Early ordovician microbial reef mounds of the tribes Hill formation, Mohawk Valley, New York

Abstract

Tribes Hill domal thrombolites, termed here microbial reef mounds, occupied the basal part of meter-scale shallowing-upward cycles. They are part of a high-energy facies that a sharp, transgressive surface, separates from an underlying low-energy peritidal setting. This erosional surface served as the surface on which one of the reef mounds established itself during initial transgression before further deepening. The others overlie a floor of skeletal grainstone reflecting a high-stand sea-level facies tract. Skeletal grainstone composes the fill between the mounds. One channel and several aggrading hummocks occupy inter-reef mound areas resulting from storm events in a subtidal setting.