scholarly journals Pyrochlore-Group Minerals in the Granite-Hosted Katugin Rare-Metal Deposit, Transbaikalia, Russia

Minerals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 490
Author(s):  
Anastasia E. Starikova ◽  
Ekaterina P. Bazarova ◽  
Valentina B. Savel’eva ◽  
Eugene V. Sklyarov ◽  
Elena A. Khromova ◽  
...  
Keyword(s):  
Nepheline Syenite ◽  
Rare Metal ◽  
Granitic Rocks ◽  
Ore Deposit ◽  
Metal Deposit ◽  
Pyrochlore Group ◽  
Magmatic Stage ◽  
Rare Metal Deposit ◽  
Late Magmatic Stage ◽  
High Concentrations

Pyrochlore group minerals are the main raw phases in granitic rocks of the Katugin complex-ore deposit that stores Nb, Ta, Y, REE, U, Th, Zr, and cryolite. There are three main types: Primary magmatic, early postmagmatic (secondary-I), and late hydrothermal (secondary-II) pyrochlores. The primary magmatic phase is fluornatropyrochlore, which has high concentrations of Na2O (to 10.5 wt.%), F (to 5.4 wt.%), and REE2O3 (to 17.3 wt.%) but also low CaO (0.6–4.3 wt.%), UO2 (to 2.6 wt.%), ThO2 (to 1.8 wt.%), and PbO (to 1.4 wt.%). Pyrochlore of this type is very rare in nature and is limited to a few occurrences: Rare-metal deposits of Nechalacho in syenite and nepheline syenite (Canada) and Mariupol in nepheline syenite (Ukraine). It may have crystallized synchronously with or slightly later than melanocratic minerals (aegirine, biotite, and arfvedsonite) at the late magmatic stage when Fe from the melt became bound, which hindered the crystallization of columbite. Secondary-I pyrochlore follows cracks or replaces primary pyrochlore in grain rims and is compositionally similar to the early phase, except for lower Na2O concentrations (2.8 wt.%), relatively low F (4 wt.%), and less complete A- and Y-sites occupancy. Secondary-II pyrochlore is a product of late hydrothermal alteration, which postdated the formation of the Katugin deposit. It differs in large ranges of elements and contains minor K, Ba, Pb, Fe, and significant Si concentrations but also low Na and F. Its composition mostly falls within the field of hydro- and keno-pyrochlore.

scholarly journals Y-REE mineralization in biotite-arfvedsonite granites of the Katugin rare-metal deposit, Transbaikalia, Russia

2019 ◽  
Vol 487 (1) ◽  
pp. 88-92 ◽  
Author(s):  
A. E. Starikova ◽  
E. V. Sklyarov ◽  
V. V. Sharygin
Keyword(s):  
Rare Metal ◽  
Chemical Data ◽  
Host Granite ◽  
Ree Mineralization ◽  
Granite Formation ◽  
Metal Deposit ◽  
Mineral Phases ◽  
Magmatic Stage ◽  
Rare Metal Deposit ◽  
Melt Segregation

We provide the results of study of the extremely enriched in Y-REE carbonate-fluorine isolations from biotite-arfvedsonite granite of the Katugin rare metal deposit. New chemical data of isolations mineral phases - gagarinite-(Y), tveitite-(Y), fluocerite-(Ce), basnaesite, fluornatropyroclore, are delivered. Carbonate-fluoride globule in quartz of hosting granite gives possibility to estimate crystallization order. This finding might be the evidence of silicate-fluorine immiscibility suggested before for Y-REE segregations in the Katugin granites. Fluorine melt segregation took likely place at the magmatic stage of biotite-arfvedsonite granite formation. It causes host granite depletion with fluorine and redistribution of REE and Y in fluorine salt melt.

