Middle thrust sheets in the caledonide orogen, sweden: The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion

Research output: Chapter in Book/Report/Conference proceedingBook chapter

Standard

Middle thrust sheets in the caledonide orogen, sweden : The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion. / Gee, David G.; Klonowska, Iwona; Andréasson, Per Gunnar; Stephens, Michael B.

Geological Society Memoir. 1. ed. Geological Society of London, 2020. p. 517-548 (Geological Society Memoir; Vol. 50, No. 1).

Research output: Chapter in Book/Report/Conference proceedingBook chapter

Harvard

Gee, DG, Klonowska, I, Andréasson, PG & Stephens, MB 2020, Middle thrust sheets in the caledonide orogen, sweden: The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion. in Geological Society Memoir. 1 edn, Geological Society Memoir, no. 1, vol. 50, Geological Society of London, pp. 517-548. https://doi.org/10.1144/M50-2018-73

APA

Gee, D. G., Klonowska, I., Andréasson, P. G., & Stephens, M. B. (2020). Middle thrust sheets in the caledonide orogen, sweden: The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion. In Geological Society Memoir (1 ed., pp. 517-548). (Geological Society Memoir; Vol. 50, No. 1). Geological Society of London. https://doi.org/10.1144/M50-2018-73

CBE

Gee DG, Klonowska I, Andréasson PG, Stephens MB. 2020. Middle thrust sheets in the caledonide orogen, sweden: The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion. In Geological Society Memoir. 1 ed. Geological Society of London. pp. 517-548. (Geological Society Memoir; 1). https://doi.org/10.1144/M50-2018-73

MLA

Vancouver

Gee DG, Klonowska I, Andréasson PG, Stephens MB. Middle thrust sheets in the caledonide orogen, sweden: The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion. In Geological Society Memoir. 1 ed. Geological Society of London. 2020. p. 517-548. (Geological Society Memoir; 1). https://doi.org/10.1144/M50-2018-73

Author

Gee, David G. ; Klonowska, Iwona ; Andréasson, Per Gunnar ; Stephens, Michael B. / Middle thrust sheets in the caledonide orogen, sweden : The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion. Geological Society Memoir. 1. ed. Geological Society of London, 2020. pp. 517-548 (Geological Society Memoir; 1).

RIS

TY - CHAP

T1 - Middle thrust sheets in the caledonide orogen, sweden

T2 - The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion

AU - Gee, David G.

AU - Klonowska, Iwona

AU - Andréasson, Per Gunnar

AU - Stephens, Michael B.

PY - 2020

Y1 - 2020

N2 - Nappes of continental outer and outermost margin affinities (Middle Allochthon) were transported from locations west of the present Norwegian coast and thrust eastwards onto the Baltoscandian foreland basin and platform. They are of higher metamorphic grade than underlying thrust sheets and most are more penetratively deformed. These allochthons are treated here in three groups. The lower thrust sheets comprise Paleoproterozoic crystalline basement (e.g. Tännäs Augen Gneiss Nappe) and greenschist facies, Neoproterozoic, siliciclastic metasedimentary rocks (e.g. Offerdal Nappe). These are overthrust by a Cryogenian’Ediacaran succession intruded by c. 600 Ma dolerites (Baltoscandian Dyke Swarm) with an affinity to mid-ocean ridge basalt containing normal to enriched incompatible element contents (Särv Nappes). The upper sheets are dominated by higher-grade allochthons (Seve Nappe Complex) with similar, mainly siliciclastic sedimentary protoliths, more mafic magmatism and some solitary ultramafic bodies. Within this early Ediacaran continent’ocean transition zone (COT) assemblage, generally metamorphosed in amphibolite facies, some nappes experienced migmatization, and eclogites are present. Evidence of ultrahigh-pressure metamorphism has been obtained from garnet peridotites and eclogites; recently, microdiamonds have been discovered in paragneisses. Subduction of the COT started by the late Cambrian and accretion continued through the Ordovician, prior to the Baltica–Laurentia collision. Thrusting of all these Middle allochthons onto the foreland basin exceeds a distance of 400 km.

AB - Nappes of continental outer and outermost margin affinities (Middle Allochthon) were transported from locations west of the present Norwegian coast and thrust eastwards onto the Baltoscandian foreland basin and platform. They are of higher metamorphic grade than underlying thrust sheets and most are more penetratively deformed. These allochthons are treated here in three groups. The lower thrust sheets comprise Paleoproterozoic crystalline basement (e.g. Tännäs Augen Gneiss Nappe) and greenschist facies, Neoproterozoic, siliciclastic metasedimentary rocks (e.g. Offerdal Nappe). These are overthrust by a Cryogenian’Ediacaran succession intruded by c. 600 Ma dolerites (Baltoscandian Dyke Swarm) with an affinity to mid-ocean ridge basalt containing normal to enriched incompatible element contents (Särv Nappes). The upper sheets are dominated by higher-grade allochthons (Seve Nappe Complex) with similar, mainly siliciclastic sedimentary protoliths, more mafic magmatism and some solitary ultramafic bodies. Within this early Ediacaran continent’ocean transition zone (COT) assemblage, generally metamorphosed in amphibolite facies, some nappes experienced migmatization, and eclogites are present. Evidence of ultrahigh-pressure metamorphism has been obtained from garnet peridotites and eclogites; recently, microdiamonds have been discovered in paragneisses. Subduction of the COT started by the late Cambrian and accretion continued through the Ordovician, prior to the Baltica–Laurentia collision. Thrusting of all these Middle allochthons onto the foreland basin exceeds a distance of 400 km.

U2 - 10.1144/M50-2018-73

DO - 10.1144/M50-2018-73

M3 - Book chapter

AN - SCOPUS:85087027640

T3 - Geological Society Memoir

SP - 517

EP - 548

BT - Geological Society Memoir

PB - Geological Society of London

ER -