Early Proterozoic layered intrusions in the northeastern part of the Fennoscandian Shield

Alapieti, T. T.; Filén, B. A.; Lahtinen, J. J.; Lavrov, M. M.; Smolkin, V. F.; Voitsekhovsky, S. N.

doi:10.1007/bf01162681

Cited by 141 publications

(57 citation statements)

References 16 publications

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“…Indeed, Ca-rich pyroxene and plagioclase are virtually absent in the rocks at PadosTundra, in contrast to layered intrusions (2.4-2.5 Ga) in the Fennoscandian Shield (e.g., Alapieti et al, 1990;. This feature may well point to a fairly low content of Ca in the parental magma of the Pados-Tundra complex.…”

Section: Calcic and Fe-mg Amphibolesmentioning

confidence: 74%

“…In the Fennoscandian (Baltic) Shield, Paleoproterozoic layered intrusions (2.4-2.5 Ga in age) are relatively common in northwestern Russia, i.e., in Russian Karelia and in the Kola Peninsula, and in Finland (e.g., Alapieti et al, 1990). In contrast, igneous complexes of mafic-ultramafic compositions of other age groups are comparatively rarer and poorly characterized.…”

Section: Introductionmentioning

confidence: 99%

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The structure and cryptic layering of the Pados-Tundra ultramafic complex, Serpentinite belt, Kola Peninsula, Russia

Barkov¹,

Aa²,

Martin³

2017

Bull Geol Soc Finland

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The Paleoproterozoic Pados-Tundra ultramafic complex, ~6 x 1.5-2.1 km in size and ~2.1 Ga in age, located in the Kola Peninsula of Russia, is the main representative of the Serpentinite belt in the northern Fennoscandian Shield. It is composed of fragmented or foliated bodies of dunite-harzburgite -orthopyroxenite; these have an elevated potential for Cr and the platinum-group elements (PGE). In general, the complex consists of the Dunite Zone (olivine cumulates) and Orthopyroxenite Zone (orthopyroxene + olivine cumulates, interlayered); its upper zones of more evolved rocks of mafic compositions appear to have been removed by erosion. The complex shows well-recognized patterns of cryptic layering, documented along cross-sections in grains of olivine and Ca-poor pyroxene. Narrow ranges of high-Mg compositions are observed in olivine ] and orthopyroxene [Wo <0.1-3.0 En 85.1-91.2 Fs 8.1-12.5 ]. Their trends of crystallization indicate that cumulate olivine, orthopyroxene, and olivine-orthopyroxene rocks (dunite and orthopyroxenite, with subordinate harzburgite and olivine-bearing orthopyroxenite) become, in general, more evolved toward the internal portions of the complex; stratigraphically lower and early-crystallizing cumulates are exposed closer to its outer contact. The compositions of early phases of cumulus origin, Fo 91 olivine and En 91 , orthopyroxene are notably magnesian, implying an elevated Mg# in the parental magma. The anomalously Cr-Al-rich grains of serpentine (up to ~2.5 wt.% Cr 2 O 3 and ~4.0wt.% Al 2 O 3 ), hitherto unreported, are present in specimens of dunite near the northeastern margin of the complex. Supercooling and metastable crystallization likely affected the melt in the eastern portion of the complex near the Dunite block (i.e., host for segregations and stratiform-like layers of chromitite) and relatively close to the outer contact. An uncommon mineralization of the PGE is associated with the chromitite deposits at Pados-Tundra.

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Section: Calcic and Fe-mg Amphibolesmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

The structure and cryptic layering of the Pados-Tundra ultramafic complex, Serpentinite belt, Kola Peninsula, Russia

Barkov¹,

Aa²,

Martin³

2017

Bull Geol Soc Finland

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“…3.7), which is dependent upon the local palaeotectonic and depositional settings. However, despite their variable lithology and petrology, the Sumian system rocks share two important features: (1) the volcanic rocks are coeval and may even be partly comagmatic with the 2440-2430 Ma layered gabbronorite intrusions (Alapieti et al 1990;Melezhik and Sturt 1994;Hanski et al 2001b;Chashchin et al 2008;Kulikov et al 2010); and (2) isotope geochemistry of the various sedimentary units in the upper part of the Sumian system show massindependent fractionation of sulphur isotopes ( Fig. 3.6; Reuschel et al 2009).…”

Section: The Sumian System 2505-2430 Mamentioning

confidence: 95%

3.2 Litho- and Chronostratigraphy of the Palaeoproterozoic Karelian Formations

Hanski

Melezhik

2012

Reading the Archive of Earth’s Oxygenation

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“…By examining the dike composition or chilled margin and bulk compositions of individual intrusive bodies, Lahtinen et al (1989), Alapieti et al (1990), SainiEidukat et al (1997) and Vogel et al (1998) proposed two compositionally distinct parental magma types for the early Paleoproterozoic layered intrusions. The first is referred to as boninitic as it is characterized by relatively high MgO and Cr contents, intermediate SiO 2 and low TiO 2 contents.…”

Section: Mafic Layered Intrusionsmentioning

confidence: 98%

Early Paleoproterozoic felsic and mafic magmatism in the Karelian province of the Fennoscandian shield

Lauri

Mikkola

Karinen

2012

Lithos

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Early Proterozoic layered intrusions in the northeastern part of the Fennoscandian Shield

Cited by 141 publications

References 16 publications

The structure and cryptic layering of the Pados-Tundra ultramafic complex, Serpentinite belt, Kola Peninsula, Russia

The structure and cryptic layering of the Pados-Tundra ultramafic complex, Serpentinite belt, Kola Peninsula, Russia

3.2 Litho- and Chronostratigraphy of the Palaeoproterozoic Karelian Formations

Early Paleoproterozoic felsic and mafic magmatism in the Karelian province of the Fennoscandian shield

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