Dextral stripe-slip duplexes of Mesozoic age along the Hitra-Snåsa and Verran Faults, Møre-Trøndelag Fault Zone, Central Norway.

Abstract

The prominent, ENE-WSW, Verran and Hitra-Snåsa Faults of the long-lived Møre-Trøndelag Fault Zone (MTFZ) have been investigated employing methods ranging from Landsat TM lineament analysis down to the scale of field mapping and detalied study of the fault rock products. The fault structures along the Hitra Snåsa and Verran Faults, as reflected in the geological map picture, are thought to have originated as a sinistral transpressive system of Late Devonian age, especially for the Hitra-Snåsa lineament. Subsequent to Devonian time fault-displacive strike-slip movement reversed in sense and shifted locus towards the Verran Fault system during the Late Jurassic or Early Cretaceous. During this strike-slip reversal, some earlier fractures related to the sinistral system were rejuvenated within the stress field of the evolving dextral duplex system. The Beitstadfjord basin is considered to be floored by Middel Jurassic sediments (found locally as shoreline, plant-fossiliferous boulders), and is here interpreted as in in-line grabenal basin formed as a consequence of the Mesozoic, dextral, strike- slip movement along the Verran Fault system.