Feldspar of alkali-granite complex Khaldzan-Buregteg (Western Mongolia): features of structure and chemical composition
Composition, structure and other features of minerals are the most important genetic characteristics reflecting the conditions of etheir formation and allowing reconstructing the life of a geological object. Feldspar due to its crystallization in a wide range of temperatures and pressures, isomorphi...
| Main Authors: | , , |
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| Format: | Article |
| Language: | Russian |
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Tomsk Polytechnic University
2016-10-01
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| Series: | Известия Томского политехнического университета: Инжиниринг георесурсов |
| Subjects: | |
| Online Access: | http://izvestiya-tpu.ru/archive/article/view/1808 |
| Summary: | Composition, structure and other features of minerals are the most important genetic characteristics reflecting the conditions of etheir formation and allowing reconstructing the life of a geological object. Feldspar due to its crystallization in a wide range of temperatures and pressures, isomorphic substitutions and breakdown of solid solutions, is the important object of mineralogical studies. The aim of the study is to identify characteristics of a structure and chemical composition of feldspar from multiphase alkali-granite complex Khaldzan-Buregteg in Western Mongolia. Object of the research: alkaline granitic formation of Lake zone of Western Mongolia, which brings together a number of large massifs of the Khaldzan-Buregteg group (Ulaan-Khuren, Gurvan-Uneet, Ulaan-Unet, Tsogtu-Ula, Tsohni Ula, Khaldzan-Buregteg) of Early Paleozoic age, as well as the late-magmatic differentiates granitoid - pegmatites and postmagmatic derivatives - hydrothermalites and metasomatic rocks. Research methods. The authors have carried out the comprehensive study of feldspar, including optical and morphological analysis of the mineral, using X-ray diffraction, X-ray fluorescent, X-ray microanalysis as well as quantitative and semi-quantitative spectral analysis. Results. The paper describes the morphology and habitus of the investigated feldspar; perthitic structures of the mineral were studied; the X-ray diffraction characteristics of K-feldspar and plagioclase were determined. The authors obtained the data on chemical composition of feldspar and calculated the crystallochemical formulas of the mineral. It was ascertained that all the considered species rocks of the complex Khaldzan-Buregteg (nordmarkites, granites, pegmatites and metasomatites) have two-feldspar composition with predominance of potassium phase. The maximum microcline dominates among potassium feldspar, low albite dominates among plagioclase. Based on the typomorphic characteristics the authors carried out the genetic typing of potassium feldspar, determined rocks crystallization temperature, evaluated the evolution of the mineral formation environment on the object. It was determined that the regular change of structural and chemical features of feldspars is observed from high-temperature granite phases to lower-temperature late-magmatic and post-magmatic derived formations. |
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| ISSN: | 2500-1019 2413-1830 |