scholarly journals The Bystrinskii gabbro massif: the first data concerning composition, age and formation affiliation

LITOSFERA ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 55-69
Author(s):  
V. N. Smirnov ◽  
I. I. Kazakov ◽  
V. S. Ponomarev ◽  
Yu. L. Ronkin ◽  
E. V. Storozhenko
Keyword(s):  
Rare Earth ◽  
Upper Mantle ◽  
Middle Urals ◽  
Research Subject ◽  
Tectonic Plate ◽  
Predominant Type ◽  
Composition Structure ◽  
Isotope Dating ◽  
Geological Position ◽  
Multichannel Spectrometer

Research subject. The research covered the geological position, material composition and rock age of a comparatively small (about 32 km2) Bystrinskii gabbro massif. This massif underlies a tectonic plate package consisting of serpentinized dunits and harzburgites of the ophiolite association in the Eastern boundary of the Middle Urals. Methods. The content of petrogenic elements was measured by the Х-ray fluorescence method using an Х-ray multichannel spectrometer CPM-35. The analysis of rare-earth element contents was conducted using a NexION 300S mass-spectrometer. The composition of rock-forming minerals was studied using an Х-ray microanalyzer CamecaSX100. The age of the massif was determined by the 147Sm-143Nd method of isotope dating. Amphibole geobaometers were used to determine the depth of the rock formation. Results. According to the petro- and geochemical features and composition of the rock-forming minerals, the 147Sm-143Nd isotope age of the rocks was found to be 587 Ma. It was shown that gabbroids in the massif are represented by two petrographic varieties. The predominant type of the rocks is gabbrodolerites, which are similar to the isotropic gabbros of undisturbed ophiolite sections in terms of mineral composition, structure, geochemical features and the depth of formation (not more than 2–3 km). The mapping results showed the massif under study to be the largest among those described thus far. The medium grained gabbroids, which are present in lesser quantities, differ sharply from gabbrodolerites in terms of lower contents of Fe, Ti, both rockforming (K, Na) and rare (Li, Rb, Cs) alkalis, Ba, V, Y, Nb, Zr, Hf and elements of rare-earth group, as well as by significantly higher quantities of Ca, Mg and Cr. The depth of their formation is 10–12 km, which corresponds to the upper mantle. Conclusions. The obtained information demonstrates that fragments of two levels of the ophiolite section are tectonically aligned in the Bystrinskii massif: relatively shallow isotropic gabbros of the upper part of the ophiolite section and deep gabbros of the mantle part of the ophiolite section.

Sea-floor evolution: rare-earth evidence

1971 ◽  
Vol 268 (1192) ◽  
pp. 663-706 ◽  
Keyword(s):  
Rare Earth ◽  
Mantle Source ◽  
Upper Mantle ◽  
Gulf Of Aden ◽  
Low Velocity ◽  
East Pacific ◽  
Mid Ocean Ridge ◽  
Low Velocity Layer ◽  
Ocean Ridge ◽  
Velocity Layer

