The Mount Scott Intrusive Suite, Wichita Mountains, Oklahoma

摘要: In the last 50 years the Mount Scott Granite and three other granite bodies—the Rush Lake Granite, the Medicine Park Granite, and the Saddle Mountain Granite—have been characterized and mapped as separate lithodemic units within the eastern Wichita Mountains of southwestern Oklahoma. These are part of the Wichita Granite Group (WGG), products of felsic magmatism during Eocambrian rifting of the Southern Oklahoma Aulacogen. Like all members of the WGG, these are pink-to-red A-type alkali feldspar granites. Each is porphyritic and wholly or partially granophyric, as are other WGG members. These units, however, share contact and compositional relationships that suggest a common reservoir in the crust that ultimately fed shallow (locally subvolcanic) tabular plutonic bodies, and that each constitutes part of the multilobed Mount Scott Intrusive Suite. Using the voluminous Mount Scott Granite as a parent composition, the other three granite bodies are reasonably modeled as products of major-element crystal fractionation. The results, collaborated by trace-element trends, suggest that two daughter liquids formed through plagioclase and hornblende crystallization. One daughter fraction produced the Medicine Park Granite and part of the Rush Lake Granite, the second daughter fraction produced the remainder of the Rush Lake Granite. Compositional parameters indicate the site of fractionation was 7 to 8 km deep in the crust. Contact relationships indicate that these early liquids rose to intrude a shallow horizon 1 to 2 km below the surface. These early fractions were quickly followed by the magma that gave rise to the Mount Scott …