Post-orogenic evolution of the Appalachian mountain system and its foreland

Denudation estimates are usually calculated as long-term averages or present-day instantaneous rates, and the temporal aspect of denudation is commonly examined through comparison of different stages of landscape evolution: geologists have long used the Appalachians for such studies.; Petrology and geochronology have provided a geological basis for estimating cooling and denudation of Appalachian metamorphic belts, but regional-scale data have been lacking for adjacent sedimentary basins. Integrated maturation parameters (coal rank, conodont CAI) indicate that the present surface of the Appalachian Basin experienced Alleghenian burial of 2-6 km and temperatures of 80-{dollar}250spcircrm C.{dollar}; Primary apatite fission-track analyses from Virginia and West Virginia have been added to compiled data to provide detailed cooling patterns for eastern North America. Apatite fission-track ages increase from {dollar}<{dollar}100 Ma on the Piedmont to {dollar}>{dollar}500 Ma on the Canadian Shield. Inverse modeling techniques, which invert a track-length distribution into a range of possible thermal histories, were developed and applied to the Appalachians on a regional scale.; Regional integration of fission-track, maturation, thermochronologic, and metamorphic data provide detailed spatial and temporal patterns of denudation for eastern North America. Rates were 200-300 m/my for the Permian in the Piedmont, while Appalachian Basin denudation was as low as 10 m/my during the Triassic. Cretaceous rates were generally very low ({dollar}<{dollar}10 m/my), while rates increased up to 95 m/my throughout the eastern US in the Late Tertiary. Long-term average rates are 10-65 m/my, compatible to previous estimates of 40 m/my. Eroded volume from eastern North America is similar to the total and through time Atlantic/Gulf Coast sedimentary volumes.; Paleotopographic maps have been constructed by isostatically restoring eroded rock volumes to the present topography. Regional patterns strongly suggest that mountains evolve from strong to poor correlation of denudation with elevation in about 150 my. Significant topography persists much longer ({dollar}>{dollar}290 my). Accelerated erosion and increased relief during the past 30 my was not the result of renewed tectonic uplift and peneplain dissection, but rather related to the Late Tertiary drop in global sea-level.