Geochemistry and Isotope Composition of Paleoproterozoic Granites and Felsic Volcanics of the Elash Graben: Evidence of the Heterogeneity of the Early Precambrian Crust

2021 ◽  
Vol 62 (10) ◽  
pp. 1175-1187
Author(s):  
A.D. Nozhkin ◽  
O.M. Turkina ◽  
K.A. Savko
Keyword(s):  
Isotope Composition ◽  
Volcanic Rocks ◽  
Rare Metal ◽  
Temporal Association ◽  
Metal Deposit ◽  
Wide Range ◽  
Rare Metal Deposit ◽  
Geochronological Study ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Abstract —The paper presents results of a petrogeochemical and isotope–geochronological study of the granite–leucogranite association of the Pavlov massif and felsic volcanics from the Elash graben (Biryusa block, southwest of the Siberian craton). A characteristic feature of the granite–leucogranites is their spatial and temporal association with vein aplites and pegmatites of the East Sayan rare-metal province. The U–Pb age of zircon from granites of the Pavlov massif (1852 ± 5 Ma) is close to the age of the pegmatites of the Vishnyakovskoe rare-metal deposit (1838 ± 3 Ma). The predominant biotite porphyritic granites and leucogranites of the Pavlov massif show variable alkali ratios (K2O/Na2O = 1.1–2.3) and ferroan (Fe*) index and a peraluminous composition; they are comparable with S-granites. The studied rhyolites of the Tagul River (SiO2 = 71–76%) show a low ferroan index, a high K2O/Na2O ratio (1.6–4.0), low (La/Yb)n values (4.3–10.5), and a clear Eu minimum (Eu/Eu* = 0.3–0.5); they are similar to highly fractionated I-granites. All coeval late Paleoproterozoic (1.88–1.85 Ga) granites and felsic volcanics of the Elash graben have distinct differences in composition, especially in the ferroan index and HREE contents, owing to variations in the source composition and melting conditions during their formation at postcollisions extension. The wide range of the isotope parameters of granites and felsic volcanic rocks (εNd from +2.0 to –3.7) and zircons (εHf from +3.0 to +0.8, granites of the Toporok massif) indicates the heterogeneity of the crustal basement of the Elash graben, which formed both in the Archean and in the Paleoproterozoic.

scholarly journals Eudialyte Group Minerals from the Lovozero Alkaline Massif, Russia: Occurrence, Chemical Composition, and Petrogenetic Significance

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1070
Author(s):  
Julia A. Mikhailova ◽  
Yakov A. Pakhomovsky ◽  
Taras L. Panikorovskii ◽  
Ayya V. Bazai ◽  
Victor N. Yakovenchuk
Keyword(s):  
Chemical Composition ◽  
Nepheline Syenite ◽  
Granite Gneiss ◽  
Lovozero Massif ◽  
Eudialyte Group ◽  
Magmatic Stage ◽  
Late Magmatic Stage ◽  
Volcaniclastic Rocks ◽  
Layered Complex ◽  
Alkaline Massif

The Lovozero Alkaline Massif intruded through the Archean granite-gneiss and Devonian volcaniclastic rocks ca. 360 Ma ago and formed a large laccolith-type body. The lower part of the massif (the Layered complex) is composed of regularly repeating rhythms: melanocratic nepheline syenite (lujavrite, at the top), leucocratic nepheline syenite (foyaite), foidolite (urtite). The upper part of the massif (the Eudialyte complex) is indistinctly layered, and lujavrite enriched with eudialyte-group minerals (EGM) prevails there. In this article, we present the results of a study of the chemical composition and petrography of more than 400 samples of the EGM from the main types of rock of the Lovozero massif. In all types of rock, the EGM form at the late magmatic stage later than alkaline clinopyroxenes and amphiboles or simultaneously with it. When the crystallization of pyroxenes and EGM is simultaneous, the content of ferrous iron in the EGM composition increases. The Mn/Fe ratio in the EGM increases during fractional crystallization from lujavrite to foyaite and urtite. The same process leads to an increase in the modal content of EGM in the foyaite of the Layered complex and to the appearance of primary minerals of the lovozerite group in the foyaite of the Eudialyte complex.

Ba-dominant fluoroaluminates from the Katugin rare-metal deposit (Transbaikalia, Russia)

2017 ◽  
Vol 472 (1) ◽  
pp. 67-71 ◽  
Author(s):  
A. E. Starikova ◽  
V. V. Sharygin ◽  
E. V. Sklyarov
Keyword(s):  
Rare Metal ◽  
Metal Deposit ◽  
Rare Metal Deposit
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