Kazakhstan Deposits Research Articles

The loess sequence from Remisowka (northern boundary of the Tien Shan Mountains, Kazakhstan)—Part I: Luminescence dating

Similar to the Chinese loess, the loess deposits surrounding the high mountain regions of Central Asia play an important role in understanding the climate and environmental change during the Pleistocene in Eurasia. Despite their thickness and widespread distribution, the loess deposits in southeast Kazakhstan have so far not been investigated in detail. The Remisowka loess–palaeosol sequence is located in the vicinity of the North Tien Shan Mountains at an altitude of 1070 m above sea level. In the profile under study nine loess layers were distinguished, intercalated by eight pedocomplexes and so indicating a similar cyclicity like the loess–palaeosol sequences in Central Asia and China. At the Remisowka section, 12 loess samples were taken to set up a more reliable chronological model for the section, using a luminescence dating approach. Polymineral fine grains were investigated by infrared optically stimulated luminescence applying the multiple aliquot additive dose protocol. Preliminary fading experiments were carried out for one sample taken from the uppermost loess layer. While the results of the uppermost layer are in agreement with geological age estimates and indicate a correlation to the Late Glacial, age underestimation is very likely for the samples below the first weak palaeosol. No significant age increase with depth was recognised. The reason for this age underestimation is not yet fully understood but could be related to anomalous fading. Further methodological approaches are necessary as well as a combination of different chronometric techniques for improvement of the results.

Architecture and mineral deposit settings of the Altaid orogenic collage: a revised model

The Altaids are an orogenic collage of Neoproterozoic–Paleozoic rocks located in the center of Eurasia. This collage consists of only three oroclinally bent Neoproterozoic–Early Paleozoic magmatic arcs (Kipchak, Tuva–Mongol, and Mugodzhar–Rudny Altai), separated by sutures of their former backarc basins, which were stitched by new generations of overlapping magmatic arcs. In addition, the Altaids host accreted fragments of the Neoproterozoic to Early Paleozoic oceanic island chains and Neoproterozoic to Cenozoic plume-related magmatic rocks superimposed on the accreted fragments. All these assemblages host important, many world-class, Late Proterozoic to Early Mesozoic gold, copper–molybdenum, lead–zinc, nickel and other deposits of various types. In the Late Proterozoic, during breakup of the supercontinent Rodinia, the Kipchak and Tuva–Mongol magmatic arcs were rifted off Eastern Europe–Siberia and Laurentia to produce oceanic backarc basins. In the Late Ordovician, the Siberian craton began its clockwise rotation with respect to Eastern Europe and this coincides with the beginning of formation of the Mugodzhar–Rudny Altai arc behind the Kipchak arc. These earlier arcs produced mostly Cu–Pb–Zn VMS deposits, although some important intrusion-related orogenic Au deposits formed during arc–arc collision events in the Middle Cambrian and Late Ordovician. The clockwise rotation of Siberia continued through the Paleozoic until the Early Permian producing several episodes of oroclinal bending, strike–slip duplication and reorganization of the magmatic arcs to produce the overlapping Kazakh–Mongol and Zharma-Saur–Valerianov–Beltau-Kurama arcs that welded the extinct Kipchak and Tuva–Mongol arcs. This resulted in amalgamation of the western portion of the Altaid orogenic collage in the Late Paleozoic. Its eastern portion amalgamated only in the early Mesozoic and was overlapped by the Transbaikal magmatic arc, which developed in response to subduction of the oceanic crust of the Paleo-Pacific Ocean. Several world-class Cu–(Mo)-porphyry, Cu–Pb–Zn VMS and intrusion-related Au mineral camps, which formed in the Altaids at this stage, coincided with the episodes of plate reorganization and oroclinal bending of magmatic arcs. Major Pb–Zn and Cu sedimentary rock-hosted deposits of Kazakhstan and Central Asia formed in backarc rifts, which developed on the earlier amalgamated fragments. Major orogenic gold deposits are intrusion-related deposits, often occurring within black shale-bearing sutured backarc basins with oceanic crust. After amalgamation of the western Altaids, this part of the collage and adjacent cratons were affected by the Siberian superplume, which ascended at the Permian–Triassic transition. This plume-related magmatism produced various deposits, such as famous Ni–Cu–PGE deposits of Norilsk in the northwest of the Siberian craton. In the early Mesozoic, the eastern Altaids were oroclinally bent together with the overlapping Transbaikal magmatic arc in response to the northward migration and anti-clockwise rotation of the North China craton. The following collision of the eastern portion of the Altaid collage with the Siberian craton formed the Mongol–Okhotsk suture zone, which still links the accretionary wedges of central Mongolia and Circum-Pacific belts. In the late Mesozoic, a system of continent-scale conjugate northwest-trending and northeast-trending strike–slip faults developed in response to the southward propagation of the Siberian craton with subsequent post-mineral offset of some metallogenic belts for as much as 70–400 km, possibly in response to spreading in the Canadian basin. India–Asia collision rejuvenated some of these faults and generated a system of impact rifts.

