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Date submitted2022-02-22
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Date accepted2022-09-15
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Date published2022-11-10
The problem of the genesis of the Mesoarchean aluminosilicate rocks from the Karelian craton and their possible use as a quartz-feldspar raw material
The article presents original data obtained in the study of the chemical and mineral compositions of the Late Archean aluminosilicate rocks (formerly called silicites) from the Koikari and Elmus structures of the Vedlozero-Segozero greenstone belt of the Karelian craton (Central Karelia). A comprehensive study of these formations revealed their complex genesis as a result of the late imposition of hydrothermal and metamorphic alteration on sedimentary and volcanic-sedimentary rocks of feldspar-quartz composition. Due to the superimposed metasomatic (temperature?) impact on feldspar-quartz siltstones, Fe was removed from microinclusions in quartz and feldspar and its oxides were concentrated along the grain boundaries. Minerals such as monazite, parisite, allanite are also located either along the grain boundaries of quartz and feldspars, or together with calcite they fill microfractures, which makes it possible to get rid of them when preparing quartz-feldspar concentrates using various beneficiation technologies. According to most indicators limited by GOSTs, individual samples in their natural form meet the requirements for quartz-feldspar raw materials for use as part of batch in the production of diverse types of glass. Additional beneficiation of the feedstock (grinding, screening into narrow classes and further magnetic separation) leads to a decrease in Fe 2 O 3 content to normalized values. The resulting quartz-feldspar concentrates with various particle sizes can be used in the production of building material and fine ceramics (sanitary and ceramic products, facing and finishing tiles, artistic, household porcelain and faience). The homogeneity of the mineral and chemical composition, the possibility of compact extraction and beneficiation (including in mobile small-sized installations) increase the prospects and competitiveness of this non-traditional feldspar raw material from Central Karelia.
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Date submitted2008-10-05
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Date accepted2008-12-30
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Date published2009-12-11
Thermobaric granite crystallization conditions of the severniy massif (the Chukotka) in accordance with the feldspars study data
- Authors:
- V. I. Alekseev
The Kamentsev I.E. and Sorokin N.D. method is used to investigate the dependence of Al-Si-ordering and structure of alkaline feldspars decomposition in different granites from the Severny massif (Chukotka) under thermobaric conditions of their crystallization. The temperature and pressure on the granite system in the initial period of feldspars ordering are determined quantitatively for the first time for the region. Progressive pressure change which exceeds lithostatic load by 750 МPа at the late stage of lithium-fluoride granites formation is revealed. It is hypothesized that the deposits similar to explosive ore-bearing breccia can be discovered in the Chukotka. The conclusion on possibility to apply the Sobolev-Dobretsov concept of superpressure to interpret the process of rare-metal magmatism is drawn.
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Date submitted1951-08-23
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Date accepted1951-10-03
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Date published1952-11-20
Feldspars of ceramic pegmatites of the Southern Karelia
- Authors:
- S. A. Rudenko
Recently, a discussion has developed regarding the genesis of pegmatites. The beginning of this discussion was laid by D. S. Korzhinsky in 1937. In 1944, A. N. Zavaritsky demonstrated the inconsistency of the physicochemical substantiation of the pegmatite process proposed by Vogt and Niggli and accepted by A. E. Fersman. Later, in 1947, he put forward a new theory of the genesis of pegmatites, contradicting the idea that pegmatites are a product of direct crystallization of residual melt (A. E. Fersman's theory). According to A. N. Zavaritsky, the main structural features of pegmatites are created as a result of recrystallization of certain igneous rocks. Next, V. D. Nikitin, who studied ceramic and mica pegmatites (1946-1951), based on a detailed analysis of the relationships between individual minerals and structural components of pegmatites, developed ideas about the genesis of pegmatites of this specific type, which are basically consistent with the theory of A. N. Zavaritsky. However, much effort is still needed to more fully resolve issues related to establishing all the features of the transformations that both the deposits as a whole and the individual minerals that make them up undergo during the complex and lengthy process of pegmatite formation. This article highlights the main features of the evolution of feldspars in ceramic pegmatites of Southern Karelia.