scholarly journals Magmatic Material in Sandstone Shows Prospects for New Diamond Deposits within the Northern East European Platform

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 339
Author(s):  
Elena Agasheva
Keyword(s):  
Lithospheric Mantle ◽  
Thermal State ◽  
Lower Boundary ◽  
Kimberlite Pipe ◽  
Depth Range ◽  
East European ◽  
Window Width ◽  
Upper Level ◽  
Composition Structure ◽  
Binary Mixing

A detailed study of sandstones recovered from the upper part of the recently discovered KL-01 magmatic pipe in the southern part of the Arkhangelsk diamondiferous province (ADP), containing magmatic material and rare kimberlite indicator minerals, is presented in this paper. Results are compared to the composition of crater samples of the highly diamondiferous Vladimir Grib kimberlite pipe and several poorly to non-diamondiferous ADP pipes. To identify the type of magmatic material admixture, a model of binary mixing between country Vendian sandstones and typical ADP magmatic rocks based on correlations of La/Yb and Zr/Nb ratios and Ni contents is proposed. The modeling results show that the type of magmatic component in the KL-01 samples can be identified as kimberlite, with a maximum admixture of 20 vol.%. Kimberlite indicator mineral geochemistry did not exclude the interpretation that the composition, structure, thermal state and metasomatic enrichment of the lithospheric mantle sampled by the KL-01 pipe were suitable for the formation and preservation of diamonds. The lower boundary of the sampled lithospheric mantle could be in the depth range of 175–190 km, with a diamond window width of 55–70 km. Thus, the sandstones could represent the upper level of the crater of a new kimberlite pipe.

Density structure of the lithospheric mantle: upscaling from minerals to peridotites

2021 ◽  
Author(s):  
Luca Faccincani ◽  
Barbara Faccini ◽  
Federico Casetta ◽  
Maurizio Mazzucchelli ◽  
Fabrizio Nestola ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Lithospheric Mantle ◽  
Equations Of State ◽  
Thermal State ◽  
Bulk Composition ◽  
Chemical Compositions ◽  
Density Structure ◽  
Earth Planet ◽  
Mantle Peridotites ◽  
Geodynamic Processes

<p>The knowledge of the density structure of the lithospheric mantle is critical to our comprehension of tectonic and magmatic events occurring within the lithosphere and crucial to model the evolution of complex geodynamic processes (e.g., subduction dynamics, mantle plume upwelling etc). Furthermore, a thorough understanding of the density evolution at mantle conditions is essential to interpret geophysical data such as seismic tomography (e.g., Afonso et al., 2008; Stixrude and Lithgow-Bertelloni, 2012).</p><p>The density of mantle peridotites is related to chemical composition, modal abundance and elastic properties of their constituent minerals, which in turn are controlled by pressure, temperature and bulk composition of the system. Accordingly, the elastic properties of mantle minerals combined with the thermal state of the lithosphere can predict how the physical properties (e.g., density, elastic <em>moduli</em>) of mantle peridotites vary with depth. To this aim, (i) we examined the existing literature data (compressibility, thermal expansion and elasticity) suitable to constrain the elastic properties of peridotite minerals and (ii) we addressed the density structure of two potential lithospheric mantle sections (fertile and depleted) across different thermal regimes from the perspective of the Equations of State (EoS) of their constituent minerals.</p><p>In a mantle characterized by a relatively cold geotherm (45 mWm<sup>-2</sup>), the density of a depleted peridotitic system remains nearly constant up to about 4 GPa, while it moderately increases in a fertile system. In a mantle characterized by a relatively hot geotherm (60 mWm<sup>-2</sup>), the density of both depleted and fertile systems decreases up to about 3 GPa, due to the more rapid raise of temperature compared to pressure, and then it increases downwards.</p><p>These preliminary results show that the thermal state of the lithosphere produces a first-order signature in its density structure, with few differences owing to different modes and crystal chemical compositions.</p><p><strong>References</strong></p><p>Afonso, J.C., Fernàndez, M., Ranalli, G., Griffin, W.L., Connolly, J.A.D., 2008. Integrated geophysical-petrological modeling of the lithosphere and sublithospheric upper mantle: Methodology and applications. Geochemistry, Geophys. Geosystems 9, Q05008.</p><p>Stixrude, L., Lithgow-Bertelloni, C., 2012. Geophysics of Chemical Heterogeneity in the Mantle. Annu. Rev. Earth Planet. Sci. 40, 569–595.</p>

Thermal state and composition of the lithospheric mantle beneath the Daldyn kimberlite field, Yakutia

1996 ◽  
Vol 262 (1-4) ◽  
pp. 19-33 ◽  
Author(s):  
W.L. Griffin ◽  
F.V. Kaminsky ◽  
C.G. Ryan ◽  
S.Y. O'Reilly ◽  
T.T. Win ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Thermal State ◽  
Kimberlite Field

