A. V. Maslov
Institute of Geology and Geochemistry, Urals Branch of RAS
Annotation This publication provides an overview of the rare earth elements systematics in Pre-Ordovician phosphorites from various regions of the world. Based on the analysis of significant data bank it shows that currently there are no universal parameters, guided by which, could be more or less clearly to judge sedimentary and diagenetic environments of formation of phosphate rock in the first place – redox environments. Any reconstruction of this plan require a careful analysis of how the geological facts, and extensive and diverse geochemical information.
G. A. Petrov, G. N. Borozdina, N. I. Tristan, G A. Il’yasova
Uralian Geological Survey Expedition
Institute of Geology and Geochemistry of Russian Academy of Science
Annotation At the poorly studied area of Northern Urals the Early-Paleozoic volcanic complexes were allocated, dated and characterized. Volcanic rocks in researching area were formed during period from Late Ordovician to Early Devonian and were attributed to Palnikshor (Vyja), Shemur, Pavda, Imennya and Sos’va (Tura) formations. The greatest attention was paid to Silurian volcanic strata; it was found that they are do not differ from the Pavda and Imennya formations of Middle Urals by the age, facies features and geochemical parameters. Rocks of sulphide deposits bearing Shemour formation have a low scale at the researching area, so it is not possible to predict the presence of large and medium cupper deposits.
Institute of Geology Komi SC UB RAS
Annotation The Palaeozoic of the norther part of the Pay-Khoy carbonate parautochthone is composed of mainly shallow-water (shoal) limestones and dolostones containing numerous bitumen deposits. Increased concentrations of the bitumen locate in the areas of dolomitisation and tectonized zones with strikes of 20–40°, 60–70°, 110–130°. Conodont colour alteration indexes range from 3.5 up to 5.5 in the Palaeozoic rocks of the parautochthone. This indexes correspond to MK4-MK3 and upper stages of catagenesis (temperature of maturation is about 180–350°Ń). Clear stratigraphical trend of degree of the maturation exists: mean temperature changes from 300°C in the Ordovician rocks to 170–200°C in the Middle Carboniferous rocks. The trend allows supposing that the Lower Palaeozoic was in the “oil window” in the Middle Carboniferous. In this time mobilization of the organic matter from the Lower Palaeozoic deposits followed by hydrocarbon migration through the jointing zones of northern and north-eastern strike occurred. The migrated hydrocarbon composes the bitumen deposits in the carbonate Palaeozoic rocks.
Institute of Geology and Geochemistry, Urals Branch of RAS
Annotation We have studied mineral and chemical composition of lamproites from Kalymbaevsky Complex the Middle Trias. These lamproites were developed in Magnitogorsk and Eastern-Urals megazones of the Southern Urals. We have established the presence of olivine, phlogopite, diopside phenocrysts. We have registered the presence of globular structures, consisting of sanidine and interstitial glass. We have also shown the presence in the base of rocks microlites of aluminous diopside-augite and alkaline pyroxenes of aegirin-augite series, which previously were taken for alkaline and sub-alkaline amphiboles. We have established high sulfur concentration in the apatite which, without magmatic sulfides in the rocks, witnesses for oxidation of lamproite magmas. For the first time precise geochemical data for microelemental and isotopic Sr, Nd composition of rocks are given. It was found that the South Urals rocks have a intermediate composition between lamproites and potassium alkaline basalts. Their source was the enriched mantle with the value ?Ndi = +0.7–+3.9. We have shown uncertainty of geochronological data, according to which lamproite magmatism could be initiated 197–240 or 300–310 Ma.
