Reconstructing the structural evolution of metamorphic core complexes is critical to understanding how large-magnitude extension is accommodated in the middle to upper crust. This dissertation focuses on the Miocene geometric and kinematic evolution of the Buckskin-Rawhide metamorphic core complex in west-central Arizona, addressing controversial topics including the geometric development of mid-crustal shear zones, the formation of detachment fault corrugations, and the transition from detachment faulting to more distributed deformation. Detailed microstructural data from mylonites in the lower plate of the Buckskin-Rawhide detachment fault indicate that early Miocene mylonitization was characterized by consistent top-NE-directed shear and ~450-500°C deformation temperatures that varied by [less-than or equal to]50°C across a distance of ~35 km in the extension direction. The relatively uniform deformation conditions and strain recorded in mylonitized ~22-21 Ma granitoids are incompatible with models in which the lower plate shear zone represents the down-dip continuation of a detachment fault. Instead, lower plate mylonites initiated as a subhorizontal shear zone that was captured and rapidly exhumed by a moderately to gently dipping detachment fault system. Structural data and geologic mapping demonstrate that the prominent NE-trending Buckskin-Rawhide detachment fault corrugations are folds produced by extension-perpendicular (NW-SE) shortening during core complex extension. Dominant NE-directed slip on the detachment fault was progressively overprinted by NW- and SE-directed slip associated with corrugation folding. Orientation patterns of upper plate bedding across the corrugations are compatible with folding about a NE-trending axis. Extension-perpendicular shortening in the lower plate is recorded by synmylonitic constriction and folding. Upright m-scale and km-scale lower plate folds parallel the detachment fault corrugations and developed primarily by postmylonitic flexural slip that was coeval with detachment faulting. The total amount of NW-SE shortening across the lower plate is ~10%, but the amount of NW-SE shortening recorded by the younger detachment fault is only ~1%. The relatively late-stage development of corrugations in the Buckskin-Rawhide metamorphic core complex suggests that extension-perpendicular shortening was primarily driven by a reduction of vertical stresses through crustal thinning and tectonic denudation. Brittle fault data document the transition from large-magnitude, NE-directed extension to distributed E-W extension and right-lateral faulting. Following exhumation to brittle conditions, lower plate mylonites were extended up to ~20-30% by NE-dipping, syndetachment normal faults. Towards the end of detachment faulting, the extension direction rotated clockwise, and some portions of the Buckskin detachment fault record a transition from dominant top-NE slip to ENE- and E-directed slip. After detachment faulting ceased, E-W extension was accommodated primarily by steeply NE-dipping, right-lateral and oblique right-lateral-normal faults. The cumulative amount of right-lateral shear across the core complex is probably 7-9 km, which is the amount needed to restore the topographic trend of lower plate corrugations into alignment with the dominant extension direction. Postdetachment right-lateral/transtensional faulting across the Buckskin-Rawhide metamorphic core complex reflects the increasing influence of the Pacific-North American transform plate boundary towards the end of the middle Miocene. / text

The importance of skin processing technologies, in the history and dispersal of humankind around the planet cannot be overstated. This area of material culture is often underrepresented as a research topic, and has been hampered, in part, by the lack of a systematic analysis methodology targeted at specifically this material type. This research aimed to develop a methodology for determining the tanning technologies in use during prehistory, from extant archaeologically recovered processed skin objects. The methodology is a product of macroscopic and microscopic observations of a large sample reference collection, used to produce a database of defining characteristics and tendencies for each of six tannage types. The sample collection is made up of twenty-two species identified as economically important from both Europe and North America. Six sample pieces of skin were taken from a single individual of each of the twenty-two species, and processed using six tanning technologies, the use of which covered a large geographic area and time frame. A second reference collection of clothing and utilitarian items, made from traditionally processed skins, was used to add a section of in-life use traces to the database of discriminating traits. The developed methodology was tested by examining archaeologically recovered and ethnographically collected skin objects, from museum collections across North America and Europe. Objects from many different preservation contexts, including wet, dry, and frozen sites were analysed to determine whether or not the discriminating traits survived interment. It was found that defining characteristics and tendencies do exist between the main tannage technologies, and can be recorded at multiple levels of observation. The analysis of skin objects in museum collections confirmed that at least some defining characteristics and tendencies survived in all preservation contexts. In addition, the preservation of in-life use traces proved to be diagnostic of not only tannage type, but small sections of chaîne opératoire and object biography as well. Overall, this research has demonstrated that archaeologically preserved objects made from processed skin can provide information about the tannage technologies in use prehistorically, as well as more detailed information such as manufacturing sequences and the conditions of use an object was subjected to. Thus, analysis of this nature can be used to access information on a more individual level than previously believed.

Detailed botanical surveys and vegetation ecology studies of serpentine habitats in California are rare (Kruckeberg, 1984). This investigation of Rawhide Hill was intended to provide this type of information.