PALEOCURRENT AND PROVENCE ANALYSIS OF AN INCISED-VALLEY FILL AT ECHO CLIFF, KS

Echo Cliff, located southwest of Dover, KS, is a 75-foot exposure of channel-fill deposits accumulated in incised valleys that cut down into the Pennsylvanian marine succession during a sea-level fall. Much of the material filling the channel is believed to have come from the uplands to the north and northwest, but to date no systematic study of the provenance of these sediments was carried out. The purpose of this study is to reconstruct the sediment pathways and to identify potential source areas. A detailed facies analysis, with construction of a sedimentary log including facies attributes and systematic measurement of paleocurrents, will guide the collection of samples for petrographic analysis. The facies identified will be organized in a facies table and grouped into facies associations. Samples from different facies will be collected to prepare thin sections for provenance analysis. Systematic quantitative petrography, through point-counting of 300 points per thin section following the Gazzi-Dickinson method, will provide compositional data on primary constituents, including accessory minerals. Compositional data will be used to determine the types of rocks that contributed to the sedimentary load. The integration between paleocurrent and compositional analyses in the sediments exposed at Echo Cliff, with the analysis of regional geological maps, will point to potential source areas upstream for the incised-valley fill deposits.