Abstracts Category : Other

Mapping the Outer Margin of the Serpent Mound ImpactStructure to Assess the Outer Limit of Deformation: Adams,Highland, and Pike Counties, Ohio

by David S Vanadia

The Serpent Mound structure is a complex impactstructure in southern Ohio named after Great Serpent Mound, anancient effigy mound situated on the structure's western flank. Itis located west of the Allegheny escarpment within Adams, Highland,and Pike counties. The impact occurred between the MiddleMississippian and Late Permian, since which time any obviousexpression of the crater rim has been removed by erosion. Pastmapping efforts have revealed a centrally uplifted regionsurrounded by a ring of downward displaced strata within a faultedarea 4.5-5 mi (7.3-8 km) in diameter, which is generally taken tobe the crater's size. However, the Middle Silurian-Upper Devoniancontact has been shown to be displaced downward over a region 14 kmin diameter centered on the impact structure and, based on complexcrater morphometry, the rim diameter should be 6.2-15 mi (10-25km). The intent of this study is to locate any structural evidenceof the crater rim through field mapping so that the size of thestructure can be more accurately described.The outermost concentricnormal fault or ring monocline is commonly used to define thediameter of impact structures, but neither have been located.However, a series of radial folds occur in the Drakes Formation 5.3mi (8.5 km) from the center of the crater. Such folds commonlyresult from concentric shortening during the collapse of thetransient crater rim as material moves away from the concentricfault scarp and into the crater, and so becomes constricted. Basedon the extent of radial folding, if impact related, the outer limitof deformation and the minimum apparent diameter of the SerpentMound impact structure is 10.6 mi (17 km).Advisors/Committee Members: Nance, R. Damian (Advisor).