ABSTRACT

Environmental reconstruction for the Cambrian portion of the Taconic Sequence, New York and Vermont, indicates a depositional environment analogous with a modern slope fan-basin-plain model. Carbonate sediment and generally coarse quartz sand were removed from the Cambrian shelf and deposited with muds of the slope, now slates and siltstones, by a variety of processes at work on the slope and within submarine canyons. The shelf-derived sediment can be divided into six main lithofacies, each bearing the imprint of the principal process or processes involved in its deposition. These include: (1) carbonate clast conglomerates (inferred products of debris flow), (2) massive, coarse sandstones (apparent deposits of fluidized sediment flow and grain flow), (3) graded sandstones and limeston s (presumed turbidites), (4) parallel-laminated sandstones and limestones (probable turbidites), (5) thin, structureless micrites (inferred deposits of vertical settling-out of suspension), and (6) current-ripple-laminated limestones and sandstones (thought to be the products of reworking by contour-following bottom currents or submarine overbank levee deposits). All of these processes were working together or in opposition. Analysis indicates that only the lower slope and base-of-slope portion of the early Paleozoic continental margin has been preserved in the Taconic Sequence.