Carbonate eolianites areabundant in the lower Chesterian Upper Mississippian succession in the Appalachian and Illinois
Basins The eolianites arequartz peloid grainstones composed of well rounded very fine to fine sand size peloids wholeooids broken
ooids that have been re rounded skeletal fragments and generally finer grained subangular frosted quartz Eolian deposits are I to 8
m thick and tens of meters to many kilometers wide They have wedge sets of planar and tangential sharply defined inverse graded
laminae with dips of up to 20 degrees.
A high resolution sequence stratigraphic framework was generated using the available biostratigraphy and closely spaced strati
graphic sections and core and tracing regional disconformities marked by breccia calcrete and soil horizons between the sections
EolianiIe units backstep within the transgressive part of the Chesterian supersequence and are absent from the highstand part which is dominated by siliciclasticsand likely formed in a more humid setting Withinthird order and fourth order sequences the eolianites occur updip in disconformity bounded parasequences In the transgressive and early highstand systems tracts of sequences eolianiIes overlie exposure surfaces and are preserved in the transgressive parts of the parasequences In the late highstand parts of sequences eolianites are preserved in the regressive parts of parasequences and are capped by sequence bounding disconformities marked by breccia and calcrete.
The abundance of carbonaIe eolianiIes in the Upper Mississippian is likely due to seasonal semiarid climate and moderate amplitude
fourth order eustatic sea level changes The reservoir potential of the eolianites is limited by tight packing and calcite cementation
However recognition of the eolianites is critical to understanding the vertical and lateral distribution of reservoir facies within the
sequence stratigraphic framework because they indicate subaerial conditions and commonly mark subtle sequence boundaries.