LINKING LATE PALEOZOIC PLATE-TECTONIC SETTING WITH GEOLOGIC EVENTS, SOUTHWEST NORTH AMERICA

Although the general late Paleozoic plate-tectonic setting of western Pangaea is well established, details concerning the nature of the plate margins of western and southern North America remain in dispute. For example, the fit of North America, South America, and Africa is fixed within relatively tight tolerances from Early Pennsylvanian through the Permian. However, along the western margin of Pangaea, a triangular embayment framed by SW North America and NW South America defined a region of uncertain and complex paleogeography -- a region that potentially had major influence on the development of both the Ancestral Rocky Mountains and the Cordilleran arc. The following aspects of this region are analyzed and modelled using paleogeographic and paleotectonic maps: 1) the configuration of the peri-Gondwanan Mexican terranes and associated arcs along the southern margin; 2) the number and polarity of arcs and fringing arcs along the Cordilleran margin; 3) the geometry, age, and extent of the presumed transform margin along SW North America and the geometry of transforms farther east; 4) the location of the Caborca block during the late Paleozoic. Each of these aspects have end-member solutions that can be evaluated with the models, both independently and together, and compared with the geologic history of SW North America including that of the Ouachita-Marathon orogen (and its extent into Mexico), the Ancestral Rockies, and the embryonic Cordilleran arc.