Early Cenozoic Eurekan strain partitioning and decoupling in central Spitsbergen, Svalbard

Abstract. The present study of field, petrological, exploration well, and seismic data describes backward-dipping duplexes comprised phyllitic coal bedding-parallel décollements thrusts localized along lithological transitions in tectonically thickened Lower Devonian to lowermost Upper Devonian; uppermost Devonian–Mississippian; Pennsylvanian–lowermost Permian sedimentary strata the Wood Bay and/or Wijde Grey Hoek formations; Billefjorden Group; Wordiekammen Formation, respectively. shows that these structures partially decoupled Devonian–Permian rocks Gipsdalen groups from Andrée Land Group Mimerdalen Subgroup during early Cenozoic Eurekan deformation central Spitsbergen. strain decoupling explains differential between overlying central–northern Spitsbergen without requiring an episode (Ellesmerian) contraction Late Devonian. Potential formation mechanisms for include shortcut faulting as a roof décollement fault-bend hanging wall (or ramp) anticline, imbricate fan, antiformal thrust stack, fault-propagation folds over reactivated or overprinted basement-seated faults. interpretation Reindalspasset indicates might be preserved east Fault Zone, suggesting Zone did not accommodate reverse movement Hence, thrusting Proterozoic basement Balliolbreen fold within may explained by combination down-east Carboniferous normal with associated footwall rotation exhumation, subsequent top-west Zone. Finally, major east-dipping faults, like consist several discrete, unconnected (soft-linked stepping) or, most probably, offset fault segments were varying degrees due partitioning sub-orthogonal NNE-dipping