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The Mesozoic Mogollon Highlands, Arizona: An Early Cretaceous Rift Shoulder

1986; University of Chicago Press; Volume: 94; Issue: 5 Linguagem: Inglês

10.1086/629077

1537-5269

William L. Bilodeau,

Geological formations and processes

The Mogollon Highlands have long been considered the southern source terrane for much of the early-to-middle Mesozoic fluvial sedimentary rocks of the southern Colorado Plateau. Because of the lack of Mesozoic sedimentary strata in the Mogollon region, many workers have suggested these highlands were located in central Arizona and New Mexico. New evidence suggests that during the Triassic and most of the Jurassic, a large highland did not exist in central Arizona-New Mexico but was present as a continental margin volcanic arc in southern Arizona and northern Mexico. At this time, central Arizona would be more aptly called the Mogollon Slope. Early Jurassic Navajo-equivalent sands were blown south from the Colorado Plateau area, across the Mogollon Slope, to become intercalated with volcanics along the northeast side of the arc. The first good evidence for a structural and topographic highland in the Mogollon area is in the Early Cretaceous, when the uplifted northeast flank of the Bisbee rift basin tilted the region to the northeast. Erosion removed most of the earlier Mesozoic sediments in the region, and the Late Cretaceous Dakota Sandstone transgressed and overstepped the subsiding rift shoulder. The term "Mogollon Highlands" should be limited to this Early Cretaceous rift shoulder.