Carboniferous strata can be described, interpreted, and correlated using six scales of allocyclic transgressive-regressive (T-R) units. These T-R units are inferred to be the net result of deposition during cycles of sea-level change. All Pennsylvanian and Lower Permian strata constitute one second-order T-R unit, or synthem. The Pennsylvanian System contains third-, fourth-, fifth-, and sixth-order T-R units that can be correlated across both marine and nonmarine facies in the Appalachian Basin. This permits differentiation of allocyclic T-R units from autocyclic T-R units or fluvial autocyclic units. The hierarchical approach is also useful for predicting the location of marine horizons, coals, claystones, and various types of stratigraphic breaks. A hierarchical scheme of allocyclic T-R units could be combined with biostratigraphic, radiometric, and magnetostratigraphic data to form a practical chronostratigraphic framework for the Carboniferous.

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