Brittle faulting in the Thor-Odin culmination, Monashee complex, southern Canadian Cordillera: constraints on geometry and kinematics

摘要

Regionally recognized dextral strike-slip faulting is present in the Monashee complex of the southern Canadian Cordillera but is overprinted and partially obscured by subsequent extension. Eocene brittle faults and fractures within the Thor-Odin culmination of the Monashee complex are divisible into three distinct sets. Initial 340 deg -010 deg trending strike-slip faults (set 1) were locally overprinted and reactivated by normal faults with a 325 deg -020 deg trend (set 2). A third set of 255 deg -275 deg trending fractures (set 3) are interpreted as conjugates to set 1, reactivated as transfer faults to the set 2 normal faults. Large regional faults weather recessively, forming topographic lineaments that transect the Monashee complex. The Victor Creek Fault defines one such lineament. Detailed mapping within the northern Thor-Odin culmination reveals piercetnent points (fold hinges) on the east side of the fault that are not readily matched on the west side. The minimum displacement required on the Victor Creek Fault to down-drop the fold hinge below the level of exposure on the west side is 1370 m, assuming normal down-to-the-west displacement. The geometry of the fault is consistent with a set 1 dextral strike-slip fault, however. Matching the piercement points in the study area with possible equivalents to the north indicates 55-60 km of dextral strike-slip displacement.