Age range of formation of sedimentary-volcanogenic complex of the Vetreny Belt (the southeast of the Baltic Shield)

Mezhelovskaya, S. V.; Korsakov, A. K.; Межеловский, А Д; Bibikova, Elena

doi:10.1134/s0869593816020040

Cited by 13 publications

(7 citation statements)

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“…In this diagram, plagioharzburgites of the paleochannel fall into the field of the Monche-pluton harzburgites differing from them by higher contents of Al2O3 and CaO (twofold) at the same MgO content [9]. The diagram also reflects clear differences in differentiation in komatiitic basalts volcanics which are assigned to comagmatic formations of layered intrusions [25,26] and in the Monchepluton. The differences in differentiation trends are due to the fact that crystallization of the olivine phase played the main role in volcanic rocks, while in the Monchepluton and other layered intrusions of the Paleoproterozoic age in the region, a more complex grading of olivine-chromite and olivine-orthopyroxene paragenesis into orthopyroxene-plagioclase paragenesis occurred.…”

mentioning

confidence: 99%

Magma feeding paleochannel in the Monchegorsk ore region: geochemistry, isotope U-Pb and Sm-Nd analysis (Kola region, Russia)

Smolkin

Bayanova

Serov

et al. 2022

PMI

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A comprehensive study of a 340 m thick lenticular-sheet body of ultramafic composition penetrated by structural well M-1 at a depth of about 2.2 km was accomplished. Its main volume is composed of plagioharzburgite; fine-grained rocks of norite and orthopyroxenite chilling zones are preserved on endocontacts. The rocks of the body are similar in composition to the rocks near the underlying ore-bearing layered intrusion – the Monchepluton. The age of intrusion of the ultramafic body is 2510 ± 9 Ma (U-Pb, ID-TIMS, zircon) and, taking into account analytical errors, is comparable with the formation period of the Monchepluton (2507-2498 Ma). According to the study of the Sm-Nd system in rocks and minerals, a positive value of the eNd (+1.1) parameter was established, similar to that in dunites and chromitites of the Monchepluton. Based on these results, the ultramafic body penetrated at depth was assigned to the magma feeding paleochannel through which the ultramafic, weakly contaminated magma entered the overlying magma chamber. This body is a unique example of a magma-feeding system for the ore-bearing layered intrusion of Precambrian age.

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confidence: 99%

Magma feeding paleochannel in the Monchegorsk ore region: geochemistry, isotope U-Pb and Sm-Nd analysis (Kola region, Russia)

Smolkin

Bayanova

Serov

et al. 2022

PMI

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“…Это значение изотопного возраста соответствует верхнему возрастному рубежу людиковийского надгоризонта и близко к возрасту долеритов, секущих породы заонежского горизонта -1919±18 млн лет (SIMS, n=12, MSWD=0.18, Th/U от 0.20 до 0.56) [Priyatkina et al, 2014]. Значительный вклад в накопление зерен dZr могли внести долериты с возрастом 1956±5 млн лет (SIMS; n=9; MSWD=0.18, Th/U от 1.81 до 3.72) [Stepanova et al, 2014a] и вулканиты заонежского комплекса с датировками 1982±4.5 и 1961±5.1 млн лет (ID-TIMS) [Martin et al, 2015]. Следы продуктов размыва Кончезерского силла, датированного в интервале 1975-1980 млн лет, Th/U от 1.75 до 4.63 [Puchtel et al, 1992[Puchtel et al, , 1998], могут присутствовать среди шести датировок зерен dZr (2.10-1.98 млрд лет) из пробы KL-555.…”

Section: возможные первичные источники зерен обломочного циркона из к...unclassified

On the Time and Conditions of Formation of the Shoksha Quartzite-Sandstones of the South Onega Depression Based on the New Data From Isotope Geochronology

Кузнецов

Kolodyazhnyi

Romanyuk

et al. 2023

Geodin. tektonofiz.

