"Numerous sandstone filled depressions hosted in upper Cambrian to Middle Ordovociain dolostones in south-central Missouri have historically been identified as Pennsylvanian paleokarst structures. U-Pb detrital zircon geochronology is at odds the time of formation and sedimentological evidence challenges their classification. "Filled sink" deposits yield primary zircon age populations of 2.8-2.6 Ga (~50% of all analyzed grains), 1.2-1.1 Ga (~25%), 1.8-1.6 Ga (~15%) and 1.5-1.3 Ga (~10%). These zircon populations most likely originated from the Superior Craton and Midcontinent Rift and/or Grenville orogen, respectively. The Warrensburg and Moberly channel-fill sandstones of central Missouri were identified as good candidates for Pennsylvanian aged strata to which results from "filled sinks" may be compared. In contrast to "filled sink" deposits, channel-fill sandstones contain a population of Paleozoic zircon grains presumably derived from exhumed plutons of the uplifting and eroding Appalachian Mountains to the east. Existing data from Ordovician clastic strata (e.g., the Roubidoux and St. Peter Sandstones) in central Missouri show zircon age distributions that are strikingly similar to those "filled-sink" deposits. We suggest that the Taconic orogeny led to modest uplift in central Missouri, resulting in a significant disconformity below the St. Peter sandstone during the middle Ordovician. Far-field tectonism appears to have caused a reorganization of sediment dispersal pathways from the Archean Superior craton to the north to the growing mountains to the east, and in the process created a depositional hiatus forming the filled-sinks. The Taconic orogeny then proceeded to provide a source for detritus which arrived in the Missouri basin as early as the Upper Mississippian"--Abstract, page iv.
Hogan, John Patrick
Chapman, Alan D.
Geosciences and Geological and Petroleum Engineering
M.S. in Geology and Geophysics
Missouri University of Science and Technology. Rock Mechanics and Explosives Research Center
Missouri University of Science and Technology
viii, 51 pages
© 2016 Daniel Nathan Meehan I, All rights reserved.
Thesis - Open Access
Electronic OCLC #
Meehan, Daniel Nathan I, "Late Ordovician tectonism in the North American midcontinent: Constraints from U-Pb detrital zircon geochronology" (2016). Masters Theses. 7744.