Quartz Mountain - Geology

Geology

Quartz Mountain is one of the westernmost peaks in the Wichita Mountains. In simplest terms, the Wichita Mountains are rocky promontories and rounded hills made of red and black igneous rocks, light-colored sedimentary rocks, and boulder conglomerates. The Wichita Mountains were formed in four distinct geologic episodes. 1. Magmatism induced by continental rifting just prior to and in the Cambrian Period produced the granites and rhyolites (the red rocks), gabbroic rocks, anorthosites, and diabases (the black rocks). 2. Subsidence resulted in burial by sandstones and carbonates (the light-colored rocks) during the early Paleozoic. 3. Uplift during the Pennsylvanian Ouachita Orogeny brought these rocks to the surface as mountains. 4. Weathering and erosion during the Permian Period flattened the mountains and produced a mantle of conglomerates. The mountains themselves are Permian landforms covered and preserved by river-borne sediments in the Permian and partially excavated only in recent geological times. Exposure of these fossil mountains is greatest towards the southeast; much of the western part of the Permian range remains buried under sandstones and shales.

Quartz Mountain is made of granite emplaced during the early Cambrian period. Like the other granite knobs nearby, and the larger masses of granite in the eastern Wichita Mountains, theses rocks are part of the Wichita Granite Group. Most of Quartz Mountain and the other exposures in the park are homogenous pink-red Lugert granite. However, the flank of Quartz Mountain, as well as the adjacent peaks to the west are made of a corser grained, red Reformatory Granite. The Reformatory Granite is quarried locally in and around the appropriately named town of Granite; the park's numerous monuments are polished monoliths of the quarry products. A mixed zone between the two units reveals that these are two separate pulses of magma intruding the same level of the crust, and that the Lugert post-dates the intrusion of the Reformatory. Numerous miarolitic cavities and hydrothermal veins pervade this zone and its surroundings. Both contain appreciable amounts of quartz.