Uppermost Carboniferous Stratigraphy and Depositional History Near Huntington, West Virginia: ABSTRACT

Abstract

Excellent exposures of Conemaugh strata are present in road cuts along both sides of the Ohio and Big Sandy rivers near their confluence. Dense locality spacing permits a detailed 3-dimensional reconstruction of these repetitive, vertically and laterally diverse rocks. Most of the succession was deposited by an actively prograding delta and consists of upper-delta-plain channel, natural levee, lacustrine, and oxidized flood-plain deposits. Lesser amounts of lower delta-plain sediments include laminated, interdistributary bay and backswamp deposits, and a few thin coal seams and seat rocks. Intercalated into the lower delta-plain sediments is one prominent, laterally extensive marine unit correlated with the Ames Member of southeastern Ohio. In this area, the Ames is tripartite and as much as 40 ft thick. The lowest part is a bluish-green, calcareous, highly fossiliferous shale, with a megafauna dominated by Neochonetes. It becomes coarser grained and less fossiliferous upward and is succeeded by a brackish-marine, fissile, maroon shale with pectens and ostracods. The maroon shale similarly grades upward into a massive, calcareous, crinoidal sandstone, formed as a regressive barrier, that ranges in thickness from 0 to 22 ft within a few miles. The entire marine succession was formed under extremely nearshore End_Page 794------------------------------ conditions of reduced salinity and belongs to the Cavusgnathus-biofacies. End_of_Article - Last_Page 795------------