Magmatic evolution of Li–F, rare-metal granites: a case study of melt inclusions in the Khangilay complex, Eastern Transbaikalia (Russia)

Micas incorporate a wide variety of elements in their crystal structures. Elements occurring in significant concentrations in micas include: Si, IVAl, IVFe3+, B and Be in the tetrahedral sheet; Ti, VIAl, VIFe3+, Mn3+, Cr, V, Fe2+, Mn2+, Mg and Li in the octahedral sheet; K, Na, Rb, Cs, NH4, Ca and Ba in the interlayer; and O, OH, F, Cl and S as anions. Extensive substitutions within these groups of elements form compositionally varied micas as members of different solid-solution series. The most common true K micas (94% of almost 6750 mica analyses) belong to three dominant solid-solution series (phlogopite–annite, siderophyllite–polylithionite and muscovite–celadonite). Theirclassification parameters include: Mg/(Mg+Fetot) [=Mg#] formicas with VIR >2.5 a.p.f.u. and VIAl <0.5 a.p.f.u.; Fetot/(Fetot+Li) [=Fe#] formicas with VIR >2.5 a.p.f.u. and VIAl >0.5 a.p.f.u.; and VIAl/(VIAl+Fetot+Mg) [=Al#] formicas with VIR <2.5 a.p.f.u. The common true K micas plot predominantly within and between these series and have Mg6Li <0.3 a.p.f.u. Tainiolite is a mica with Mg6Li >0.7 a.p.f.u., or, fortr ansitional stages, 0.3–0.7 a.p.f.u. Some true K mica end-members, especially phlogopite, annite and muscovite, form binary solid solutions with non-K true micas and with brittle micas (6% of the micas studied). Graphical presentation of true K micas using the coordinates Mg minus Li (= mgli) and VIFetot+Mn+Ti minus VIAl (= feal) depends on theirclassification according to VIR and VIAl, complemented with the 50/50 rule.

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“…B, most commonly <0.05 a.p.f.u. (Č erný et al, 1995;Badanina et al, 2004). The bulk of the dioctahedral micas also contain <0.15 a.p.f.u.…”

Section: Tetrahedral Sheetmentioning

confidence: 99%

True and brittle micas: composition and solid-solution series

Tischendorf¹,

Förster²,

Gottesmann³

et al. 2007

Mineral. mag.

150

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“…immiscibility may play an important role in the evolution volatile-rich magmatic system and particularly in the evolution of Li-F-rich granitic magmas (e.g., Kamenetsky and Kamenetsky, 2010, Peretyazhko et al, 2007, Roedder, 1992, Roedder and Coombs, 1967, Shchekina et al, 2013, Veksler, 2004and Veksler et al, 2012. High concentrations of alkali and earth alkali metals favor liquid immiscibility and high concentrations of non-silicate anions (e.g., F − , CO 3 2− ) permit their efficient separation.…”

Section: Studies Of Natural Examples and Experimental Results Have Dementioning

confidence: 99%

“…431 dike differ in density and viscosity. Hydrosaline melts have low densities and low viscosities compared to aluminosilicate-dominated melts , Peretyazhko, 2010, Veksler, 2004and Veksler and Thomas, 2002, and the density contrast of the two melt phases could thus have caused segregation of the hydrosaline melt into structurally higher positions. However, the zoning of both lower ongonite from core to margin (as revealed in drill core) as well as upper ongonite to topazite (as exposed in the exploratory trench) suggests that the hydrosaline melt separated toward both -the upper and the lower -dike margins, which cannot be explained by simple densitydriven segregation.…”

Section: Comparison Of Ore Mineral Assemblages In the Ongonites And Tmentioning

confidence: 99%

Differentiated rare-element mineralization in an ongonite–topazite composite dike at the Xianghualing tin district, Southern China: An electron-microprobe study on the evolution from niobium–tantalum-oxides to cassiterite

