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1.
Oxide-silicate ore deposits containing approximately 10% of Ni reserves of Russia are located in the Sverdlovsk, Chelyabinsk, and Orenburg districts of the Urals. Garnierite is among the most important industrial minerals of supergene nickel deposits. We studied this mineral in metasomatites and ores of the Cheremshan, Sinar, Elov, Sakhara, and Buruktal deposits based on the chemical, thermal, and X-ray phase analysis data. It is shown for the first time that garnierites of the Ural province are composed of both exogenous and hydrothermal mineral associations. The spatial distribution of minerals suggests that the hydrothermal association is a lateral and vertical (depth) continuation of mineralization in the Uralian supergene deposits. This conclusion widens significantly the scope of prospecting for new mineralized sectors in old deposits and the possibility of discovery of new deposits.  相似文献   

2.
On the basis of a representative collection of ultramafic rocks and chromite ores and a series of technological samples from the largest (Central and Western) deposits in the Rai-Iz massif of the Polar Urals and the Almaz-Zhemchuzhina and Poiskovy deposits in the Kempirsai massif of the southern Urals, the distribution and speciation of platinum-group elements (PGE) in various type sections of mafic-ultramafic massifs of the Main ophiolite belt of the Urals have been studied. Spectral-chemical and spectrophotometric analyses were carried out to estimate PGE in 700 samples of ultramafic rocks and chromite ores; 400 analyses of minerals from rocks, ores, and concentrates and 100 analyses of PGE minerals (PGM) in chromite ores and concentrates were performed using an electron microprobe. Near-chondritic and nonchondritic PGE patterns in chromitebearing sections have been identified. PGE mineralization has been established to occur in chromite ore from all parts of the mafic-ultramafic massifs in the Main ophiolite belt of the Urals. The PGE deposits and occurrences discovered therein are attributed to four types (Kraka, Kempirsai, Nurali-Upper Neiva, and Shandasha), which are different in mode of geological occurrence, geochemical specialization, and placer-forming capability. Fluid-bearing minerals of the pargasite-edenite series have been identified for the first time in the matrix of chromite ore of the Kempirsai massif (the Almaz-Zhemchuzhina deposit) and Voikar-Syn’ya massif (the Kershor deposit). The PGE grade in various types of chromite ore ranges from 0.1–0.2 to 1–2 g/t or higher. According to technological sampling, the average PGE grade in the largest deposits of the southeastern ore field of the Kempirsai massif is 0.5–0.7 g/t. Due to the occurrence of most PGE as PGM 10–100 mm in size and the proved feasibility of their recovery into nickel alloys, chromites of the Kempirsai massif can be considered a complex ore with elevated and locally high Os, Ir, and Ru contents. The Nurali-Upper Neiva type of ore is characterized by small-sized primary deposits, which nevertheless are the main source of large Os-Ir placers in the Miass and Nev’yansk districts of the southern and central Urals, respectively.  相似文献   

3.
VMS deposits of the South Urals developed within the evolving Urals palaeo-ocean between Silurian and Late Devonian times. Arc-continent collision between Baltica and the Magnitogorsk Zone (arc) in the south-western Urals effectively terminated submarine volcanism in the Magnitogorsk Zone with which the bulk of the VMS deposits are associated. The majority of the Urals VMS deposits formed within volcanic-dominated sequences in deep seawater settings. Preservation of macro and micro vent fauna in the sulphide bodies is both testament to the seafloor setting for much of the sulphides but also the exceptional degree of preservation and lack of metamorphic overprint of the deposits and host rocks. The deposits in the Urals have previously been classified in terms of tectonic setting, host rock associations and metal ratios in line with recent tectono-stratigraphic classifications. In addition to these broad classes, it is clear that in a number of the Urals settings, an evolution of the host volcanic stratigraphy is accompanied by an associated change in the metal ratios of the VMS deposits, a situation previously discussed, for example, in the Noranda district of Canada.Two key structural settings are implicated in the South Urals. The first is seen in a preserved marginal allochthon west of the Main Urals Fault where early arc tholeiites host Cu–Zn mineralization in deposits including Yaman Kasy, which is host to the oldest macro vent fauna assembly known to science. The second tectonic setting for the South Urals VMS is the Magnitogorsk arc where study has highlighted the presence of a preserved early forearc assemblage, arc tholeiite to calc-alkaline sequences and rifted arc bimodal tholeiite sequences. The boninitc rocks of the forearc host Cu–(Zn) and Cu–Co VMS deposits, the latter hosted in fragments within the Main Urals Fault Zone (MUFZ) which marks the line of arc-continent collision in Late Devonian times. The arc tholeiites host Cu–Zn deposits with an evolution to more calc-alkaline felsic volcanic sequences matched with a change to Zn–Pb–Cu polymetallic deposits, often gold-rich. Large rifts in the arc sequence are filled by thick bimodal tholeiite sequences, themselves often showing an evolution to a more calc-alkaline nature. These thick bimodal sequences are host to the largest of the Cu–Zn VMS deposits.The exceptional degree of preservation in the Urals has permitted the identification of early seafloor clastic and hydrolytic modification (here termed halmyrolysis sensu lato) to the sulphide assemblages prior to diagenesis and this results in large-scale modification to the primary VMS body, resulting in distinctive morphological and mineralogical sub-types of sulphide body superimposed upon the tectonic association classification.It is proposed that a better classification of seafloor VMS systems is thus achievable using a three stage classification based on (a) tectonic (hence bulk volcanic chemistry) association, (b) local volcanic chemical evolution within a single edifice and (c) seafloor reworking and halmyrolysis.  相似文献   