V. G. Korinevsky, E. V. Korinevsky, V. A. Kotlyarov, S. M. Lebedeva, I. A. Blinov, A. B. Mironov, M. B. Shtenberg
Institute of Mineralogy Urals Branch of RAS
Annotation The authors consolidated disparate information about sapphirine-bearing rocks of the Urals. It is shown that they belong to genetically different entities. There are the intrusive rocks (hornblendites, gabbros), bodies of eclogites and eclogite-lyke rocks, high-metamorphizied Paleozoic bauxite (emery rocks). Given the most complete petrographic and mineralogical characteristics the corundum-bearing sapphirine-spinel hornblendites which compose clastolithe blocks in lenses of serpentinite melange among Kyshtim suite gneisses of the Il’meno-Vishnevogorsky complex. For the first time the data of X-ray, Mossbauer and Infrared spectroscopy of sapphirine from the hornblendites, chemical compositions of most minerals in the rocks are given. The conclusion about the magmatic origin of the sapphirine-spinel hornblendites of the Urals is made.
K. S. Ivanov, N. P. Kostrov
Institute of Geology and Geochemistry Urals Branch of RAS
Annotation A new 2D model had been built for the geological structure of the Urals and West Siberia along the eastern part of Europrobe seismic reflection profiling in the Urals (ESRU) up to the depth of 15 km. For the first time at the cost of anomalous fields analysis on the parallel profiles applicability of the method was evaluated in the course of density and magnetic susceptibility modeling. The fulfilled studies have confirmed high quality of works of the ESRU’s authors under guidance A.V. Rybalka. Our model makes more concrete ideas on Earth crust structure along ESRU. It is shown that actual width of the Platinum Bearing Belt is much bigger than shown on geological maps. Into Serov fault zone two meridional ultrabasites plates of different degree of serpentinization were singled out. In the most eastern one according to the model can assume the presence of chromites. The most significant difference of the West Siberia part of ESRU (beginning approximately from 390 km of the model) from more western “Uralian” parts is the bigger “stretching” of entire structures of Earth crust. We suppose that this structure stretching and raising of deep metamorphic rocks is a consequence of early Triassic stretching accompanied by forming Triassic systems of West Siberia graben-rifts.
Key words: Ural, West Siberia, deep structure, seismic profile, gravity and magnetic modeling
V. S. Ivanchenko, Yu. G. Astrachantsev, N. A. Beloglazova, I. I. Glukhikh, L. G. Strokina
Institute of Geophysics, Urals Branch of RAS S. V. Kalugina
Company “EVRAZ KGOK”
Annotation The work shows the results of measurements magnetization (natural complete, natural residual and induced magnetization, inclination of angles complete and residual magnetization, ratio Koenigsberger) titanomagnetite ores Gusevogorskoye deposit in natural situ. The data was received by results of a three-component borehole magnetometer, measurement in explosive holes in Kachkanar. It is concluded that the observed changes in the natural residual magnetization indicate the formation of titanomagnetite ores in different thermodynamic areas as a result of subsequent geological processes that led to the disintegration of solid solutions. The main magnetic phase of these deposits were quite similar in composition and magnetic structure.
V. A. Popov
Institut of Mineralogy, Urals Branch of RAS
Annotation The temperature range of the formation of skarns suggests the melting of limestones in the heat-and-mass transfer columns of the Earth’s crust. The ontogenic analysis of structures of the carbonate rocks in some Ural skarn objects indicates the presence of bodies, which were formed from melts-fluids. According to the classification, these bodies should be termed carbonatites.
Key words: carbonatites, skarns, ontogenic analysis of mineral aggregates structures
S. E. Znamensky
Institute of Geology Ufa Science Centre Russian Academy of Sciences
Annotation REE and Y patterns for calcite and pyrite of the Orlovka gold deposit were considered. Two environments, in which evolved ore-forming fluid, are determined: early high-temperature (>200–250?C) and later low-temperature (<200?C). The high-temperature environment characterizes conditions of fluid formation during a progressive stage of greenschist dynamometamorphism of host rocks. Positive Eu and Y anomalies in calcite are its indicator. Minerals of ore paragenesis (calcite and pyrite) formed in low-temperature conditions, which probably existed during a regressive stage. It is shown that negative Ce anomalies in calcite could be caused by fluid-limestone interaction and also by a presence of sea or meteoric water in ore formation. Values of Y/Ho ratios for calcite display a participation of sea water. Values of Y/Ho ratios for pyrite correspond to these rations for effusive and volcanogenic-sedimentary wall rocks.