Upper Proterozoic stratigraphy and depositional environments of the Tossåsfjället Group, Särv Nappe, southern Swedish Caledonides

Kumpulainen, Risto A.

doi:10.1080/11035898009454506

Cited by 54 publications

(39 citation statements)

References 30 publications

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“…In contrast to the underlying lower grade Särv nappes (Strömberg 1961), with their wellestablished stratigraphy of the Tossåsfjället Group, comprising thick fluvial to shallow marine feldspathic sandstones, overlain by carbonates, tillites and more sandstones (Kumpulainen 1980;Nystuen et al 2008), the Seve metasediments are known in less detail. Amphibolites and highly deformed and metamorphosed sandstones dominate the lower nappes, generally accompanied by subordinate marbles and calcsilicate rocks.…”

Section: The Seve Nappe Complexmentioning

confidence: 95%

Tectonometamorphic evolution of the Åreskutan Nappe – Caledonian history revealed by SIMS U–Pb zircon geochronology

Ladenberger

Be’eri-Shlevin

Claesson

et al. 2013

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Secondary ionization mass spectrometry (SIMS) U-Pb dating of zircons from the Å reskutan Nappe in the central part of the Seve Nappe Complex of western central Jämtland provides new constraints on the timing of granulite-amphibolite-facies metamorphism and tectonic stacking of the nappe during the Caledonian orogeny. Peak-temperature metamorphism in garnet migmatites is constrained to c. 442 + 4 Ma, very similar to the ages of leucogranites at 442 + 3 and 441 + 4 Ma. Within a migmatitic amphibolite, felsic segregations crystallized at 436 + 2 Ma. Pegmatites, cross-cutting the dominant Caledonian foliation in the Nappe, yield 428 + 4 and 430 + 3 Ma ages. The detrital zircon cores in the migmatites and leucogranites provide evidence of Late Palaeoproterozoic, Mesoproterozoic to Early Neoproterozoic source terranes for the metasedimentary rocks. The formation of the ductile and hot Seve migmatites, with their inverted metamorphism and thinning towards the hinterland, can be explained by an extrusion model in which the allochthon stayed ductile for a period of at least 10 million years during cooling from peaktemperature metamorphism early in the Silurian.In our model, Baltica-Laurentia collision occurred in the Late Ordovician-earliest Silurian, with emplacement of the nappes far on to the Baltoscandian platform during the Silurian and early Devonian, Scandian Orogeny lasting until c. 390 Ma.

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Section: The Seve Nappe Complexmentioning

confidence: 95%

Tectonometamorphic evolution of the Åreskutan Nappe – Caledonian history revealed by SIMS U–Pb zircon geochronology

Ladenberger

Be’eri-Shlevin

Claesson

et al. 2013

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“…The overthrust Middle Allochthon is dominated in lower parts by longtransported, basement-derived thrust sheets and Neoproterozoic sandstone successions. In upper parts, dolerite dyke-swarms become an increasingly important component, intruding Cryogenian and Ediacaran successions (Kumpulainen, 1980(Kumpulainen, , 2011. Metamorphic grade increases upwards throughout the Lower and Middle allochthons and, in the uppermost parts (Seve Nappe Complex), amphibolite, granulite, HP and UHP assemblages provide evidence of Ordovician to early Silurian subduction systems along the continental margin.…”

Section: Introductionmentioning

confidence: 97%

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

Gee

Andréasson

Lorenz

et al. 2015

Precambrian Research

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“…600 Ma dolerite dyke swarms. The sedimentary host rocks are composed of Neoproterozoic sandstones with subordinate carbonates and tillites (Kumpulainen, 1980). The uppermost tectonic unit in the Middle Allochthon (Andréas-H. Lorenz et al: COSC-1 -drilling of a subduction-related allochthon 3 son and Gee et al, 2008), previously included in the Upper Allochthon, is the Seve Nappe Complex, composed in most areas of three units (Sjöström, 1983;van Roermund, 1985;Bergman and Sjöström, 1997): a lower part of similar protolith to the Särv Nappe, but ductilely deformed in amphibolite (locally eclogite) facies; a central part (e.g.…”

Section: The Caledonides -The World's Major Mid-palaeozoic Mountain Beltmentioning

confidence: 99%

COSC-1 – drilling of a subduction-related allochthon in the Palaeozoic Caledonide orogen of Scandinavia

et al. 2015

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Abstract. The Collisional Orogeny in the Scandinavian Caledonides (COSC) scientific drilling project focuses on mountain building processes in a major mid-Palaeozoic orogen in western Scandinavia and its comparison with modern analogues. The project investigates the subduction-generated Seve Nape Complex. These in part under ultra-high-pressure conditions metamorphosed outer continental margin and continent-ocean transition zone assemblages were emplaced onto the Baltoscandian platform and there influenced the underlying allochthons and the basement. COSC-1 is the first of two ca. 2.5 km deep, fully cored drill holes located in the vicinity of the abandoned Fröå mine, close to the town of Åre in Jämtland, central Sweden. It sampled a thick section of the lower part of the Seve Complex and was planned to penetrate its basal thrust zone into the underlying lowergrade metamorphosed allochthon. The drill hole reached a depth of 2495.8 m and nearly 100 % core recovery was achieved. Although planning was based on existing geological mapping and new high-resolution seismic surveys, the drilling resulted in some surprises: the Lower Seve Nappe proved to be composed of rather homogenous gneisses, with only subordinate mafic bodies, and its basal thrust zone was unexpectedly thick (> 800 m). The drill hole did not penetrate the bottom of the thrust zone. However, lower-grade metasedimentary rocks were encountered in the lowermost part of the drill hole together with garnetiferous mylonites tens of metres thick. The tectonostratigraphic position is still unclear, and geological and geophysical interpretations are under revision. The compact gneisses host only eight fluid conducting zones of limited transmissivity between 300 m and total depth. Downhole measurements suggest an uncorrected average geothermal gradient of ∼ 20 • C km −1 . This paper summarizes the operations and preliminary results from COSC-1 (ICDP 5054-1-A), drilled from early May to late August 2014, and is complemented by a detailed operational report and the data repository.Published by Copernicus Publications on behalf of the IODP and the ICDP.

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Upper Proterozoic stratigraphy and depositional environments of the Tossåsfjället Group, Särv Nappe, southern Swedish Caledonides

Cited by 54 publications

References 30 publications

Tectonometamorphic evolution of the Åreskutan Nappe – Caledonian history revealed by SIMS U–Pb zircon geochronology

Tectonometamorphic evolution of the Åreskutan Nappe – Caledonian history revealed by SIMS U–Pb zircon geochronology

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

COSC-1 – drilling of a subduction-related allochthon in the Palaeozoic Caledonide orogen of Scandinavia

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