4.
The presented overview of hypergene metallogeny of the Urals is largely based on original data of the author. All bauxite, Co–Ni oxide–silicate, and high-grade ferromanganese our deposits, gold, platinum, and diamond placers, as well as brown coal, kaoline, refractory, and other economic-grade mineral deposits, currently mined in the Urals are hosted in hypergene zones and related hypergene blankets of different ages. Prospects for diverse mineral deposits are estimated with a special emphasis on thermal hypergene deposits (Ni, Au, and others) that are atypical for the Urals but favorable for mining under conditions of the market economy owing to the presence of high-grade ore bodies.  相似文献   

5.
《Ore Geology Reviews》2006,28(1-4):203-237
VMS deposits of the South Urals developed within the evolving Urals palaeo-ocean between Silurian and Late Devonian times. Arc-continent collision between Baltica and the Magnitogorsk Zone (arc) in the south-western Urals effectively terminated submarine volcanism in the Magnitogorsk Zone with which the bulk of the VMS deposits are associated. The majority of the Urals VMS deposits formed within volcanic-dominated sequences in deep seawater settings. Preservation of macro and micro vent fauna in the sulphide bodies is both testament to the seafloor setting for much of the sulphides but also the exceptional degree of preservation and lack of metamorphic overprint of the deposits and host rocks. The deposits in the Urals have previously been classified in terms of tectonic setting, host rock associations and metal ratios in line with recent tectono-stratigraphic classifications. In addition to these broad classes, it is clear that in a number of the Urals settings, an evolution of the host volcanic stratigraphy is accompanied by an associated change in the metal ratios of the VMS deposits, a situation previously discussed, for example, in the Noranda district of Canada.Two key structural settings are implicated in the South Urals. The first is seen in a preserved marginal allochthon west of the Main Urals Fault where early arc tholeiites host Cu–Zn mineralization in deposits including Yaman Kasy, which is host to the oldest macro vent fauna assembly known to science. The second tectonic setting for the South Urals VMS is the Magnitogorsk arc where study has highlighted the presence of a preserved early forearc assemblage, arc tholeiite to calc-alkaline sequences and rifted arc bimodal tholeiite sequences. The boninitc rocks of the forearc host Cu–(Zn) and Cu–Co VMS deposits, the latter hosted in fragments within the Main Urals Fault Zone (MUFZ) which marks the line of arc-continent collision in Late Devonian times. The arc tholeiites host Cu–Zn deposits with an evolution to more calc-alkaline felsic volcanic sequences matched with a change to Zn–Pb–Cu polymetallic deposits, often gold-rich. Large rifts in the arc sequence are filled by thick bimodal tholeiite sequences, themselves often showing an evolution to a more calc-alkaline nature. These thick bimodal sequences are host to the largest of the Cu–Zn VMS deposits.The exceptional degree of preservation in the Urals has permitted the identification of early seafloor clastic and hydrolytic modification (here termed halmyrolysis sensu lato) to the sulphide assemblages prior to diagenesis and this results in large-scale modification to the primary VMS body, resulting in distinctive morphological and mineralogical sub-types of sulphide body superimposed upon the tectonic association classification.It is proposed that a better classification of seafloor VMS systems is thus achievable using a three stage classification based on (a) tectonic (hence bulk volcanic chemistry) association, (b) local volcanic chemical evolution within a single edifice and (c) seafloor reworking and halmyrolysis.  相似文献   

