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The Caledonian tectonothermal evolution of the Northwestern Terrane, Svalbard
Stockholm University, Faculty of Science, Department of Geological Sciences. (PetroTectonics Centre)
(English)Article in journal (Refereed) Submitted
Abstract [en]

Mineral-chemical data of metapelites from the Proterozoic Krossfjorden Complex constrain the Late Caledonian tectonic evolution of Svalbard’s Northwestern Terrane and record a clockwise P-T path. The oldest deformation event (D2) related to orogenesis in the Northwestern Terrane records crustal thickening and incipient melting of the crust at c. 430 Ma. Continued heating during prograde metamorphism at c. 420 Ma resulted in the main migmatization event (D3) and related granitoid genesis at c. 850 °C and >6 kbars. Following the peak P-T conditions, the crust was uplifted and cooled to 645-683 °C and 3-5k bars. Unconformably above the Late Silurian aged high-T rocks and granitoid intrusives are Early Devonian (c. 416-411) cover sequences indicating rapid exhumation of the crystalline basement. This suggests that the peak metamorphic conditions were followed by near isothermal decompression. The clockwise P-T-t path of the Krossfjorden Complex of Svalbard’s Northwestern Terrane is remarkably similar to rocks from the Krummedal Sequence and Smallefjord Sequence of central East Greenland, confirming the close link between these areas prior to the Late Caledonian orogeny.

Keyword [en]
Svalbard, East Greenland, Caledonides, migmatites, clockwise P-T
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:su:diva-39363OAI: diva2:319609
Available from: 2010-05-18 Created: 2010-05-18 Last updated: 2010-06-08Bibliographically approved
In thesis
1. The tectonic evolution of northwest Svalbard
Open this publication in new window or tab >>The tectonic evolution of northwest Svalbard
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Svalbard represents the uplifted and exhumed northwest corner of the Barents Sea Shelf. Pre-Carboniferous rocks of Svalbard are divided into the Eastern, Northwestern and Southwestern Terranes, were amalgamated during the Caledonian Orogen and are separated by north-south-trending strike-slip faults. Even though our knowledge of Svalbard’s pre-Carboniferous history has increased dramatically during the last two decades, a major issue remains: Where did the different tectonostratigraphic terranes of Svalbard originate? The answer to this question has profound significance for the entire eastern Laurentian margin, which spans two supercontinent cycles, from the amalgamation and breakup of Rodinia to the amalgamation of Pangea. This thesis constrains the tectonothermal evolution of Svalbard’s Northwestern Terrane (NWT) using ion microprobe and LA-ICP-MS U-Pb zircon geochronology and electron microprobe thermobarometry on metasediments, clastic rocks and granitoids. Detrital zircon age populations of metasediments from the NWT suggests that they (e.g. the Krossfjorden Group) were deposited at c. 1000 Ma in a remnant ocean basin setting outboard the Eastern Grenville Province and were subsequently deformed and intruded by Late Grenvillian granitoids during the final suturing of Rodinia. Thus, a northern branch of the Grenvillian/Sveconorwegian orogeny is not present. This older history of the NWT is extensively overprinted by Late Caledonian deformation and metamorphism, with peak metamorphic conditions of 850 °C at >6 kbars, and subsequent migmatization of the Krossfjorden Group at c. 420 Ma. Based on these data, together with the detrital zircon age population from overlying Late Silurian-Early Devonian clastic rocks, a unifying model is proposed involving fragments from the Grampian orogen and Avalonian crust originally accreted to the Laurentian margin, subsequently transported northwards along sinistral strike-slip faults during Scandian deformation.

Place, publisher, year, edition, pages
Stockholm: Department of Geological Sciences, Stockholm University, 2010. 22 p.
, Meddelanden från Stockholms universitets institution för geologiska vetenskaper, 339
Svalbard, Rodinia, Laurentia, Zircon, Provenance, Migmatites, Clockwise P-T
National Category
Research subject
urn:nbn:se:su:diva-39364 (URN)978-91-7447-056-7 (ISBN)
Public defence
2010-06-24, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 13:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: In press.Available from: 2010-05-23 Created: 2010-05-18 Last updated: 2010-08-04Bibliographically approved

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Pettersson, Carl Henrik
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