DETRITAL-ZIRCON SIGNATURES OF MISSISSIPPIAN SUCCESSIONS IN SOUTHERN MIDCONTINENT AND ITS IMPLICATIONS

Partly re-emergent Canadian Shield and onset of orogenic belts forming on the continental margins from the east and south bring in significant siliciclastic influxes in southern midcontinent region. Consequently, Paleozoic sedimentation in southern midcontinent of the North America transit from dominantly carbonate rich succession in Late Cambrian through Early Mississippian, transition period in Later Mississippian, and a more clastic rich succession in Pennsylvanian. In this study, we present results of U-Pb detrital-zircon geochronology from 16 samples of Mississippian sandstones from southern Illinois Basin, southern Missouri, and northern Arkansas. Results show that its age distributions can be subdivided into six groups: ~350-500, ~900-1350, ~1360-1500, ~1600-1800, ~1800-2300, and > ~2500 Ma, and include virtually all major basement provenances of North American craton. Regional correlation suggests that influx of clastics from the Appalachian orogenic belt to the east did not start until Late Mississippian (Chesterian) in the southern midcontinent. Most of Mississippian sediment were likely derived and/or recycled from the Canadian Shield and the Appalachian orogenic belt. Substantial increase of Yavapai-Mazatzal grains (~ 1600–1800 Ma) suggest that Precambrian basement uplifts, potentially related to the Transcontinental Arc and/or Ancestral Rocky Mountains to the west, are needed to account for the marked enrichment of Late Paleoproterozoic grains. New detrital zircon data from this study provide insights into Paleozoic paleogeographic reconstruction, and further constraints for a transcontinental sediment dispersal model to link sources from partly re-emergence Canadian Shield to the north, unroofing of Precambrian basement uplift to west, and onset of the Appalachian orogenic belt from east-northeast.