Time of manifestation of uplift in the territory of the North Caucasus
The ssion-track dating method makes it possible to reconstruct the evolution of uplifts caused by tectonic processes.The purpose of research in the structural-formation zones (SFZ) of the Greater Caucasus (GC) are: 1) determination of the range of uplift in time;2) identi cation of zoning in the time of manifestation of the uplift;3) clari cation of the connection between the manifestation of uplift and regional processes (thrust, collision, etc.).The objects of research are apatite crystals from granitoid and metamorphic rocks of the pre-Alpine basement. Research methodology. 44 samples weighing up to 15 kg each were taken from the massifs of granitoid and metamorphic rocks by the method of chips, with measurements of coordinates and elevations. Monomineral fractions of apatite were isolated by otation and separation in heavy liquids. From each sample, 300-500 apatite crystals were taken, which were divided into two parts. In one part, the induced track density was determined - it was heated for ve hours at 550 ° C to remove spontaneous tracks, and the second did not heat up. Then, samples of apatite in two parts were irradiated in a nuclear reactor. After irradiation, both spontaneous (ps) and induced track (pi) portions of the samples were placed in epoxy resin plates and etched under the same conditions (1 % HNO3, 5 minutes, 20 °C). The tracks were counted using an optical microscope. Results. The distribution of ssion-track (FT) uplift ages in the SFZ GC showed that the Elbrus transverse fault is the western boundary of the Trans-Caucasian transverse uplift (T-CTU) zone, which is traced along the left side of the river valley. Baksan from the head of the river Azau in the south and up to Kavminvody in the north, dividing the GC territory into two blocks with different history of uplifts: western (from the Belaya river in the west to the Baksan river in the east) and eastern (from the Baksan river valley in the west to the Ardon river valley and possibly further east).Then, samples of apatite in two parts were irradiated in a nuclear reactor. After irradiation, both spontaneous (ps) and induced track (pi) portions of the samples were placed in epoxy resin plates and etched under the same conditions (1 % HNO3, 5 minutes, 20 ° C). The tracks were counted using an optical microscope. Results. The distribution of ssion-track (FT) uplift ages in the SFZ GC showed that the Elbrus transverse fault is the western boundary of the Trans-Caucasian transverse uplift (T-CTU) zone, which is traced along the left side of the river valley. Baksan from the head of the river Azau in the south and up to Kavminvody in the north, dividing the GC territory into two blocks with different history of uplifts: western (from the Belaya river in the west to the Baksan river in the east) and eastern (from the Baksan river valley in the west to the Fiagdon river valley and possibly further east).An important role in the distribution of uplift times is played by the Elbrus transverse fault, which has features of rift-like structures.The research results have, in addition to scienti c and practical importance - they are necessary when choosing safe places for the construction of small hydroelectric power plants in the mountainous regions of Russia.