-
Date submitted2024-03-11
-
Date accepted2024-11-07
-
Date published2025-03-06
Geochemical characteristics of weathering crusts on the Dzhezhimparma Ridge and the Nemskaya Upland (South Timan)
Numerous local varieties of weathering crusts are known in the South Timan. They differ in their position in the section, type of weathering products, substrates, and occurrence. The aim of the research is to identify patterns in the distribution of rock-forming, rare and rare earth elements and the composition of clay minerals in clay formations of the weathering crusts. The main task is to describe the occurrence and geochemical features that enable determining the genetic type and formation conditions of weathering crusts. The paper presents the results of a study of the distribution of petrogenic, rare earth, rare elements, and clay minerals in weathering crust of different ages, genetic types and occurrence conditions on the Dzhezhimparma Ridge and the Nemskaya Upland in the South Timan. We found that hydromica-kaolinite-type weathering crust is developed after the Late Riphean Dzhezhim Fm. rocks in the basement-cover contact zone on the Dzhezhimparma Upland, and the layer of fine-grained rock at the base of the Devonian section previously considered a weathering crust was formed as a result of mechanical destruction of the Devonian sandstones during movement in the thrust zone. In the Vadyavozh quarry located on the Nemskaya Upland, we studied and described the formations of Mesozoic-Cenozoic areal and linear weathering crusts after the Late Riphean Dzhezhim Fm. rocks. We found that micaceous siltstones in the siltstone-sandstone strata of the Dzhezhim Fm. are associated with the Riphean stage of crust formation and are composed of weathering crust material redeposited in the epicontinental basin.
-
Date submitted2022-04-15
-
Date accepted2022-11-17
-
Date published2023-04-25
Uranium in man-made carbonates on the territory of Ufa
The paper presents the results of analyzing uranium content in man-made carbonates (scale crusts) on the territory of Ufa based on examination of 42 samples. The median uranium content in the investigated samples stands at 1.44 mg/kg, which is significantly lower than the background values (scales from the Lake Baikal water, a clarke of sedimentary carbonate rocks) and data on other settlements of the Republic of Bashkortostan. Low values of uranium content are probably associated with the effects of the three leading factors, i.e. specific subsurface geology of the territory (gypsum, limestone); types of water supply; water treatment processes for the centralized type of water supply. Spatial distribution of uranium in man-made carbonates is characterized with uniformity, which is disturbed in two cases, i.e. a change of the water supply type (from centralized to individual); and material of the vessels used for boiling the water. No significant differences were detected when comparing samples of man-made carbonates associated with different sources of water supply (the bucket and infiltration types of water intake) and the types of household filters.
-
Date submitted2022-03-21
-
Date accepted2022-06-15
-
Date published2022-07-26
Ti-Fe-Cr spinels in layered (stratified) complexes of the western slope of the Southern Urals: species diversity and formation conditions
- Authors:
- Sergey G. Kovalev
- Sergey S. Kovalev
Materials on geochemistry and ore Fe-Ti-Cr mineralization of rocks composing layered (stratified) bodies of the western slope of the Southern Urals are presented. A detailed analysis showed similarity in the redistribution of REE, noble metals, and Fe-Ti-Cr mineralization of practically all parameters in rocks of the Misaelga and Kusin-Kopan complexes. It has been established that the parameters of metamorphism, which influenced components redistribution in Fe-Ti-Cr minerals of the layered complexes, correspond to Misaelga – T = <550-750 °С, P = 0.1-2.8 kbar, Kusin-Kopan – T = <550-630 °С, P = 0.3-0.7 kbar, and Shuidinsky complexes – T = <550-760 °С, P = 0.5-2.5 kbar. The result of modelling the melt crystallization process showed that the Kusin-Kopan complex is an intrusive body with an ultramafic horizon in the idealized cross-section. Due to collisional processes, the lower part of the intrusion has been detached from the upper part. The proposed structure of the Kusin-Kopan complex sharply increases its prospects for such types of minerals as platinum group minerals + sulphide copper-nickel mine-ralization and/or chromites.
