Abstract In the Mississippian Moncton Sub-basin, New Brunswick, Canada, 3D seismic data reveal structure within the Mississippian McCully gas field. The asymmetric basin, elongated NE–SW, is bounded to the SE and NW by major dextral fault zones. Curved en-echelon extensional faults strike ESE–WNW. Gentle folds trend NE–SW. Contractional faults show varied orientations. These features are all consistent with deformation of the basin in an environment of dextral transtension. Analogous faults in outcrops, ~13 km to the SW, constrain sub-seismic deformation, and show that deformation occurred soon after deposition, before complete lithification. Strike-slip basins undergo concurrent extension, contraction, and rotation producing complex kinematic history which can be unraveled using the heaves and orientations of fault arrays. Based on measurements from the 3D data set, a horizon in the gas field displays an apparent stretch of ~1.14, and a perpendicular apparent shortening of ~0.976. Faults are oriented, on average, at ~40° to the shear zone boundary. These values show that the basin was deformed in transtension with overall angle of transtension alpha ≈47° to 50°. However, part of this deformation post-dated the overlying Sussex Group; removal of this component suggests alpha was in the range 62–65° during deposition of the Horton Group. Variations across the shear zone indicate that deformation was heterogeneous in space and time; an initial large strike-slip component transitioned to more divergent deformation as the deformation zone widened. Fault curvature likely reflects propagation during development of these heterogeneities. Overall, the deformation reflects an oblique-rift environment with ~N–S extension, that developed between major dextral strike-slip faults. These results show that with 3D seismic data sets it is possible to reconstruct details of strain history in transtensional basins that are potentially useful for understanding basin compartmentalization and fluid flow over time.

中文翻译：

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加拿大新不伦瑞克省 McCully 气田过渡带断层发育

摘要 在加拿大新不伦瑞克的密西西比蒙克顿子盆地，3D 地震数据揭示了密西西比麦卡利气田内的结构。不对称盆地，细长的 NE-SW，以主要的右旋断层带与 SE 和 NW 为界。弯曲的梯级伸展断层袭击 ESE-WNW。温和的褶皱趋势 NE-SW。收缩断层显示出不同的方向。这些特征都与盆地在右旋张拉环境下的变形一致。露头中的类似断层，距西南约 13 公里，限制了次地震变形，并表明变形发生在沉积后不久，完全岩化之前。走滑盆地同时发生伸展、收缩和旋转，产生复杂的运动历史，可以使用断层阵列的隆起和方向来解开这些历史。根据 3D 数据集的测量结果，气田中的地平线显示出~1.14 的表观拉伸和~0.976 的垂直表观缩短。断层的方向平均与剪切带边界成 40°。这些值表明盆地发生了变形，整个变形角α ≈47°到50°。然而，这种变形的一部分落后于上覆的苏塞克斯群。该成分的去除表明，在霍顿群沉积期间，α 值在 62-65° 的范围内。剪切带的变化表明变形在空间和时间上是不均匀的；随着变形带变宽，初始大走滑分量转变为更发散的变形。断层曲率可能反映了这些非均质性发展过程中的传播。全面的，变形反映了在主要的右旋走滑断层之间形成的~N-S 延伸的斜裂谷环境。这些结果表明，使用 3D 地震数据集可以重建张张盆地中应变历史的细节，这对于理解盆地分区和随时间推移的流体流动可能有用。