Age of the Ust’-Gilyui sequence in the Stanovoi Complex of the Selenga-Stanovoi Superterrain, Central Asian fold belt

According to the results of U-Pb geochronological investigations, the age of the amphibolite protoliths (metabasalts) in the Ust??-Gilyui sequence within the Stanovoi Complex of the Amazar-Gilyui structural and formational zone in the Selenga-Stanovoi Superterrain of the Central Asian fold belt can be estimated at 193 ± 1 Ma. The Nd model age of the Ust??-Gilyui metasedimentary rocks is in the interval of t _Nd(DM) = 1.1?C3.1 Ga. This information along with the previously obtained geochronological data are indicative of the fact that the Ust??-Gilyui sequence consists of metasedimentary and metavolcanic rocks of various ages: (1) volcanic rocks with the age of 193 ± 1 Ma; (2) metasedimentary and metavolcanic rocks broken through by the Paleozoic granitoids dated to 370 Ma and characterized by minimum estimations of t _Nd(DM) = 1.1 Ga, i.e., rocks with an age of 1.1?C0.4 Ga. In addition, it is quite possible that this sequence also includes more ancient rocks. The SSS Amazar-Gilyui structural and formational zone is likely to be a tectonic mélange composed of the metasedimentary and metavolcanic rocks of the Mesozoic and, probably, Paleozoic and Early Precambrian ages. The studied zone was formed in the Mesozoic, most likely, in the course of the collision processes initiated by the closing up of the Mongol-Okhotsk Ocean.     

Discharge of Salt Groundwater in the Estuary of the Razdol’naya River (Amur Bay) in February 2020

Water Resources - In February 2020, geochemical tracers along with hydrochemical and hydrological characteristics were used to reveal a discharge site of salt groundwaters in the head of the...     

General approaches to the assessment of the state and the prediction of changes in the reliability of power line river crossings

The procedure for assessment developed in the paper for the conditions of northwestern, central, and southern European Russia is an efficient means for comparative analysis of power lines in terms of individual and integral impact of hazardous hydrological and slope processes on their vulnerability, for determining of the periodicity of monitoring observations and the composition of such studies.     

Age and origin of the Kitoi sillimanite schist deposit,eastern Siberia

Doklady Earth Sciences -     

Protoliths of the metamorphic rocks of the Fedorov Complex, Aldan shield: Character, age, and geodynamic environments of origin

Geochemical data indicate that the protoliths of the overwhelming majority of the metamorphic rocks composing the Fedorov Complex in the Aldan granulite megacomplex were volcanic rocks of three groups, which occur in different proportions in the complex: (i) volumetrically predominant (no less than 90%) continuous differentiated island-arc basalt-andesite-dacite-rhyolite series, (ii) within-plate basalts, whose composition was similar to that of low-Ti traps, and (iii) basalts of composition similar to that of continentalrift basalts. The U-Pb zircon crystallization age of the metamorphosed basaltic andesites of the Fedorov Complex was estimated at 2006 ± 3 Ma, which testifies, when considered together with preexisting geochronological data, that the complex was produced during a time span of no longer than 25 m.y. A model is proposed according to which the complex was produced within the geodynamic system of the active continental margin of the Olekma-Aldan continental microplate and the Fedorov island arc.     

Radium Isotopes and Nutrients in Razdolnaya River Estuary (Amur Bay,the Sea of Japan) in the Period of Summer Flood

Water Resources - The activity of dissolved radium isotopes 223Ra, 224Ra, 228Ra, the concentrations of nutrients: ammonium, nitrates, nitrites, phosphates, silicates, total nitrogen, and total...