Isotope ratio 87Sr/86Sr was determined for the first time for the Ufalei and Sakhara supergene nickel deposits. The average obtained 87Sr/86Sr ratio in the Sakhara deposit (0,70838) is higher then in the Ufalei deposit (0,70697). In both deposits 87Sr/86Sr ratio increases from low-altered serpentinite rocks of the lower part of the deposits (0,70583 and 0,70687) to exogenous iron-oxide rocks of the upper part of the deposits (0,70917 and 0,71004).
Chromitites of Nizhni Tagil massif veins in length from a few centimeters to several meters. The contents of rare earth elements in the platinum-veined chromitites characterized by reduced compared with the enclosing dunite values. In quantitative terms, is dominated by light rare earth elements. The positive correlation between the rare-earth elements and platinum group metals in the samples with normal contents. High and extremely high content of PGE in the chromite-platinum ores Nizhni Tagil massif are not accompanied by a significant increase in the concentrations of REE.
Platinum mineralization in Svetly Bor massif is represented by two promising mineral assemblages: chromite-platinum and platinum-type dunite. Body platinum of chromites lie within the fields of small-and medium-grained dunite central part of the array. Spinel epigenetic vein platinum chromites of Svetly Bor clinopyroxenite-dunite massif have some geochemical features such as high iron content, low chromium and titanium. Changing the chemical composition of the constituent minerals chromites is the result of processes of serpentinization of dunites host and is accompanied by the emergence of new mineral phases. Noble metal mineralization is represented by fine of up to 50 microns, mostly idiomorphic grains isoferroplatinum, tetraferroplatinum, osmiridium.
Contents of platinum group elements (PGE), gold and silver in oxide-silicate nickel ores of the Buruktal, Ufalei and Elov supergene nickel deposits are determined in relation to their ophiolitic dunite-harzburgite bedrock.
Possibility of the natural electric field formation in conditions of the lateritic weathering crust of the ultra basic rocks in presence of extended in depth magnetite bearing bodies is proved. Theoretical curves of concentration of the dissolved oxygen and oxidized forms of magnetite are obtained. It is enough satisfied coincidence with the experimental data.
We have analysed chemical of nepouites. NiO content in then ranges from 13,00 to 35,18 %, MgO from 18,29 to 44,61 %, i.e. the composition of nepouite corresponds to the composition of Mg-nepouite. General row of chemical element mobility in lizardite – nepouite ores of the Elov supergene nickel deposit is the following: (Mo, Sb, Se, W)20-35 > (Sn, As, Ni)10-20 > (Pb, Be, U)3-7 > (Ti, Ga, Mn)1-3 > (Th, Rb, Si)~1 > (Al, V, Co, Tm, Zn, Mg)0,6-0,9 > (Yb, Ca, Cu)0,4-0,5 > (Sc, Cr, Zr, Sr, Ba, Y, Ta, TR)0,1-0,4 > (Cs, Nb; Ag, Te, Bi, Au)< 0,01-0,1.
The main geochemical barrier in supergene Buruktal nickel deposit is oxygen oxidized barrier in upper ferrous-oxide zone of the deposit. It makes sharp decrease of chemical element migration. Nevertheless, ore mineral concentrations present oft in complex geochemical barriers: absorbed-oxidized, carbonate-reducing and others. Every type of the geochemical barriers is able to concentrate specific association of migrated elements. That reflected on the different values of coefficients of enrichment in different types of Buruktal metasomatites. Oxidized barrier is more effective for elements with different valence (Fe, Mn), and absorbed clay, ferrous-oxide und manganese-oxide barriers are more effective for the main part of microelements.
In the Buruktal supergene nickel deposit, iron oxides possess vertical mineralogical zoning (bottom-up): magnetite-maghemite-goethite-hematite. The main rock- and ore-forming mineral in the iron-oxide zone of the deposit is magnetite, presented by three generations: primary relic magnetite, surviving from ultramafic rocks; secondary magnetite, forming at serpentinization process and neogenic supergene magnetite. Supergene magnetite, like a goethite, is nickel ore mineral, containing about 1 % NiO. Under the complex thermal analysis data, maghemite-magnetite and goethite have two main diagnostic maximums: exothermal effect of magnetite, caused by magnetite oxidation to maghemite in the interval 317‑340 °С, displays maximum at 327 °С («magnetite» point), and endothermic effect of goethite, connected with loss of constitutional water of the mineral and its transition to hematite in the interval 269‑296 °С, displays maximum at 288 °С («goethite» point).