Metasomatic processes in the lithospheric mantle beneath the V. Grib kimberlite pipe (Arkhangelsk diamondiferous province, Russia)

2015 ◽  
Vol 56 (12) ◽  
pp. 1701-1716 ◽  
Author(s):  
E.V. Shchukina ◽  
A.M. Agashev ◽  
S.I. Kostrovitsky ◽  
N.P. Pokhilenko
Keyword(s):  
Lithospheric Mantle ◽  
Kimberlite Pipe

scholarly journals An integrated biostratigraphical analysis of the Volkhov–Kunda (Lower Ordovician) succession at Fågelsång, Scania, Sweden

2003 ◽  
Vol 50 ◽  
pp. 75-94
Author(s):  
Svend Stouge ◽  
Arne Thorshøj Nielsen
Keyword(s):  
Sea Level ◽  
East European Platform ◽  
Water Environment ◽  
Black Shales ◽  
Outer Shelf ◽  
Cool Water ◽  
East European ◽  
Lower Ordovician ◽  
Upper Level ◽  
Micritic Limestone

The Komstad Limestone is composed of dark grey to black micritic limestone deposited in an outer shelf environment on the margin of the East European Platform. It represents an interval of low sea level during the late Volkhov to early Kunda that led to the spread of limestones into the shale-dominated western lithofacies belt. The Baltoniodus norrlandicus, Lenodus antivariabilis, Lenodus variabilis, Yangtzeplacognathus crassus and Lenodus pseudoplanus conodont zones were identified in the upper Volkhov to lower Kunda interval. Based on the most recent taxonomic and biostratigraphical framework, the Megistaspis limbata (with two subzones), Asaphus expansus and Asaphus raniceps trilobite zones were identified. A shale intercalation in the lower part of the Komstad Limestone contains the graptolites Phyllograptus cor in association with Glyptograptus sp. and is referred to Darriwilian 1 (Upper Arenig). In the Baltoscandian zonation this matches the upper part of the Didymograptus hirundo graptolite Zone. The upper level of the Komstad Limestone and the basal part of the overlying Almelund Shale do not contain graptolites, whereas the succeeding black shales of the Almelund Shale belong to the Holmograptus lentus Zone (Llanvirn). The Arenig-Llanvirn boundary is situated at or very near the top of the Komstad Limestone. The conodont assemblage in the lower part of the Komstad Limestone at Fågelsång is associated with forms of Gondwanan affinity, which probably reflects the cool water environment of the outer shelf setting. The higher part of the limestone contains the Whiterockian conodont species Dzikodus sp. and Histiodella tableheadensis. These important Laurentian forms occur together with abundant Gothodus sp. 1 and Cyclopyge umbonata in the base of the Asaphus expansus Zone. The arrival of the Laurentian taxa – as well as Cyclopyge with an ‘Gondwana’ affinity – is related to a transient sea level rise at the base of the A. expansus trilobite Zone.

scholarly journals Administrative corruption in the static model of balancing common and private interests

2021 ◽  
pp. 9-19
Author(s):  
Olga Ivanovna Gorbaneva
Keyword(s):  
Level Sets ◽  
Lower Boundary ◽  
Static Model ◽  
Optimization Approach ◽  
Level System ◽  
Private Interests ◽  
Descriptive Approach ◽  
Upper Level ◽  
The Impact

  This article is dedicated to examination of corruption in the previously researched static model of balancing common and private interests (SOCHI-models). In the previously considered two-level system, between the upper non-corrupted level and the lower – agents, is introduced the average level which in exchange for a bribe, can weaken the influence of the upper level. The upper level sets the minimum amount of resources for an agent to spend on general purposes. A supervisor, in exchange for a bribe, the role of which is played by the share of agent’s private income, can reduce this lower boundary, allowing the latter to spend more resources on private purposes. This article reviews the three-level hierarchical system “Principal-Supervisor-Agents”, where the supervisor uses the administrative corruption mechanism, which requires two descriptive and optimization approaches towards its examination. The descriptive approach suggests that the considered functions of bribery are known; while the optimization approach implies the use of Germeyer’s theorem. The author explores the impact of administrative corruption upon systemic congruence of the SOCHI-model: it is proven that the administrative corruption can only reduce congruence. The author finds the conditions that can beat or reduce administrative corruption can, as well as conditions when corruption is disadvantageous for supervisor or agent. The article determines the circle of agents that supervisor can exert influence upon.  

