pdf № 302, February

DOI: 10.19110/geov.2020.2.1

A modification of the technique for reconstructing concentrations of radiogenic helium in deep underground waters using quartz extracted from the drilled borehole core was developed and tested. In order to isolate the component of sample internal volume, stable at the temperature of the experiments, it was proposed to subject the samples to short-term preheating, at which inclusions opening at low temperatures should break down. The P_He values in the samples reconstructed in the course of the development of the samples indicate plausibility and good reproducibility of the results. The samples of quartz from the Kola Superdeep Borehole were also used to test the preliminary sorting of samples by recording the helium yield curves during linear heating of the sample. It is shown that in this way it is possible to choose potentially suitable samples, to diagnose the presence of gas-liquid decrepitating inclusions and helium sites that are not related to the crystal structure of quartz. Methodological considerations about planning such a research and methods of verification of the results are outlined.

Keywords: helium, groundwater, diffusion, isotopes, retention, residence time.

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DOI: 10.19110/geov.2020.2.2

We presented possible application of principles generally determining the mechanism of formation of technological properties of minerals and ores in a common geological- technogenic environment. The systematic approach to mineralogical studies by a set of physical methods and the data analysis on special features of composition and structure of the ores and rocks, taking into account technological data, allowed correctly evaluating enrichment of solid minerals.

Keywords: technological mineralogy, technological properties of minerals, geological-technogenic system, ontogenesis, heterogeneity of mineral.

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DOI: 10.19110/geov.2020.2.3

Modern evidences of hot heterogeneous Earth accretion explain problems of genesis of geospheres, magmas and magmatic rocks. Fractionation of magma ocean caused the crust formation from the top acid layer and mantle from the lower mafic layers. Ascending residual melts from different layers of magma ocean formed different magmatic rocks on ancient platforms in sequence granite — autonomous anorthosite — basites — alkaline rocks and carbonatite — kimberlite. Ascending mantle substance, heated by the core, formed huge superplumes and modern geodynamic settings in Phanerozoic. Eclogites was formed by the melt compression crystallization in the impact craters on the bottom of magma ocean. Their decompression melting in ascending plumes formed ocean basites and traps. Friction melting of product of magma ocean differentiation formed magmas of subduction and collision areas.

Keywords: hot heterogeneous accretion, magma ocean, magma genesis.

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DOI: 10.19110/geov.2020.2.4

Abiotic, biotic and anthropogenic factors inhibit normal life of microorganisms. We have presented that the mineral carrier provides integrity and increases the growth of microalgal cells under stress conditions. Microalgae Chlorella vulgaris, immobilized on an analcime-containing rocks (biogeosorbent), are resistant to increased salinity (34 ‰) and organic pollutants (phenolic water with a concentration of 10 µg/dm³). The advantage of the synergetic complex of the biogeosorbent from its individual components is the reduction of the period of water purification from phenols. Biodestruction of 83 % of phenols in model water occurs in 3 days.

Keywords: stress factors, phenolic water, seawater, mineral carrier, analcime-containing rocks, microalgae, biogeosorbent, sorption, biodestruction.

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DOI: 10.19110/geov.2020.2.5

Study of carbon isotopes of organic matter in conodont elements seems to be a promising approach in reconstruction of the ancient pelagic ecosystems and in isotope stratigraphy. Evaluation of influence of thermal maturity on the isotopic composition of organic matter (d¹³C_org) in conodonts is an actual problem. Experimental study demonstrates that thermal maturity of conodont elements in the Conodont Alteration Index (CAI) interval from 1 to 4 causes d¹³C_org depletion varying from 0.2 up to 2.6 ‰. The depletion is much less than changes in conodont d¹³C_org caused by the vital effect. Thus, conodont elements with CAI < 4 can be used for organic carbon isotope study with minor caution.

Keywords: conodonts, carbon isotope composition, thermal maturity.

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