STRATIGRAPHIC PROBLEMS IN SOUTHERN WEST VIRGINIA: ADDRESSING DISCREPANCIES AND BRIDGING GAPS THROUGH RECENT BEDROCK MAPPING AND MAP COMPILATION

Active 1:24,000 scale bedrock mapping of the Rupert and Rainelle 7.5-minute quadrangles in southeastern West Virginia serves as a link between WVGES mapping of the New River Gorge National Park area and the eastern state margin. Recent mapping in Summers and western Greenbrier counties has been constrained to the late Mississippian Mauch Chunk Group and has highlighted discrepancies across adjacent areas. Previously the Mauch Chunk Group was split into three formations using channelized sandstone members to define contacts: from oldest to youngest, the Bluefield, Hinton, and Bluestone formations. However, the use of channel sandstones is problematic due to their localized, laterally discontinuous occurrence. In addition, misidentification of a contact-forming channel sandstone is common given the occurrence of numerous identical quartz arenitic sandstones, leading to further mapping inconsistencies. Newer approaches to mapping the Mauch Chunk have relied on marine zones, including the Avis Limestone and the Reynolds Limestone, to split the group, which proved to be more laterally extensive and reliable as marker beds. The incorporation of LiDAR imagery has been a significant advancement for updating linework in areas of West Virginia mapped before LiDAR availability. Future work proposes geochronological analysis on Mauch Chunk channel sandstones to determine if they can be differentiated. The Rupert and Rainelle bedrock map compilation has provided the opportunity to resolve mis-matched geology along different map boundaries and revise Mauch Chunk unit assignments in adjacent, recently mapped quadrangles. This continued work is fundamental in supporting the need for a formal re-description and re-definition of the Mauch Chunk Group in order to prevent future discrepancies in bedrock mapping. The addition of new geochronologic data may provide further support for de-definition of this stratigraphic interval.