Anatomy of a 10 km scale sheath fold, Mount Hay ridge, Arunta Region, central Australia: The structural record of deep crustal flow

摘要: [1] Mount Hay ridge, Arunta Region, central Australia, exposes a 10 km scale, antiformal sheath fold formed in the deep crust (P ≈ 0.6–0.9 GPa) Proterozoic time. Tilting and exhumation during Devonian Alice Springs orogeny resulted an oblique cross section, such that once subhorizontal now has moderately dipping, gently folded axial plane overturned southern limb. Fabric types (e.g., S = L, L > S) were mapped field, finite strain data collected from widely distributed gabbroic granulite unit. sets exhibit remarkable correspondence confirm common assumption fabric type is directly related to for crustal rocks. Both reveal distinct pattern of oblate on limbs grading into prolate hinge. There no field evidence significant localization, measured magnitudes are consistent across fold. Thus, we infer different structural domains record though coeval paths compatibility was maintained domain boundaries. The uniformity foliation, lineation, mesoscale orientations Mount magnitude maximum stretch indicate subsidiary structures single, progressive deformational event. Based its geometry, inferred scale enclosing shear zone (≥8 thickness), regional tectonic correlations, subhorizontal, crustal-scale flow Paleoproterozoic Strangways (1740–1690 Ma). deformation with formation either one side channel or through detachment flow.