Major Palaeoproterozoic shear zones of the central Fennoscandian Shield

Kärki, Aulis; Laajoki, K.; Luukas, Jouni

doi:10.1016/0301-9268(93)90077-f

Cited by 59 publications

(33 citation statements)

References 31 publications

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“…From c. 1.85-1.84 Ga onwards, much of the regional deformation partitioned into regional folds and ductile crustal-scale shear zones throughout the Fennoscandian shield (e.g. Ehlers & Lindroos, 1990;Kärki et al, 1993;Sjöström & Bergman, 1998;Högdahl, 2000;Väisänen, 2002;Soesoo et al, 2004). Some of these shear zones follow crustal discontinuities that have been interpreted as terrane boundaries (e.g.…”

Section: Introductionmentioning

confidence: 99%

Microstructures associated with the Sottunga-Jurmo shear zone and their implications for the 1.83-1.79 Ga tectonic development of SW Finland

Torvela¹,

Ehlers²

2010

Bull Geol Soc Finland

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This petrographic study of rock samples from the area of a large-scale shear zone, the Sottung-Jurmo shear zone, in SW Finland, illuminates the thermal development of and strain distribution within the rocks during the last development stages of the shear zone. The results indicate relatively high temperatures during the deformation phases that created the gneisses and the mylonites, strain partitioning through time and continued transpression from S-SW until at least c. 1.79 Ga. This has implications to the latest tectonic models since the results together with previous studies suggest a compartmentalisation of regional stresses between the area SW of the shear zone and central Fennoscandia. The results also suggest that the uplift rate increased during the late stage of the transpression.

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Section: Introductionmentioning

confidence: 99%

Microstructures associated with the Sottunga-Jurmo shear zone and their implications for the 1.83-1.79 Ga tectonic development of SW Finland

Torvela¹,

Ehlers²

2010

Bull Geol Soc Finland

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“…Interestingly, this is also the approximate age of the epigenetic Au-mineralisations in northern Finland as recorded by monazite from the Saattopora Au-deposit and by the Pb-Pb ages of several other Au-occurrences over a wide area (Mänttäri 1995). 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.…”

Section: Discussionmentioning

confidence: 97%

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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“…Younger phases of shear tectonics then produced new shear zones and reactivated older ones in the northern and central Fennoscandian Shield. The generation of the dextral, N-S-trending ductile shears of the Hirvaskoski Shear Zone (HSZ) was associated with deformation stage D 3 which is described in detail by Kärki et al (1993). Stage D 4 caused E-W-trending folding and created dextral NW-SEtrending and sinistral NE-SW-trending shear struc- Kuhmo, III.…”

Section: Geological Setting and Grani-toid Typesmentioning

confidence: 99%

“…Kärki et al 1993). The structural evolution is divided into an early phase that involved the formation of thrust nappes at the craton margin and the creation of related folds of pre-D 1 and D 1 stages (eg.…”

Section: Geological Setting and Grani-toid Typesmentioning

confidence: 99%

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Timing of Palaeoproterozoic crustal shearing in the central Fennoscandian Shield according to U-Pb data from associated granitoids, Finland

Vaasjoki¹,

Kärki²,

Laajoki³

2001

Bull Geol Soc Finland

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Granitoids in the Finnish part of the Fennoscandian Shield were created by numerous Archaean and Palaeoproterozoic tectonic events. Late phases of Palaeoproterozoic, Svecokarelian deformation created ductile, crustal-scale shear zones, of which the N-S striking Hirvaskoski Shear Zone and the NE-SW striking Oulujärvi Shear Zone were strongly affected by the latest deformation stages, D 3 and D 4 . These shear tectonic events deformed ductilely prekinematic granitoids and caused intrusion of synkinematic igneous rocks, but the D 3 and D 4 fault rocks are also penetrated by postkinematic intrusives.Archaean granitoids behaved mostly as rigid blocks unaffected by Palaeoproterozoic deformation. However, inherited Archaean zircons occur in some obviously Proterozoic granitoids, and others contain heterogeneous zircon populations. Granitoids lacking structures of the earliest deformations, D 1 and D 2 , contain inherited zircon populations partially reset during the Svecokarelian orogeny and have been sheared ductilely during stages D 3 and D 4 . Granitic rocks yielding zircon ages of 1.82-1.80 Ga show no features associated with these shearing events and penetrate the D 4 fault rocks setting a minimum age for these deformation events. This age marks also the end of convergent tectonics in the central Fennoscandian Shield. Monazite data from a variety of rocks demonstrates a regional cooling below the 600°C isotherm at 1.8 Ga.

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Major Palaeoproterozoic shear zones of the central Fennoscandian Shield

Cited by 59 publications

References 31 publications

Microstructures associated with the Sottunga-Jurmo shear zone and their implications for the 1.83-1.79 Ga tectonic development of SW Finland

Microstructures associated with the Sottunga-Jurmo shear zone and their implications for the 1.83-1.79 Ga tectonic development of SW Finland

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

Timing of Palaeoproterozoic crustal shearing in the central Fennoscandian Shield according to U-Pb data from associated granitoids, Finland

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