PALEOGEOGRAPHY AND TECTONIC EVOLUTION OF LATE PALEOZOIC SEDIMENTARY BASINS, SOUTHWESTERN NORTH AMERICA

A complex array of sedimentary basins developed across SW North America from Late Devonian through Permian. These basins contrast in geometry, tectonic style, nature of sedimentary fill, and subsidence history. They mark a dynamic interval of geologic history during the evolution of western North America from passive margin to Cordilleran margin. Basins developed on continental North America can be grouped into three major types: 1) foreland basins associated with accretion of arcs and microcontinents of the Antler, Sonoma, Marathon, and Ouachita orogenies; 2) intra-cratonic basins adjacent to (yoked with) cratonic uplifts of the Ancestral Rocky Mountains; and 3) cratonic basins distal to both of above. As the Cordilleran margin evolved, a suite of backarc, forearc, interarc, and subduction-zone basins formed off the western margin of the continent. Basin fill reflects geologic setting, especially distance from source terranes. Conglomerate, sandstone and mudstone, typically redbeds, dominate areas proximal to active uplift; carbonates and fine-grained siliciclatics dominate basin centers; the later sharply onlap and overlap the former during eustatic highstands. A series of paleogeographic maps in closely spaced time slices dramatically illustrate basin evolution and associated regional tectonic events. Despite the contrasting aspects of basin history across the region, a coherent model for the late Paleozoic geologic evolution of SW North America is shown in the paleogeographic time slices. The tectonic events shown on the evolving time slices suggest a strong time-space relation between the deformation of cratonic North America (Greater Ancestral Rocky Mountains orogenic events including the associated basins), and collisional events along the SW continental margin.