scholarly journals TTZ-SOUTH seismic experiment

2021 ◽  
Vol 43 (2) ◽  
pp. 28-44
Author(s):  
T. Janik ◽  
V. Starostenko ◽  
P. Aleksandrowski ◽  
T. Yegorova ◽  
W. Czuba ◽  
...  
Keyword(s):  
High Velocity ◽  
Velocity Model ◽  
Data Cube ◽  
P Wave ◽  
Depth Range ◽  
Time Inversion ◽  
Crust And Upper Mantle ◽  
Moho Interface ◽  
East European ◽  
First Arrival

The wide-angle reflection and refraction (WARR) TTZ-South transect carried out in 2018 crosses the SW region of Ukraine and the SE region of Poland. The TTZ-South profile targeted the structure of the Earth’s crust and upper mantle of the Trans-European Suture Zone, as well as the southwestern segment of the East European Craton (slope of the Ukrainian Shield). The ~550 km long profile (~230 km in Poland and ~320 km in western Ukraine) is an extension of previously realized projects in Poland, TTZ (1993) and CEL03 (2000). The deep seismic sounding study along the TTZ-South profile using TEXAN and DATA-CUBE seismic stations (320 units) made it possible to obtain high-quality seismic records from eleven shot points (six in Ukraine and five in Poland). This paper presents a smooth P wave velocity model based on first-arrival travel-time inversion using the FAST (First Arrival Seismic Tomography) code. The obtained image represents a preliminary velocity model which, according to the P wave velocities, consists of a sedimentary layer and the crystalline crust that could comprise upper, middle and lower crustal layers. The Moho interface, approximated by the 7.5 km/s isoline, is located at 45—47 km depth in the central part of the profile, shallowing to 40 and 37 km depth in the northern (Radom-Łysogуry Unit, Poland) and southern (Volyno-Podolian Monocline, Ukraine) segments of the profile, respectively. A peculiar feature of the velocity cross-section is a number of high-velocity bodies distinguished in the depth range of 10—35 km. Such high-velocity bodies were detected previously in the crust of the Radom-Łysogуry Unit. These bodies, inferred at depths of 10—35 km, could be allochthonous fragments of what was originally a single mafic body or separate mafic bodies intruded into the crust during the break-up of Rodinia in the Neoproterozoic, which was accompanied by considerable rifting. The manifestations of such magmatism are known in the NE part of the Volyno-Podolian Monocline, where the Vendian trap formation occurs at the surface.

scholarly journals Oxidation State of the Lithospheric Mantle Beneath Komsomolskaya–Magnitnaya Kimberlite Pipe, Upper Muna Field, Siberian Craton

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 740 ◽  
Author(s):  
Anna Dymshits ◽  
Igor Sharygin ◽  
Zhe Liu ◽  
Nester Korolev ◽  
Vladimir Malkovets ◽  
...  
Keyword(s):  
Oxygen Fugacity ◽  
Oxidation State ◽  
Siberian Craton ◽  
Lithospheric Mantle ◽  
Redox State ◽  
Kimberlite Pipe ◽  
Good Explanation ◽  
Redox Conditions ◽  
Lateral Heterogeneity ◽  
Physical Processes

The oxidation state of the mantle plays an important role in many chemical and physical processes, including magma genesis, the speciation of volatiles, metasomatism and the evolution of the Earth’s atmosphere. We report the first data on the redox state of the subcontinental lithospheric mantle (SCLM) beneath the Komsomolskaya–Magnitnaya kimberlite pipe (KM), Upper Muna field, central Siberian craton. The oxygen fugacity of the KM peridotites ranges from −2.6 to 0.3 logarithmic units relative to the fayalite–magnetite–quartz buffer (∆logfO2 (FMQ)) at depths of 120–220 km. The enriched KM peridotites are more oxidized (−1.0–0.3 ∆logfO2 (FMQ)) than the depleted ones (from −1.4 to −2.6 ∆logfO2 (FMQ)). The oxygen fugacity of some enriched samples may reflect equilibrium with carbonate or carbonate-bearing melts at depths >170 km. A comparison of well-studied coeval Udachnaya and KM peridotites revealed similar redox conditions in the SCLM of the Siberian craton beneath these pipes. Nevertheless, Udachnaya peridotites show wider variations in oxygen fugacity (−4.95–0.23 ∆logfO2 (FMQ)). This indicates the presence of more reduced mantle domains in the Udachnaya SCLM. In turn, the established difference in the redox conditions is a good explanation for the lower amounts of resorbed diamonds in the Udachnaya pipe (12%) in comparison with the KM kimberlites (33%). The obtained results advocate a lateral heterogeneity in the oxidation state of the Siberian SCLM.

