mineralization

Geochemistry of Granites Associated with Tantalum and Niobium Mineralization

Genetic Modelling of Greisen-Style Tin Systems

Geologic Characteristics and Genetic Problems Associated with the Development of Granite-Hosted Deposits of Tantalum and Niobium

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