A3 Refereed book chapter or chapter in a compilation book
Paleoproterozoic (2.0-1.8 Ga) syn-orogenic sedimentation, magmatism and mineralization in the Bothnia-Skellefteå lithotectonic unit, Svecokarelian orogen
Authors: Skyttä P, Weihed P, Högdahl K, Bergman S, Stephens MB
Editors: M. B. Stephens, J. Bergman Weihed
Publication year: 2020
Book title : Sweden: Lithotectonic Framework, Tectonic Evolution and Mineral Resources
Journal name in source: SWEDEN: LITHOTECTONIC FRAMEWORK, TECTONIC EVOLUTION AND MINERAL RESOURCES
Journal acronym: GEOL SOC MEM
Series title: Geological Society Memoirs
Volume: 50
First page : 83
Last page: 130
Number of pages: 48
ISBN: 978-1-78620-460-8
ISSN: 0435-4052
DOI: https://doi.org/10.1144/M50-2017-10
Abstract
The Bothnia-Skelleftea lithotectonic unit is dominated by turbiditic wacke and argillite (Bothnian basin), deposited at 1.96 (or older)-1.86 Ga, metamorphosed generally under high-grade conditions and intruded by successive plutonic suites at 1.95-1.93, 1.90-1.88, 1.87-1.85 and 1.81-1.76 Ga. In the northern part, low-grade and low-strain, 1.90-1.86 Ga predominantly magmatic rocks (the Skellefte-Arvidsjaur magmatic province) are enclosed by the basinal components. Subduction-related processes in intra-arc basin and magmatic arc settings, respectively, are inferred. Changes in the metamorphic grade and the relative timing of deformation and structural style across the magmatic province are linked to major shear zones trending roughly north-south and, close to the southern margin, WNW-ESE. Zones trending WNW-ESE and ENE-WSW dominate southwards. Slip along the north-south zones in an extensional setting initiated synchronously with magmatic activity at 1.90-1.88 Ga. Tectonic inversion steered by accretion to a craton to the east, involving crustal shortening, ductile strain and crustal melting, occurred at 1.88-1.85 Ga. Deformation along shear zones under lower-grade conditions continued at c. 1.8 Ga. Felsic volcanic rocks (1.90-1.88 Ga) host exhalative and replacement-type volcanogenic massive sulphide deposits (the metallogenic Skellefte district). Other deposits include orogenic Au, particularly along the 'gold line' SW of this district, porphyry Cu-Au-Mo, and magmatic Ni-Cu along the 'nickel line' SE of the 'gold line'.
The Bothnia-Skelleftea lithotectonic unit is dominated by turbiditic wacke and argillite (Bothnian basin), deposited at 1.96 (or older)-1.86 Ga, metamorphosed generally under high-grade conditions and intruded by successive plutonic suites at 1.95-1.93, 1.90-1.88, 1.87-1.85 and 1.81-1.76 Ga. In the northern part, low-grade and low-strain, 1.90-1.86 Ga predominantly magmatic rocks (the Skellefte-Arvidsjaur magmatic province) are enclosed by the basinal components. Subduction-related processes in intra-arc basin and magmatic arc settings, respectively, are inferred. Changes in the metamorphic grade and the relative timing of deformation and structural style across the magmatic province are linked to major shear zones trending roughly north-south and, close to the southern margin, WNW-ESE. Zones trending WNW-ESE and ENE-WSW dominate southwards. Slip along the north-south zones in an extensional setting initiated synchronously with magmatic activity at 1.90-1.88 Ga. Tectonic inversion steered by accretion to a craton to the east, involving crustal shortening, ductile strain and crustal melting, occurred at 1.88-1.85 Ga. Deformation along shear zones under lower-grade conditions continued at c. 1.8 Ga. Felsic volcanic rocks (1.90-1.88 Ga) host exhalative and replacement-type volcanogenic massive sulphide deposits (the metallogenic Skellefte district). Other deposits include orogenic Au, particularly along the 'gold line' SW of this district, porphyry Cu-Au-Mo, and magmatic Ni-Cu along the 'nickel line' SE of the 'gold line'.
UTU Research Portal