scholarly journals On the specification of the chronostratigraphic scheme of the Buzko-Rosynskyi block of the Ukrainian Shield

2020 ◽  
pp. 20-23
Author(s):  
V. P. Bezvynnyi ◽  
M. M. Kostenko
Keyword(s):  
Iron Ore ◽  
Magnetic Anomalies ◽  
Amphibolite Facies ◽  
Ukrainian Shield ◽  
Crystalline Schist ◽  
Stratigraphic Sequence ◽  
Early Precambrian ◽  
Current Correlation ◽  
Low Probability ◽  
Local Temperature Increase

In the current correlation chronostratigraphic scheme of early Precambrian of the Ukrainian Shield, among Neoarchean supra crystalline formations of the Buzko-Rosynskyi block, it is identified the Rosynsko-Tikytska series, which consist of the Myzynivska and Lysianska strata and the independent Volodarsko-Bilotserkivska strata, which are located on the same stratigraphic level in the scheme. According to the results of the mapping of metamorphic formations within this block during the geological survey of scale 1:200 000 (articles “Bila Tserkva”, “Uman”, “Lyubashivka”, “Kotovsk”, “Haisyn”, “Skvyra”) it is established these stratas are located in the section in a following order: the lower one is the Myzynivska, the middle one is the Volodarsko-Bilotserkivska and the upper one is the Lysianska and they form a single Rosynsko-Tikytska series. Also, these works did not confirm the presence in the region of the Bilotserkivska group of magnetic anomalies of two-pyroxene schale among the rocks of the Volodarsko-Bilotserkivska strata. This is a sign of their higher metamorphism degree. The hypersthene is present in the area of the Volodarka then only in high-iron rocks. Its presence is associated with a local temperature increase during metamorphism due to the high oxidative ability of iron. This indicates the possibility of its crystallization under conditions of amphibolite facies. A powerful argument in favor of this is the occurrence of a relatively thin carbonate-ferruginous-siliceous strata among thick amphibolite-gneiss and crystalline-schist-amphibolite strata which metamorphosed under amphibolite facies conditions. It indicates the low probability that the metamorphism of the iron ore could occur locally in other conditions. The obtained new data on the composition of the Rosynsko-Tikytska series and the actual stratigraphic sequence of stratas in it, indicates the necessity of making appropriate changes in the current correlation chronostratigraphic scheme of early Precambrian formations of the Ukrainian Shield.

scholarly journals Petrographic Study of Sedimentary Iron Ore in Shendi -Atbara Basin, River Nile State, Sudan.

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Abubaker A. M. A. Abasher ◽  
Sadam H.M.A. Eltayib ◽  
El Sheikh M. Abdelrahman ◽  
Mohammed M.A. Amlas
Keyword(s):  
Chemical Weathering ◽  
Iron Ore ◽  
Field Work ◽  
Chemical Precipitation ◽  
Office Work ◽  
River Nile ◽  
Stratigraphic Sequence ◽  
Thin Sections ◽  
Geological Conditions ◽  
Petrographic Study

This paper presents the results of petrographic study of sedimentary iron ore from surface strata of the Shendi -Atbara Basin, River Nile State, Sudan. The aims of this study are to investigate the geological behavior and geological conditions affecting precipitation of sedimentary iron ore. The methodologies have been used to realize the objectives of this study included; field work, office work and labrotary work include thin sections and polished sections analysis. According to field observation sedimentary iron ore can broadly be considered as occurring in three major classes: Ferribands iron, ferricrete iron and oolitic iron ores. The modes of occurrence of iron ore was described at the outcrops and vertical sedimentary profiles revealed that the iron occurred in study area at different types in stratigraphic sequence such as cap, beded and interbeded conformable with Shendi Formation. Petrographic study of iron ore in collected samples using polarized microscope and ore microscope includes study of the textures and structures of ores to obtain ore history. The main types of textures and structures in studied samples are oolitic, granular, lamellar and bands. According to these results the origin of iron ore is formed by chemical precipitation during chemical weathering of surrounding areas in continental lacustrine environment. The iron ore in study area is potential for future mining works and steals industry.

A Discussion on the evolution of the Precambrian crust - The early Precambrian gneisses of the Godthåb district, West Greenland

1973 ◽  
Vol 273 (1235) ◽  
pp. 343-358 ◽  
Keyword(s):  
Amphibolite Facies ◽  
Calc Alkaline ◽  
Isotopic Data ◽  
Early Precambrian ◽  
West Greenland ◽  
Metasedimentary Rocks ◽  
Parent Rocks

Intensely metamorphosed and deformed basic dykes, the Ameralik dykes, have been used to divide the amphibolite-facies gneisses of the Godthåb district into the Amitsoq gneisses (older) and the Nuk gneisses. Metavolcanic and metasedimentary rocks (the Malene supracrustals), and stratiform meta-anorthosites are also present and are probably younger than the Amitsoq gneisses, but are older than the Nuk gneisses. The Amitsoq gneisses contain abundant fragments of Ameralik dykes. They appear to have been derived from homogeneous granitic (s.l.) parents, but most of them have been intensely reworked before and/or after the intrusion of the Ameralik dykes and are now banded gneisses. They range from dioritic to granitic in composition and potassic varieties are common. Isotopic data indicate that the parent rocks of the gneisses were emplaced or metamorphosed about 3750 Ma ago. Ameralik dykes are absent from the Nuk gneisses, which are the most abundant rocks in the area. These gneisses are derived from intrusive calc-alkaline parents, mainly tonalites and granodiorites, and represent a massive addition of granitic material to this level of the crust about 3080 Ma ago, after the first supracrustal rocks had been laid down.

