Apatite fission-track thermochronology of the Appalachian foreland basin from the Virginia Piedmont to eastern Ohio

Apatite fission-track ages have been determined for 29 samples from two transects in the southern Appalachians. The northern transect extends from the VA Piedmont northwest through the Valley and Ridge Province, Cumberland Plateau, and into the Appalachian foreland of southeastern OH. An additional transect was collected from the Pine Mountain thrust in southeastern KY extending northwest to the Cincinnati Arch. Precambrian gneisses and granites from the VA Piedmont yield reset apatite fission-track ages ranging from 103 [+-] 6 to 138 [+-] 11 Ma. Ordovician through Mississippian sedimentary rocks from the Valley and Ridge Province of VA-WV also yield reset apatite fission-track ages ranging from 120 [+-] 8 to 144 [+-] 20 Ma. The cooling histories for the Piedmont and Valley and Ridge rocks of VA and WV thus appear similar, having cooled rapidly between about 103 and 144 Ma. Pennsylvanian samples from the Cumberland Plateau of WV yield rest apatite fission-track ages of 112 [+-] 7 to 169 [+-] 13 MA in the southeast which grade into partially reset (mixed ages) northwest of Charlestown (133 [+-] 13 to 156 [+-] 10 Ma). The Permian Dunkard Formation from the OH-WV border yielded a mixed age of 197 [+-] 13 Ma, suggestingmore » that the Permian has not been subjected to temperatures > 100 C for times greater than 1 Ma, since it was deposited. Mississippian--Pennsylvanian samples from eastern KY yield reset apatite fission-track ages which decrease from the Pine Mt. Thrust (186 [+-] 16 Ma) to Mozelle, KY (136 [+-] 12 Ma), then increase toward the Cincinnati Arch (166 [+-] 18 [minus] 186 [+-] 21 Ma). This is consistent with older apatite fission-track ages (200 Ma) from Ordovician K-bentonites in the vicinity of the Cincinnati Arch.« less