-
Date submitted2022-04-06
-
Date accepted2022-06-15
-
Date published2022-07-26
Geological and structural position of the Svetlinsky gold deposit (Southern Urals)
The paper presents the geological and structural position of the large Svetlinsky gold deposit in the Kochkar anticline (Southern Urals), localized in the zone of the Late Paleozoic (D 3 ) deep thrust of the western dip. The study confirms and clarifies the notion of its multiphase and polychronism. The thrust caused bending moments in its wings, subsidence of the lying crust, emergence of a shallow marine basin with rapid accumulation of terrigenous carbonate sediments (C 1 v), and formation of numerous landslide structures. The heating of rocks in the anticline core was accompanied by granitization and dome formation. A small Svetlinsky dome formed in the immediate vicinity of the thrust, creating a thermobaric gradient field (С 2 ). The zone of dome dynamic influence also includes the adjoining thrust area, complicated by a series of sub-vertical thrusts of sub meridional strike and numerous steeply dipping subparallel cracks of the latitudinal strike, synchronously filled with vein quartz and accompanied by hydrothermal metasomatic rock transformations. The formation of the gold deposit occurred during the post-collisional relaxation stage (from P 1 to, probably, the Early Jurassic). The association of gold mineralization with the Svetlinsky dome is indicated by the presence of native gold in Neogene ravine placers in the dome area and marbles of the Svetlinsky deposit, in association with fluorite, F-phlogopite, Cr-muscovite, pink topaz, pure quartz, and native sulphur. The presence of native gold in Neogene ravine placers in the dome area and marbles of the Svetlinsky deposit, in association with fluorite, F-phlogopite, Cr-muscovite, pink topaz, pure quartz, and native sulphur, indicates the association of gold mineralization with the Svetlinsky dome.
-
Date submitted2020-08-20
-
Date accepted2021-11-30
-
Date published2021-12-27
Indicator role of rare and rare-earth elements of the Northwest manganese ore occurrence (South Africa) in the genetic model of supergene manganese deposits
- Authors:
- Aleksandr N. Evdokimov
- Benedict L. Pharoe
The authors analyzed the content of a number of rare and rare-earth elements in the rocks of the Northwest manganese ore occurrence, confined to the Neoarchean dolomites of the Malmani series of the Transvaal Basin. 30 samples of manganese ores and host rocks were analyzed by ICP-MS and XRF methods. Average values of Post-Archean Australian Shale (PAAS) were used as the geochemical standard for data calculation and normalization. The concentrations of elements normalized on PAAS reveal the LREE anomaly in manganese ores. Positive Ce and negative Y–anomalies indicate the hydro-genetical type of sedimentation of ore minerals from manganese-bearing aqueous solutions. This is consistent with the ratios of the elements: Ce and Y SN /Ho SN , Ce and Nd, Fe – Mn – (Co + Ni + Cu) × 10. A clear correlation between the contents of rare-earth elements in manganese nodules and the underlying Malmani dolomites indicates their close genetic relationship. Negative Ce and positive Y–anomalies in manganese wad minerals indicate differences in the conditions of their formation. The manganese wad formed earlier than the rest of the ore with the active participation of microorganisms.
