Uranium Fission-track Dating of Glass Shards from Selected Volcanic Ash Deposits in the Southern High Plains Border Region

Abstract

A desire to obtain a better understanding of the Pleistocene geomorphic evolution of and soil development in western and central Okl~homa, south central Kansas, and the eastern part of the Texas Panhandle was the primary motivation for this research. A major lithologic discontinuity occurs between the Permian bedrock and the unconsolidated sediments which rest upon it over much of the area. Volcanic ash deposits are included in the alluvial and eolian deposits. Ash deposits are potential time marker beds for reference in soil and landscape development interpretations because it is possible to date them. The upland terraces of the major rivers were of particular interest because they are important to the agriculture of the area, are a major water source for many parts of the area, and the soils described on them are well developed. The initial proposal for this project was the dating of the ash deposits and a detailed study of soils associated with some of the ashes. A year into the project it became apparent that the soils part had to be dropped. Dating of 35 ash deposits proved to be time consuming and provided enough valuable information to make this thesis. The results of the dating are fairly consistent with results reported by other researchers involved in the dating of volcanic ash deposits. Continued characterization and correlation research on the ashes dated in this study should make them unique and valuable time markers for use in interpreting the Pleistocene geomorphic evolution of a large and important region. A better understanding of the soil development in the unconsolidated deposits of the region should also be accomplished by using the dated ash deposits as time marker beds.