Abstract

More than 14,000 feet of Middle Cambrian through Upper Pennsylvanian carbonate and clastic rocks of the Cache allochthon are exposed on northern Wellsville Mountain in the Honeyville, Utah, quadrangle. Documented or inferred unconformities in this area occur between the following formations: St. Charles Formation/Garden City Limestone, Laketown Dolomite/Water Canyon Formation, Water Canyon Formation/Hyrum Dolomite, Beirdneau Formation/Lodge-pole Limestone and Great Blue Limestone/West Canyon Limestone. The top of the Oquirrh Formation is not exposed; although the upper part may be Permian in age, no Permian fusulinids have been found.

The Paleozoic rocks generally dip 25° to 60° northeast in the south, but the dips swing to the northwest at the northern end of the mountain around a steeply plunging, lateral ramp anticline. The ramp anticline is associated with an inferred thrust fault, herein referred to as the Wellsville thrust, that may be a slice of the Absaroka thrust fault. High-angle faults striking N. 40° to 70° E. show evidence of strike-slip displacement in the lower Paleozoic rocks but die out higher in the section. They may be tear faults related to Sevier orogenic thrusting. Low- to moderate-angle (20° to 50°), west-dipping extensional normal faults off-set the tear faults. The position and character of the major faults bounding Wellsville Mountain, the Wasatch and West Cache faults, were influenced by Mesozoic structural patterns that change markedly between Wellsville Mountain and the Junction Hills to the north.