A systematic survey of rare-earth (r.e.) abundances in submarine tholeiitic basalts along mid-oceanic ridges has been made by neutron activation analysis. The r.e. fractionation patterns are remarkably uniform along each mid-oceanic ridge and from one ridge to another (Juan de Fuca Ridge, East Pacific and Chile Rise, Pacific-Antarctic, Mid-Indian and Carlsberg Ridge, Gulf of Aden, Red Sea Trough and Reykjanes Ridge). The patterns are all depleted in light r.e. except for three samples (Gulf of Aden and Mid-Indian Ridge) which are unfractionated relative to chondrites. They contrast markedly with tholeiitic plateau basalt which are shown to be related to the early volcanic phases associated with continental drift. Tholeiitic plateau basalts are light r.e. enriched as are most continental rocks. Mid-ocean ridge basalts are also distinguishable from spatially related oceanic shield volcanoes of tholeiitic composition (Red Sea Trough-Jebel Teir Is., East Pacific Rise-Culpepper Island). Thus on a r.e. basis there are tholeiites within tholeiites. The r.e. difference between mid-ocean ridge tholeiites and tholeiitic plateau basalts can be related to distinct thermal and tectonic régimes and consequently magmatic modes and rates of intrusions from the low velocity layer in the upper mantle. The difference between continental and oceanic volcanism appears to be triggered by: (1) presence or absence of a moving continental lithosphere over the low velocity layer, and (2) whether or not major rifts tap the low velocity layer through the lithosphere. Fractional crystallization during ascent of melts before eruption at the ridge crest does not affect appreciably the relative r.e. patterns. R.e. in mid-ocean ridge basalts appear to intrinsically reflect their distribution in the upper mantle source, i.e. the low velocity layer. Based on secondary order r.e. variation of mid-ocean ridge basalts: (1) If fractional crystallization is invoked for the small r.e. variations, up to approximately 50 % extraction of olivine and Ca-poor orthopyroxene in various combinations can be tolerated. However, only limited amount of plagioclase or Ca-rich clinopyroxene can be extracted, the former because of its effect on the abundance of Eu abundance and the latter because of its effect on the [La/Sm] e.f. ratio, alternatively. (2) If partial melting during ascent is invoked, and a minimum of 10% melting is assumed, the permissible degree of melting of originally a lherzolite upper mantle may vary between 10 and 30% . It is not possible to establish readily to what extent these two processes have been operative as they cannot be distinguished on the basis of r.e. data only. However, there is evidence indicating that both have been operative and are responsible for the small r.e. variations observed in mid-ocean ridge basalts. An attempt to correlate second order r.e. variations along or across mid-oceanic ridges with spreading rate, age, or distance from ridge crests has been made but the results are inconclusive. No r.e. secular variation of the oceanic crust is apparent. R.e. average ridge to ridge variations are attributed to small lateral inhomogeneities of the source of basalts in the low velocity layer, and to a certain extent, to its past history. The remarkable r.e. uniformity of mid-oceanic ridge tholeiites requires a unique and simple volcanic process to be operative. It calls for upward migration of melt or slush from a relatively homogeneous source in the mantle—the low velocity layer, followed by further partial melting during ascent. The model, although consistent with geophysics, may have to be reconciled with some evidence from experimental petrology. Models for r.e. composition of the upper mantle source of ridge basalt, formation of layers 2 and 3, and the moho-discontinuity, are also presented.

Composition–Structure–Property Correlations in Rare-Earth-Doped Heavy Metal Oxyfluoride Glasses

2019 ◽  
Vol 123 (36) ◽  
pp. 22478-22490 ◽  
Author(s):  
Carsten Doerenkamp ◽  
Eduar Carvajal ◽  
Claudio J. Magon ◽  
Walter J. G. J. Faria ◽  
J. Pedro Donoso ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Rare Earth ◽  
Structure Property ◽  
Oxyfluoride Glasses ◽  
Composition Structure ◽  
Rare Earth Doped ◽  
Property Correlations

scholarly journals Brockite in wallrock metasomatites of the Safyanovskoe copper-sulphide deposit (Middle Urals)

2020 ◽  
Vol 59 (3) ◽  
pp. 35-40
Author(s):  
Elena Industrovna SOROKA ◽  
◽  
Lyubov’ Vladimirovna LEONOVA ◽  
Mikhail Egorovich PRITCHIN ◽  
◽  
...  
Keyword(s):  
Rare Earth ◽  
South Urals ◽  
Middle Urals ◽  
Copper Sulphide ◽  
The Urals ◽  
Sulphide Deposit ◽  
Environment Change ◽  
Rare Earth Minerals ◽  
Composition Of Minerals ◽  
Academy Of Sciences

The relevance of the work is due to the need to study ore copper-sulphide deposits in the Urals. Purpose of the work: description of accessory brockite in metasomatites of the Safyanovskoe copper-sulphide deposit. Research methodology: the chemical composition of minerals was determined using the Jeol JSM-6390LV scanning electron microscope with an INCA Energy 450 X-Max 80 energy dispersive attachment from Oxford Instruments (Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg). Results and conclusions. For the first time for the Safyanovskoe copper-sulphide deposit (Middle Urals), an aqueous rare earth phosphate of calcium and thorium, brockite, has been determined; it belongs to the group of rhabdophane (Ca,Th,REE)[PO]4 ∙ _H2 O. The mineral is rare for the Urals and was described earlier in granite pegmatites of the Middle and South Urals, as well as in dikes of metaplagiogranites of the Bazhenov ophiolite complex. Brockite was found in the rocky metasomatites of the Safyanovskoe copper-sulphide deposit after crystalline lithoclastic tuff (tuffaceous sandstone) of acid composition. The main mass of the rock consists of quartz, kaolinite (sericite), carbonates (dolomite, Fe-magnesite) with rare inclusions of pyrite. Brockite is found in the dolomite-quartz matrix of the sample in intergrowths with REE-goyazite – strontium aluminophosphate. It is assumed for the Safyanovskoe copper-sulphide deposit that an alumina association with an ore mineral association and rare earth minerals, in particular, REE-alumophosphates and phosphates, will form closely at the same time as the temperature drops and the redox conditions of the mineral formation environment change.

