PHYSICAL AND CHEMICAL STUDIES OF OVERROOF ROCKS OF CLAY SHALES OF THE DZHERDANAK DEPOSIT

The purpose of this study is study of the physical and chemical properties of the overburden of the Dzherdanak deposit. The chemical and mineralogical composition of the overburden of the Djerdanak deposit has been studied by the methods of X-ray and thermography, electron microscopy and infrared spectroscopy. The main phases are quartz, kaolinite and muscovite. The study of the fine structure of the rock under an electron microscope showed the homogeneity of the rock with pronounced uniform inclusions, which is preserved even after firing. Changes in the rock after firing at 1050 °C have been determined. The formation of mullite at this temperature has been established.

AGRO ECOLOGICAL CONDITIONS OF DARK GREY SOIL IN IMERETI REGION

Georgia, in particular, the dark grey soils of the middle belt of the Imereti mountain-forest zone are widespread. This soil is of bioclimatic type which analogues are found in many regions of the world forest zone and are formed in geographical and landscape conditions similar to Georgia. According to the vertical zoning, forest dark grey soils are spread from 600-900 meters above sea level to 2000-2100 meters. In Imereti, in the lower zone of the distribution of these soils, they border the yellow and red soils, and in the upper zone, the subalpine soils of the mountain-meadow.They, like the relief of the territory of all mountainous countries, the relief strip of forest dark grey soils in Imereti is very difficult in relief. It is fragmented, which in turn is related to the geological structure, lithological composition of rocks, tectonic processes, erosion-denudation occurrences and more.The thickness of the soil changes with the inclination of the slope, gravel, properties, the greater the slope, the less soil moisture, the slower the soil is washed away, and the dryness of the soil is known to be unfavorable for the plant. Under these conditions, a very small amount of humus-accumulation horizon is formed, which is unsatisfactory in terms of soil protection importance and fertility. At the same time it is noteworthy that the soils of the southern exposure are hotter than those of the north.Dark grey soils are developed on the Tertiary and post-Tertiary sandstones, clays and their overcrop products in the southern Imereti region, which includes the northern slopes of the Meskheti Range, within the Zestafoni, Bagdati, Samtredia, Vani districts. Soil-forming rocks are Lower and Middle Eocene sandstones, marls, clay-shales, erupted (andesites, tuffs) rocks.These soils are developed under broadleaf (hornbeam, chestnut, oak) and deciduous-coniferous forest cover.Sandy soils are spread in Khoni, Baghdati, Vani, Tkibuli, Chiatura, Kharagauli, Imereti region.

Meaning, Measurement, and Field Application of Fully Softened Shear Strength of Stiff Clays and Clay Shales

Fully softened shear strength mobilized in first-time slope failures, introduced by Skempton in 1970, corresponds to a random edge-face arrangement and interaction of clay particles in an entirely destructured fabric of stiff clays and clay shales. A series of triaxial compression tests was conducted on reconstituted normally consolidated specimens of 15 stiff clay and clay shale compositions. Based on the laboratory results an empirical correlation for secant fully softened friction angle, ϕ'fssσ'n, was developed for clay compositions with plasticity index in the range of 10 to 250%, in effective normal stress range of 10 to 700 kPa. The laboratory measurements confirm an empirical equation for fully softened shear strength in terms of parameters ϕ'fss100 and mfs. The field application of secant fully softened friction angle was examined by stability analyses of 63 first-time slope failures in 38 geologic materials. These include 45 slope failures with a segment of observed slip surface at residual condition and the back-scarp mobilizing fully softened shear strength, and 18 slope failures with entire observed slip surface at fully softened condition. The back-calculated fully softened secant friction angles for first-time slope failures are in good agreement with ϕ'fssσ'n correlation based on laboratory tests.

