Description
Permian through Triassic rocks in the Maverick Spring Range are in excess of seven-thousand feet in thickness. Permian rocks are made up of approximately 4,900 feet of Arcturus Group and 1,530 feet of Park City Group. Triassic rocks approximately six-hundred feet thick are found disconformably above Permian rocks. Tertiary sediments are found to lie unconformably on Paleozoic sediments in the northern and east-central part of the study area and undifferentiated Tertiary volcanics are found to lie with angular unconformity on Triassic and Permian rocks in the southern part of the study area. The Arcturus Group is made up of the Riepetown Formation, Pequop Formation and Loray Formation in the study area. Section measurement revealed 129 feet of Riepetown Formation, 4,195 feet of Pequop Formation and 560 feet of Loray Formation. The rocks of the Arcturus Group represents a regressive depositional sequence with the Riepetown Formation being deposited in water less than sixty meters deep, and the Loray Formation representing an environment oscillating between shallow marine and hypersaline conditions. The Park City Group is made up of the Kaibab Formation, Plympton Formation and Gerster Formation. Section measurement revealed 188 feet of Kaibab Formation, 235 feet of Plympton Formation and 1,100 feet of Gerster Formation. The Kaibab Formation represents shallow water deposits by a sea advancing from south to north. The Plympton Formation represents shallow water deposition with large amounts of silica being added to form chert, most probably derived from the eugeosynclinal volcanic island arc by airborne ash. The Gerster Formation represents a near shore, high energy environment, most probably a shallow bank. Triassic deposits, represented by the Thaynes Formation, appear to have been deposited in a near shore depositional environment. Tertiary sediments are thought to be Humboldt Formation and represent fluvial deposits. Permian through Triassic rocks in the Maverick Spring Range represent a homocline, with an average dip of 30 degrees to the east. These rocks may represent the western limb of a north-south trending syncline. The area is broken by a closely spaced system of high angle faults which may represent the surface expression of a gravity slide from the west, or possibly the shattered upper plate of a thrust fault system concealed beneath. A possible intrusive body is located in the east-central part of the mapped area. The age of this intrusive is most probably Tertiary and genetically linked to the Tertiary basalt flows found capping the area in the south. Deformation responsible for the homoclinal nature of strata is of Late Mesozoic to Early Tertiary age. The attitude of sediments of the Humboldt Formation is thought to be due to a second episode of high angle faulting in the Tertiary.
