Cenozoic paleogeography of the central Mogollon Rim–southern Colorado Plateau region, Arizona, revealed by Tertiary gravel deposits, Oligocene to Pleistocene lava flows, and incised streams

摘要: Eocene to Pleistocene paleogeography of the Mogollon Rim–southern Colorado Plateau region in central Arizona is interpreted by use Tertiary sedimentary deposits and mafic lavas that have been correlated on bases provenance pebbles, stratigraphic sequence, geomorphic positions flows, published K-Ar ages, tracing lava flows vents, textures structures. Five categories are (1) Paleocene(?) Oligocene(?) fluvial lacustrine margin were derived from local distant southern sources; (2) Miocene valleys at base Rim (3) Pliocene locally gravel pediments canyons along rim; (4) lag beneath sheet plateau; (5) channel-filling plateau. Mafic used upper Oligocene lower basalt minette Transition Zone; pahoehoe draped over Rim; middle cones scattered across region; basalts Mormon San Francisco volcanic fields. Basalt ten (ca. 12 Ma) 6 flow fields, traced low-profile vent structures, cover nearly 30% a 9000 km2 area depict times eruption. Principal conclusions are: developed near its present position after Precambrian rocks had unroofed during Paleocene Epochs, before late early volcanism; erosional quiescence Paleogene, Triassic strata stripped off sweep southwest northeast; incision meanders Slope occurred Epochs as result integration Little River with Grand Canyon.