-
Date submitted2020-08-20
-
Date accepted2021-04-01
-
Date published2021-06-24
Features of the mineral and chemical composition of the Northwest manganese ore occurrence in the Highveld region, South Africa
- Authors:
- Aleksandr N. Evdokimov
- Benedict L. Pharoe
The Northwest manganese ore mineralisation is located at a relative distance from traditionally known manganese mining areas in a new manganese-bearing region (Highveld) in the Northwest Province, Republic of South Africa. The ore occurrence was studied on farms: Buchansvale 61 IQ, Weltevreden 517 JQ, Rhenosterhoek 343 JP and Kafferskraal 306 JP. The data obtained from studying the geology of the area pointed out to interests regarding the development criterias for search of similar ore mineralisations in the northwest region of South Africa. The ore occurs predominantly in the form of powdered manganese wad, manganese nodules and crusts, confined to the karstic structures of the upper section of the dolomites. X-ray powder diffraction (XRD), Scanning electron microscopy with energy dispersive link (SEM-EDS) and X-ray fluorescence were utilized to unveil the mineral and chemical composition of the ore samples. The present study therefore presents the results on both chemical and mineral composition of manganese ores, and their depth and longitudinal distribution. Karstic areas causing an increased local thickness of the ore body were identified. The geochemical and microspcopic study of the ores indicates their supergene nature. The main ore minerals includes cryptomelane, lithiophorite, purolusite, hollandite and romanechite associated with impurity components of Ba, Ce, Co, La, Cr, Zn and V.
-
Date submitted2020-11-20
-
Date accepted2021-03-30
-
Date published2021-06-24
Petrochemical features of tholeiites from the Shaka ridge (South Atlantic)
The article presents original data of chemical composition of tholeiitic basaltoids and andesites, dredged from the Shaka Ridge (South Atlantic) in the course of field research in spring 2016 on the scientific expedition vessel “Akademik Fedorov”. The analytical part of the work on estimating the contents of petrogenic, trace and rare-earth elements was carried out using the classical method (“wet chemistry”), X-ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The studied samples demonstrate elevated concentrations of large-ion lithophile elements, or LILE, (Ba, Rb, Pb) and light rare earth elements, or LREE, (La, Ce, Nd, Sm) relative to high field strength elements, or HFSE, (Nb, Ta) and heavy rare earth elements, or HREE, (Dy, Yb, Lu). The specifics of trace element geochemistry suggest a significant contribution of crustal or subduction components to the magmas of the Shaka Ridge. Discrimination diagrams of basaltoids and allied rocks with fields of different geodynamic settings indicate that they were formed in the setting of the mid-ocean ridge basalt (MORB). The reason behind the appearance of subduction and crustal marks in the rocks is possibly associated with assimilation of crustal matter by magmas or lies in their inheritance from the mantle source.
-
Date submitted2009-08-26
-
Date accepted2009-10-23
-
Date published2010-02-01
The North African campaign and its role in the World War II
- Authors:
- O. O. Tikhonov
- K. V. Fedorov
- O. Yu. Plenkov
The paper focuses on the North African Campaign of 1940-1943 and studies its role in the World War II. It stresses the key role of the Suez Canal in the foreign policy of the United Kingdom in the first half of the 20 th Century and reviews overall strategies of the conflicting parties paying a special attention to German tactics in desert conditions, which partially explain phenomenal success of the German troops headed by field marshal Rommel in this theater of military operations.
-
Date submitted2008-10-04
-
Date accepted2008-12-23
-
Date published2009-12-11
Importance of taphonomic researches for solution of biotopes and ecological-facial ostracod communities of some Silurian and lower devonian ostracoda from the South Tien Shan
- Authors:
- E. D. Michailova
Importance of taphonomic researches of ostracod remains from the Middle Paleozoic deposits of the South Tien Shan for solution of ecological-facial and biostratigraphical problems is demonstrated. The allochthonous and subautochthonous ostracod burials of some Silurian and lower Devonian stratigraphic units from the South Tien Shan are described. Six stable pattern types of ecological-facial ostracod communities, connected with different paleoenvironments are presented. The development of communities is traced through lower Silurian and lower Devonian.
-
Date submitted2008-10-10
-
Date accepted2008-12-23
-
Date published2009-12-11
Modern methods of hydrogeological investigations in terms of prospecting of titanium-magnetic iron deposit «South-East Gremiakha»
The paper considers the contemporary level of hydrogeological investigations during prospecting of deposits. It is suggested to use numerical modeling, sensors, computer programs for pumping tests. These methods are illustrated by prospecting of the South-East Gremiakha deposit.