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The first results of U-Pb isotope dating of detrital zircons (dZr) from red-colored quartzitic-sandstones of the Shoksha formation (Shoksha horizon) are presented. The Shoksha formation completes the Vepsian sub-horizon (Vepsian) of the Lower Proterozoic of Karelia and is distributed within the South Onega trough. A sample (KL-555) of red-colored quartzitic sandstones was taken from the lower part of the section of the Shoksha formation in the same name deposit within the southwestern Cis-Onega Lake region. The 79 dZr grains isolated from this sample were analyzed by the staff of the Chemistry-Isotopic Analytic Laboratory of the GIN RAS using the equipment of the Shared Research Facilities of the GIN RAS. The weighted average of the three youngest U-Pb isotope dates for dZr grains is 1906±13 Ma. Taking into account the known isotopic dates of gabbro-dolerites from the Ropruchei sill, that cuts through the Shoksha formation, it makes possible to constrain the time of the Shoksha formation accumulation by ~1.90–1.75 Ga. A significant part of the carried out analyzes has yielded a high degree of discordance of the dates. The features of the distribution of the figurative points of these analyzes in the diagram with concordia suggest that the rocks of the studied section of the Shoksha formation were subjected to the alteration that disturbed the U-Pb isotope system of these zircon grains in the Phanerozoic.The set of obtained dates for dZr grains has been compared with the known ages of the crystalline complexes of the basement of the East European Platform. The age sets of dZr grains from sample KL-555 and rocks of the Ladoga group, developed along the margin of the Svecofennian accretionary orogen, are very similar (p similarity coefficient in Kolmogorov – Smirnov test is 0.27) and characterize mainly tectonic–magmatic events that had immediately preceded the manifestation of the Svecofennian orogeny (1.9–1.87 Ga). Therefore, the rocks of the Ladoga group could highly probably be a secondary source for the Shoksha quartzites. Based on a comparative analysis of ages and thorium-uranium ratios (Th/U) in dZr grains from sample KL-555, it was concluded that some of the studied dZr grains with high Th/U>1.5 originate from Ludicovian mafic rocks, but those with low Th/U<0.1 originate from ultra-high-pressure formations, such as eclogites known in the Salma, Kuru-Vaara and Gridino.A paleo-geographic scheme for the Late Vepsian is proposed, showing that the highly mature Shoksha sandstones were generated under continental conditions in a local basin due to the accumulation of clastic material carried by an extensive and branched

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“…Table 1. U-Pb age zircon (ID-TIMS) and Sm-Nd analysis of igneous rocks [13][14][15][16][17][18][19][20][21][22]. Ruiga Olivine-bearing gabbronorite 2415 ± 5 [22] *: Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS); **: sensitive high-resolution ion microprobe, high-resolution secondary ion mass spectrometry (SIMS-SHRIMP-II).…”

Section: Geologic Settingmentioning

confidence: 99%

“…The ~4000 m thick Vetreny Belt formation occurs in the northeastern Vetreny Belt. It displays various facies of lava, pillow, diatreme, and hypabyssal types [42][43][44][45][46]. Layered flows with spinifex structures of olivine and pyroxene types, containing relics of olivine, augite, pigeonite, plagioclase (andesine), and alumochromite, are widespread.…”

Section: Intrusionmentioning

confidence: 99%

Layered Intrusions of Paleoproterozoic Age in the Kola and Karelian Regions

2023

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Large-scale layered intrusions of a peridotite–pyroxenite–gabbronorite complex, to which Cr, Ni, Cu, and PGE deposits and ore occurrences are confined, were emplaced into the Baltic paleocontinent 2.50–2.45 Ga. Layered intrusions in the Monchegorsk Ore District, including the Monchepluton and Imandra–Umbarechka Complex, as well as the gabbro-anorthosite complex of the Main Ridge, were analyzed earlier geochemically and isotopically. In the present paper, the authors analyze layered intrusions in the Kola region (Mount Generalskaya) and Karelia (Kivakka, Kovdozero, and the Burakovsky Pluton). The primary composition of mantle magmas for the layered intrusions is assumed to be identical to that of the komatiitic basalts making up the volcanogenic units of the Vetreny Belt and the Imandra–Varzuga zone. A general model for the formation of layered intrusions includes superplume uplift in the early Paleoproterozoic, the generation of mantle magmas and their injection into the lower portion of the earth crust, the formation of deep-seated and intermediate magma chambers, and the intense contamination of the granulite–metamorphic complex followed by the generation of magma chambers provoked by single or multiple injections.

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Age range of formation of sedimentary-volcanogenic complex of the Vetreny Belt (the southeast of the Baltic Shield)

Cited by 13 publications

References 1 publication

Magma feeding paleochannel in the Monchegorsk ore region: geochemistry, isotope U-Pb and Sm-Nd analysis (Kola region, Russia)

Magma feeding paleochannel in the Monchegorsk ore region: geochemistry, isotope U-Pb and Sm-Nd analysis (Kola region, Russia)

On the Time and Conditions of Formation of the Shoksha Quartzite-Sandstones of the South Onega Depression Based on the New Data From Isotope Geochronology

Layered Intrusions of Paleoproterozoic Age in the Kola and Karelian Regions

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