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Vol 72, No 2 (2017)
- Year: 2017
- Articles: 8
- URL: https://journals.rcsi.science/0145-8752/issue/view/10662
Article
The Taratash indenter and its role in the geological structure of the Urals
Abstract
This work presents the results of studying zones bounded by the Archean and Early Proterozoic Taratash block, which breaks the meridional structure of the Urals, pinching its structural zones at the latitude of the town of Miass. The mesostructures of rupture zones, microtextures of tectonites, anisotropy of the magnetic susceptibility, and seismic-wave propagation rate in blastomylonites were studied. The kinematic history of the Taratash block consists of two phases: (1) exhumation in the Middle Riphean under conditions of crustal extension; and (2) the formation of an indenter in the Late Paleozoic under conditions of compression.
95-105
The crystallization temperature of vein quartz estimated from the concentration of the titanium paramagnetic center in quartz: A case study of the Peschanka porphyry copper–molybdenum–gold deposit, Western Chukchi Peninsula, Russia
Abstract
The concentration of the Al and Ti paramagnetic impurity centers in pre-ore and ore-stage quartz at the Peschanka porphyry copper–molybdenum–gold deposit in the Western Chukchi Peninsula, Russia were determined using electron paramagnetic resonance spectroscopy (EPR). The [AlO4-/h+]0 concentration in pre-ore and ore-stage quartz varies from 29 to 124 and from 13 to 101 at. ppm, respectively. The contents of the [TiO4-/Li+]0 and [TiO4-/H+]0 centers reach 20 and 6.3 at. ppm, respectively. Pre-ore quartz associated with the formation of biotite–potassium feldspar–quartz alteration and ore-stage quartz associated with the formation of quartz–sericite rocks followed by the ore deposition differ considerably in the Ti center content, especially the [TiO4-/H+]0 center. The [TiO4-/H+]0 concentration is much higher in the pre-ore quartz (>2 at. ppm) than that in the ore-stage quartz related to copper mineralization (<2 at. ppm). The [TiO4-/Li+]0 concentration also decreases from pre-ore to ore-stage quartz. Taking the data we obtained into account, the formation temperature of pre-ore and ore-stage quartz estimated from a titaniumin-quartz geothermometer is 590–470°C (weighted average 520°C) and 510–310°C (weighted average 430°C), respectively. The obtained temperature range of 590 to 310°C is similar to that determined from homogenization of fluid inclusions in quartz.
106-114
Early island-arc granitoids of the Shchuchinskaya zone of the Polar Urals: U–Pb (SIMS) zircon isotope data
Abstract
Granitoids of the Rechnoy and Yalya-Pe paleovolcanoes, which were ascribed to the Silurian Khoimpe complex during a geological mapping, and granitoids of the Nganotsky-1 and Nganotsky-2 plutons that were ascribed to the Early Devonian Yunyaga complex were studied in the Shchuchinskaya zone of the Polar Urals. It was established that according to the mineral and chemical compositions the rocks of the plutons studied correspond to island-arc granitoids of I-type. Zircons from granitoids of the Rechnoy and Yalya-Pe paleovolcanoes and the Nganotsky-1 pluton yielded concordant U–Pb (SIMS) isotope ages of 456 ± 6, 454 ± 4, and 463 ± 3 Ma, respectively, which indicates the existence of an island arc within the Shchuchinskaya zone starting from the Middle–Late Ordovician. Based on the obtained zircon ages of granitoids, the country volcanics were ascribed to the Syaday Formation; the upper stratigraphic boundary of their formation was specified as the Middle–Upper Ordovician.
115-125
The new gold deposit in the Lower Amur region: Chulbatkan, Khabarovsk region
Abstract
The main characteristics of the Chulbatkan gold deposit are considered. This deposit consists of steeply dipping plate- and lens-shaped bodies with dessimination-veinlet mineralization in Late Cretaceous plagiogranites (Lower Amur complex) controlled by the NE- and NW-trending faults. The host rocks are affected by hydrothermal and metasomatic processes (beresitization, silicification, and carbonation). The only useful component in low-grade sulfide and non-rush ore is gold, while the silver content is insignificant. The resource potential of the deposit is estimated at 50 tons.
126-131
The mineral–geochemical evidence of contact transformation of ores of the Dzhusinskoe pyrite–polymetallic deposit (Southern Urals)
Abstract
The Dzhusinskoe pyrite–polymetallic deposit is characterized by an abundant concentration of dykes of basic and intermediate rocks. Thermal metamorphism of ore-host rocks and the recrystallization of ore minerals are associated with the intrusion of post-ore dykes. A regular increase in the homogenization temperature from 156° at a distance from a dyke to 287–305°C in the contact zone was established. Highly saline (6.4–15.7 wt % NaCl eq.) CO2–H2O–NaCl fluids under high pressure (up to 1500 bar) can be associated with the processes of contact and regional metamorphism.
132-138
Radiocarbon dating of small landslides on the slopes of the Mzymta River valley
Abstract
This paper reports the results of the first study aimed at determination of the age of landslides on the southern slope of the Psekhako Ridge and northern slope of the Aibga Ridge (Western Caucasus) using radiocarbon dating of organic material incorporated into the landslide body.
139-142
The studies of the sorption properties of soils at the base of the ash storage of the projected power station on Sakhalin Island
Abstract
The soil sorption properties were determined for the base of ash storage at a proposed power station on Sakhalin Island. The analyses of aqueous extracts of the coal ashes that are intended for use at the station resulted in the identification of potential pollutant elements that might be transferred with the infiltrate of atmospheric precipitation. The composition of the infiltrate-modeling solution was selected based on the data. The sorption capacity of the covering soil by identified pollutants was evaluated at static and dynamic conditions, along with the degree of potential desorption of these pollutants.
143-152
The influence of thawing and consolidation conditions on the deformation properties of thawing soils
Abstract
The results of laboratory studies of the effects of thawing conditions (plane-parallel or three dimensional) on the deformation characteristics (thawing and compression coefficients) of thawing soils (sand, sandy loam, and clay loam) with preset physical properties of massive and layered cryogenic textures are presented. It was found that the values of the thawing coefficient are greater for three-dimensional thawing, whereas those of the compression coefficient are larger for plane-parallel thawing. These data made it possible to establish that the deformation characteristics of thawing soils can be determined experimentally irrespective of thawing conditions.
153-158