Kinematics of the Isfjorden-Ymerbukta Fault Zone: A dextral oblique-thrust ramp in the Tertiary fold-thrust belt of Spitsbergen

The NNE-trending Isfjorden-Ymerbukta Fault Zone is an oblique structural element within the NNW-trending Tertiary transpressional fold-thrust belt of Spitsbergen, Arctic Norway. It can be traced for nearly 50 km, and separates two different structural domains in the fold-thrust welt of Oscar II Land, Central Spitsbergen. The fault zone is more than 500 m wide and contains several segments of highly folded/rotated, faulted and cleaved Triassic through Paleocene rocks. Displacement across the fault zone can be decomposed into (i) a reverse, top-to-the-ENE component with a minimum 650 m vertical throw, and (ii) a horizontal dextral component of approximately 5-10 km. Displacement across the fault decreases northward along strike, where the fault zone merges into parallelism with a ramp-system of the fold-thrust belt. Inherited, underlying Devonian(?)-Carboniferous structures may have controlled the location of the fault zone. Detailed studies of map and mesoscale faults and folds reveal complex geometries an...