The magnitude of the transverse contraction of the Middle Tien Shan along the “Karabuk” profile at the late orogenic stage

The detailed geological profile “Karabuk” constructed in recent years, crossing the triad of alpine structures “Naryn Depression - Baibichetoo Uplift - Atbashi Depression [[CHECK_DOUBLEQUOT_ENT]] in the central part of Tien Shan, provides new material for studying the style and parameters of deformations at the late phase of the Indian - Eurasian plate collision. Using original methodological techniques and in accordance with the basic principles of balanced sections method, the horizontal deformation of the rock complex of the Cenozoic sedimentary cover (a meridional reduction in the width of the orogenic belt) was determined, starting from the end of the Neogene. Variations in the thickness of the cover layers determined during the research were taken into account. The presented tectonic reconstruction demonstrates the structure of a single Naryn-Atbashi sedimentary basin before the intense deformations at the late orogenic phase. It is significant, that the magnitude of deformations on individual segments of the profile differs markedly. The cover of the Atbashi depression is more deformed, its width has decreased by 6 km (about 17%) in this section, while the borders of the wider Naryn depression have converged by only 3.7 km (8%). The total South-North contraction of the NBA system measured by us during the Cenozoic is about 10 km (12% of its original width). The values of the contraction from south to north (the horizontal component of the deformation) obtained by us compared with the values given by other researchers.

Precambrian obducted serpentinites in the Rhodope Massif

The Precambrian metamorphic complex in the Rhodope Massif is built of two lithostratigraphic units: the lower is an ancient granite-gneiss continental crust – Prarhodopian Group (PRG), and the upper one – a Neoproterozoic metamorphosed volcano-sedimentary rock complex – Rhodopian Group (RG). The lower stratigraphic levels of the RG are occupied by an ophiolitic association consisting of serpentinites, amphibolites, and metagabbros. The serpentinites constantly occupy the same level between the continental gneisses surface of the PRG and the base of the RG. The high degree of serpentinization (85–95%) indicates low temperature hydration metamorphism on the surface of an ultrabasic ocean plate. The formation of the Rhodope ophiolitic association has taken place in a Neoproterozoic supra-subduction zone in three stages: a. serpentinization at the ocean floor; b. obduction of serpentinite fragments, scraped from soft and plastic hydrated coat of the sliding ultrabasic plate; c. SSZ-type autochthonous Neoproterozoic (610–566 Ma) basic volcanism, including and covering serpentinite bodies. This determines a heterogeneous nature of the ophiolitic association. The lower granite-gneiss complex – PRG may have been a part of some microcontinent after the breaking of the supercontinent Rodinia. The formation of a supra-subduction zone – SSZ and the obduction of serpentinite fragments started during ocean closure preceding the amalgamation of supercontinent Gondwana.

TAEZHNY EPITHERMAL DEPOSIT OF SILVER ORE (SIKHOTE-ALIN): REGIONAL POSITION, FORMATION CONDITIONS, GEOCHEMISTRY AND MINERAL COMPOSITION

The Taezhny is a silver with gold (Au:Ag = 1:100) vein deposit with a pronounced mineralogical and geochemical selenium specializationof ores. The deposit is located in the eastern part of the Sikhote-Alin orogenic belt, 700 km north of Vladivostok. The regional position of the describable ore-bearing area, similar to the Mexican deposits of the Guanajuato area typical of the Pacific region, is determined by its relationto the Early Cretaceous island-arc terrane with a distinct geochemical enrichment in silver of its folded rock complex. Quartz vein bodies are located in submeridional fracturesfeathering NE-trending sinistral strike slip faults.The near-ore alteration is dominated bysericitization and silicification of host sandstones. The main silver minerals are freibergite, acanthite, and Se-containing pyrargyrite, polybasite, stephanite. Kustelite, electrum, aguilarite, allargentum, and discrasite are much less abundant. The mineralogical and geochemical zoning of ore bodies emphasized by a highly productive Ag-sulfosalt assemblage enriched in Sein the upper part of veins and the poor ores with predominant acanthite at depth is revealed.The veins were formed with the participation of sodium chloride solutions saturated with CO2 and CH4, at the temperature range from 400 to 150° C. The deposition of productive sulfosalt-bearingassemblages occurred with a suddendecrease in pressure under conditions of discharge of magmatic-meteoric fluids in circulation zones in the sandstones under the screen of volcanic rocks overlying the Kema terrane.

Analysis of the Sub-Surface Distribution of Graphite Minerals Using the Geoelectrical Resistivity Method in the Sabilambo Village, Kolaka Regency, Southeast Sulawesi Province

Southeast Sulawesi Province is one of the regions in Indonesia that has abundant mineral resources, the availability of several types of minerals is strongly influenced by the diversity of rock formations that make up the area. The metamorphic complex is one of the rock formations in the Southeast Sulawesi Province. Where the rock complex is divided into 2 (two), namely: Pompangeo Complex and Mekongga Complex, the distribution area of this metamorphic rock is estimated around 50% of the total land area of Southeast Sulawesi Province. This rock complex is very possible to contain mineral deposits, one of which is graphite mineral deposits. However, the problem that is now is the identification of the potential for subsurface distribution of graphite excavated material has not been carried out. Therefore, this research was conducted to determine the potential for subsurface distribution of graphite mineral deposits is using geoelectrical resistivity method where is using Wenner-Schlumberger configuration, this research activity was conducted in the Sabilambo Village in Kolaka Regency, where most of the research area is metamorphic complex. Based on the result of the resistivity analysis, subsurface distribution of graphite mineral deposits in the study area can be found on the surface to a depth of 33.5 meters below ground level, with layer thickness between 1.25 to 27.77 meters and has a resistivity value of 14.9 Ωm – 86.1 Ωm.