Tectonic fractures of meridian spread, masked by block system of neotectonic breaks, play the leading role in structural control of nickel mineralization in supergene nickel deposits in the Urals. The deposits have long-term genesis and polygenic character. They are characterized by intensive tectonic and hydrothermal workup of Paleozoic substrate and block structure with small amplitude of vertical displacement. All of them have a two-floor structure, where upper supergene floor has a «background» of lower hydrothermal floor. This fact considerably increases the field of geological prospecting and searching of new oxide-silicate nickel deposits in the Uralian region.
In the basic and ultrabasic rocks of the Gulinsky massif of the Maymecha-Kotui province of the Kondersky massif of the Aldan province in the series of rocks: dunites - olivinites - peridotites - clinopyroxenites - gabbro, the content of rare earth elements increases, and the content of elements of the platinum group decreases. The content of noble metals in ultrabasic rocks correlates well with the content of rare earth elements and poorly with the content of other geochemical groups of elements.
The study of geochemistry of zonal phenite halos - determination of the full spectrum of chemical elements taken out of the magmatic body and revealing the nature of their distribution in the zones of the metasomatic column - is an actual task of the study of alkaline metasomatites, the solution of which has a certain prospecting value.
The problem of the origin of alkaline rocks and formations has been the subject of a considerable amount of research, many, often quite contradictory points of view have been expressed ...
The Sokolovskoye magnetite ore deposit is one of the largest in the Turgai Trough. It lies among sedimentary volcanogenic rocks of Lower Carboniferous age (Civ + n), monoclinally falling to the east at angles from 40 to 60°. Structurally, the deposit is confined to the eastern wing of the anticlinal fold.
The deposit lies among dislocated and metamorphosed sedimentary-volcanogenic rocks of Paleozoic age (Valerian Formation), which have a monoclinal bedding with a westward dip at an angle of 40-45°. The deposit consists of three stratum-shaped ore bodies occurring in accordance with volcanogenic-sedimentary rocks: Western, Eastern and Southeastern. The age of the ore-bearing strata of the Sarbaiskoye deposit has so far been determined by foraminifera from the core of the well located near the Western ore body (middle-upper Visenian to Lower Namur). Our faunal discovery belongs to the tuffite horizon composing the hanging wall of the Eastern ore body ...
The Sokolovskoye contact-metasomatic deposit of magnetite ores lies among sedimentary-volcanogenic rocks of the Valerian Formation monoclinally dipping to the east at an angle of 40-60°. In the southern part of the deposit, within the pit, the host rocks and magnetite ores have meridional strike and are tilted to the west at an angle of 70-80°, which is associated with displacement along the South Sokolov thrust. This thrust, dipping to the northwest at an angle of 45-48°, limits the ore zone of the Sokolovskoye deposit from the south. According to N. I. Rudenko, the tectonic structure of the deposit and its open pit part is blocky. In the west, between limestones and ores, N. I. Rudenko distinguishes a pre-metallic meridional disturbance, which is considered as the main solution-feeding disturbance. Parallel to the main one in the central part of the ore zone is the Central meridional disturbance, extending limitedly within the open pit ...
Явления гибридизма исследовались в плутоне "Сидоровский Урал"расположенном в северо-восточной части Минусинской котловины. Этот плутон является восточным окончанием цепочки существенно нордмаркитовых тел, вытянутой по северному борту Минусииской котловины на стыке ее с Восточным Саяном. Пространственно и генетически нордмаркитовые интрузии тесно связаны с нижнедевояркими основными субщелочными и кислыми эффузивными породами, с которыми они образуют единую магматическую ассоциацию краевой части Минусинской депрессии. По глубине залегания нордмаркитовые интрузии относятся к интрузиям малых глубин, геохимически характеризуются преобладанием натрия над калием и с редкоземельной минеральзацией.
Tungsten-cassiterite deposits in Jiangxi Province are the largest in the world (they account for more than 50% of the world's tungsten production). Great industrial value, rare association of minerals, peculiar genetic features make these deposits extremely important, interesting and fertile material for research. Nevertheless, there are almost no published works devoted to the questions of their genesis and mineralogy. In fact, the only one is an extremely general work by Ke-Chinsu, devoted to a regional overview of the deposits. Some additions to this work can be found in the monograph by Lee and Wang Chun Yu. In addition, a description of these deposits was given by V. A. Tokarev for the Mining Museum at the Leningrad Mining Institute.
