Direct Ar-40/Ar-39 K-feldspar dating of Late PermianEarly Triassic brittle faulting in northern Norway

作者：Davids Corine; Benowitz Jeff A^*; Layer Paul W; Bergh Steffen G

来源：Terra Nova, 2018, 30(4): 263-269.

DOI：10.1111/ter.12333

While the offshore post-Caledonian extensional history of the north Norwegian passive margin is well constrained, the tectonic relationship between onshore and offshore regions is less clear because of limited age constraints on the timing of rifting onshore. Ar-40/Ar-39 dating of K-feldspar from hydrothermally altered fault rocks in a Precambrian gneiss complex in northern Norway was used to study the timing of extensional faulting onshore. In addition, Ar-40/Ar-39 dating of K-feldspar from the host rock provided insight into the regional rock cooling history prior to brittle deformation. Results indicated a dominant Late Permian-Early Triassic (similar to 265-244Ma) faulting event and found no evidence for later reactivation, which has been documented offshore. The region cooled to below the closure temperature for Ar-40/Ar-39 K-feldspar in the Carboniferous to Early Permian, prior to the main brittle faulting event. Ar-40/Ar-39 dating of fault zone K-feldspar products provided a means to date brittle faulting events.

• 出版日期2018-8