Isotopic dating of very early Precambrian amphibolite facies gneisses from the Godthaab district, West Greenland

1971 ◽  
Vol 12 (3) ◽  
pp. 245-259 ◽  
Author(s):  
Oxford isotope geology laboratory ◽  
L.P. Black ◽  
N.H. Gale ◽  
S. Moorbath ◽  
R.J. Pankhurst ◽  
...  
Keyword(s):  
Amphibolite Facies ◽  
Isotopic Dating ◽  
Early Precambrian ◽  
West Greenland

scholarly journals ON THE AGE OF THE CHARNOCKITOIDS OF THE TASHLYK COMPLEX OF THE INHUL REGION OF The UKRAINIAN SHIELD

2021 ◽  
Vol 43 (3) ◽  
pp. 73-84
Author(s):  
O.M. Ponomarenko ◽  
L.M. Lisna ◽  
L.M. Stepanyuk ◽  
L.V. Shumlyanskyy ◽  
V.M. Mineeva ◽  
...  
Keyword(s):  
Amphibolite Facies ◽  
Ukrainian Shield ◽  
Early Proterozoic ◽  
Granulite Metamorphism

Zircons from charnockitoids of the Tashlyk complex from the Pryinhul syncline were studied and dated in order to determine their chronostratigraphic position. Zircons of two age generations were identified, namely the Early Archean (ca. 3 Ga) and the Early Proterozoic (2.0±0.1 Ga). The presence of the former generation indicates that the protolith for charnockites have been represented by the rocks older than the Spasove Series, which is considered to be Proterozoic in age. At ca. 2.0±0.1 Ga Archean rocks together with rocks of the Inhul-Inhulets Series, underwent granulite metamorphism. This event resulted in crystallization of the second (Paleoproterozoic) generation of zircon in charnockites. Archean zircons found in the rocks of the Tashlyk complex, which correspond morphologically to granitoid of the amphibolite facies, differ from Eoarchean zircons in enderbites of the Haivoron complex, which partially retain their appearance during the Neoarchean and Paleoproterozoic tectonic-magmatic events.

scholarly journals The early Archaean to Proterozoic history of the Isukasia area, southern West Greenland

1986 ◽  
Vol 154 ◽  
pp. 1-80
Author(s):  
A.P Nutman
Keyword(s):  
Volcanic Rocks ◽  
Amphibolite Facies ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Stratigraphic Sequence ◽  
Supracrustal Belt ◽  
History Of ◽  
High Grade Metamorphism ◽  
Polyphase Metamorphism ◽  
Chemical Sediments

The c. 3800 Ma Isua supracrustal belt and associated smaller bodies of supracrustal rocks are intruded by >3600 Ma orthogneisses. A coherent stratigraphic sequence is recognised consisting of interlayered metabasic rocks, metasediments derived from volcanic rocks, chemical sediments, and metabasic and ultramafic intrusions. Despite repeated deformation and high-grade metamorphism sedimentary structures are locally preserved. The depositional environment was probably an immersed volcanic region remote from areas of significantly older crust. Conglomeratic structures in a metachert and banded iron formation unit suggest shoaling and shallow water conditions. Felsic sediments locally preserve evidence of deposition from turbidite flows. The Isua supracrustal rocks are regarded as thin fragments of a thicker, more extensive sequence. The orthogneisses that intrude the supracrustal rocks consist of 3750-3700 Ma multiphase tonalites (the grey gneisses) which were first intruded by the basic Inaluk dykes, then by abundant shallow-dipping swarms of c. 3600 Ma granite sheets (the white gneisses) and finally by c. 3400 Ma pegmatitic gneiss sheets. These early Archaean rocks were metamorphosed under amphibolite facies conditions and repeatedly deformed prior to intrusion of the Tarssartôq basic dykes in the mid Archaean. In the late Archaean (3100-2500 Ma) there was polyphase metamorphism up to amphibolite facies grade and two or more stages of deformation and local intrusion of granitic gneiss sheets and pegmatites. However, despite general strong deformation there is a large augen of low deformation preserved within the arc of the Isua supracrustal belt. During the Proterozoic there was intrusion of basic dykes, major faulting with associated recrystallisation under uppermost greenschist to lowermost amphibolite facies conditions, followed by heating and intrusion of acid dykes at c. 1600 Ma. No profitable mineralisations have been located.

