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

中文翻译：

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斯瓦尔巴特群岛中部斯匹次卑尔根的早期新生代尤里坎菌株分配和分离

摘要。沿这些结构的Eurekan应变解耦解释了Andrée土地群/ Mimerdalen子群的下-最下上泥盆纪岩石与Spitsbergen中北部Billefjorden和Gipsdalen岩层的上层泥盆纪-二叠纪沉积地层之间的差异变形，而无需发生（Ellesmerian ）在泥盆纪晚期收缩。平行于顺理理的断层和逆冲的潜在形成机制包括捷径断裂，和/或在断层弯曲的悬挂壁（或坡道）背斜中，作为扇形扇形，反形式的逆冲叠层和/或作为断层弯曲的顶壁形成。断层传播在重新激活/叠印的基底层断层之上折叠。对Reindalspasset中地震数据的解释表明，Andrée土地群和Mimerdalen子群的泥盆纪沉积岩可能保存在Billefjorden断裂带以东，这表明Billefjorden断裂带在泥盆纪晚期不适应反向运动。因此，沿着下石炭纪沉积岩沿Balliolbreen断层上冲以及斯匹次卑尔根中部Andrée土地群和Mimerdalen子群地层内的褶皱构造的逆冲作用可能是由下东石炭纪正断层和相关的底盘旋转共同解释的。掘尸，随后沿Billefjorden断层带逆时针逆冲推进。最后，研究表明，主要的东倾断层，例如Billefjorden断层带，