Study of the tectonic structure and modern geodynamics of the nickel-copper-sulfide Kun-Manyo deposit at the stage of its field the development

Currently, the Kun-Manyo nickel-copper-sulfide deposit in the north of the Khabarovsk Krai is being prepared for development, with part of the reserves expected to be mined by underground mining. To justify the rational order of opening and excavation of sub-ore reserves it is necessary to have objective information on rock mass condition, which can be received as a result of complex geodynamic and geomechanical investigations. The established geodynamic position of the deposit, determined by its location at the junction of actively interacting large tectonic elements of the Euro-Asian tectonic plate – the tectonic stress of the North Asian craton and the Amur plate, as well as within the modern Olekmo-Stanovo seismic zone, has allowed the massif of the field area to be classified as tectonically stressed. An analysis of the data of the GPS-observation points on the territory of the Russian part of the Amur tectonic plate, the results of calculations of the vector field of velocities of modern movements of points, made within the framework of the ITRF – 2000 coordinate system, as well as the results of in-situ geomechanical studies of rock massifs of the Amur Plate’s rock-bump hazardous deposits, have made it possible to establish the current tectonic regime of the deposit area – a region of intense modern compression with a predicted intensity of more than 50 MPa. By methods of morphometric analysis and remote sensing, it has been found that the relative relief excesses were significant (700–1000 m), which may lead to an uncompensated horizontal component of geostatic stress. The most extended lineaments of the relief have predominantly southeasterly extension. The identified features of the tectonic structure and regional neotectonics have made it possible to determine the most probable direction and magnitude of the current main horizontal compression, which could be further used in solving various geomechanical problems in the exploitation of the field.

STRUCTURE OF ALDAN-MAYA SEDIMENTARY BASIN

The boundaries and inner structure of the Aldan-Maya sedimentary basin located in the east of the North Asian craton are specified on basis of seismographic and geological evidence synthesis.

AGE AND SOURCES OF PROTOLITHS OF METASEDIMENTARY ROCKS IN THE EASTERN TUKURINGRA TERRANE OF THE MONGOL-OKHOTSK FOLD BELT: RESULTS OF U-TH-PB, LU-HF, AND SM-ND ISOTOPE STUDIES

The article presents detrital zircon U-Th-Pb and Lu-Hf isotope data for metasedimentary rocks from the eastern Tukuringra Terrane, as well as whole-rock Sm-Nd isotope data. Our analyses show that the zircons in metasedimentary rocks are mostly early Mesozoic in age. Early Paleozoic and Neoproterozoic zircons are also common, whereas early Precambrian zircons are virtually absent. The age of the youngest zircon population places a lower age limit on the age of the Tungalin Formation at 204 Ma (Late Triassic, Rhaetian), the Dugda Formation at 181 Ma (Early Jurassic, Toarcian), and the Tangomen Formation at 189 Ma (Early Jurassic, Pliensbachian). Essentially all Mesozoic, Paleozoic and Neoproterozoic zircons are characterized by Neo- and Mesoproterozoic Hf-model ages (tHf(DM) = 1.41–0.46 Ga, tHf(C) = 1.55–0.49) and Mesoproterozoic Nd-model ages (tNd(DM) = 1.25–1.10 Ga, tNd(С) = 1.31–1.14). Our results suggest that sediments for deposition were sourced mainly from the continental Amuria Superterrane, but not from the southern margin of the North Asian Craton.