Brittle deformation adjacent to the Awatere strike-slip fault in New Zealand: Faulting patterns, scaling relationships, and displacement partitioning

摘要

On the coast of South Island, New Zealand, the active dextral-reverse Awatere fault has <2 km finite dextral slip and initiated 22 m to 1.5, consistent with an elastic-plastic model of fault growth. Younger domino-style oblique-normal faults resulted in oblique extension of the Awatere fault zone, with mean ₁ oriented 30° clockwise from its strike. Transtension may have been caused by divergence between rotating, crustal-scale fault blocks, the result of a mode II fault tip to the east, which caused a local rotation of stress trajectories. The early faults are relict, and their kinematics is a poor index of slip sense on the mature fault. Close to the Awatere fault, dextral-reverse faults are synthetic to that mature structure. Their disposition indicates incremental compression acting 45°–50° clockwise to the strike of the Awatere fault. These youngest faults mirror the slip kinematics of the adjacent mature fault. Their attitude is controlled apparently by local kinematics, not by far-field stress orientations.