About new promising fi elds and ore occurrences of the southern slope of Greater Caucasus (Azerbaijan)

Статья посвящена перспективности новых выявленных рудопроявле- ний азербайджанской части Большого Кавказа. Установлено, что как колчеданно-по- лиметаллические, так и медно-пирротиновые и серно-колчеданные руды различных месторождений и рудопроявлений занимают весьма различные стратиграфические уровни разреза, начиная от тоара до верхнего аалена включительно. Весь этот воз- растной интервал, по существу, состоит из чередующихся слоев глинистых сланцев аргиллитов, песчаников и алевро-песчаников. Геолого-структурные позиции и резуль- таты опробования позволяют отнести эти участки к перспективным и считать их объектами дальнейшего изучения комплексом геолого-геохимических и геофизи- ческих исследований и буровых работ. Приводится краткое описание наиболее инте- ресных и более детально изученных проявлений рудных месторождений и проявлений. The article is devoted to the prospects of new identifi ed ore occurrences in the Azerbaijanian part of the Greater Caucasus. It is established that both pyrrhic-polymetallic and copper-pyrrhotite and sulfur-pyrrhotite ores of various deposits and ore occurrences occupy very different stratigraphic levels of the section, starting from the Toar to the upper Aalen inclusive – and it is important to note that this entire age range essentially consists of alternating layers of clay shales, mudstones, sandstones, and siltstones. The geological and structural positions and the results of testing allow us to classify these areas as promising and consider them objects of further study by a complex of geological, geochemical and geophysical studies and drilling operations. A brief description of the most interesting and more thoroughly studied manifestations of ore deposits and manifestations is given.

COMPARATIVE ASSESSMENT OF TROPICAL RAINFOREST SOILS FORMED FROM DIFFERENT GEOLOGIC FORMATIONS IN SOUTHEASTERN NIGERIA

Data on the nature, properties and potentials of soils is grossly inadequate in the rainforest belt of southeastern Nigeria. As such, policymakers and other land users have tended to subscribe to unduly generalized ideas about the soils of the region. This has led to improper land use planning and aggravated land degradation. This necessitated the need for the comparative evaluation of the nature and potentials of the soils of the region to determine their degree of variability. Profile pits were dug in four towns underlain by different geologic formations: Umungwa (Benin Formation), Umuawa Ogii (Nsukka Formation), Ikpem (Igbaku Sandstones) and Amuro (Imo Clay Shales). The soils were characterized and classified using the World Reference Base for Soil Resources (WRB), United States Department of Agriculture (USDA) Soil Taxonomy and land capability classification. The variability of soils across the different sites was subsequently analysed using the coefficient of variation (CV). The results show that the variability of sand across the study sites was moderate (20 – 21 %), silt was high (63 %), clay ranged from moderate (34 %) to high (52 %), while hydraulic conductivity was very high (128 – 144 %). Similarly, with regards to the chemical properties, soil pH and base saturation ranged from moderate (20 – 49 %) to high (52 %), while effective cation exchange capacity (ECEC) and aluminium saturation were high (70 – 77 %). It was concluded that the soils of southeastern Nigeria are very heterogeneous. Undue generalization should consequently be discouraged.

New methods for preventing crumbling and collapse of the borehole walls

Purpose. To increase the stability of the wellbore during its construction in unstable rocks. Methodology. To solve the set tasks, an integrated approach is used in the work, which includes critical analysis and generalization of scientific and technical achievements in combination with theoretical and experimental research. Findings. Factors influencing the stability of the borehole walls in conditions prone to rock slides and rock falls are analyzed. Expediency of using baths for strengthening the walls of wells in deposits of clay rocks, including clay shales, has been established and substantiated. A formulation of a fuel-bituminous bath has been proposed, the installation of which in a well for 78 hours makes it possible to increase the initial compressive strength of rocks, which will ensure the integrity of the borehole walls. It is recommended to use corrugated casing pipes to cover the sections of the wellbore where there is intensive crumbling and collapse of rocks. Originality. For the first time, the main factors of wall destruction have been established and a method has been developed to prevent the destruction of walls of directional wells composed of rocks prone to loss of stability under the action of drill string loads. Practical value. To combat the collapse of the walls of the well composed of rocks, prone to loss of stability, the authors suggested setting up fuel-bituminous baths in the range of complications. In case when the collapse of the walls of the well can not be prevented with a fuel-bitumen bath, it is proposed to overlap the area of collapse with the casing using advanced corrugated casing pipes with the injection of adhesive into the rock mass in the near-wellbore zone. The use of an adhesive material increases the contact area of the metal shell with the rock, which collapses increasing the stability of the borehole walls.

