Известия Томского политехнического университета: Инжиниринг георесурсов (May 2019)
New data on geochemistry and petrology of Topolninsky complex in Gorny Altai
Abstract
The relevance of the discussed issue is caused by the need of researching petro-geochemistry and petrologic peculiarities of gabbrogranitoid complexes which are related with gold-copper-skarn ore mineralization. The main aim of the research is to study geochemistry of rock types of Topolninsky complex in Gornyn Altai using canonic classification and experimental diagrams on genesis and petrology of magmatites. The methods used in the study. Chemical composition on the major petrogenic elements was determined by silicate assay by X-ray fluorescence (XRF) techniques. Rare elements were determined by inductively coupled plasma on the mass spectrometry «ОРTIMA-4300», for Cu, Zn, Pb, Li - by methods of ISP-AES, the rest elements, including REE wre determined by ISP-MS methods in the VSEGEI Laboratory (St-Petersburg). Absolute age of granitoids was defined by U-Pb method SHRIMP II on zircon in the VSEGEI Laboratory (St-Petersburg). Results. The authors have corrected the absolute age of granitoids formation in Topolninsky complex. For Topolninsky massif by 10 point it is 397,4-4,4 million years, for Karaminsky massif it is 399,3-4,6 million years, corresponding to a border of Lower and Middle Devonian. The paper describes a direct zoning in Karaminsky massif formation. More evolution phases of leucogranites in it are located in the center of massif but early gabbros are on the periphery. The authors estimated different petrochemical coefficients, indices, modules for the rocks of the complex used for decoding the genesis. The ratios of strontium isotopes (87Sr/86 Sr for granodiorites of Topolninsky massif is 0,70556, but for Karaminsk leucogranites is 0,70618) identify mantle nature of melts, formed with crust material contamination. The paper indicates the space and paragenetic relation of different types of ore mineralization with granitoids of Topolninsky complex.
