scholarly journals Gaivoron—Zavallia section of the Middle Pobuzhzhіa is the most representative part of the granulite complex of the Ukrainian Shield (structural-tectonophysical results and magnetometric studies)

2021 ◽  
Vol 43 (4) ◽  
pp. 42-75
Author(s):  
S.V. Мychak ◽  
М.І. Bakarzhieva ◽  
A.V. Marchenko ◽  
M.M. Reshetnyk ◽  
L.V. Farfuliak ◽  
...  
Keyword(s):  
Layered Medium ◽  
Ukrainian Shield ◽  
Magnetic Characteristics ◽  
Shear Deformations ◽  
Structural Formation ◽  
Gneiss Complex ◽  
Composition And Structure ◽  
Granulite Complex ◽  
Alternative Approaches ◽  
Tectonic Forces

In the article according to the geological and geophysical data of the well-exposed areas of development of Archean rocks of the Ukrainian Shield, two alternative approaches to establishing the structure and stratigraphy of the oldest granulite complexes are discuss. The outcrops of the enderbite-gneiss complex up to 3.6—3.8 billion years old are located along the Southern Bug River between the Gaivoron town and the Zavallia village. The first, «stratigenic-metamorphogenic» approach assumes that the main features of the composition and structure of the Lower Archean complexes are inherited from the original stratotypic strata. These strata are transformed in the conditions of quasi-isochemical metamorphism with preservation of the sequence of formation in section and the primary constitution in the form of stratification, rhythmicity, direction of change of their composition vertically and laterally. On the structural-formation map and geological section of the Gaivoron—Zavallia section, the Archean granulite complex is shown in the form of a synclinorium composed of four adjacent formations, which are equated to the world of metamorphosed volcanic-sedimentary rocks. The second, «deformation-metamorphogenic» approach, which is supported by the authors of this article, is based on the idea that the granulite complex of Pobuzhzhіa is a subvertically layered medium formed by tangential tectonic forces. The latter lead to shear deformations and displacement of matter at the atomic-molecular (with mineral transformation of rocks) and rock masses at the regional level. This creates structural and textural elements that are superimposed on the primary structure of rocks and often erase it. Field structural-tectonophysical, tectonofacial and magnetometric studies, its results are presented in the article. It was performed specifically to compare these two concepts. Magnetometric studies have shown that the enderbite-gneiss complex of the district by its magnetic characteristics belongs to the middle and lower crust of the Ukrainian Shield.

“Magnetic Exchange Interactions in Fe/TbFe Bilayers”

1987 ◽  
Vol 103 ◽  
Author(s):  
E. E. Marinero ◽  
G. S. Sprokel ◽  
H. Notarys
Keyword(s):  
Exchange Coupling ◽  
Azimuthal Angle ◽  
Depth Profiling ◽  
Ferromagnetic Layer ◽  
Exchange Interactions ◽  
Magnetic Characteristics ◽  
Magnetic Exchange ◽  
Kerr Rotation ◽  
Composition And Structure ◽  
Magnetic Exchange Coupling

ABSTRACTWe report on magnetic exchange coupling phenomena between Fe and TbFe thin films. The structures are grown utilizing D.C. magnetron sputtering from separate Tb and Fe targets and their magnetic characteristics are measured utilizing VSM and Longitudinal Kerr Rotation. In addition, Auger depth profiling and x-ray diffraction studies were conducted to study film composition and structure.Uniaxial alignment of the Fe moment in the plane of the substrate is revealed by the longitudinal Kerr measurements. The coercivity of the Fe layer varies from 19 Oe to 130 Oe depending on the azimuthal angle between the normal to the plane of the bilayer and the direction of the external field. The hysterisis loops vary in shape from rectangular in the alignment direction to S-shape in the direction orthogonal to this direction.These effects are discussed in terms of magnetic exchange coupling interactions between the ferromagnetic layer and the ferrimagnetic alloy.

3.5 Ga U-Pb (SHRIMP-II) age of granulites from the Pobuzhie granulite complex (Ukrainian Shield)

2014 ◽  
Vol 456 (2) ◽  
pp. 726-730 ◽  
Author(s):  
S. B. Lobach-Zhuchenko ◽  
T. V. Kaulina ◽  
V. A. Glebovitskii ◽  
A. V. Yurchenko ◽  
Sh. K. Baltybaev ◽  
...  
Keyword(s):  
Ukrainian Shield ◽  
Granulite Complex

Composition and age of metaorthopyroxenite xenoliths and host enderbite gneisses in the Pobuzhie granulite complex, Ukrainian Shield

2012 ◽  
Vol 442 (2) ◽  
pp. 202-206 ◽  
Author(s):  
S. B. Lobach-Zhuchenko ◽  
V. V. Balaganskii ◽  
N. G. Berezhnaya ◽  
S. A. Sergeev ◽  
O. L. Galankina ◽  
...  
Keyword(s):  
Ukrainian Shield ◽  
Granulite Complex

scholarly journals GEODYNAMICS

GEODYNAMICS ◽  
2011 ◽  
Vol 2(11)2011 (2(11)) ◽  
pp. 104-106
Author(s):  
E.E. Karnaukhova ◽  
◽  
V.A. Korchin ◽  
Keyword(s):  
Mineral Composition ◽  
Elastic Properties ◽  
Propagation Velocity ◽  
Cross Correlation ◽  
Texture Features ◽  
Ukrainian Shield ◽  
Composition And Structure ◽  
Different Depths ◽  
Waves Propagation

The influence of mineral composition and structure-texture features on elastic properties of rocks of the Ukrainian Shield at different pressure and temperatures has been research. Statistically grounded cross-correlation dependences longitudinal and transversal waves propagation velocity from mineral composition at different depths were obtained.