The design, fabrication and characterization of rare-earth containing multilayer supramolecular films with nanometer-scale controlled composition, structure and properties

2003 ◽  
Vol 532-535 ◽  
pp. 1017-1024 ◽  
Author(s):  
Maria N. Antipina ◽  
Radmir V. Gainutdinov ◽  
Irina V. Golubeva ◽  
Yury A. Koksharov ◽  
Artem P. Malakho ◽  
...  
Keyword(s):  
Rare Earth ◽  
Nanometer Scale ◽  
Structure And Properties ◽  
Fabrication And Characterization ◽  
Composition Structure

Compositional and thermal state of the upper mantle beneath the Bering Sea basalt province: evidence from the Chukchi Peninsula of Russia

1997 ◽  
Vol 34 (6) ◽  
pp. 789-800 ◽  
Author(s):  
Vyacheslav V. Akinin ◽  
Julia Apt ◽  
Michael F. Roden ◽  
Don Francis ◽  
Elizabeth Moll-Stalcup
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Bering Sea ◽  
Upper Mantle ◽  
Earth Element ◽  
Chukchi Peninsula ◽  
Mantle Lithosphere ◽  
Nunivak Island ◽  
Seward Peninsula ◽  
The Bering Sea

Nephelinites and basanites of the Enmelen volcanic field, Chukchi Peninsula, Russia, contain upper mantle xenoliths of relatively calcium- and magnesium-rich spinel lherzolites, pyroxenites, and megacrysts. The phase assemblages of the lherzolites require equilibration near 1.5 GPa, and calculated equilibration temperatures for most inclusions are in the range 850–1030 °C. These temperatures are similar to those calculated for lherzolite inclusions from other Bering Sea localities (Nunivak Island and Seward Peninsula) and are higher than temperatures expected for likely conductive geotherms beneath these volcanic fields. The relatively high temperatures may be the result of magma intrusion into the mantle lithosphere and consequent perturbation of the geotherm shortly before entrainment of the xenoliths in basalt. Two Enmelen lherzolites equilibrated at higher temperatures (1230–1240 °C) and provide further evidence for heating due to intrusive magmas. Some spinel lherzolite inclusions have flat rare earth element patterns and major and trace element abundances close to that of the bulk silicate earth. Based on the occurrence of similar fertile peridotites at Nunivak Island and Seward Peninsula, near-primitive mantle compositions appear to be common in the upper mantle beneath the Bering Sea. These peridotites may represent recent additions to the mantle lithosphere from mantle plumes related to the volcanism. Other Enmelen inclusions are relatively light rare earth element-enriched group I lherzolites metasomatized by a silicate melt, group II pyroxenites precipitated from a variety of melts, and augite megacrysts with convex-upward rare earth element patterns consistent with precipitation from the host basalts at high pressures.

scholarly journals Ree and Sr-Nd Isotope Compositions of Clinopyroxenites, Phoscorites and Carbonatites of the Seblyavr Massif, Kola Peninsula, Russia

Mineralogia ◽  
2007 ◽  
Vol 38 (1) ◽  
pp. 29-45 ◽  
Author(s):  
Elena Balaganskaya ◽  
Hilary Downes ◽  
Daniel Demaiffe
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Kola Peninsula ◽  
Mantle Source ◽  
Upper Mantle ◽  
Late Stage ◽  
Narrow Range ◽  
Nd Isotope ◽  
Single Batch ◽  
Mineral Accumulation

Ree and Sr-Nd Isotope Compositions of Clinopyroxenites, Phoscorites and Carbonatites of the Seblyavr Massif, Kola Peninsula, RussiaClinopyroxenites, phoscorites and carbonatites from the Devonian Seblyavr intrusion (Kola Peninsula, Russia) have petrographic characteristics indicating that they are accumulative in origin. Their geochemical (major and rare earth elements) compositions can be accounted for by mixtures of their major rock-forming minerals and accessory phases, i.e. they reflect the record of mineral accumulation. All of the analysed Seblyavr rocks are strongly LREE-enriched with (La/Yb)N mostly ranging from 38 to 189. However, a dolomite carbonatite with hydrothermal LREE-Sr mineralization has an extreme (La/Yb)N value of 1659. Such late-stage dolomite carbonatites were formed by hydrothermal (rather than magmatic) processes. Whole-rock samples of representative magmatic lithologies from Seblyavr have initial 87Sr/86Sr and εNd that fall in a very narrow range from 0.7031 to 0.7033 and +4.9 to +5.9, respectively. We therefore conclude that clinopyroxenites, phoscorites and carbonatites were formed by differentiation and crystallization of a single batch of melt. The parental melt was derived from a depleted upper mantle source that had been meta-somatised prior to melting.

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