Leaching of gold from off-grade products

Kinetics of sulfide decomposition and gold dissolution during electrochemical extraction is described. The results are presented for the experiments on electrochemical extraction of gold from sulfide ores of the Kazakhstan deposits using sodium salt at the “ABS” Concern. The economically efficient parameters of applying leaching technology for rebellious sulfide ores are determined.

Biochronological significance of Amynodontidae (Mammalia, Perissodactyla) from the Paleogene of Kazakhstan

Five taxa of amynodontid rhinoceroses have been named from Kazakhstan. We consider only two of these valid, and recognize three amynodontid taxa from Paleogene deposits in Kazakhstan:Cadurcodon ardynensis(=Cadurcodon zaisanensis; =Amynodon tuskabakensis) from the upper Eocene (Ergilian)-lower Oligocene (Shandgolian) of the Zaysan basin,Zaisanamynodon borisovi, from the Ergilian of the Zaysan basin andCadurcodon kazakademius, from Shandgolian strata in the vicinity of the Chelkar-Teniz lake basin.Gigantamynodon akespensis, from the upper Oligocene north of the Aral Sea is a rhinocerotid, not an amynodontid. Close similarity of the amynodontids of Kazakhstan to those of Mongolia and China supports direct correlation of Ergilian and Shandgolian strata across Asia.

Strophomenid and triplesiid brachiopods from an Upper Ordovician carbonate mound in central Kazakhstan

Ten species of strophomenid and triplesiid brachiopods are described from the Late Ordovician (late Caradoc to early Ashgill) Dulankara Regional Stage of Central Kazakhstan. They represent part of a diverse brachiopod assemblage, which was discovered in the top of a carbonate mound in the northern Betpak-Dala Desert. This brachiopod assemblage includes mostly genera not recorded previously from contemporaneous deposits in Kazakhstan, although they may be related to the long-lived lineages which appeared in the area during Llanvirn or Llandeilo. New taxa are: the plectambonitoids Bandaleta plana gen. et sp. nov., Shlyginia perplexa sp. nov., Sortanella quinquecostata gen. et sp. nov., Anoptambonites subcarinatus sp. nov., Anisopleurella ampla sp. nov., Craspedelia roomusoksi sp. nov., and triplesioid Triplesia sortanensis sp. nov.

Langban; an exhalative sedimentary deposit?

Chemical, mineralogical, and isotope analyses of hausmannite, braunite, and hematite ores from Laangban, Sweden, show that the precursor of this deposit has several similarities in its mineralogy, chemistry, and oxidation state with many deposits of Devonian and Recent ages, such as some deposits in Kazakhstan, in the Red Sea hot brine depressions, and in the East Pacific Rise. Possibly Rammelsberg, Meggen, Franklin Furnace, and Sterling Hill also belong to this type of deposit, for which an exhalative-sedimentary origin is proposed.

Distribution patterns and structural zonation of coal deposits of Central Kazakhstan

Distribution patterns and structural zonation of coal deposits of Central Kazakhstan

Some aspects of the problem of geochemical methods of prospecting for concealed mineralization

This paper describes a number of different geochemical approaches to the search for concealed ore deposits. The first approach discussed is a broad one that relates mineralization to the types of rock that may occur in a region. Attention is focussed on hydrothermal deposits and their association with specific types of igneous rocks and their differentiation trends. A second considers the control of the structure and physico-chemical properties of the host rocks on the localization of ore bodies. A number of factors, such as effective and total porosity and the brittleness of rocks also plays an important role in determining the nature and extent of dispersion haloes of the elements around ore deposits. In some instances it is possible to predict the presence of ore bodies at depth from the type of composition of metasomatized rocks that occur at the surface. The use of mercury and fluorine in the search for concealed deposits has been given detailed consideration. Methods based on fluorine may be effective in the discovery of skarn, greisen, hydrothermal and rare metal deposits. When using the fluorine content of waters from a taiga-permafrost terrain, it is important to consider the effect of the organic content of the water. In searching for Cu-Ni deposits of the Noril'sk type it is suggested that intrusive complexes characterized by high degrees of differentiation and containing picritic and taxitic facies enriched in Mg, Ni and Co and depleted in alkalis are the most prospective. Ore deposits of this type may have dispersion haloes of Ag, Bi, Zn and Pb which are associated with ore-controlling faults. Magnesian and calcareous skarns, feldspathic and serpentine-chlorite-prehnite rocks may form broad contact haloes with ore-bearing intrusions. The use of gases in prospecting for Cu-Mo deposits in Central Kazakhstan have been investigated with positive results. Gas surveys carried out in conjunction with geophysical methods makes it possible to distinguish zones of Cu-Mo mineralization from zones containing pyrite and carbonaceous material, all of which give similar geophysical responses. The occurrences of uranium in aquifers on the flanks of artesian basins within arid regions is used as an example of the use of geochemical zonation in prospecting. The same approach may be used in prospecting for copper-bearing sandstones.

