Rifting of continental lithosphere during extensional tectonics can be accomplished in a variety of ways including uniform lithospheric thinning and detachment tectonics in which extension is not uniform with depth. Each model predicts different subsidence histories subsequent to extension and these should be reflected in the sediments in filling the rift basins. Where rapid subsidence phase is followed by a slower negative exponential phase associated with contraction during cooling of the rifted lithosphere, whereas the thermal phase is reduced or absent if surface extension and rifting is detached from under- lying unextended lithosphere. The Newark Basin of Triassic- Jurassic age in the central Appalachians now consists of sediments interpreted to represent only the initial rapid subsidence phase. It is unclear if thermal phase sediments were never deposited (implying detachment tectonics) or deposited but removed by erosion (implying uniform lithosphere extension). This project will collect and interpret detrital apatite fission-track ages from a transect across the basin in an attempt to determine the maximum amount of sediment that could have been removed by erosion before Cretaceous overlap sediments were deposited. Results will bear on rifting style of the initial breakup and formation of the present Atlantic ocean, and will provide a well- documented example of continental-scale extension that can be used in comparisons to other rift basins.
