Evidence of a tectonically driven sequence succession in the Middle Ordovician Taconic foredeep

Abstract

The late Mohawkian through early Cincinnatian (Ordovician) Trenton Group carbonates and coeval siliciclastic succession of the central Mohawk Valley, New York State, were deposited in a foreland basin during the Taconic orogeny. Development of this facies mosaic records changes in stacking patterns that took place during episodic basin deepening and simultaneous carbonate-ramp shallowing along a ramp to basin transect located on the distal slope of the foreland basin. Differential rates of subsidence across the region produced accommodation rates that increased by an order of magnitude from west to east. High rates of siliciclastic sediment supply and even higher subsidence rates resulted in a thick, deep-water succession in the eastern part of the study region. The coeval Trenton Group succession in the west formed under conditions of moderate sediment supply and lower subsidence rate, resulting in a net shallowing-upward succession. These relationships suggest that active margin tectonism was the proximate cause of the Mohawk Valley facies architecture.