Sweden: Lithotectonic Framework, Tectonic Evolution and Mineral Resources
CONTAINS OPEN ACCESS
The solid rock mass of Sweden forms a natural field laboratory revealing insight into the westward growth and reworking of one of the planet's ancient continental nuclei. Three major geological units are exposed in different parts of the country: the western part of the Fennoscandian Shield, mainly sedimentary rocks deposited on this crystalline rock mass and the Caledonide orogen. This volume synthesizes the tectonic evolution of Sweden over more than 2500 million years from the Neoarchean to the Neogene. Following an introduction describing the lithotectonic framework of the country and the organization of the volume, the tectonic evolution is addressed essentially chronologically. Different phases of intracratonic rifting, accretionary orogeny, continent–continent collisional orogeny and platformal sedimentation are identified. Sweden is one of Europe's major suppliers of metals, and the country's mineral resources are also presented in the context of the lithotectonic framework. Sweden: Lithotectonic Framework, Tectonic Evolution and Mineral Resources has been designed to interest a professional geoscientific audience and advanced students of Earth Sciences.
Chapter 21: Middle thrust sheets in the Caledonide orogen, Sweden: the outer margin of Baltica, the continent–ocean transition zone and late Cambrian–Ordovician subduction–accretion
Published:January 03, 2020
David G. Gee, Iwona Klonowska, Per-Gunnar Andréasson, Michael B. Stephens, 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", Sweden: Lithotectonic Framework, Tectonic Evolution and Mineral Resources, M. B. Stephens, J. Bergman Weihed
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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...