Paleomagnetism and age of Mafic Plutons, Wichita Mountains, Oklahoma

A paleomagnetic reconnaissance (43 samples) of the Raggedy Mountain Gabbro Group, which is comprised of a layered complex of anorthosites, anorthositic gabbros, and massive gabbro, shows: (1) stable remanent magnetization and (2) consistent directions which differ significantly from those of the nearby Cambrian Wichita Granite Group, with exception of one site near the granite contact. These results suggest a Precambiran age for the gabbro group. The difference in pole positions between the granitic and mafic groups demonstrates that the plutonic episodes responsible for the mafic and granitic magmas are significantly separated in time. Models of formation of the Wichita aulacogen should be altered to account for the difference in time between the mafic and silicic plutonism.