6.
Massive sulphide deposits in the Urals are found within volcanic and volcanic-sedimentary sequences of Ordovician to Middle Devonian ages. Four types of economic sulphide deposits have been recognized: Cyprus, Besshi, Urals and Baimak. The Cyprus-type copper sulphide deposits are hosted by mafic volcanites that occur in the basal parts of Palaeozoic volcanic sequences. The Besshi-type copper-zinc deposits are located within clastic sedimentary rocks intercalated with basalts and andesites. Zinc-copper deposits of the Urals-type are hosted by bimodal rhyolite-basalt assemblages, which occur at a higher stratigraphic level than those of Cyprus- and Besshi-types. The Baimak-type zinc-copper-barite deposits are associated with intrusive quartz porphyries which occur in the upper parts of bimodal volcanic successions. In addition there are some sulphide deposits of zinc-lead-barite and zinc-copper composition hosted by Ordovician terrigenous sequences which occur within depressions in Precambrian blocks. These types of sulphide deposits have been formed at various stages of divergence and convergence of the Earth's crust during the orogenic history of the Urals. Received: 27 June 1997 / Accepted: 14 May 1998  相似文献   

7.
Three stratificated levels of magnesite-bearing dolomites—Lower Riphean (Bakal-Satka-Suran), Middle Riphean (Avzyan), and Upper Riphean (Min’yar)—are recognized in the Riphean section of the Bashkir Anticlinorium of the southern Urals. Dolomites contain submicroscopic (~1 μm) magnesite dissemination (MgO/CaO > 0.714). The Lower and Middle Riphean magnesite-bearing dolomites host metasomatic magnesite stocks, lenses, pockets, and large stratiform lodes formed as products of hydrothermal activity. No metasomatic magnesite bodies are known in areas without indications of the hydrothermal reworking of magnesite-bearing dolomites. Magnesite deposits of the southern Urals are typical elisional-hydrothermal products related to sedimentation and lithogenesis of carbonate rocks in isochemical system of sedimentary basin. Juvenile components did not participate in the formation of magnesite deposits in the southern Urals.  相似文献   

8.
铂族元素的地球化学行为及全球主要铂族金属矿床类型   总被引:2,自引:0,他引:2  
全球铂族金属矿床主要有6种类型,分别为:(1)镁铁质-超镁铁质层状岩体铂族金属矿床;(2)镁铁质-超镁铁质Cu-Ni硫化物矿床伴生的铂族金属矿床;(3)Urals杂岩体型铂族金属矿床;(4)蛇绿岩型铂族金属矿床;(5)与热液相关的铂族金属矿床;(6)外生型铂族金属矿床。除第4类型外其他类型的铂族矿床都具有经济意义。铂族金属矿床的形成主要与幔源岩浆性质及岩浆演化过程密切相关。大规模的幔源岩浆活动及在岩浆演化过程中具有产生硫饱和的条件是形成铂族金属矿床的有利条件,同时岩浆期后的热液作用能使铂族元素迁移并在特定条件下富集,对铂族金属矿床的形成有利。镁铁质-超镁铁质层状侵入体形成铂族金属矿床的有利条件是岩浆分异作用强,并且具有能产生高R因子的环境;镁铁质-超镁铁质Cu-Ni硫化物矿床中形成铂族金属矿床的有利条件是硫化物熔体的结晶分异作用;Urals型杂岩体中,由于岩浆在早期演化过程中硫的不饱和,形成的主要铂族矿物为Pt-Fe、Pt-Ir合金,且主要与铬铁矿共生,在岩浆演化硫饱和阶段可形成富Pd的铂族矿物,且与Cu-Fe-V-Ti-P金属共生;蛇绿岩型杂岩体中,主要形成的铂族矿物为含Ir- 、Os- 、Pt- 的合金或少量硫化物矿物,且主要赋存于铬铁矿中。  相似文献   

9.
Based on recent publications and our long-standing investigations, the most reasonable ways were proposed to obtain the manganiferous raw material for the Uralian metallurgic industry, which lost the traditional raw base (Ukrainian and Georgian deposits) after the USSR breakdown. The Urals is region is perspective for the discovery of two types of manganese deposits. (1) Insignificantly metamorphosed siliceous–carbonate ores with silica modulus MSi (i.e., MnO : SiO2) ranging from 1 to 2 and manganese content of 17–20%. The most promising are the areas with different-age, mainly carbonate rocks in the Urals (Northern and Polar) and Pai-Khoi regions. (2) Oxide, mainly pyrolusite–psylomelane ores with Mn content of 30–35% in the Meso–Cenozoic manganese hats developed in the Paleozoic manganiferous (volcanogenic–siliceous and carbonate–siliceous) rocks and noneconomic (small) deposits. The most promising areas are Late Cretaceous and Paleogene peneplains of the Southern Urals (Trans-Uralian and Zilair regions). It is necessary to intensify works on the improvement of concentration technique for manganese ores and to carry out the marketing study of the expediency of replacing imported manganiferous concentrates by those obtained from the Uralian ores.  相似文献   