New data on distribution of indium in ore deposits of Central Kazakhstan

Iron, tin, tungsten, copper, and polymetallic deposits are examined and the paper investigates the mineral distribution of indium in mineral deposits in central Kazakhstan. Indium is a relatively rare element; of the 18 formations examined only five revealed high concentrations of indium. Economic accumulations were discovered only in Early and Late Variscan skarnitic formations with lead-zinc, copper, and bismuth mineralizations. Among the hypogene minerals, indium was found in sulfides, and silicates. Among supergene minerals indium was found only in oxides, carbonates, and silicates. Sphalerites are the principal collector of indium. No connection between the enrichment in indium and the typomorphic peculiarities of different varieties of sphalerites could be established. In mineral deposits with higher indium concentration, a paragenetic connection of this element with tin is noticeable. Regular enrichment of sphalerites in indium would admit as most probable an isomorphous replacement of zinc and biv...

MONTMORILLONITIZATION OF HYDROMICAS AS A CRITERION OF TERTIARY 0IL-BEARING FORMATIONS IN DAGESTAN

Studies of clay minerals from surface samples and cores from 20 wells in terrigenous Tertiary deposits (Maykopian through Akchagylian) of Kazakhstan have lead to the following conclusions. The deposits were formed mostly under reducing conditions. The section is characterized by hydromicas (more or less degraded) with an addition of kaolinite, chlorite, and montmorillonite, in various proportions. Hydromicas from Meotian and Akchagylian rocks are slightly altered, while those from potentially productive underlying deposits (Samatian through Maykopian) are considerably montmorillonitized — hydromica with a considerable portion of potassium leached out and replaced by other cations (Mg, Ca) and water molecules (H20). Montmorillonite is present to a considerable extent as a mechanical addition to degraded hydromica of clay intercalations in deep water intervals of the section. All montmorillonitized (degraded) hydromicas and montmorillonites show features of the nonswelling parent minerals — micas and hydrom...

Composition and properties of chromite ores from new deposits in Kazakhstan

The chromite ores from the four deposits studied show a varying composition and a variety of physical properties due to their modification by secondary processes — metamorphosis and ancient weathering. In chemical composition, most of the chromite ore samples after averaging come up to the required standard for the production of normal types of chrome magnesite parts. As far as this property is concerned, it is only some of the samples from deposit B which are unsatisfactory. For the production of important types of chrome-magnesite refractories, the ores need to be enriched or screened so as to separate the high-grade varieties. All the mineralogical compositions of the chromite ores can be combined into six types with the following cementing binders: 1) serpentine; 2) serpentine-carbonate; 3) serpentine-carbonate-brucite; 4) serpentine-carbonate-chlorite; 5) serpentine-carbonate-amphibole; 6) serpentine-carbonate-quartz with the possible development in each one of iron oxides and hydroxides. The centralized preparation of raw material and the organization of the enrichment of low-grade varieties will help to supply the refractory industry with chromite powders with identical composition and physical properties.

SOME LAWS GOVERNING THE MIGRATION OF COPPER, LEAD, AND ZINC IN WATER, AND THEIR SIGNIFICANCE IN PROSPECTING

The author attempts to explain some of the problems of hydrochemical prospecting by study of the migration of certain metals in water. In general the metal content of natural waters is lower than might be expected from their solubilities in pure water. In deposits of Kazakhstan there is a strong influence on the concentration of these elements by the chemical composition and pH of the water. Lead and copper contents are strongly dependent on pH (decreasing with greater pH) and zinc less so. The pH limit of indistinct and discontinuous hydrochemical anomalies is about 7 for copper, 7.2 for lead, and 7.5 for zinc. The predominantly alkaline or neutral waters of raremetal deposits precludes usage of copper, lead, and zinc as indicators. Careful studies are therefore necessary to adequately evaluate anomalies. Data from diverse, unmineralized rocks indicates that limestones and carbon-enriched bottom deposits, and acid intrusives and their tuffs, are most active in lead sorption. The structure of rocks and mi...

On the Question of Iron and Steel Plant Location in Kazakhstan

AbstractAmong the iron-ore deposits of Kazakhstan, current attention is focused on the deposits of central Kazakhstan, as a raw-material source for the Karaganda steel plant, and on the Kustanay deposits, as an ore supply source for the steel plants of the southern Urals. The author discusses the potential utilization of a third iron-ore area situated on the north shore of the Aral Sea.