Open AccessUranium-lead age of granites Chigirin massif
Author(s) -
L.M. Stepanyuk,
N.M. Konoval,
O.B. Vysotsky,
Т.I. Dovbush,
Olena Bilan
Publication year - 2020
Publication title -
geohìmìâ ta rudoutvorennâ
Language(s) - English
Resource type - Journals
eISSN - 2617-3395
pISSN - 2224-6487
DOI - 10.15407/gof.2020.41.077
Subject(s) - massif , microcline , geology , geochemistry , plagioclase , biotite , porphyritic , zircon , leucogranite , monazite , pegmatite , batholith , feldspar , sericite , pluton , metamorphic rock , quartz , gneiss , paleontology , tectonics
The age of granites of the Chyhyryn massif – 2040.0 ± 1.1 million years – was determined by the uranium-lead isotope method for accessory monazite. According to the results of mineral studies of zircon crystals, the conclusion that granites this mass, as well as granitoids of Novoukrainsky, is formed due to the crust, which indicates the presence of relict nuclei of substrate rocks in the middle of the crystals of this mineral. It is proposed to combine in one (for example, Kropyvnytskyi) complex All two-field spar granitoids of the Ingul megablock, leaving in the composition of the new Ukrainian just gabbroids, intrusive nature and a deep source that does not create doubts. The Chyhyryn massif has an area of over 3,500 km2, located in the northern part of the Ingul megablock. The main volume of rocks that make up the array is occupied by granites, which in their composition correspond to the granites of the Kirovograd complex. According to structural features, trachytoid and porphyritic granites differ among them, and biotite and garnet-biotite granites differ in composition. The inclusions are usually represented by a microcline (occupying 40-50% of the rock volume), having a tabular shape, 3-8 mm in size, which often contain small inclusions of quartz and plagioclase. Large plate crystals of the microcline are often crushed from the edges. In addition to the microcline, plagioclase crystalline crystals up to 5 mm in size occur in areas. Porphyry-like granites of the Chyhyryn massif, common within the Golovkivsky quarry. Monocytes from biotite granite were dated to determine the time of formation of the Chyhyryn massif. Granite was selected in the Golovkivsky quarry, located south of the village. Skelivka.