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ABSTRACT: Petrology of Mississippian Carbonate Eolianites and Associated Facies: Ste. Genevieve Limestone of Indiana

J. R. Dodd, T. W. Brown, C. D. Harris, K. W. Leonard, C. W. Zuppann

Descriptions of carbonate eolianites of pre-Pleistocene age are rare. Based largely on sedimentary structures and facies associations, Hunter has recently identified eolian deposits in the middle Mississippian Ste. Genevieve Limestone near Corydon, Indiana. Eolianite grainstones contain a diverse assemblage of allochems, including a variety of skeletal grains, ooids (some broken and abraded), peloids, intraclasts, and abundant quartz silt. Carbonate grains, which rarely exceed 0.5 mm, are usually more spherical than grains from associated marine units. Eolian units contain cross-laminations that sometimes coarsen upward. No evidence for vadose cement was found in the eolianite units; the extensive solution packing suggests that cementation did not occur until burial to considerable de th.

Marine grainstones, which probably formed on shallow shoals or an open platform, are common in the section. They contain a diverse assemblage of skeletal grain types as well as ooids, peloids, and intraclasts; however, one grain type (such as ooids) frequently dominates an individual unit. Detrital quartz grains are rare. Rounding of grains is usually good, but sphericity of skeletal grains which were not originally spherical is low. Fine laminations are uncommon, and no systematic grading is found on a thin-section scale. Grains and fossils in excess of 10 mm are common in the marine units.

Carbonate mud-rich rocks that probably formed in a shallow lagoonal setting also occur in the Ste. Genevieve section as do poorly developed exposure surfaces with pedogenic features.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990