Evolution of the Archaean Aulian Gneiss Complex, Middle Dnieper gneiss-greenstone terrain, Ukrainian Shield: SHRIMP UPb zircon evidence

1996 ◽  
Vol 78 (1-3) ◽  
pp. 65-78 ◽  
Author(s):  
A.V. Samsonov ◽  
I.V. Chernyshev ◽  
A.P. Nutman ◽  
W. Compston
Keyword(s):  
Ukrainian Shield ◽  
Gneiss Complex

scholarly journals Network-based metrics of resilience and ecological memory in lake ecosystems

2019 ◽  
Author(s):  
David I. Armstrong McKay ◽  
James G. Dyke ◽  
C. Patrick Doncaster ◽  
John A. Dearing ◽  
Rong Wang
Keyword(s):  
Net Energy ◽  
Ecosystem Resilience ◽  
Lake Ecosystems ◽  
Ecological Memory ◽  
Composition And Structure ◽  
Lake Erhai ◽  
Alternative Approaches ◽  
Network States ◽  
Resilience Indicators

AbstractSome ecosystems undergo abrupt transitions to a new regime after passing a tipping point in an exogenous stressor, for example lakes shifting from a clear to turbid ‘eutrophic’ state in response to nutrient-enrichment. Metrics-based resilience indicators have been developed as early warning signals of these shifts but have not always proved reliable indicators. Alternative approaches focus on changes in the composition and structure of an ecosystem, which can require long-term food-web observations that are typically beyond the scope of monitoring. Here we prototype a network-based algorithm for estimating ecosystem resilience, which reconstructs past ecological networks solely from palaeoecological abundance data. Resilience is estimated using local stability analysis, and eco-net energy: a neural network-based proxy for ‘ecological memory’. We test the algorithm on modelled (PCLake+) and empirical (lake Erhai) data. The metrics identify increasing diatom community instability during eutrophication in both cases, with eco-net energy revealing complex eco-memory dynamics. The concept of ecological memory opens a new dimension for understanding ecosystem resilience and regime shifts, with eco-memory potentially increasing ecosystem resilience by allowing past memorised eco-network states to be recovered after disruptions.

scholarly journals Iron- and Nickel Enriched Olivine from Phlogopite Harzburgite of the Bug Granulite Complex (Ukrainian Shield)

2021 ◽  
Vol 43 (1) ◽  
pp. 16-24
Author(s):  
S.B. LOBACH-ZHUCHENKO ◽  
Yu.S. EGOROVA ◽  
S.G. SKUBLOV ◽  
V.V. SUKACH ◽  
O.L. GALANKINA
Keyword(s):  
Partition Coefficients ◽  
Major Elements ◽  
Degree Of Polymerization ◽  
Ukrainian Shield ◽  
Ni Content ◽  
Epma Analysis ◽  
Mantle Peridotites ◽  
Granulite Complex ◽  
Homogeneous Chemical ◽  
Sims Analysis

An abundance of the trace elements has been determined in olivine of the Archean spinel-bearing phlogopite harzburgite enclave (sample UR17/2) from the Bug granulite complex of the Ukrainian Shield by SIMS analysis. Major elements were analyzed in the olivine by SEM-EDS and EPMA analysis. The olivine shows a homogeneous chemical composition: MgO — 45.20—45.64 wt.%, FeO — 13.66—14.23 wt.%, with Fo85—86 and Fe/Mn ratio of 68.3—68.6 which corresponds to the ratio of 60—70 in olivine of peridotites. Ni content in the UR17/2 olivine ranges from 4730 to 5612 ppm, which is higher than in olivine from mantle peridotites, high magnesium OIB and Hawaiian picrites. The olivine has average content of Ti — 20.6 ppm, Nb — 0.03 ppm, Zr — 0.32—0.60 ppm, the low total REE (0.1—0.5 ppm). The olivine crystallization temperature, calculated using an Al-in-olivine thermometer, corresponds to ~ 900°C. Enrichment in Fe and Ni is the main feature that distinguishes the UR17/2 olivine from other mantle-derived olivine. Сomposition of the UR17/2 olivine and host harzburgite indicates an influence of T, P, the oxygen fugacity and composition of parent magma on the partition coefficients of Fe and Ni. Сomposition and structure (degree of polymerization) of magma are the main factors responsible for the olivine enrichment by iron and nickel.

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