Shale types and sedimentary environments of the Upper Ordovician Wufeng Formation-Member 1 of the Lower Silurian Longmaxi Formation in western Hubei Province, China

By performing scanning electron microscopy, microscopic observations, whole-rock X-ray diffraction analysis, organic geochemistry analysis, and elemental analysis on drill core specimens and thin sections, in this study, we classified the shale types of the Wufeng Formation-Member 1 of the Longmaxi Formation in western Hubei, southern China, and explored the development characteristics and formation environments of the different shale types. The results show that (1) the shales of the Wufeng Formation-Member 1 of the Longmaxi Formation are composed of three types of shale: siliceous shale, mixed clay-siliceous shale, and clay shale. The siliceous shale is a type of shale unique to deep-water environments; clay shale is the main type of shale formed in shallow-water environments; and mixed clay-siliceous shale falls between the two. (2) The changes in shale type are characterized by multiple depositional cycles in the vertical direction with strong heterogeneity and an obvious tripartite character, and the siliceous shales gradually thicken as they laterally extend northwestward, with their last depositional cycle gradually ending at a later time. (3) The Late Ordovician-Early Silurian paleoenvironment can be divided into six evolutionary stages (A, B, C, D, E, and F) from early to late. In particular, the sea level was relatively lower in stages A and F when the bottom water was mainly oxygen rich with higher terrigenous inputs and a lower paleoproductivity, which led to the formation of clay shales poor in organic matter but rich in terrigenous quartz clasts. The sea level was higher in stages B, C, and D when the bottom water was anoxic with lower terrigenous inputs and a higher paleoproductivity, which led to the formation of siliceous shales rich in organic matter and biogenic silica. The total organic carbon (TOC) contents of siliceous shales decrease in the order of stage C > stage D > stage B, which is mainly attributed to the different degrees of water restriction in the three stages and the consequently different paleoproductivities. Stage E corresponds to the mixed clay-siliceous shales, the depositional environment of which is between those of the siliceous shales and the clay shales, thereby resulting in the mineral composition and TOC content of the mixed clay-siliceous shales being between those of the other two shale types.

Geochemical evaluation of Campanian-Maastritchian clay-shale sediments of Patti formation, Southern Bida and Mamu Formation, northern Anambra basins

Two basins (Southern Bida and Northern Anambra Basins) were investigated to deduce weathering, paleooxygenation, provenance, depositional environment and tectonic setting, as well as to establish a relationship between the two basins. The obtained high values of calculated weathering indices such as Chemical index of alteration (CIA > 90), Chemical Index of Weathering (CIW > 90), Plagioclase Index of Alteration (PIA > 90) and the Al2O3-(CaO + Na2O)-K2O ternary relationship for the clay – shale sediments from both basins indicate intense weathering in the source area. Important geochemical ratios such as V/Cr, Cu/Zn, Ni/Co, (Cu+Mo)/Zn, revealed predominantly oxic conditions for the clay – shale sediments from both basins, although, a more reducing or an anoxic condition cannot be ruled out for the clay – shale sediments from the Southern Bida basin due to high ratios of U/Th (1.93-5.67) and Cu/Zn (0.19-5.00). In addition, the Sr/Ba ratios (0.16–3.50) for the clay-shales from the Southern Bida basin indicated an alternated marine and continental paleo-depositional settings and only continental setting (Sr/Ba ratios = 0.22 – 0.50) for the Northern Anambra basin. The Th/Sc, La/Sc, Th/Co and the LREE/HREE ratios showed a derivation of the shale and clay deposits from similar felsic-rich source rock while the log of (K2O/Na2O) vs SiO2, revealed a Passive Margin tectonic setting for the two Basins. There is insignificant differences between the geochemical classifications, weathering, source rock/provenance and tectonic settings of clay-shale sediments of both sedimentary basins, however, there exist slight disparity in their salinity conditions and redox settings. Keywords: Geochemistry, Clay-shale, Provenance, Tectonic Setting, Northern Anambra and Southern Bida Basins