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GEOREF RECORD

Upper and uppermost thrust sheets in the Caledonide Orogen, Sweden; outboard oceanic and exotic continental terranes

Michael B. Stephens
Upper and uppermost thrust sheets in the Caledonide Orogen, Sweden; outboard oceanic and exotic continental terranes (in Sweden; lithotectonic framework, tectonic evolution and mineral resources, M. B. Stephens (editor) and J. Bergman Weihed (editor))
Memoirs of the Geological Society of London (2020) 50: 549-575

Abstract

Three separate stacks of thrust sheets (Koli Nappe Complex) constitute the Upper Allochthon in the Caledonide orogen, Sweden. This thrust complex is dominated by late Cambrian-Ordovician successions deposited in subduction-related, marginal oceanic basins. Magmatic activity at c. 488 Ma (Lower Koli) and c. 492-476 Ma (Middle Koli) is linked to rifted volcanic arcs and Zn-Cu-Fe-(Pb-Au-Ag) sulphide mineralization; serpentinite bodies with talc deposits are also conspicuous. Renewed magmatic activity, both plutonic (Upper and Middle Koli) and mafic volcanic (Middle and Lower Koli), occurred at c. 440-434 Ma during crustal extension. Late Ordovician shallow-marine sedimentation, deepening upwards into an early Silurian succession also prevailed (Lower Koli). Silurian (c. 430 Ma and later) folding, eastwards-vergent thrusting and greenschist or lower amphibolite facies metamorphism preceded upright, orogen-parallel and orogen-transverse open folding. Juxtaposition of an arc-related terrane to an ancient continental margin, comprising slices of gneiss and marble, in the Middle Koli occurred prior to c. 437 Ma and the eastwards-vergent thrusting; remnants of an Ordovician amphibolite facies tectonothermal event are also preserved in the Upper Koli. The tectonic roof to the Koli complex contains amphibolite facies mica schist, gneiss and marble, derived from the Laurentian continental margin, and a major gabbroic pluton (Rodingsfjallet Nappe Complex, Uppermost Allochthon).


ISSN: 0435-4052
Coden: GSLMAD
Serial Title: Memoirs of the Geological Society of London
Serial Volume: 50
Title: Upper and uppermost thrust sheets in the Caledonide Orogen, Sweden; outboard oceanic and exotic continental terranes
Title: Sweden; lithotectonic framework, tectonic evolution and mineral resources
Author(s): Stephens, Michael B.
Author(s): Stephens, M. B.editor
Author(s): Bergman Weihed, J.editor
Affiliation: Lulea University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Lulea, Sweden
Affiliation: Lulea University of Technology, Lulea, Sweden
Pages: 549-575
Published: 2020
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 120
Accession Number: 2020-042965
Categories: Solid-earth geophysicsIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps, 2 tables, sect.
N55°15'00" - N69°15'00", E11°00'00" - E24°15'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 2020
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