Petrochemistry of the Paleoproterozoic Udokan copper-bearing sedimentary complex

The maturity of terrigenous material of the Paleoproterozoic Udokan copper-bearing sedimentary complex is considered. The average values of hydrolyzate module (HM), alumina-silica module (AM), and Pettijohn’s coefficient of maturity appreciably vary throughout the Udokan Complex. Among cupriferous sandstones, rocks of the Aleksandrovka Formation are characterized by the highest maturity, whereas rocks of the Chitkanda Formation are distinguished by the lowest maturity. The maturity of cupriferous sandstones of the Sakukan Formation corresponds to that of host rocks. The maturity of cupriferous sandstones from the Aleksandrovka Formation is much higher than that of host rocks. In the Chitkanda Formation, the cupriferous sandstones are much less mature than host rocks. Climatic conditions in provenances estimated from the Nesbitt index of chemical weathering or chemical index of alteration (CIA) may be characterized as temperate ones without prominent climatic features. Most CIA values range from 46 to 66. The formation of copper-bearing sediments was closely related to the periods of volcanic activity.     

Abodes for life in carbonaceous asteroids?

Thermal evolution models for carbonaceous asteroids that use new data for permeability, pore volume, and water circulation as input parameters provide a window into what are arguably the earliest habitable environments in the Solar System. Plausible models of the Murchison meteorite (CM) parent body show that to first-order, conditions suitable for the stability of liquid water, and thus pre- or post-biotic chemistry, could have persisted within these asteroids for tens of Myr. In particular, our modeling results indicate that a 200-km carbonaceous asteroid with a 40% initial ice content takes almost 60 Myr to cool completely, with habitable temperatures being maintained for ∼24 Myr in the center. Yet, there are a number of indications that even with the requisite liquid water, thermal energy sources to drive chemical gradients, and abundant organic “building blocks” deemed necessary criteria for life, carbonaceous asteroids were intrinsically unfavorable sites for biopoesis. These controls include different degrees of exothermal mineral hydration reactions that boost internal warming but effectively remove liquid water from the system, rapid (1-10 mm yr⁻¹) inward migration of internal habitable volumes in most models, and limitations imposed by low permeabilities and small pore sizes in primitive undifferentiated carbonaceous asteroids. Our results do not preclude the existence of habitable conditions on larger, possibly differentiated objects such as Ceres and the Themis family asteroids due to presumed longer, more intense heating and possible long-lived water reservoirs.     

Long-wave planetary radar: Radar sounding of the soil of Phobos in the <Emphasis Type="Italic">Phobos-Grunt</Emphasis> project

The specific features of the radar sounding of the soil of Phobos during the performance of the Russian Phobos-Grunt project have been considered. The parameters of the long-wave subsurface sounding radar designed in order to study the electrophysical characteristics of the soil of Phobos, reveal the depth structure, estimate the rock density, and perform radar mapping of the satellite relief and surface roughness have been justified. The scheme of the experimental sounding of the soil of Phobos is presented.     

Estimating the influence of seismic and meteorological factors on the accuracy of measurements by relative gravimeters

Continuous high-precision long-term gravity measurements are carried out at the geophysical observatory located in the experimental base of Vladimir State University. The long time series of gravity acceleration and its standard deviation are obtained. The factors responsible for the increases in the studied deviations are analyzed. The recommendations for improving the accuracy of relative gravity measurements are formulated.     

Key elements of construction and exploitation of a land-based seismic-gravimetric complex

Creation of a seismic-gravimetric complex that can operate automatically for several years allows one to record the movements of the test masses of seismometers and gravimeters simultaneously in different frequency bands. The overlapping of these frequencies takes place in the region of tenths of a Hertz. The seismic-gravimetric complex contains two relative CG-5 gravimeters, one absolute A10 gravimeter, one three-component Ugra seismic station, one automatic meteorological station, and a two-frequency GPS receiver. The relative gravimeters are used as the basic instrument. For these devices the problem of displacement of the gravimeter scale “zero” was solved. To perform long-term monitoring observations using the seismic-gravimetric complex, a gravimetric observatory was built in the area with a low level of technogenic noises. As a result of the preliminary geophysical observations, it turned out that the informative parameter is a root-mean-square deviation of the measured gravity force values.     

The large Bystrinskoe Cu–Au–Fe deposit (Eastern Trans-Baikal Region): Russia’s first example of a skarn–porphyry ore-forming system related to adakite

The Bystrinskoe skarn-porphyry Cu–Au–Fe deposit (Eastern Trans-Baikal Region) is confined to skarn zones, which were formed along the contact of granitoids referred to the Shakhtama intrusive complex (J_2–3), with terrigenous–carbonate sedimentary rocks. Commercial (Cu–Au–Fe ± W, Mo) mineralization was formed due to the regional postcollision development involving the intrusion of porphyritic granitoids, the derivatives of oxidized adakite highly magnesian magmas enriched in water, sulfur, and metals, which could develop under melting of garnet-bearing amphibolite in the mafic lower crustal arc.