Genesis of a Magnetite Layer in the Gabbro-10 Intrusion, Monchegorsk Complex, Kola Region: U–Pb SHRIMP-II Dating of Metadiorites

Groshev, N. Yu.; Припачкин, П. В.; Karykowski, Bartosz T.; Malygina, A. V.; Rodionov, N. V.; Belyatsky, B. V.

doi:10.1134/s1075701518060028

Cited by 5 publications

(25 citation statements)

References 8 publications

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“…The lower contact of the layer with the metagabbro is abrupt and oriented subhorizontally; the upper boundary is also sharp, but drawn conditionally depending on the size and shape of Archean diorite fragments. In accordance with the data of the analysis of hand specimen samples, the ore contains up to 5% of TiO 2 and 0.1% of V 2 O 5 [13].…”

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...supporting

confidence: 83%

“…At the same time, the composition of trace elements (Y, Zr, Nb, Ta, etc.) in the Gabbro-10 metadiorites and Archean basement diorite-gneisses somewhat differ [13].…”

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 92%

“…The massive varieties contain grains of saussuritized plagioclase and blocks of micropegmatite. It is typical that the metadiorites constantly contain 2-5 vol.% of magnetite and, thus are clearly visible in the magnetic field [13].…”

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 99%

“…The breccia cement is represented by metadiorites and magnetite rocks, and fragments with a size of up to 6 meters across from Archean basement diorites with numerous veinlets of the cement material. A 1-2 m thick layer composed of magnetite of up to 90 vol.% occurs at the bottom of the breccia zone [13].…”

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 99%

“…The results of local U-Pb isotope age determination of the rocks of the Gabbro-10 massif are described by [13]. On the basis of morphology and internal structure of grains, the studied zircon from the metadiorites was divided by the authors into several generations.…”

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 99%

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Archean Rocks of the Diorite Window Block in the Southern Framing of the Monchegorsk (2.5 Ga) Layered Mafic-Ultramafic Complex (Kola Peninsula, Russia)

et al. 2020

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The intermediate rocks classified as diorite-gneisses occur within the southern part of the Monchegorsk (2.5 Ga) layered mafic-ultramafic complex (Kola Peninsula, Russia). These diorite-gneisses belong to a block historically known as the diorite window (DW) block. The same rocks occur in a framing of the Monchegorsk complex. The DW block is predominantly composed of diorite-gneisses and, to a lesser degree, of amphibolites. Multi-ordinal banding, complex folding, boudinage and metamorphic transformations, garnet porphyroblasts, and tourmaline veinlets are typical of the diorite-gneisses. In accordance with the U-Pb isotope data, the age of the diorite-gneisses in the DW block is 2736.0 ± 4.6 Ma. The Sm-Nd mineral (garnet, biotite, and tourmaline) isochron for the DW rocks has yielded an age of 1806 ± 23 Ma (related to the processes of the Svecofennian orogeny). The DW diorite-gneisses are compared with the metadiorites of the Gabbro-10 massif. The latter is a part of the Monchegorsk complex, with U-Pb crystallization age of 2498 ± 6 Ma. On the basis of geological and isotope-geochemical data, it is shown that the DW rocks belong to the Archean basement while the Gabbro-10 metadiorites probably represent one of the late-magmatic phases of the Monchegorsk complex.

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Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...supporting

confidence: 83%

“…At the same time, the composition of trace elements (Y, Zr, Nb, Ta, etc.) in the Gabbro-10 metadiorites and Archean basement diorite-gneisses somewhat differ [13].…”

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 92%

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 99%

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 99%

Section: Gabbro-10 Massif: Structure Petrography Geochemistry and Geo...mentioning

confidence: 99%

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Archean Rocks of the Diorite Window Block in the Southern Framing of the Monchegorsk (2.5 Ga) Layered Mafic-Ultramafic Complex (Kola Peninsula, Russia)

et al. 2020

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The Olivine Horizon of the Layered Monchegorsk Pluton (Kola Region, Russia): Additional Magma Injection Based on Integrated Geological and Geochronological Data

