Collaborative Research: Sourcing A-type Granites in Ancient Rifts

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9316567 Wright The Wichita granites of the Southern Oklahoma Aulacogen, a classic illustration of A-type granites intruded in a continental rift, represent an opportunity to develop new insights into granite sourcing. Limited, new chemical and isotopic data on the Wichita granites suggest derivation by crystal fractionation of basalt with minor crustal involvement contrary to most previously proposed models. A combined chemical and isotopic study of selected granites from this important group of A-type granites can successfully identify sources and processes involved in A- type granite petrogenesis in crustal rifts. The Wichita Granites have already been subdivided into three chemical groups. Textural, mineralogic, and chemical studies of selected granite sheets, representing the three chemical groups, will clarify these suites. Combining geochemical data with isotopic data will allow us to see through fractionation effects in order to characterize sources. Geochronological studies of zircon and titanite should define crystallization ages and potentially source ages. Such a study is required in a well constrained tectonic setting if the source of A-type granites is to be understood.