The Svecofennian orogen: a collage of microcontinents and island arcs

Korja, T.; Lahtinen, Raimo; Nironen, Mikko

doi:10.1144/gsl.mem.2006.032.01.34

Cited by 98 publications

(82 citation statements)

References 67 publications

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“…The Fennoscandian Shield comprises an Archaean core in the northwest; surrounding this are younger arcs and microcontinents that amalgamated during the Svecofennian orogeny at ~ 2.1-1.9 Ga (Korja et al, 2006;Lahtinen et al, 2009). At ~1.85 Ga, a subduction zone initiated on the southwest margin (present-day position) of the continent, producing the Transcandinavian Igneous Belt (TIB; see Högdahl et al, 2004).…”

Section: Geological Settingmentioning

confidence: 99%

Sedimentary recycling in arc magmas: geochemical and U–Pb–Hf–O constraints on the Mesoproterozoic Suldal Arc, SW Norway

Roberts

Slagstad

Parrish

et al. 2012

Contrib Mineral Petrol

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The Hardangervidda-Rogaland Block within southwest Norway is host to ~1.52-1.48 Ga continental building, and variable reworking during the ~1.1-0.9 Ga Sveconorwegian orogeny. Due to the lack of geochronological and geochemical data, the timing and tectonic setting of early Mesoproterozoic magmatism has long been ambiguous. This paper presents zircon U-Pb-Hf-O isotope data combined with whole-rock geochemistry to address the age and petrogenesis of basement units within the Suldal region, located in the centre of the Hardangervidda-Rogaland Block. The basement comprises variably deformed grey gneisses and granitoids that petrologically and geochemically resemble mature volcanic arc lithologies.U-Pb ages confirm that magmatism occurred from ~1521 to 1485 Ma, and conspicuously lack any xenocrystic inheritance of distinctly older crust. Hafnium isotope data range from εHf (initial) +1 to +11, suggesting a rather juvenile magmatic source, but with possible involvement of late Palaeoproterozoic crust. Oxygen isotope data range from mantle-like (δ 18 O ~5‰) to elevated (~10‰) suggesting involvement of low-temperature altered material (e.g. supracrustal rocks) in the magma source. The Hf-O isotope array is compatible with mixing between mantle-derived material with young low-temperature altered material (oceanic crust/sediments) and older low-temperature altered material (continent-derived sediments). This, combined with a lack of xenoliths and xenocrysts, exposed older crust, AFC trends and S-type geochemistry, all point to mixing within a deep-crustal magma-generation zone. A proposed model comprises accretion of altered oceanic crust and the overlying sediments to a pre-existing continental margin, underthrusting to the magma generation zone, and remobilisation during arc magmatism. The geodynamic setting for this arc magmatism is comparable to that seen in the Phanerozoic (e.g. the Sierra Nevada and Coast ranges batholiths), with compositions in the Suldal Sector reaching those of average upper continental crust. As within these younger examples, factors that drive magmatism towards the composition of the average continental crust include the addition of sedimentary material to magma source regions, and delamination of cumulate material. Underthrusting of sedimentary materials and their subsequent involvement in arc magmatism is perhaps a more widespread mechanism involved in continental growth than is currently recognized. Finally, the Suldal Arc magmatism represents a significant juvenile crustal addition to SW Fennoscandia.

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Section: Geological Settingmentioning

confidence: 99%

Sedimentary recycling in arc magmas: geochemical and U–Pb–Hf–O constraints on the Mesoproterozoic Suldal Arc, SW Norway

Roberts

Slagstad

Parrish

et al. 2012

Contrib Mineral Petrol

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“…The Shield comprises Archean and Paleoproterozoic terranes that were merged during the Svecofennian and Lapland-Kola orogenies at 1.9 Ga ago (GORBATSCHEV and BOGDANOVA 1993;DALY et al 2006;KORJA et al 2006 The Archean terranes (WKC, CKC, BP) formed between 3.7 and 2.7 Ga and were welded together in Neoarchean collisions at 2.9 Ga (SLABUNOV et al 2006). As a response to a mantle plume, the Neoarchean orogenic domain rifted at the beginning of the Paleoproterozoic Era (AMELIN et al 1995;HEAMAN 1997;SORJONEN-WARD et al 1997;HANSKI and HUHMA 2005;MELEZHIK 2006;LAHTINEN et al 2008).…”

