PHYSICAL AND CHEMICAL FEATURES OF THE SAVRAN ORE FIELD (UKRAINIAN SHIELD)

Abstract

The article reveals the features of the polycyclic course of the processes of formation of metamorphic complexes of the Dniester-Bug geoblock in general, and the Savran-Synitsivska area in particular. It is found that they have different intensity of manifestation of thermal endogenous processes in spatially close and similar in composition rocks. At the level of mineral composition, this is reflected in the absence of certain minerals, or certain generations of minerals, as well as in the crystal anatomy of accessory minerals-geochronometers - zircon and monazite; which is an additional source of information when dating the main geological processes.Particular attention is paid to establishing the time of formation of granite massifs and pegmatoid bodies within the Mayske deposit, as processes that preceded the formation of ore mineralization. It has been established that the age of aplite-pegmatoid granites of the Southern massif is (2.379 ± 0.076) billion years [1], while the U-Pb age of vein pegmatoid granites is (2.040 ± 0.050) billion years [2]. The large time gap (over 300 million years) between the formation of the massif of aplite-pegmatoid and veined pegmatoid granites contradicts geological observations, according to which pegmatoid granites are a veined facies of leucocratic aplite-pegmatoid granites. Most likely, the figure (2.379 ± 0.076) billion years for zircon-I corresponds to the early stages of the formation of the Southern massif of aplitic- pegmatoid granites. The formation of granite massifs, pegmatoid formations and intensive metasomatic processing of the stratum at about 2.0 billion years is confirmed by the U-Pb age of monazite from charnockites in the Pervomaisk region (2.06+0.001) billion years [2] and Re-Os data of the age of molybdenites from pegmatites is (2.06+0.009) billion years, and 2.02 billion years – from biotite- quartz-oligoclase metasomatites of the Maiskoye deposit [3].The course of the processes of silicic-alkaline metasomatism, palingenesis, and acid leaching and their role in ore formation are analyzed. It has been established that deposits with formation depths of 8 to 15 km (Mayske deposit) are characterized by vein and vein mineralization with a predominance of pyrite, arsenopyrite, and pyrrhotite in the composition of ores; peri-ore changes are represented by zones of carbonatization, muscovitization, biotitization, and albitization.