Carbonate-shale cycles in the Middle Devonian of New York: An evaluation of models for the origin of limestones in terrigenous shelf sequences Available to Purchase

Thin, widespread carbonate beds in the predominantly siliciclastic Hamilton Group (Middle Devonian) of New York appear to represent biogenic accumulations of winnowed, shallow (normal to storm wave base) shelf areas, rather than products of transgression-induced sediment starvation, as frequently assumed. In western New York, these fossiliferous limestones form the centers of subsymmetrical marine cyclothems. Carbonates are overlain and underlain by calcareous, gray to black, laminated shales, and they grade laterally into siltstones or sandstones that cap upward-coarsening sequences in central New York. Thus, the limestones appear to represent shallow-water facies of regressive hemicycles, instead of transgressive maxima, as argued by earlier workers.