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Evidence For Arid-Land Fluvial Systems In Western Equatorial Pangaea During The Guadalupian (Middle Permian): The Cloud Chief Formation In Western Oklahoma, U.S.A.


A renewed interest in the Permian Midcontinent of the U.S.A. has led to new depositional models for most of the stratigraphic units of western Oklahoma in which these units are interpreted as lacustrine and eolian in origin. However, with these new interpretations, the question remains as to what is the source of the large volumes of fine-grained mudstones that are common within these rocks. In this study, we measured 43 stratigraphic sections within the Guadalupian Cloud Chief Formation of western Oklahoma. Seven facies were recognized within the measured sections. These facies include gypsum, channelized very fine sandstone, massive mudstones, sandstones, variegated mudstones, ripple cross-laminated very fine sandstone, and interbedded sandstone and mudstone. We interpret these facies to represent subenvironments of widespread arid-land fluvial systems. Our interpretations fit well with other recent work calling for arid non-marine conditions within the Midcontinent during the middle Permian. In addition, the presence of extensive fluvial systems provides a convenient explanation for the source of the large volumes of fine-grained sediments comprising the middle Permian rocks of western Oklahoma