Inverted metamorphic sequences in Alpine fault mylonites produced by oblique shear within a plate boundary fault zone, New Zealand

摘要

Low-grade albite- and peristerite-mylonites occur as a northeast-tapering, 200-300 m wide zone structurally above basal cataclasite on the Alpine fault (New Zealand). They form an inverted metamorphic sequence grading eastward into an ~1-km-wide, amphibolite-facies- derived mylonite zone in the hanging wall. Their mineralogy matches low-grade protoliths that occur 100-110 km to the southeast. This displacement is compatible with distributed lateral and vertical shear within the mylonite zone since inception of signifi cant convergence on the plate boundary in the late Neogene.