UPPER CAMBRIAN LOWER ORDOVICIAN (SAUK) PLATFORM CARBONATES OF THE NORTHERN APPALACHIAN (GONDWANA) PASSIVE MARGIN

Sauk platform carbonates of the northern Appalachian passive (Gondwana ) margin are composed of high-frequency stacking patterns containing f ifth-order depositional cycles. Most of the these cycles, termed paras equences in this study, display upward-shoaling peritidal patterns, co mmonly terminating in emergence. Parasequence surfaces are erosional r esulting from this emergence and have associated karst features, espec ially solution-collapse breccia. The carbonates, mostly fine- to mediu m-crystalline and locally vuggy dolostones, are generally of low perme ability. Solution-collapse breccias increase whole-rock permeability t hrough fractures. In addition to solution-collapse breccias, emergence generated terra-rossa soil now lithified, as well as silcrete, now ch ert, and caused the dedolomitization of dolostones. Upward-coarsening facies cycles, in which flat-pebble conglomerates overlie erosional su rfaces, are thought to be storm generated. Yet storm deposits with int raclasts sufficiently angular to be termed breccia may also terminate parasequences. Fifth-order upward-shoaling peritidal parasequences may be the result of extraterrestrial forcing or tectonic events causing rapid eustatic or relative changes in sea-level, respectively Hence po rosity-permeability development may likewise relate to these mechanism s. During the Sauk interval anomalous storm periods may have held sway on a global scale and generated upward-coarsening parasequences. Stor m-weather periods probably resulted from astronomical changes (extrate rrestrial forcing). porosity and permeability in the storm deposits ma y also be controlled by extraterrestrial forcing functions.