Section: Geological and Geophysical Settingmentioning

confidence: 99%

“…1; AMELIN et al 1995;HEAMAN 1997;SORJONEN-WARD et al 1997;ERNST and BUCHAN 2001;HANSKI and HUHMA 2005;MELEZHIK 2006). The northern part of the Shield is a collage of Archean and Paleoproterozoic terranes that were accreted in the Svecofennian and Lapland-Kola orogenies approximately 1.9-1.8 Ga ago (GORBATSCHEV and BOGDANOVA 1993;DALY et al 2006;KORJA et al 2006). The majority of the collisional terrane boundaries are in NW-SE direction.…”

Section: Introductionmentioning

confidence: 99%

“…In Central Lapland, however, the change from Archean to Paleoproterozoic lithologies is more complex resulting in additional boundaries in NE-SW and N-S directions. It is an area where both Archean and Paleoproterozoic terranes either halt or intertwine with each other and where the lithologies are dominated by rift related volcano-sedimentary sequences (DALY et al 2006;KORJA et al 2006;SLABUNOV et al 2006). The area is also transected by NW-SE-directed strike slip faults (Sirkka Line/Kittilä Shear Zone (KSZ), Meltaus Shear zone (MSZ); GAÁ L et al 1989;PATISON et al 2006;KORJA and HEIKKINEN 2008).…”

Section: Introductionmentioning

confidence: 99%

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Crustal Architecture of the Inverted Central Lapland Rift Along the HUKKA 2007 Profile

Tiira

Janik

Kozlovskaya

et al. 2013

Pure Appl. Geophys.

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Abstract-We have studied the lateral velocity variations along a partly buried inverted paleo-rift in Central Lapland, Northern Europe with a 2D wide-angle reflection and refraction experiment, HUKKA 2007. The experiment was designed to use seven chemical explosions from commercial and military sites as sources of seismic energy. The shots were recorded by 102 stations with an average spacing of 3.45 km. Two-dimensional crustal models of variations in P-wave velocity and Vp/Vs-ratio were calculated using the ray tracing forward modeling technique. The HUKKA 2007 experiment comprises a 455 km long profile that runs NNW-SSE parallel to the Kittilä Shear Zone, a major deformation zone hosting gold deposits in the area. The profile crosses Paleoproterozoic and reactivated Archean terranes of Central Lapland. The velocity model shows a significant difference in crustal velocity structure between the northern (distances 0-120 km) and southern parts of the profile. The difference in P-wave velocities and Vp/Vs ratio can be followed through the whole crust down to the Moho boundary indicating major tectonic boundaries. Upper crustal velocities seem to vary with the terranes/compositional differences mapped at the surface. The lower layer of the upper crust displays velocities of 6.0-6.1 km/s. Both Paleoproterozoic and Archean terranes are associated with high velocity bodies (6.30-6.35 km/s) at 100 and 200-350 km distances. The Central Lapland greenstone belt and Central Lapland Granitoid complex are associated with a 4 km-thick zone of unusually low velocities (\6.0 km/s) at distances between 120 and 220 km. We interpret the HUKKA 2007 profile to image an old, partly buried, inverted continental rift zone that has been closed and modified by younger tectonic events. It has structural features typical of rifts: inward dipping rift shoulders, undulating thickness of the middle crust, high velocity lower crust and a rather uniform crustal thickness of 48 km.

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“…Nironen, 2005). The Uusimaa belt and the Häme belt, which is another volcano-sedimentary sequence to the north of the Uusimaa belt, together form a terrane called southern Svecofennia (Kähkönen, 2005), although Korja et al (2006) regard the Uusimaa and Häme belts as separate (suspect) terranes. All existing age determinations of volcanic and synvolcanic plutonic rocks within southern Svecofennia are bracketed between ~ 1.90 − 1.88 Ga (Patchett & Kouvo, 1986;Vaasjoki, 1994;Reinikainen, 2001;Ehlers et al, 2004;Skyttä et al, 2005, Torvela et al, 2008.…”

Section: Geological Settingmentioning

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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The Svecofennian orogen: a collage of microcontinents and island arcs

Cited by 98 publications

References 67 publications

Sedimentary recycling in arc magmas: geochemical and U–Pb–Hf–O constraints on the Mesoproterozoic Suldal Arc, SW Norway

Sedimentary recycling in arc magmas: geochemical and U–Pb–Hf–O constraints on the Mesoproterozoic Suldal Arc, SW Norway

Crustal Architecture of the Inverted Central Lapland Rift Along the HUKKA 2007 Profile

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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