1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield

Eklund, Olav; Konopelko, Dmitry; Rutanen, Henrikki; Fröjdö, Sören; Shebanov, Alexey

doi:10.1016/s0024-4937(98)00027-9

Cited by 120 publications

(58 citation statements)

References 35 publications

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“…Apatite contents rarely exceed 1 vol.% of magmatic rock. Unusual host rocks in which it does, are mantle related within-plate intrusions, i.e., carbonatites, alkaline ultramafic rocks, nepheline syenites, nelsonites, gabbro-norites, trachytic volcanics, nevoites and ladogites (Eklund et al 1998;Dymek and Owens 2001;Belousova et al 2002). In the rare cases where enhanced apatite contents and phosphorus concentrations in granitoids are encountered, they are the results of hybridization with mantle-derived melts affected by carbonate metasomatism (e.g., Eklund et al 1998) or the formation of magmatic cumulates due to accumulation of early-formed crystals in relatively low viscosity-, water-and fluorine-rich magma (Dorais et al 1997;Gawęda 2008;Duchesne et al 2010).…”

Section: Introductionmentioning

confidence: 99%

The petrogenesis of granitoid rocks unusually rich in apatite in the Western Tatra Mts. (S-Poland, Western Carpathians)

et al. 2013

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In the bottom part of the tongue-shaped, layered granitoid intrusion, exposed in the Western Tatra Mts., apatite-rich granitic rocks occur as pseudo-layers and pockets between I-type hybrid mafic precursors and homogeneous S-type felsic granitoids. The apatite-rich rocks are peraluminous (ASI01.12-1.61), with P 2 O 5 contents ranging from 0.05 to 3.41 wt.% (<7.5 vol.% apatite), shoshonitic to high-K calcalkaline. Apatite is present as long-prismatic zoned crystals (Ap 1 ) and as large xenomorphic unzoned crystals (Ap 2 ). Ap 1 apatite and biotite represent an early cumulate. Feldspar and Ap 2 textural relations may reflect the interaction of the crystal faces of both minerals and support a model based on local saturation of (P, Ca, F) versus (K, Na, Al, Si, Ba) in the border zones. Chondrite-normalized REE patterns for the apatite rocks and for pure apatite suggest apatite was a main REE carrier in these rocks. Minerals characteristics and the whole rock chemistry suggest both reduced S-type and I-type magma influenced the apatite-rich rocks. The field observations, mineral and rock chemistry as well as mass-balance calculations point out that the presence of apatite-rich rocks may be linked to the continuous mixing of felsic and mafic magmas, creating unique phosphorus-and aluminium-rich magma portions. Formation of these rocks was initially dominated by the complex flowagecontrolled and to some extent also gravity-driven separation of early-formed zoned minerals and, subsequently, by local saturation in the border zones of growing feldspar and apatite crystals. Slow diffusion in the phosphorus-rich magma pockets favoured the local saturation and simultaneous crystallization of apatite and feldspars in a crystal-ladden melt.

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Section: Introductionmentioning

confidence: 99%

The petrogenesis of granitoid rocks unusually rich in apatite in the Western Tatra Mts. (S-Poland, Western Carpathians)

et al. 2013

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“…Several felsic intrusions in southern and central Finland, such as Puruvesi (Nykänen 1983), Ruokolahti (Nykänen 1988), Mikkeli (Patchett & Kouvo 1986), Takiankangas (Kärki 1995), Anttola (Korsman 1984), Parkkila (Simonen 1982) and Hanko (Huhma 1986), also belong to this age group. Furthermore, Eklund et al (1998) have outlined a belt consisting of at least fourteen 1.8 Ga old post-collisional shoshonitic intrusions in southern Finland and Russian Karelia. These intrusions range from ultramafic, calc-alkaline potassium lamprophyres to peraluminous granites and are believed to have been derived from a lithospheric mantle source affected by carbonate metasomatism.…”

Section: Discussionmentioning

confidence: 99%

“…These intrusions range from ultramafic, calc-alkaline potassium lamprophyres to peraluminous granites and are believed to have been derived from a lithospheric mantle source affected by carbonate metasomatism. Eklund et al (1998) concluded that the regional distribution of such intrusions may indicate that large volumes of 1.8 Ga juvenile material resides in unexposed parts of the crust. Direct evidence for the presence of lower crust of this age is now available from eastern Finland (this study, Hölttä et al 2000) and from the Belomorian Mobile Belt in Kola Peninsula (Downes et al in prep).…”

Section: Discussionmentioning

confidence: 99%

An ion microprobe U-Th-Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland

Peltonen¹,

Mänttäri²

2001

Bull Geol Soc Finland

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“…Hopgood et al, 1983, Ehlers et al, 2004Eklund & Shebanov, 2005;Nironen, 2005). (ii) Geochemical compositions of postorogenic intrusions in Finland show mantle characteristics that are highly enriched in Sr, Ba, P, LILEs and LREEs and have a strong negative Nb-Ta anomaly (Eklund et al, 1998;Andersson et al, 2006a and references therein). The composition of the Salittu gabbro is different having an EMORB-type chemistry, similar to the volcanic rocks in the Salittu Formation , which prompts a synvolcanic interpretation for the intrusion.…”

Section: Age Of Metamorphismmentioning

confidence: 99%

U-Th-Pb zircon geochronology on igneous rocks in the Toija and Salittu Formations, Orijärvi area, southwestern Finland: Constraints on the age of volcanism and metamorphism

Väisänen¹,

Kirkland²

2008

Bull Geol Soc Finland

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Zircons from a felsic volcanic rock in the Toija Formation and a synvolcanic gabbro intrusion in the Salittu Formation within the Orijärvi area were dated by U-Th-Pb SIMS in order to provide depositional constraints on these formations. Zircon crystals from the felsic rock preserve a two-stage crystallisation history with zoned core domains and homogeneous rim domains. Inner domains yield a 1878 ± 4 Ma concordia age, interpreted to determine the crystallisation of this rock. Rims yield a 1815 ± 3 Ma concordia age interpreted to determine the regional metamorphism. Small rounded zircon grains from the Salittu gabbro, located within the Jyly shear zone, yield a concordia age of 1792 ± 5 Ma. We interpret the grain textures to suggest that they recrystallised from inherited zircon seeds during the heat and fluid flow into the shear zone. Although no direct ages for the Salittu Formation have been recovered, field relationships imply that it was deposited between 1878 − 1875 Ma.

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1.8 Ga Svecofennian post-collisional shoshonitic magmatism in the Fennoscandian shield

Cited by 120 publications

References 35 publications

The petrogenesis of granitoid rocks unusually rich in apatite in the Western Tatra Mts. (S-Poland, Western Carpathians)

The petrogenesis of granitoid rocks unusually rich in apatite in the Western Tatra Mts. (S-Poland, Western Carpathians)

An ion microprobe U-Th-Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland

U-Th-Pb zircon geochronology on igneous rocks in the Toija and Salittu Formations, Orijärvi area, southwestern Finland: Constraints on the age of volcanism and metamorphism

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