10.
11.
New data on the Vendian age of the volcanogenic–sedimentary sequence of the Uraltau zone (Southern Urals) were obtained. The U/Pb (SHRIMP-II) isotope age obtained for zircons from rhyolite tuffs is 591.5 ± 3.5 Ma. The sequence under consideration is intruded by Vendian granites and overlain unconformably by Ordovician terrigenous and volcanogenic deposits. The composition of Vendian volcanics and granites testifies that they were formed in a suprasubduction setting at the continental margin, complexes of which are known in the Middle and Northern Urals.  相似文献   

12.
The Southern Urals exemplifies hydrogeochemical environments at mining districts. Information obtained by studying the geochemistry of nonferrous-metal industrial wastes (both mine and dump drainage) is important not only because these wastes are potential sources of base metals but also in the context of geoecological problems. The Southern Urals is one of Russia’s principal producers of Cu and Zn concentrates for metallurgical processing: the region produces 12–15% Cu and 49% Zn concentrates in the country and 35% Cu and 69% Zn concentrates in the Urals. The Yubileinoe, Podol’skoe, Sibai, Uchaly, Novy Uchaly, and Gai deposits are the largest in the Urals. The ores of these deposits contain certain components (Se, Te, Cd, Co, Ga, Ge, In, Be, etc.) that are environmental contaminants. The volume of mine and dump drainage in the Southern Urals amounts to 9 million m3/year, and its mineralization varies from 3.0 to 30–40 g/L, occasionally as high as 365 g/L, with a sulfate, chloride–sulfate calcic–magnesian, magnesian–sodic, and magnesian–calcic composition of the waters. The minor and trace elements of the regional waste waters whose concentrations exceed the regional background values are Cu, Zn (one to four orders of magnitude), As, Cd (one to three orders of magnitude), Li and Be (one to two orders of magnitude). All waste waters transfer various contaminants into environmental subsystems and most actively modify the composition of the groundwaters. At the same time, dump drainage is a potentially important secondary source of valuable mineral components.  相似文献   

13.
In suture zones of the Urals, geological and physical-chemical conditions for formation of large ore and nonmetalliferous deposits existed during each geodynamical environment of development of the Urals. The development was predetermined by the duration and discontinuous-continuous existence of these structures, and the latter promoted the development of polygenetic and polychronic pegmatites of various types (by depth and productivity) and other postmagmatites. It has been shown in the example of the Ufalei metamorphic block that pegmatites of different ages (from R2 to P) are often spatially combined. In this paper, two age diagrams are presented: the first one is for geological events that took place in the Ufalei metamorphic block; the second one is for Vendian pegmatites in it. The value of this paper is determined by the fact that the data obtained in Ufalei block could be used for study of postmagmatites within its analogs, which are gneissic-amphibolitic complexes of the Northern Urals, and especially by the fact that the project “Polar Urals, Industrial Urals” is implemented there.  相似文献   

14.
A probabilistic mineral resource assessment of metal resources in undiscovered porphyry copper deposits of the Ural Mountains in Russia and Kazakhstan was done using a quantitative form of mineral resource assessment. Permissive tracts were delineated on the basis of mapped and inferred subsurface distributions of igneous rocks assigned to tectonic zones that include magmatic arcs where the occurrence of porphyry copper deposits within 1 km of the Earth's surface are possible. These permissive tracts outline four north-south trending volcano-plutonic belts in major structural zones of the Urals. From west to east, these include permissive lithologies for porphyry copper deposits associated with Paleozoic subduction-related island-arc complexes preserved in the Tagil and Magnitogorsk arcs, Paleozoic island-arc fragments and associated tonalite-granodiorite intrusions in the East Uralian zone, and Carboniferous continental-margin arcs developed on the Kazakh craton in the Transuralian zone. The tracts range from about 50,000 to 130,000 km2 in area. The Urals host 8 known porphyry copper deposits with total identified resources of about 6.4 million metric tons of copper, at least 20 additional porphyry copper prospect areas, and numerous copper-bearing skarns and copper occurrences.Probabilistic estimates predict a mean of 22 undiscovered porphyry copper deposits within the four permissive tracts delineated in the Urals. Combining estimates with established grade and tonnage models predicts a mean of 82 million metric tons of undiscovered copper. Application of an economic filter suggests that about half of that amount could be economically recoverable based on assumed depth distributions, availability of infrastructure, recovery rates, current metals prices, and investment environment.  相似文献   