Chashchin,

Sergeev

2023

Geosciences

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The paper presents the first SIMS SHRIMP U-Pb data for zircon from an olivine horizon within the Nyud intrusion of the ore-bearing layered Monchegorsk pluton (Monchepluton) in the Kola Region, Russia. A 100–150 m-thick olivine horizon occurs nearly horizontally between the melanocratic and mesocratic norite of the Nyud intrusion, which disturbs its normal cumulus stratigraphic sequence. In addition, the pyroxene-plagioclase hornfelses are present at the upper contact with the olivine horizon. Twenty-three zircon grains were extracted from the large-volume olivine plagio-orthopyroxenite sample and clustered into two populations. The first population of magmatic zircon (n = 8) has a concordant and weighted average 207Pb/206Pb age of 2484.3 ± 5.6 Ma, which characterizes the formation time of the olivine horizon rocks. This serves as evidence of the olivine horizon that forms as a result of additional magma injection, which does not contradict the geological data. The 207Pb/206Pb age of single-grain zircon is 2414 ± 25 Ma, which indicates the time of postmagmatic transformations. The second population of zircon (n = 16) has a concordant and weighted average U-Pb age of 2700.6 ± 4.6 Ma, which indicates zircon absorption by olivine horizon magma probably from the rocks of the Archean greenstone belt.

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Paleoproterozoic Layered Intrusions of the Monchegorsk Ore District: Geochemistry and U–Pb, Sm–Nd, Re–Os Isotope Analysis

Smolkin

Mokrushin

2022

Minerals

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The paper concerns the geochemical analysis of rocks from the ore-bearing layered intrusions that belong to two age groups of the Monchepluton and the Imandra–Umbarechka Complex (2.50 and 2.44 Ga) and the largest gabbro-anorthosite of the Main Ridge Complex (2.51–2.45 Ga). The intrusion of these complexes happened at different depths when the endogenous and geodynamic settings changed at the beginning of the Paleoproterozoic Era. Five megacycles are distinguished in a generalized cross-section of the two-chamber Monchepluton. The megacycles differ in rock composition, rock geochemical features, and mineralization types, i.e., the chromite, sulfide Cu–Ni–PGE and low-sulfide PGE types. The abrupt changes in isotope indicators (εNd, 87Sr/86Sr) mark their boundaries. At a depth of 2037–2383 m, the M-1 borehole intersects a standalone intrusive body that is essentially a magma feeder channel. The intrusive body’s geochemical characteristics and U–Pb isotope age correlate to the Monchepluton rocks. The gabbro-anorthosite massifs united in the Main Ridge Complex were intruded in the following order: the Monchetundra, Chunatundra, Volchetundra, and Losevo–Medvezhye tundras. The largest Monchetundra massif was formed as a result of multiple intrusions of mafic magmatic melt from the deep reservoirs. The melts intruded in two stages, i.e., 2.51–2.49 Ga and 2.48–2.47 Ga, and their composition changed gradually. The gabbro-pegmatites and coeval harrisite dykes are more recent ones (2.46–2.45 Ga). The summarized results of the U–Pb, Sm–Nd, and Re–Os systems research allowed us to establish genetic relations between the studied geological objects. We proposed a model where there was an uplift of a mantle plume to the lower crust area at the age of 2.5 Ga, the deep mantle reservoirs were formed, and a large-scale interaction happened between the parental magma and granulite–eclogite complex rocks. Local contamination and assimilation processes took place during the uplifting of magmas in areas where the magmatic feeding system contacted the host amphibolite–gneiss Archean complexes.

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Genesis of a Magnetite Layer in the Gabbro-10 Intrusion, Monchegorsk Complex, Kola Region: U–Pb SHRIMP-II Dating of Metadiorites

Cited by 5 publications

References 8 publications

Archean Rocks of the Diorite Window Block in the Southern Framing of the Monchegorsk (2.5 Ga) Layered Mafic-Ultramafic Complex (Kola Peninsula, Russia)

Archean Rocks of the Diorite Window Block in the Southern Framing of the Monchegorsk (2.5 Ga) Layered Mafic-Ultramafic Complex (Kola Peninsula, Russia)

The Olivine Horizon of the Layered Monchegorsk Pluton (Kola Region, Russia): Additional Magma Injection Based on Integrated Geological and Geochronological Data

Paleoproterozoic Layered Intrusions of the Monchegorsk Ore District: Geochemistry and U–Pb, Sm–Nd, Re–Os Isotope Analysis

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