The tectonomagmatic evolution of Svalbards North-Western Terrane. : U/Pb-ages for Proterozoic crust and Caledonian magmatic evolution in Spitsbergen.

• Main Author: Myhre, Per Inge
• Other Authors: prof. Arild Andresen, prof. Fernando Corfu
• Format: Master Thesis
• Language: English
• Published: 2005
• Subjects: geokronologi tektonikk petrologi geokjemi terreng U-Pb; VDP::450; Arctic; Arctic Ocean; Krossfjorden; Smeerenburgfjorden; Svalbard; Kongsfjord*; Kongsfjorden; Krossfjord*; North Atlantic; Smeerenburgfjord*; Spitsbergen
• Online Access: http://hdl.handle.net/10852/12401; http://urn.nb.no/URN:NBN:no-12229

Combination of field studies and analytical techniques provides the basis for unravelling the tectonic evolution of the continental crust. Here field studies together with the ID-TIMS method for U/Pb-dating have been applied to a segment of the North Atlantic Caledonides, the NW Spitsbergen Terrane. The archipelago of Svalbard is situated in the Arctic Ocean and comprises Caledonian and older basement rocks underlying a Devonian-Neogene sedimentary succession. The basement is composed of several terranes separated by N-S-trending faults. Fieldwork and U/Pb dating on zircon, monazite and titanite from orthogneisses and granitoids from the NW Spitsbergen Terrane provides more detailed knowledge on the timing of 2 orogenic events in this region; the Grenvillian and the Caledonian. The Grenvillian event is represented by two samples of orthogneiss yielding crystallization ages of 962 ± 6 and 970 ± 7 Ma. Caledonian rocks dated include two samples of migmatite gneiss from the Kongsfjorden area yielding 425 ± 4 and 423 ± 1 Ma monazite ages, a migmatite leucosome (418,0 ± 0,7 Ma, Krossfjorden) and two granitoid intrusions from the Smeerenburgfjorden area with crystallization ages of 418,4 ± 0,7 and 421,6 ± 1,5 Ma. These data are in good agreement with previous interpretations that the NW Spitsbergen terrane has Laurentian affinities.