15.
中国镍资源丰富,同时也是镍资源消费大国。矿床类型相对简单,主要为岩浆型,其次为海相沉积型和风化壳型3种。矿床形成时代从中—新元古代一直延续到新生代,主要集中在新元古代和晚古生代两个高峰期;空间分布较为集中,主要分布在西北、西南和东北地区,往往具有成群分布的特征。大陆边缘裂解、碰撞造山期后伸展以及地幔柱是形成中国镍矿床的3种重要构造背景。在全国Ⅲ级成矿区带的基础上,以镍矿床的空间分布特征为基础,以成矿规律和成矿条件为依据,在全国范围内划分30个成镍带;对东天山、甘—新北山、龙首山、吉中—延边、康滇、扬子南缘等6个成镍带的主要特征进行了简单叙述;从成镍带的角度,探讨了中国镍矿找矿方向,认为深部找矿尤其值得重视。  相似文献   

16.
Doklady Earth Sciences - The lack of reliable geochronological data for the Vendian deposits of the Urals and other regions is one reason why there is still uncertainty in the age estimates of the...  相似文献   

17.
Specific features of the geochemistry of manganiferous siliceous rocks confined to Devonian volcanogenic complexes of the Magnitogorsk belt in the South Urals are discussed. It is shown that with respect to the distribution of the major petrogenic and rare earth elements, as well as base and rare metals, manganese rocks are comparable with rocks of the low-temperature hydrothermal sources in active volcanic zones of the World Ocean. Our results agree well with the existing concepts about the hydrothermal-sedimentary origin of manganese deposits in the South Urals and corroborate this hypothesis with new independently obtained data.  相似文献   

18.
The morphology of fossilized biogenic particles and the elemental composition of biogenic formations, discovered for the first time in Lower Silurian deposits within the Timan–Northern Urals region, are considered. The diversity of biogenic formations identified in stromatolites indicates a high level of activity of microorganisms forming the cyanobacterial mat and confirms the microbial origin of the Wenlockian stromatolite buildups.  相似文献   

19.
Tellurium-bearing minerals are generally rare in chimney material from mafic and bimodal felsic volcanic hosted massive sulfide (VMS) deposits, but are abundant in chimneys of the Urals VMS deposits located within Silurian and Devonian bimodal mafic sequences. High physicochemical gradients during chimney growth result in a wide range of telluride and sulfoarsenide assemblages including a variety of Cu-Ag-Te-S and Ag-Pb-Bi-Te solid solution series and tellurium sulfosalts. A change in chimney types from Fe-Cu to Cu-Zn-Fe to Zn-Cu is accompanied by gradual replacement of abundant Fe-, Co, Bi-, and Pb- tellurides by Hg, Ag, Au-Ag telluride and galena-fahlore with native gold assemblages. Decreasing amounts of pyrite, both colloform and pseudomorphic after pyrrhotite, isocubanite ISS and chalcopyrite in the chimneys is coupled with increasing amounts of sphalerite, quatz, barite or talc contents. This trend represents a transition from low- to high sulphidation conditions, and it is observed across a range of the Urals deposits from bimodal mafic- to bimodal felsic-hosted types: Yaman-Kasy → Molodezhnoye → Uzelga → Valentorskoye → Oktyabrskoye → Alexandrinskoye → Tash-Tau → Jusa.  相似文献   

20.
The geology and typification of volcanogenic massive sulfide (VMS) deposits of the Southern Urals are considered. The mineralogical-geochemical types of these deposits correlate with the composition of the underlying igneous rocks: Ni-Co-Cu deposits correlatedwith serpentinites (Ivanovka type); (Co)-Cu deposits, with basalts (Dombarovka type); Cu-Zn deposits, with basalt-rhyolite and basalt-andesite-rhyolite complexes (Ural type); and Au-Ba-Pb-Zn-Cu deposits, with basalt-andesite-rhyolite complexes with predominance of andesitic and felsic volcanics (Baimak type). The Ural-type deposits are subdivided into three subtypes: I, underlain by basalts (Zn-Cu deposits); II, hosted in felsic volcanic rocks of bimodal complexes (Cu-Zn deposits); and III, hosted in felsic volcanic rocks of continuously differentiated complexes (Zn-Cu deposits with Ba, Pb, and As). The above types and subtypes bearing local names are compared with global types of VMS deposits (MAR, Cyprus, Noranda, and Kuroko), to which they are close but not identical.  相似文献   

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