Abstract: Differentiation of Sandstone Depositional Environments in Pennsylvanian Breathitt Formation of Northeastern Kentucky and Southwestern West Virginia
Romeo M. Flores
Sandstone beds in the Breathitt Formation (Pennsylvanian) of northeastern Kentucky and southwestern West Virginia can be assigned to depositional environments using stepwise multiple-discriminant-function analysis of petrographic properties.
Analyses were performed on sandstones whose depositional environments had been determined previously by sedimentary structures, fossils, and field relations. Rock types included alluvial-plain sandstones from Princess 9 to Princess 5 coal beds, upper delta-plain sandstones from Princess 5 coal bed to Magoffin Member, and lower delta-plain sandstones from Magoffin Member to Van Lear coal bed. Differentiation of depositional environments was based on grain size and quartz, feldspar, coarse-mica, rock-fragment, matrix, and cement content; the interdependence of composition and grain size necessitated a two-part discriminant-function analysis.
Analysis of varied grain-size sandstones shows that 74% of the sample may be assigned depositional environments based on quartz, coarse-mica, and cement content. More effective differentiation was achieved when sandstones were grouped as medium, fine, and very fine grained. Eighty-four percent of the fine-grained sandstones can be classified by quartz, rock-fragment, matrix, and cement content, and 94% of the very fine-grained sandstones can be classified by cement content and grain size. Upper and lower delta sandstones can be differentiated effectively by using either size group.
Discriminant-function analysis can be used to delineate depositional environments of sandstones and associated coal beds. This statistical treatment of petrographic data may enable identification of sandstone types to assist stratigraphic correlations within depositional basins.
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC