By: D. S. Stone
Major tectonic events important in the evolution of the Uinta Mountains were evaluated through palinspastic restoration of a north-south structural cross section drawn along longitude 1090 15' in northeastern Utah. The section crosses the Uinta Mountains from Red Wash field in the Uinta Basin on the south to Clay Basin field in the Green River Basin on the north, a distance of 105 kilometers (65 mi). Surface geologic mapping, borehole, and reflection seismic information comprise the primary data base.
Interpretation is extended to deeper crustal levels and the section restored in three steps. In geochronologic order, section 1 illustrates current concepts of oblique arc/continent collision along the Cheyenne suture zone, the southern boundary of the Wyoming Archean province at the beginning of Middle Proterozoic time. Section 2 illustrates structural conditions at the end of deposition of the Middle Proterozoic Uinta Mountain Group within the Uinta rift basin or aulacogen. Section 3 portrays conditions near the end of the Upper Cretaceous, before the Laramide orogeny. This section incorporates contractional effects of several pre-Mesozoic tectonic events, including the Late Proterozoic Grand Canyon disturbance, the ancestral Rocky Mountains orogeny, and other minor pre-Laramide disturbances. Section 4 illustrates present geologic structure (after Laramide contractional inversion).
This palinspastic exercise suggests that the northsouth horizontal extension that produced the Uinta Mountain aulacogen in Middle Proterozoic time was almost completely reversed by later north-south contraction which began in Late Proterozoic time and culminated with Laramide uplift and fonnation of the Uinta Mountains.
Pages: 19 p.
Plates: 3 pl.
Scale: 1:96,000 and 1:192,000
Location: Daggett, Duchesne, Summit, and Uintah Counties
Media Type: Paper Publication