Year: 2018
Pages: 58-67
UDC: 553.411.071+903+902.03
Number: 2
Type: scientific article
DOI: http://doi.org/10.31084/2619-0087/2018-2-4
Topic: ARTICLES AND PUBLICATIONS
Authors: Kazakov, Peter V.
According to the latest data of the authors, petro-geochemical features of the pyrite-bearing paleovolcanic complexes of the Tubinsk-Gai belt of the Magnitogorsk megazone of the Southern Urals are characterized. The following complexes were formed in the Late Emsian-Early Eifelian period, containing a number of pyrite deposits: 1) Buribay basalt-rhyolite (D1e2) (Buribayskoe, Yubileinoe deposits), 2) Gaisky basalt-andesibasalt-andesite-rhyolite (D1e2) (Gaiskoye deposit), 3) Makan-October basalt-andesibasaltandesite (D1e2) (Makanskoye, Oktyabrskoye deposits), 4) Byamak basalt-andesibasalt-andesite-rhyodacite (D1e2) (series of pyrite-polymetallic deposits) and 5) Podolsky hybrid basalt-andesibasalt-andesite-rhyodacite (D2ef1) (Podolsk and other smaller deposits). The composition of the ore-bearing complexes varies regularly in the latitudinal direction (from west to east), in accordance with the eastern submersion of the subduction slab, from the island-arc tholeiitic and boninitic to the calc-alkaline and subalkaline (shoshonitic). The change in the composition of volcanic complexes is correlated with the features of mineralization (from copper-pyrite to pyrite-polymetallic). The latitudinal subduction zonation is combined with the zonation along the belt extension: from the south to the north the Gai complex containing one super-large deposit is changed by the Buribay, Makan-October and Podol complexes, containing large Yubileynoe, Podolsk and a number of mediumsized massive sulfide deposits; further on — by the Baymak complex with numerous small gold-massive sulfide-polymetallic and barite-polymetallic objects. The reduction of the total reserves of ores and metals (Cu+Zn) and the size of individual deposits correlates with the change in the size of ore-bearing structures — from the super-large (50 km in diameter) Gai ring structure to the large Makan caldera and Podol ring structure (respectively, diameters of about 3 km and 17 km) and to numerous small (0.5–1.0 km) buildings of the Baimak ore district. Refined and established petrological and geochemical features of ore-measuring complexes in combination with previously obtained data on the geological structure of the Tubinsk-Gai belt made it possible to formulate criteria for massive sulfide fertility. The productivity of massive sulfide ore formation increases in the ore-bearing complexes with the increase of volumes of tholeiitic island-arc basalts in the ore-bearing complexes and, correspondingly, with the increase of the Na2O/K2O ratio and the decrease in the TiO2, Zr, REE and La/Yb ratio.
gold, placer, Baishevsky archeological microdistrict, artifacts, Quarternary lake deposits, Southern Urals