- journal_title：Geological Magazine
- Contributor：JAROSLAW MAJKA ; STANISLAW MAZUR ; MACIEJ MANECKI ; JERZY CZERNY ; DANIEL K. HOLM
- Publisher：Cambridge University Press
- Date：2008-
- Format：text/html
- Language：en
- Identifier：10.1017/S001675680800530X
- journal_abbrev：Geological Magazine
- issn：0016-7568
- volume：145
- issue：6
- firstpage：822
- section：ORIGINAL ARTICLES
Southwest Spitsbergen, Wedel Jarlsberg Land, consists of two Proterozoic crustal blocks with differing metamorphic histories. Both blocks experienced Caledonian greenschist-facies metamorphism, but only the southern block records an earlier pervasive M1 amphibolite-facies metamorphism and strong deformational fabric. In situ EMPA total-Pb monazite geochronology from both matrix and porphyroblast inclusion results indicate that the older M1 metamorphism occurred at 643 ± 9 Ma, consistent with published cooling ages of c. 620 Ma (hornblende) and 580 Ma (mica) obtained from these same rocks. This region thus contains a lithostratigraphic profile and metamorphic history which are unique within the Svalbard Archipelago. Documentation of a pervasive late Neoproterozoic Barrovian metamorphism is difficult to reconcile with a quiescent non-tectonic regime typically inferred for this region, based on the occurrence of rift-drift sequences on the Baltic and Laurentian passive margins. Instead, our new metamorphic age implies an exotic origin of the pre-Devonian basement exposed in SW Spitsbergen and supports models of terrane assembly postulated for the Svalbard Archipelago.