The lithofacies analysis of the Mamon showed showed that secondary kaolin deposits, forming a new kaolin-bearing province in the southern part of the Voronezh anteklise, are associated with a complex of deluvial-proluvial, lacustrine-boggy, and floodplain-oxbow deposits. The main ore minerals are kaolinite, quartz and secondary iron oxides and gibbsite. The presence of both terrigenous and autistic kaolinite was revealed. An important role in the formation of the latter, as well as gibbsite, played an organic substance.

Литолого-фациальный анализ мамонской толщи верхнего девона показал, что залежи вторичного каолина, образующие новую каолиноносную провинцию в южной части Воронежской антеклизы, связаны с комплексом делювиально-пролювиальных, озёрно-болотных и пойменно-старичных отложений. Главными минералами руд являются каолинит, кварц, второстепенными - оксиды железа и гиббсит. Выявлено присутствие как терригенного, так и аутигенного каолинита. Важную роль в образовании последнего, а также гиббсита играло органическое вещество.

The lithofacies analysis of the Mamon sequence showed that secondary kaolin deposits, forming a new kaolin-bearing province in the southern part of the Voronezh Anteclise, are associated with a complex of deluvial–proluvial, lacustrine–boggy, and floodplain–oxbow deposits. The main ore minerals are kaolinite, quartz and secondary iron oxides, and gibbsite. The presence of both terrigenous and authigenic kaolinite was revealed. An organic substance played an important role in the formation of the latter, as well as gibbsite.

Analysis of the evolution of bauxite-bearing weathering crust in the geological history of Asia, as well as detailed mineralogical–geochemical and hydrogeochemical studies, has made it possible to consider supergene infiltration metasomatism as a single mechanism for the formation of the eluvial zonal profile, using the weathering crust of southern Vietnam weathering crust as an example. It is established that all weathering crust zones develop simultaneously throughout the existing fracturing as rocks interact with the solutions percolating through them. All supergene minerals are formed directly from original parent rock components rather than by staged development at each other’s expense. The resulting paragenetic assemblages of newly formed minerals result in zoning.

Transmission electron microscopy study of ferruginous quartzite (jaspilites) from the Lebedinsky field of Kursk magnetic anomaly has revealed for the first time hematite nanoformations (about 10 nm in size), sp. gr. R 3̅, which coexist with hematite, sp. gr. R 3̅ c , in the same crystallographic orientation or manifest themselves as individual nanoinclusions in the substrate of poorly crystallized magnetite. On the assumption that, in correspondence with the energy-dispersive X-ray analysis data, octahedral sites in the hematite structure can be occupied by only Fe cations, several structural models are proposed explain the hematite symmetry lowering to R 3̅.

A comparative analysis of the relationship between the morphological forms and magnetic properties of natural goethite particles from the crust of weathering of the Far East and Vietnam basalts and pure, chemically synthesized goethite particles was performed using Mössbauer spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. It is shown how the shape of biogenic goethite particles affects their magnetic properties, which significantly differ from the magnetic properties of chemically synthesized samples.

For the first time, biogenic nanomagnetite has been detected in banded iron formation of the Lebedinskii deposit of the KMA and has been demonstrated to be a primary mineral. This finding may imply a key role of metabolic processes in primary deposition of divalent iron with formation of trivalent iron minerals, the precursors of banded iron formation of the KMA.

Впервые в железистых кварцитах Лебединского месторождения Курской магнитной аномалии установлен биогенный наномагнетит, который является первичным минералом. Это обстоятельство может указывать на ключевую роль метаболических процессов в первичном отложении двухвалентного Fe c образованием минералов трёхвалентного Fe, предшественников железистых кварцитов Курской магнитной аномалии.

This paper reports the results of our recent studies and generalizes previously known data on the geology, mineralogy, geochemistry, and genesis of the Russia’s largest Latnenskoe refractory clay deposit. It is shown that conditions of its localization were defined by regional and local factors. The regional factors controlled the distribution of the clay raw material in the region, while the local factors were responsible for the genesis and composition of refractory clays of the Latnenskoe deposit. Our studies showed that the formation of refractory clays is not only related to terrigenous but also to authigenic processes of sedimentation. The terrigenous component of clays was formed by the erosion of kaolin weathering crusts of the Voronezh anteclise crystalline basement and Paleozoic sedimentary hydromica–kaolinite rocks. Authigenic processes were significantly contributed by organic matter, which determined the environmental pH and Eh parameters. It is established that the mineral matter of clays of the deposit is represented by three morphological modifications (crystalline, amorphous, and biomorphic), which were formed subsequently and (or) simultaneously and could be transformed into each other. Application of a complex of modern precision methods allowed us to reveal a previously unknown biomorphic modification of kaolinite, the major rock-forming mineral, as well as mixed-layer kaolinite-smectite in the clays. It is shown that the distribution of major and trace elements and the sulfur isotope composition in different technological types of clay depend mainly on the facies conditions of their formation. Technological properties of clay raw material are considered.

The first data on biogenic nanosiderite originally discovered in oxidized Fe-quartzites from the Lebedinsk deposit of the Kursk Magnetic Anomaly (KMA) are reported. Two generations of siderite with radically different morphology and crystal-chemical and physical properties were identified. The biogenic origin is substantiated for the late generation (nanosized siderite particles). We suggest that the early ores were transformed as a result of the evolution of the atmosphere and biosphere in the area of the KMA in the Phanerozoic. Such significant differences in the properties of biogenic nanosiderite and early rhombohedral siderite may provide evidence for their different origins. The early generation of siderite was most likely formed during an abiogenic process.

Studies of the mineral substance in the weathering crust (CW) of the basalts of Vietnam have shown that these basalts might be considered as a natural laboratory for the formation of mineral bionanostructures of specific crystal morphology and thermal and magnetic properties. It is suggested that the crystallization of goethite in the cuirass and underlying bauxites of the CW of Vietnam resulted from the coagulation of colloidal particles and of hydrated iron oxide under the impact of bacterial colonies, which determined the specific features.