Том 74, № 4 (2019)

The state-of-the-art, obtained results, and possible perspectives of short-term prediction of strong earthquakes are analyzed. Based on examples of specific research it is shown that such prediction with the required detail, accuracy, and reliability has not been carried out as of the present and is not expected to occur in the future. This is a fundamental consequence of the nonlinearity of seismic geodynamic systems that function in deterministic-chaotic manner in the fractal geomedium. The effectiveness of prediction in the form of the ratio between the numbers of successfully predicted and recorded earthquakes within some area is no more than a few percent. Frequent communications about allegedly attained short-term prediction effectiveness of almost 100% are disproven both by the absence of adequate and reliable methods and the steady extension of the list of seismic catastrophes that were not predicted.

Cenomanian–Turonian organic-rich clays deposited under periodic anoxic conditions in the basins of that time are recorded in carbonate sections. Cenomanian–Turonian boundary deposits were studied in the Biyuk-Karasu River section (Central Crimea). Dark organic-rich clays were found to intercalate with carbonate-poor clays in the formation during oceanic anoxic events. Mixed type II–III kerogens are abundant in these black beds which constitute oil source strata that are similar in their mineral assemblages but different in their organic matter contents.

A study of secondary alterations of felsic effusives with reservoir properties from the top of the West Siberian pre-Jurassic complex (Tomsk Region) was performed. The lithological, petrographic, and mineralogical features of these rocks indicate their alterations by low-temperature hydrothermal solutions, while the weathering products that are widespread at the top of the basement have not been clearly identified. The reservoir properties of the studied rocks are probably due to fracturing and leaching.

Armalcolite (Mg,Fe)Ti₂O₅ is a characteristic mineral of lunar titaniferous basalts that occurs widely in island-arc low-alkaline plagiolherzolites and olivine gabbro–norite–dolerites of the Early Bajocian Pervomaiskoe–Ayu-Dag complex of mesozoids in Crimea, especially in Balaklava sea cliffs near Sevastopol. Cumulose Mg-olivine contains inclusions of chromium spinels. Chromium spinels I are moderately chromic and ferruginous (f = 45–55) containing 8–14 and up to 1.2 wt % of Fe₂O₃ and TiO₂, respectively; they are distinguished clearly in this way from chromium spinels of alpinotype ultrabasites. Chromium spinels II are more ferruginous (f = 58–75) and contain up to 26, 2.5–9, and up to 1.8 wt % of Fe₂O₃, TiO₂, and V₂O₃, respectively. The typical basic trend from ferruginous aluminomagnesiochromite to chromium titanomagnetite is characteristic for Balaklava chromium spinels. Tabular armalcolite crystals of approximately 0.6–0.2 mm are included in intercumulus magnesium bronzite and augite, as well as in anorthite and bytownite. The treated armalcolite contains (wt %) TiO₂, 63–66; MgO, 6.9–8.4; FeO, 9.9–11.7; Fe₂O₃, 13–18; Al₂O₃ and V₂O₃, up to 1.5 each, and Cr₂O₃, up to 0.7. The armalcolite formula is (Mg_0.38–0.45\({\text{Fe}}_{{0.30 - 0.34}}^{{2 + }}\)\({\text{Fe}}_{{0.36 - 0.49}}^{{3 + }}\)V_0.04–0.05Al_0–0.06Cr_0–0.02Ti_1.73–1.77)₃O₅; minals contain (mol %): MgTi₂O₅, 38–45; Fe²⁺Ti₂O₅, 31–36; and Fe³⁺₂TiO₅, 23–27. Baddeleyite and zirconolite are associated with armalcolite. The composition of zirconolite is (Ca_0.7Y_0.2REE_0.1)Zr(Ti_1.6\({\text{Fe}}_{{0.3}}^{{2 + }}{\text{Fe}}_{{0.1}}^{{3 + }}\))₂O₇. The more recent minerals are ilmenite I, which contains 5–8 wt % MgO and 0.3–0.6 wt % MnO, as well as Mg-deficient and Mn-enriched ilmenite II replacing armalcolite. The occurrence and preservation of armalcolite and zirconolite within the near-surface basic intrusions of the Crimean Mountains is probably caused by poor development of late magmatic processes.

Successive differentiates of acid rocks from the Salmi batholith are represented by the following series: biotite–amphibole rapakivi granite, biotite granite, and highly differentiated granites (Li-siderophyllite and Li–F zinnwaldite varieties). There is a gradual increase in the content of Ta and Nb and a decrease in the Nb/Ta ratio in this rock series. A regular change in the Ta and Nb partitioning coefficients between mica and the bulk rock composition is observed as well. Comparison of Li-siderophyllite granite and Li–F granite shows that the latter has a sharp decrease in the partitioning coefficients K_{pTa, Nb}. This is due to a decrease in the content of these metals in zinnwaldite from Li–F granite and associates with the appearance of columbite in these rocks. The study of rock samples from the Salmi batholith suggests that such change of the Ta and Nb content in the mica from deeply differentiated granite and the corresponding decrease in the K_p value of these metals may be diagnostic evidence of the presence of columbite mineralization in the rock.

This paper discusses integrated geophysical studies of an esker body in the Kaluga Region. An apparent polarizability anomaly was investigated. Integrated interpretation of geophysical data, drilling results, and core analysis made it possible to clarify the nature of the anomaly and confirm that the sand–gravel deposits contain zones with a high percentage of gravel of a magmatic origin, which are characterized by higher electrical polarizability.

Experiments on the kinetics of gypso anhydrites dissolution in water (25°С, 0.1 MPa) resulted in the development of a model of the process in the form of balance equations of dissolution kinetics for gypsum and anhydrite (first and second order, respectively), as well as of the kinetics of gypsum precipitation (the second order). The data from the experiments were processed based on the Riccati equation. The calculated values were closer to the experimental data when the common-ion effect on the solubility of gypsum and anhydrite was included.