Basites of Vilyui-Markhinsky dike belt (Vilyui paleorift) and their relations with Nakyn field kimberlites

2022 ◽  
pp. 85-108
Author(s):  
Vladimir Cherenkov ◽  
Viktoria Kornilova ◽  
Yulia Golubeva ◽  
Marina Gerasimova
Keyword(s):  
High Temperature ◽  
Siberian Platform ◽  
Kimberlite Pipe ◽  
Upper Devonian ◽  
Basic Magma ◽  
Independent System ◽  
P2o5 Content ◽  
Tectonic Faults ◽  
Natural Variations

The Vilyui-Markhinsky dike belt (VMDB), which was formed as a result of Devonian rifting on the eastern margin of the Siberian Platform, is the marginal part (area of scattered rifting) of the Vilyui paleorift structure. The Nakyn field is located in the central part of the belt, but is controlled by an independent system of NNE-trending tectonic faults. The belt dyke intrudes the Nyurbinskaya kimberlite pipe. On their contact, specific breccias were formed resulting from the interaction between degassing products of basic magma with kimberlites. The typical zonality of the dyke endocontact indicates a later dyke introduction. Dolerite dikes thermally metamorphosed breccias in which high-temperature neoplasms of andradite, Al-lizardite, and clinochrysotile were generated. VMDB basites represent a single association, in which two series of rocks are distinguished: moderate-titanium (TiO2 ~ 2.5 wt. %) with normal alkalinity and low P2O5 content, and high-titanium (TiO2 ~ 4.4 wt. %), occasionally with moderate alkalinity. The differences in the dike composition are insignificant and are the result of natural variations in the composition of individual bodies. 40Ar/39Ar dating of the VMDB basites, the method characterized by the best results convergence, shows that they formed in a narrow timeframe corresponding to the Upper Frasnian – Famenian stage of the Upper Devonian (368.5 to 376.3 Ma). The location of the Nakyn field basites and kimberlites is controlled by faults of various types, orientation and age. Kimberlites formed first, and VMDB intrusions followed.

scholarly journals Genesis of Precious Metal Mineralization in Intrusions of Ultramafic, Alkaline Rocks and Carbonatites in the North of the Siberian Platform

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 354
Author(s):  
Anatoly M. Sazonov ◽  
Aleksei E. Romanovsky ◽  
Igor F. Gertner ◽  
Elena A. Zvyagina ◽  
Tatyana S. Krasnova ◽  
...  
Keyword(s):  
High Temperature ◽  
Siberian Platform ◽  
Precious Metal ◽  
Native Gold ◽  
Precious Metals ◽  
Ore Formation ◽  
Central Type ◽  
Alkaline Rocks ◽  
The North ◽  
Pge Mineralization

The gold and platinum-group elements (PGE) mineralization of the Guli and Kresty intrusions was formed in the process of polyphase magmatism of the central type during the Permian and Triassic age. It is suggested that native osmium and iridium crystal nuclei were formed in the mantle at earlier high-temperature events of magma generation of the mantle substratum in the interval of 765–545 Ma and were brought by meimechite melts to the area of development of magmatic bodies. The pulsating magmatism of the later phases assisted in particle enlargement. Native gold was crystallized at a temperature of 415–200 °C at the hydrothermal-metasomatic stages of the meimechite, melilite, foidolite and carbonatite magmatism. The association of minerals of precious metals with oily, resinous and asphaltene bitumen testifies to the genetic relation of the mineralization to carbonaceous metasomatism. Identifying the carbonaceous gold and platinoid ore formation associated genetically with the parental formation of ultramafic, alkaline rocks and carbonatites is suggested.

scholarly journals Unique Amphibole Bearing Mantle Column Beneath the Leningrad Kimberlite Pipe, West Ukukit Field, NE Yakutia

2021 ◽  
Author(s):  
Igor Victorovich Ashchepkov ◽  
Svetlana Anatolievna Babushkina ◽  
Nikolai Sergeevich Mevedev ◽  
Oleg Borisovich Oleinikov
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Low Temperature ◽  
Trace Element ◽  
Partition Coefficients ◽  
Kimberlite Pipe ◽  
Basaltic Melt ◽  
Pressure Interval ◽  
Different Levels

In the subcratonic mantle beneath Leningrad pipe, West Ukukit field, Yakutia garnet thermoba-rometry give division to 7 horizons (paleosubduction slabs). Cr-bearing amphiboles >500 reveal a broad range changing from Cr- pargasitic hornblendes to pargasites, edinites, kataforites, К-richterites with increasing pressure determined with new amphibole thermobarometer. Cr-hornblendes compiles the high-temperature branch from 3.5 GPa to Moho for basaltic melt. Amphiboles in the middle eddinites and high-pressure interval reveal different PT ranges from 35 to 40 mw/m2. Richterites near the lithosphere base both trace low –T and convective branches. The amphiboles reveal the 9 geochemical groups. The low-temperature varieties reveal Eu minima and U, Ba, Sr peaks high LILE, Sr, Rb and troughs in Nb, Pb. While high –T varieties have no Eu dips and reveal higher HFSE. Clinopyroxenes and garnets show variable trace ele-ment patterns and divisions in groups eth the plume and subduction signs. The contrasting be-haviour of Ta and Nb is regulated by the rutile partition coefficients likely for primary eclogites. Subduction and Na and K (siliceous) types of fluids percolated through the mantle with abun-dant eclogites causing amphibolization at the different levels of the mantle column. The plume melts produced hybridism and more smooth trace element patterns in reacted minerals, clino-pyroxene. monomineral thermobarometry.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

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