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The Ranger Limestone was deposited on the broad shallow Eastern shelf of the Midland basin during Missourian time. The sequence of alternating carbonate and terrigenous sediments comprising the Ranger Limestone is reflective of the overall cyclicity exhibited by the Canyon Group. An analysis of the interrelationships of the facies produced a framework for reconstructing the depositional history. Earliest carbonate deposition in the Ranger appears to have been initiated on local topographic highs of probable minor relief. Phylloid algae are abundant biotic constituents in the Ranger Limestone and probably played a key roll in the carbonate buildup. The Ranger Limestone is composed primarily of sediments that represent four major depositional environments. The carbonate env ronments recognized include an inner shelf, a transitional inner shelf, and a restricted inner shelf. These carbonate accumulations are laterally restricted by distal delta-front deposits of the Perrin delta complex.
A multivariate statistical analysis based on point-count data of lithologic and biologic constituents was utilized in the delineation of facies within the Ranger Limestone. On the basis of the detailed petrographic study four facies were defined. These facies are: (1) algal-echinoid-bryozoan wackestone, (2) algal wackestone, (3) lime mudstone, and (4) calcareous shale.
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