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We introduce a spectrum of transpressional and transtensional deformations that potentially result from oblique plate interaction. Five separate types of deformation are designated, in which a simple shear deformation is combined with an orthogonal coaxial deformation. The types vary in the amount of extension v. contraction, both parallel to the margin and vertically. The interaction between the angle of convergence, kinematic vorticity, infinitesimal strain axes, finite strain, and rotation of material lines and planes is investigated. Quantification of the finite strain indicates that the orientation, magnitude, and geometry (flattening, constriction, etc.) change continually during steady-state transpression.These results are then applied to the cases of transpression, particularly resulting from oblique plate convergence of terranes. The obliquity of plate motion and the geometry of the plate margin determine which of the types of transpression or transtension is favoured. A component of margin-parallel stretching also potentially causes terrane motion to locally exceed oblique plate motion, or move opposite to the general direction of movement between the converging plate boundaries. The kinematic models also suggest that the boundaries between converging terranes are likely to exhibit vertical foliation, but either vertical or horizontal lineation. Finally, narrow transpressional zones between colliding blocks may have very high uplift rates, resulting in exhumation of high-grade metamorphic fabrics.

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We present results from differential Global Positioning System (GPS) surveys of seven alignment arrays and four continuous GPS sites along the creeping segment of the San Andreas fault. Surveys of four alignment arrays from the central creeping segment yield 33-to 36-year average minimum slip rates of 21-26 mm/yr. These rates are consistent with previous alignment array surveys spanning a 10-year period and with rates determined by creepmeters, indicating approximate steadystate creep along the central creeping segment for at least 35 years. Motion between continuous GPS sites that span the central creeping segment is 28.2 ‫ע‬ 0.5 mm/yr for two sites that are 1 km apart and 33.6 ‫ע‬ 1 mm/yr for two sites that are 70 km apart. Slip rates therefore increase with distance from the creeping segment of the San Andreas fault. All rates reported here are significantly slower than the 39 ‫ע‬ 2 mm/yr rate predicted for motion between the Sierra Nevada-Great Valley block and the Pacific plate. Repeat surveys of three alignment arrays following the 2004 Parkfield earthquake demonstrate that its coseismic and short-term postseismic offsets decrease rapidly with distance from the epicenter, from 150 mm to 15 mm to Ͻ5 mm at respective distances of 9, 36, and 54 km to the northwest. Continuous GPS data confirm that little coseismic and postseismic slip occurred along the central creeping segment. Geodetic and geologic slip rates are compared and different models for the accommodation of transcurrent deformation across the creeping segment are discussed.