scholarly journals Stratigraphic basement and correlation of the precambrian central part cuts of the Ukrainian shield

2020 ◽  
pp. 11-16
Author(s):  
M. M. Kostenko
Keyword(s):  
Suture Zone ◽  
Ukrainian Shield ◽  
Structural Elements ◽  
The West ◽  
Early Precambrian ◽  
Carbonate Carbon

In the central part of the Ukrainian Shield are allocated two independent structural elements: Inhul block and Inhulets-Kryvyi Rih suture zone, instead of the Inhul-Inhulets region, according to the current tectonic zoning in “Correlation Chronostratigraphic Scheme of the Early Precambrian of the Ukrainian Shield”. The stratigraphic dividing of this territory has not undergone any changes. The article suggests existing Inhul-Inhulets Series in this scheme to divided into two: the Inhul (Inhul block) and the Inhulets (Inhulets-Kryvyi Rih suture zone) and several independent strattons in the Suites rank. As part of the Inhul Series, the upper part of the Inhul-Inhulets Series remains as part of the Kamianokostuvatska and Roshсhakhivska (Bratskа SFZ) and Spasivska and Checheliivska (Inhul SFZ) Suites. In the lower part of the section, there is an independent Rodionivska Suite. The West Inhulets and Kryvyi Rih-Kremenchuk SFZ stratigraphic sections of the Inhulets-Kryvyi Rih suture zone are identical and completely correlate with each other: lower Mesoarchean metaterigenic Lativska Suite is basal for both, Mesoarchean metavolcanogenic Nyzhnozelenorichanska Suite of the West-Inhulets SFZ is correlated with the Novokryvorizka Suite of the Kryvyi Rih-Kremenchuk SFZ, Paleoproterozoic Inhulez Series – respectively, with the Kryvyi Rih Series (metavolcanogenic-sedimentary Verkhnozelenorichanska Suite – with the Skeliuvatska Suite, and the metaterigenic-ferrous Artemivska Suite – with the Saksaganska), carbonate-carbon-terigenic Rodionivska Suite – with Hdantsivska. These stratigraphic units represent by themselves their own suture formations of the Inhulets-Kryvyi Rih suture zone.

scholarly journals A Geophysical Survey with Magnetic Method for Interpretation of Iron Ore Deposits in the Eastern Nusawungu Coastal, Cilacap Regency, Central Java, Indonesia

2020 ◽  
Vol 5 (1) ◽  
pp. 47-55
Author(s):  
Muhammad Sehah ◽  
Sukmaji Anom Raharjo ◽  
Azmi Risyad
Keyword(s):  
Magnetic Anomaly ◽  
Iron Ore ◽  
Magnetic Anomalies ◽  
Research Area ◽  
Ore Deposits ◽  
Magnetic Method ◽  
Contour Map ◽  
Strength Data ◽  
Central Java ◽  
Iron Ore Deposits

Geophysical survey with magnetic method to interpret the iron ore deposits in the Eastern Nusawungu Coastal, Cilacap Regency, Central Java, Indonesia was carried out during six month, i.e. March –August 2017, covering the area in the geographical position of 109.3462° – 109.3718° E and 7.6958° – 7.7098° S. This survey has produced total magnetic field strength data at each measuring point in the research area. The magnetic field strength data which have been obtained, then be processed, corrected, and mapped so that the local magnetic anomaly contour map can be obtained. The local magnetic anomaly contour map shows the distribution of magnetic anomalous sources in the subsurface of research area. The 2D-modeling of magnetic anomalies data has been carried out along the AB trajectory extending on the local magnetic anomaly contour map from the position of A(109.3463°E and 7.7023°S) to B (109.3688°E and 7.7053°S), so that some subsurface anomalous objects is obtained. The modelling results of magnetic anomalies data show that the research area is estimated to have the potential of iron ore deposits. The subsurface rocks deposits containing iron ore are estimated to be located below the AB trajectory with a length about of 164.85 meters, a depth ranging of 1.709 – 31.909 meters, and a magnetic susceptibility value of 0.0122 cgs unit. These rocks are interpreted as sand deposits which coexists with silt and clay containing iron ore grains from the alluvium formation. Further, iron ore is also estimated to be present in the rocks deposits below the AB trajectory which have a depth of 24.405 – 49.809 meters and 3.989 – 11.111 meters, with the magnetic susceptibility values of 0.0093 and 0.0073 cgs units.

Tectonic units of the Early Precambrian basement within the North China Craton: Constraints from gravitational and magnetic anomalies

2018 ◽  
Vol 318 ◽  
pp. 122-132 ◽  
Author(s):  
Suhua Jiang ◽  
Wei Cao ◽  
Sanzhong Li ◽  
Gang Wang ◽  
Ian Somerville ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Magnetic Anomalies ◽  
Precambrian Basement ◽  
Early Precambrian ◽  
The North
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