Geologic map of the Moroni Peak quadrangle, Wayne County, Utah (MP 01-5)

By: S. R. Mattox

The Moroni Peak quadrangle is 2 miles southwest of the town of Loa in Wayne County and is near the center of the Awapa Plateau, one of the easternmost High Plateaus of central Utah. The High Plateaus represent a transition zone between the fault-dominated Basin and Range Province and the relatively undeformed, subhorizontal strata of the Colorado Plateau. The quadrangle's landscape is only slightly modified by extensional faults and its strata dip gently east, features more characteristic of the Colorado Plateau. Most of the surface of the quadrangle is a low-relief tableland that slopes gently to the northeast. Several hollows and draws dissect the surface to expose volcaniclastic, volcanic, and sedimentary rocks. Exposed bedrock units range in age from Oligocene-Miocene to Miocene. In ascending order, the units include the Oligocene-Miocene volcanic rocks of Langdon Mountain, latite lava flows, and potassium-rich mafic lava flows; and Miocene Osiris Tuff, Sevier River Formation, and basalt lava flows. The volcanic rocks of Langdon Mountain record the eastward extension of a thick wedge of volcaniclastic sediment from a source on the northern Sevier Plateau. The latite lava flows erupted from vents on the Awapa Plateau. The potassium-rich mafic lava flows erupted from vents on the Awapa Plateau, possibly just northwest of the Moroni Peak quadrangle, as tectonism shifted from compression to extension. The Osiris Tuff, a widespread ash-flow tuff in the High Plateaus, assists in the correlation of units to areas outside of the quadrangle. The Sevier River Formation preserves locally derived clastic sediments that collected in topographic lows. Basalt lava flows erupted from a vent at Elsies Nipple. Quaternary sediments are limited to a few small areas and include alluvium, mixed alluvium and colluvium, and pediment-mantle alluvium. Earthquakes, flooding, rock falls, and radon pose minimal geologic hazards because of the quadrangle?s remote, undeveloped location. Sand and gravel are extracted from the quadrangle for local uses.

Other Information:
Published: 2001
Pages: 14 p.
Plates: 2 pl.
Scale: 1:24,000
Location: Wayne County
Media Type: Paper Map