@article{Ohta_Larionov_Tebenkov_Lepvrier_Maluski_Lange_Hellebrandt_2002, title={Single-zircon Pb-evaporation and 40Ar/39Ar dating of the metamorphic and granitic rocks in north-west Spitsbergen}, volume={21}, url={https://polarresearch.net/index.php/polar/article/view/2131}, DOI={10.3402/polar.v21i1.6475}, abstractNote={North-west Spitsbergen consists of a complex of Caledonian and Grenvillian crystalline rocks, situated at the north-west corner of the Barents Shelf. The aim of this study is to understand the extent of pre-Caledonian basement rocks and their protoliths. Micas and zircon grains from six rocks from north-west Spitsbergen have been dated by the 40Ar/39Ar and single-zircon Pb-evaporation methods. Two grey granites yielded Late Caledonian mica 40Ar/39Ar and zircon ages of ca. 420-430 My, with inherited zircon grains as old as 1725 My. Zircon grains from a gneissose granite xenolith in a grey granites gave crystallization ages of ca. 960 My; some grains from a migmatite neosome show similar ages. Zircon grains yielding Archean and late Palaeoproterozoic ages (1600-1800 My) are interpreted as xenocrysts of detrital origin. The youngest ages obtained from detrital zircon grains from a greenschist facies quartzite of the Signehamna unit are ca. 1800 My. Similar schists are included as xenoliths in the 960 My old gneissose granite; therefore, the sedimentary protoliths of the unit are Mesoproterozoic. The dating results suggest a significant tectonothermal event during Grenvillian time; subsequent Caledonian events had less extensive thermal effects. However, it is still a matter of debate whether Grenvillian or Caledonian metamorphism produced the majority of the migmatites. A large population of zircon grains with Late Palaeoproterozoic ages suggests a wide surface exposure of rocks of this age in the source area, with some Archean zircons.}, number={1}, journal={Polar Research}, author={Ohta Yoshihide and Larionov Alexander N. and Tebenkov Alexander M. and Lepvrier Claude and Maluski Henri and Lange Michael and Hellebrandt Barbara}, year={2002}, month={Jan.}, pages={73-89} }