Huang

Wang

Xie

et al. 2015

Ore Geology Reviews

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, et al.. Differentiated rare-element mineralization in an ongonite -topazite composite dike at the Xianghualing tin district, Southern China: an electron-microprobe study on the evolution from niobium-tantalum-oxides to cassiterite. Ore Geology Reviews, Elsevier, 2015Elsevier, , 65, pp.761-778. <10.1016Elsevier, /j.oregeorev.2014.08.008>. Differentiated rare-element mineralization in an ongonite-topazite composite dike at the Xianghualing tin district, Southern China: An electron-microprobe study on the evolution from niobium-tantalum-oxides to cassiterite Fang-Fang Huang Ru-Cheng Wang , Lei Xie, Jin-Chu Zhu , Saskia Erdmann , Xu-Dong Che, Rong-Qing Zhang AbstractOur study characterizes in detail the mineralogical, textural and compositional features of a highly evolved, composite ongonite-topazite dike and its magmatic differentiation history. We present compositional data collected by established techniques, i.e. by electron microprobe and wet-chemical analysis, which provide a detailed framework for future studies that employ state-of-the-art analytical techniques. The studied dike (referred to as the No. 431 dike) crops out within the Xianghualing area in the Nanling Range of southern China, in close spatial association with Jurassic Sn-Nb-Ta granite plutons. The rock samples in the No. 431 dike were collected from a structurally lower drill hole and a trench at higher level. The ongonite is encountered throughout the dike, but the topazite is only revealed along the margin of the upper, near-surface dike. The results of whole-rock major and trace element analyses show that the rocks of the No. 431 dike are strongly peraluminous with an average ACNK value of ~ 1.5 for ongonite and > 3.9 for topazite. They are enriched in F, 1.7 wt.% and 5.4 wt.% on average for ongonite and topazite, respectively. The rocks have low Zr/Hf and Nb/Ta ratios, and high levels of ore-forming elements including Nb, Ta, Sn, and W. Silicate and oxide mineral assemblages, textures, and compositions are also distinct for the two rock types studied. In the lower ongonite of the dike, there are abundant phenocrysts of K-feldspar, quartz, and albite, and microphenocrysts of topaz and zinnwaldite in a matrix dominated by quartz, K-feldspar, and albite. Characteristic oxides are columbite-tantalite, tapiolite, and microlite, but cassiterite is absent. The upper ongonite of the dike has a silicate assemblage similar to the lower ongonite; columbite-(Mn), uranomicrolite, and limited amounts of cassiterite are the dominant accessory minerals. The topazite is characterized by large amounts of topaz and zinnwaldite intergrown with quartz, while K-feldspar, albite, and quartz phenocrysts have rounded shapes and are relatively rare. Cassiterite is the most abundant ore mineral, while Nb-Ta oxide minerals are less abundant. We interpret the wholerock compositional trends, mineral textures, assemblages, and compositions to reflect the differentiation of an evolved, initially homogeneous magma that separated into aluminosilicate an...

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“…Both deposits are hosted by the Khangilay granite pluton and are believed to be its satellites (Figure 1) (Badanina et al, 2004;Beskin et al, 1994;Kovalenko et al, 1999;Syritso et al, 2001). In recent years the evolution of rare-metal granites, formation stages and relation to intraplate magmatism was studied.…”

Section: Introductionmentioning

confidence: 99%

Isotope systematics of ore-bearing granites and host rocks of the Orlovka-Spokoinoe mining district, eastern Transbaikalia, Russia

Dolgopolova

Seltmann

Stanley

et al. 2005

Mineral Deposit Research: Meeting the Global Challenge

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Abstract. Pb, Rb and Sr isotope data are reported for the Khangilay, Orlovka and Spokoinoe granite massifs and their host rocks in the OrlovkaSpokoinoe mining district, Eastern Transbaikalia, Russia. Pb isotope analyses indicate one common Pb source for all three granite massifs reflecting a homogenous source melt from which all magmatic members generated. Pb isotope systematics identified two possible scenarios for the source of Li-F granites: 1) a crust-mantle source where a mixture of MORB and continental-derived material were brought together in an orogenic environment; and 2) a type II enriched mantle source where subducted continental material could have been strongly implicated in volcanic suites. New Rb-Sr isotope age data yielded a 143.8±4.2 Ma age for barren granites of Orlovka and Khangilay massifs.

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Magmatic evolution of Li–F, rare-metal granites: a case study of melt inclusions in the Khangilay complex, Eastern Transbaikalia (Russia)

Cited by 96 publications

References 30 publications

True and brittle micas: composition and solid-solution series

True and brittle micas: composition and solid-solution series

Differentiated rare-element mineralization in an ongonite–topazite composite dike at the Xianghualing tin district, Southern China: An electron-microprobe study on the evolution from niobium–tantalum-oxides to cassiterite

Isotope systematics of ore-bearing granites and host rocks of the Orlovka-Spokoinoe mining district, eastern Transbaikalia, Russia

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