Absolute dating of brittle fault movements: Late Permian and late Jurassic extensional fault breccias in western Norway
✍ Scribed by Elizabeth A. Eide; Trond H. Torsvik; Torgeir B. Andersen
- Book ID
- 104463163
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 300 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0954-4879
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✦ Synopsis
^40^Ar/^39^Ar geochronological and palaeomagnetic dating methods applied to fault breccias in western Norway have isolated two brittle reactivation episodes of the syn‐post‐Caledonian, extensional Nordfjord‐Sogn Detachment. These events, of latest Permian and latest Jurassic–Early Cretaceous ages, demonstrate temporal relationships between development of chemical remanent magnetism and partial resetting of Ar isotopic systems during distinct breccia‐forming episodes. A third event of Carboniferous age was also identified in the breccias with the ^40^Ar/^39^Ar technique and is a relict unroofing signature inherited from the fault wall‐rocks. These brittle faults are significant time markers and become relevant to interpretations of offshore seismic data which attempt to place ages on faults that have undergone multiple reactivation episodes.