Abstract

The lithostratigraphic classification of crystalline basement rocks of the Wichita province, Oklahoma, is reviewed and modified to reflect new detailed information on the lithology as well as on the temporal and genetic relationships among the principal rock types present. The principal revisions involve the gabbroic, anorthositic, and intermediate rocks among which the Raggedy Mountain Gabbro Group has been partially redefined and subdivided into two formations, the Glen Mountains Layered Complex and the younger Roosevelt Gabbros. The former is subdivided into four members: the K, L, M, and G Zones. The latter is subdivided into three members: Glen Creek Gabbro, Sandy Creek Gabbro, and Mount Sheridan Gabbro. Microdiorite previously included within the Raggedy Mountain Gabbro Group is younger than the Roosevelt Gabbros and is reclassified separately from the group as a separate formation, the Otter Creek Microdiorite. Intrusion breccia and associated intermediate hybrid rocks (previously known as the Cold Springs “granite”) are here classified separately from the Wichita Granite Group as a formation called the Cold Springs Breccia.

Among the major units in the Wichita province the following are now assigned relative ages, with some ambiguity, from oldest to youngest: Tillman Metasedimentary Group (?), Glen Mountains Layered Complex, Roosevelt Gabbros, Navajoe Mountain Basalt-Spilite Group (?), Otter Creek Microdiorite, Carlton Rhyolite Group, Wichita Granite Group, Cold Springs Breccia (?).

Detailed field, petrographic, and chemical studies have served as the basis for the reclassifications and reveal a greater petrologic and petrogenetic complexity than was previously recognized within the Wichita province. The reclassification provides a useful framework for the recognition, discussion, and future investigation of these complexities, an understanding of which is critical to the understanding of the evolution and tectonic setting of the Wichita province.

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