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Vol. 18 (2015 year), No. 2
Kaulina T. V., Bayanova T. B., Talat Ahmad, Lyalina L. M., Mishra M. K., Nitkina E. A., Elizarov D. V., Serov P. A.
Evolution of the Central Indian tectonic zone:Geochemical and isotope-geochronological data
In the framework of the Russian-Indian joint research projects geochemical and geochronological study of granitoid rocks across the Central Indian Tectonic Zone has been carried out. Geochronological data suggest that the Central Indian Tectonic Zone is composed primarily of Proterozoic rocks, formed as a result of several stages of granitoid magmatism: at 2.43, 2.34-2.31, 1.73-1.72 and 1.53-1.51 Ga. Metamorphic transformations reflected by Sm–Nd and Rb–Sr systems of rocks and minerals occurred 1.37-1.1 Ga ago that allows comparing the final processes in the Central Indian Tectonic Zone with the Grenville orogeny and it can be used for the reconstruction of Rodinia
(in Russian, стр.10, fig. 3, tables. 1, ref 13, Adobe PDF, Adobe PDF 0 Kb)
Vol. 19 (2016 year), No. 1, DOI: 10.21443/1560-9278-2016-1/1
Kudryashov N. M., Skublov S. G., Kalinin A. A., Lyalina L. M.
Mineralogical and geochemical characteristics of zircon from
diorite porphyry dyke in Sergozerskoe gold occurrence (the Strel'ninsky greenstone belt, Kola region)
Mineralogical and geochemical investigation of zircon from diorite porphyry from Sergozerskoe occurrence has been carried out. Study of morphology and inner structure of zircon crystals in back scattered electron rays as well as assaying for content and distribution of Rare Earth Elements in mineral grains have given important information about conditions of crystallization and following metasomatic alteration of zircon. Zircon characteristics show that it crystallized in a melt, enriched in fluid phase. Fluid influence lasted after zircon crystallization, this reflected in uneven composition of the mineral and in configuration of REE spectra, typical for metasomatic zircon. Similar zircon characteristics have been noted in zircons from other gold occurrences in greenstone belts in the Kola region
(in Russian, стр.0, fig. 0, tables. 0, ref 0, Adobe PDF, Adobe PDF 0 Kb)
Vol. 20 (2017 year), No. 1, DOI: 10.21443/1560-9278-2017-20-1/1
Kaulina T. V., Nerovich L. I., Bocharov V. N., Lyalina L. M., Il'chenko V. L., Kunakkuzin E. L., Kasatkin I. A.
Raman spectra of impact zircons in the Jarva-varaka layered massif
(the Monchegorsk ore region, the Kola Peninsula)
Zircon crystals from granophyre norites of the Jarva-varaka massif of the Monchegorsk ore region (the Kola Peninsula) have been studied by means of back-scattered electron (BSE) imaging and Raman spectroscopy. The Jarva-varaka massif according to geological and geochemical data has been compared with the Sudbury structure, for which an impact origin is assumed. Zircon study is stipulated by zircon ability to keep signs of shock metamorphism even under granulite-facies conditions, thus it can be used for identification of ancient impact structures. BSE images reveal complicated internal texture – darker central domains (cores) and light rims without texture. Mineral inclusions in zircon are represented by sillimanite and plagioclase which indicates that the studied zircon grains were inherited from the host aluminous gneisses. Zircon crystals show variation of Raman spectra from the core of crystals with typical zircon Raman pattern to complete absence of spectral bands in the marginal parts and rims. Mineral inclusions in zircon rims also have no Raman spectra. Such patterns may be associated with the transformation of crystalline zircon (and mineral inclusions in it) to diaplectic glass under the influence of shock metamorphism, core domains were screened by rims and thus preserved their structure. The received data suggest the participation of the meteorite impact in the formation of the Jarva-varaka massif that requires further investigation.
(in Russian, стр.11, fig. 4, tables. 0, ref 28, Adobe PDF, Adobe PDF 0 Kb)
Vol. 22 (2019 year), No. 1, DOI: 10.21443/1560-9278-2019-22-1
Kaulina T. V., Lyalina L. M., Il'chenko V. L.
Sequence of REE-Th-U minerals in the Litsa uranium ore area (the Kola Region)
Mineralogical and petrographic study of REE-Th-U mineralization in rocks of the Litsa uranium ore area has been carried out to detail the sequence of formation of rare-earth, uranium and thorium minerals in rocks. The study has been aimed to Dikoe ore occurrence with the earliest in the area REE-Th-U mineralization described by previous workers. Rocks and minerals have been studied by means of optical and electron microscopy, as well as microprobe methods, this has made it possible to identify the relationship of minerals and the sequence of their crystallization. In monzodiorite veins and host biotite gneisses are found accessory minerals represented by monazite-(Ce), uraninite, zircon, apatite, and thorite, which are in close association with each other, but are formed at different stages of formation and transformation of the host rocks. Monazite-(Ce) with high thorium content (9–10 %) in association with apatite grows at the magmatic stage of monzodiorite crystallization both in the veins themselves and after the fine-grained mass of minerals in the biotite plates of the host gneisses. Magmatic zircon with elevated content of thorium and uranium crystallizes in veins together with monazite and apatite. The formation of uraninite, containing impurities of sulfur, yttrium and calcium, and associated with areas of granulation of plagioclase, occurs as a result of hydrothermal-metasomatic processes in veins simultaneously with the formation of textureless zircon rims with high calcium, iron, and hafnium content in the host gneisses. The development of galgenbergite and anglesite rims around uraninite grains reflects the next superimposed hydrothermal processes
(in Russian, стр.11, fig. 6, tables. 3, ref 12, Adobe PDF, Adobe PDF 0 Kb)