PAC Analysis Of The Discoelosia Epibole In The Lower Devonian Kalkberg Formation Of Eastern New York State

Abstract

Application of the PAC Hypothesis (Goodwin and Anderson, 1981) to shallow shelf facies containing the Dicoelosia Zone (Rickard, 1962) in the Lower Devonian Kalkberg Formation, reveals the presence of three PACs that are correlated throughout the Hudson Valley. Microfacies and paleoenvironmental analysis demonstrates that, in vertical succession, each of these PACs was deposited in a successively deeper environment of deposition. This eposodic deepening is interpreted to have occurred as a result of a sequence of two minor punctuation events and two major punctuation events. A comparison of the stratigraphic position of the Dicoelosia epibole with PACs shows the epibole to occur in two successive PACs at different locali­ties, and therefore not to be an accurate time-stratigraphic unit. The first and lower PAC contains Dicoelosia only at the basin axis near Catskill. The PAC immediately above the first PAC contains Dicoelosia only at the areas flanking the basin axis to the north and south and not at the basin axis. Therefore, since the occurrence of Dicoelosia is laterally discontinuous in both PACs, the Dicoelosia epibole does not exist as a chronostratigraphic horizon of Dicoelosia abundance.