Apatite fission-track thermochronology of the central and southern Appalachian Basin

The purpose of this dissertation is to determine the thermal history of the central and southern Appalachian Basin using apatite fission-track analysis of samples of Middle Devonian Tioga Ash Bed and Upper Paleozoic sedimentary rocks. Samples were collected in west to east transects across the Appalachian Basin of Pennsylvania, Maryland, West Virginia, and Virginia. These samples locations were chosen to test the concept of increasing paleotemperature due to increasing burial from west to east across the Appalachian Basin and to detect any thermal anomalies that exist.; It was concluded that the central and southern Appalachian Basin did not undergo a uniform block uplift after the folding and thrusting of the Alleghanian orogeny based on apatite fission-track thermochronology. Calculated time-temperature (tT) paths based on apatite fission-track apparent ages and confined track length distributions for samples from this study indicate that both the Pennsylvania and southern Appalachian had complex uplift and cooling histories.; In Pennsylvania, the Tioga and Kalkberg ash bed samples from central Pennsylvania yield modelled tT paths that indicate early post-Alleghanian (285-270 Ma) cooling with uplift estimated at beginning at {dollar}spsim{dollar}251 {dollar}pm{dollar} 25 Ma. Samples from the western Allegheny Plateau and Allegheny Front contain apatites which have reset to give fission-track ages and track lengths consistent with tT histories beginning at {dollar}<{dollar}200 Ma. In northeastern Pennsylvania on the Allegheny Plateau, the modelled tT paths show rapid cooling from temperatures in the range of 110{dollar}spcirc{dollar}-120{dollar}spcirc{dollar}C at 170-160 Ma.; In the southern Appalachian Basin, calculated tT paths indicate that uplift in the northern section was immediately post-Alleghanian folding with uplift beginning first in the northwestern section on the Cumberland Plateau at {dollar}spsim{dollar}226 {dollar}pm{dollar} 23 Ma and progressing to the eastern Valley and Ridge Province of Virginia at {dollar}spsim{dollar}119 {dollar}pm{dollar} 12 Ma. The samples from southwestern Virginia yield a mean apatite fission-track apparent age of 175 {dollar}pm{dollar} 11 Ma which may be the result of a higher heat flow, higher paleogeothermal gradient during the Upper Jurassic-Early Cretaceous extension along the Atlantic Coast.