Administrative corruption in the static model of balancing common and private interests

2021 ◽  
pp. 9-19
Author(s):  
Olga Ivanovna Gorbaneva
Keyword(s):  
Level Sets ◽  
Lower Boundary ◽  
Static Model ◽  
Optimization Approach ◽  
Level System ◽  
Private Interests ◽  
Descriptive Approach ◽  
Upper Level ◽  
The Impact

  This article is dedicated to examination of corruption in the previously researched static model of balancing common and private interests (SOCHI-models). In the previously considered two-level system, between the upper non-corrupted level and the lower – agents, is introduced the average level which in exchange for a bribe, can weaken the influence of the upper level. The upper level sets the minimum amount of resources for an agent to spend on general purposes. A supervisor, in exchange for a bribe, the role of which is played by the share of agent’s private income, can reduce this lower boundary, allowing the latter to spend more resources on private purposes. This article reviews the three-level hierarchical system “Principal-Supervisor-Agents”, where the supervisor uses the administrative corruption mechanism, which requires two descriptive and optimization approaches towards its examination. The descriptive approach suggests that the considered functions of bribery are known; while the optimization approach implies the use of Germeyer’s theorem. The author explores the impact of administrative corruption upon systemic congruence of the SOCHI-model: it is proven that the administrative corruption can only reduce congruence. The author finds the conditions that can beat or reduce administrative corruption can, as well as conditions when corruption is disadvantageous for supervisor or agent. The article determines the circle of agents that supervisor can exert influence upon.  

Mantle xenoliths from the Komsomolskaya-magnitnaya kimberlite pipe (Upper Muna kimberlite field, Siberian Craton) Evidences of the composition of the SCLM

2020 ◽  
Author(s):  
Igor Iakovlev ◽  
Vladimir Malkovets ◽  
Anastasiya Gibsher
Keyword(s):  
Rare Earth ◽  
Lithospheric Mantle ◽  
Kimberlite Pipe ◽  
Mantle Xenoliths ◽  
Coarse Grained ◽  
Peridotite Xenoliths ◽  
Rare Earth Element Distribution ◽  
Group 2 ◽  
Kimberlite Field ◽  
Group 1

<p>Peridotite xenoliths from kimberlites provide important information about the composition, structure and thermal regime of the lithospheric mantle of ancient cratons. In this paper, we present the results of mineralogical studies of peridotite xenoliths from kimberlites of the Upper Muna field. The Middle Paleozoic (D3-C1) high diamondiferous kimberlite pipe Komsomolskaya-Magnitnaya was chosen as the object of research.</p><p>We studied a collection of 180 peridotite xenoliths of the Komsomolskaya-Magnitnaya pipe, of which 104 belong to dunite-harzburgite paragenesis, 74 to lherzolite and 4 websterites.</p><p>The chemical composition of basic minerals from xenoliths was determined using JEOL JXA-8100 electron microprobe. Chemical analysis of xenolith garnet compositions was also performed using the Agilent 7700cs LAM-ICPMS method.</p><p>Based on a study of the collection of deep xenoliths, we found that the lithospheric mantle under the Upper Muna kimberlite field is composed mainly of garnet-bearing and chromite-bearing dunites and harzburgites, as well as coarse grained garnet lherzolites.</p><p>The olivine Mg# varies from 88.4 to 94.12%, while the magnitude of the majority (60%) of the studied olivines does not exceed 92% and 30% of olivines have Mg#> 93%. We identified 2 groups according Mg # olivine from xenoliths. Group 1 with “typical” mantle values Mg # 88.39-90.70mol%, it is characteristic for fertile peridotites. And group 2 with highly depleted compositions Mg # 91.20-94.12mol%. A high proportion (~ 30%) of peridotites with high magnesian olivines (Mg #> 93 mol%) indicates the presence of a block of highly depleted rocks in the lithospheric mantle beneath the Upper Muna kimberilte field.</p><p>According to the distribution of calcium and chromium in garnets, 10 out of 35 studied garnets from xenoliths belong to diamondiferous harzburgite-dunite paragenesis. According to the distribution of rare-earth elements, we distinguish two groups of garnets. Group 1 includes garnets with typical rare earth element distribution spectra typical for fertile garnets, and group 2 garnets with S-shaped spectra that are characteristic of garnet mineral inclusions in diamonds. We noted a high proportion of garnets with S-shaped REE distribution spectra (~ 66%), as well as garnets belonging to the harzburgite-dunite paragenesis, it indicate a moderate role of metasomatic changes associated with silicate melts, as well as interaction with carbonatite melts enriched in LREE.</p><p>Using clinopyroxene monomineral thermobarometry, we found that the “diamond” window in the lithosphere mantle beneath the Upper Muna field, at the time of kimberlite magmatism (~ 360 Ma) was significant (about 95 km) and was located at a depth of 125 to 220 km.</p><p>The study was supported by the Russian Science Foundation (grant No. 18-17-00249).</p>

Sign in / Sign up

Export Citation Format

Share Document