Significance of transport-parallel strain variations in part of the Raft River shear zone, Raft River Mountains, Utah, USA

摘要: This paper examines part of the Raft River shear zone (RRSZ) in northwestern Utah that exhibits an extreme transport-parallel increase strain intensity coupled with a transition from flattening to constrictional strain. Detailed geologic mapping and finite-strain, quartz-c-axis-fabric, kinematic-vorticity analyses demonstrate local necking associated elongation accommodated by stretching fault at base zone. The domain intense deformation is localized where basal cuts rheologically weak rocks. characterized field caused transport-perpendicular flow into area high elongation. Where rocks cut are strong, RRSZ locally records lower intensities, limiting amount needed any one direction and/or recording adjacent highly extended domains. rheology directly controlled style zone-normal shortening elongation, these observations provide example partitioning crustal-scale structure driven rheological transitions.