Middle thrust sheets in the caledonide orogen, sweden : The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion
(2020) In Geological Society Memoir 50(1). p.517-548- Abstract
- 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... (More)
- 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. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/f433aff8-2f5b-42bb-9716-683aabd17c21
- author
- Gee, David G. ; Klonowska, Iwona ; Andréasson, Per Gunnar LU and Stephens, Michael B.
- organization
- publishing date
- 2020
- type
- Chapter in Book/Report/Conference proceeding
- publication status
- published
- subject
- host publication
- Geological Society Memoir
- series title
- Geological Society Memoir
- volume
- 50
- issue
- 1
- edition
- 1
- pages
- 32 pages
- publisher
- Geological Society of London
- external identifiers
-
- scopus:85087027640
- ISSN
- 0435-4052
- DOI
- 10.1144/M50-2018-73
- language
- English
- LU publication?
- yes
- id
- f433aff8-2f5b-42bb-9716-683aabd17c21
- date added to LUP
- 2020-12-17 14:52:45
- date last changed
- 2022-04-26 22:36:57
@inbook{f433aff8-2f5b-42bb-9716-683aabd17c21,
abstract = {{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.}},
author = {{Gee, David G. and Klonowska, Iwona and Andréasson, Per Gunnar and Stephens, Michael B.}},
booktitle = {{Geological Society Memoir}},
issn = {{0435-4052}},
language = {{eng}},
number = {{1}},
pages = {{517--548}},
publisher = {{Geological Society of London}},
series = {{Geological Society Memoir}},
title = {{Middle thrust sheets in the caledonide orogen, sweden : The outer margin of baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion}},
url = {{http://dx.doi.org/10.1144/M50-2018-73}},
doi = {{10.1144/M50-2018-73}},
volume = {{50}},
year = {{2020}},
}