DETRITAL ZIRCON GEOCHRONOLOGY OF LATE WISCONSIN GLACIAL ERRATICS FROM WESTERN INDIANA: IMPLICATIONS FOR PROVENANCE AND LOBE ADVANCE

Turkey Run State Park, in west-central Indiana, lies within the Last Glacial Maximum interlobate region of the Lake Michigan Lobe, which advanced from the north, and slightly younger Huron-Erie Lobe, which advanced from the northeast. Approximately 100 erratic clasts were sampled from incised valleys within the park in order to determine isotopic ages by U-Pb LA-ICPMS dating. Prior to analyses, clasts were crushed, and zircon grains were hand-picked under a microscope for individual analyses. Pending analytical results, this work will advance our understanding of erratic ages and allow us to identify provenance as either Superior Province, characterized by abundant Archean clasts, or Grenville Province, dominated by Proterozoic clasts. These results will be used to verify existing surficial geologic maps and interpretations of interlobate dynamics of the Wabash River Valley region.