Timing of migmatization and granite genesis of the Northwestern Terrane, Svalbard
2007 (English)In: , 2007Conference paper (Other academic)
The pre-Devonian rocks of Svalbard can be grouped into three Caledonian terranes separated by north-south trending strike-slip faults. The paleogeography of the Southwestern and the Eastern Terranes is fairly well constrained, whereas the origin of the Northwestern Terrane (NWT) remains enigmatic. One difficulty in determining the paleogeographic origin of NWT is the complex, polyphase metamorphic history this terrane has experienced. In an attempt to understand the tectonic evolution of the NWT, a U-Pb ion microprobe study of zircons from gneisses, granitoids and migmatites from the Smerenburgfjorden Complex and Richarddalen Complex has been carried out.
Field evidence supported by age dating indicates that a Mesoproterozoic metapelitic protolith was intruded by ca. 960 Ma granitic orthogneiss. These new ion microprobe data are comparable with ages from other parts of Northwest Svalbard, and suggest that the entire NWT is underlain by Grenvillian-age (940-1039 Ma) and older basement rocks. These units were later involved in Caledonian deformation with subsequent granite genesis and migmatization at c. 417 to 433 Ma. Inherited zircons in the Caledonian granites suggest that two different protoliths were involved in Caledonian anatexis: One sourced dominantly from Greenvillian-age basement (940-1039 Ma) and another from an older early Mesoproterozoic to Paleoproterozoic basement (1500-1900 Ma). The origin of the NWT will be discussed, in light of these results.
Place, publisher, year, edition, pages
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-15780OAI: oai:DiVA.org:su-15780DiVA: diva2:182300
International Conference on Arctic Margins (ICAM V)