Eocene deformation in metasedimentary rocks of the Valdez Group was examined along the Richardson Highway between Valdez and the Copper River basin. A topographic lineament along StuartCreek and the lower Tiekel River separates two distinct structural domains: a southern domain (Domain 1) with two fabrics, and a northern domain (Domain 2) with three. Both domains possess an early, layer-parallel phyllitic cleavage (S 1 ) associated with south-directed thrust systems. In Domain 1, S 1 is steeply dipping and overprinted by a second, steeply south-dipping cleavage (S 2 ) with a subhorizontal elongation lineation, and F 2 folds are rare to absent. To the north in Domain 2, however, S 1 was fi rst tightly folded during D 2 into a series of gently inclined folds (F 2 ) and then refolded by tight to close, steeply inclined F 3 folds that are asymmetric to the north. Metamorphic mineral assemblages indicate greenschist facies conditions accompanied the deformation: Biotite grew during D 2 in Domain 1 and during D 3 in Domain 2; and metatuffs in Domain 1 contain actinolite-chloriteepidote-feldspar-quartz. Fluid inclusion analyses of multiple vein sets indicate a complex fl uid history but indicate a metamorphic temperature of 350-400 °C, consistent with the observed mineral assemblages. Uniform metamorphic grade across the belt together with spatial variations in fabrics suggests that D 2 in Domain 2 is time-equivalent with D 3 in Domain 2.We evaluate the kinematics of linear and planar fabric development through a combination of fi nite strain analysis and geometry of syn-tectonic growth-fi bers developed on sand grains. Finite strains are estimated by different methods including object shapes, object centers, and stretches estimated from growth fi bers. The strain data show a predominance of constrictional strains, particularly in Domain 1, with subhorizontal stretching parallel to the mesoscopic lineation. Strain superposition models indicate that the main deformation (D 2 ) in Domain 1 was a constrictional fl ow indicating that D 2 was marked by subhorizontal orogen-parallel elongation and simultaneous vertical and horizontal shortening. Shear sense indicators generally indicate dextral shear on steeply dipping surfaces, but are not always well developed because the constrictional fl ow deviates strongly from simple shear. These characteristics are typical of the strain facies referred to as lengthening shear to lengthening-narrowing shear fl ow. We interpret this large-scale kinematic pattern as a combined effect of distributed dextral shear and vertical shortening related to a coeval ridge-subduction event. The vertical shortening could be associated with lateral fl ow driven by on June 30, 2015 specialpapers.gsapubs.org Downloaded from 172 T.L. Pavlis, K. Marty, and V.B. Sisson