The Impact of Ohio's Extraterrestrial Visitor - Geology of the Serpent Mound Disturbance
Greg Schumacher (Ohio Geological Survey, Columbus, Ohio, USA)
2009 Midwest Chapter of the Friends of Mineralogy Symposium and Field Conference (Geology Department of Miami University, Oxford, Ohio, USA)
5 September 2009
See Schumacher’s Serpent Mound book (an Ohio Geological Survey book) - Baranoski et al. (2003).
August Foerste was the first to map the Serpent Mound Structure - made a geologic map in 1919.
There are breccia zones along creeks in the central uplift of Serpent Mound.
Planar deformation features (PDFs) have been found in Serpent Mound material.
Microdiamonds have not been looked for and not identified yet at Serpent Mound - a good research project for someone.
Serpent Mound shattercones used to be called horsetail structures.
Serpent Mound cores have “concrete rock” - very unlike anything else in Ohio. The cores have mixes of shale, Upper Ordovician fossiliferous limestone, Silurian stuff, etc. The stratigraphy has been completely disrupted.
En-echelon normal faults are present in the core. There's also shattercones, sulfide mineralization, and breccia zones between clasts.
Serpent Mound Structure - a gravity low.
Fist-sized Ohio Shale pieces occur in the Serpent Mound core - have quartz grains with impact PDFs. This was proof that Serpent Mound is indeed an impact structure.
Some Serpent Mound core thin sections have pseudotachylite melt features.
Faults radiate out from the central uplift.
Serpent Mound Impact age: Pennsylvanian-Permian, based on a paleomagnetics study.
The impacting body was probably 150-200 meters in size. It would’ve devastated Ohio, Indiana, Kentucky.
~1000-1500’ worth of rock have been removed by erosion since Serpent Mound formation. But, not sure how much rock originally sat above what we have now.
The Serpent Mound Structure is pretty limited in size at about 3000’ down.
A Serpent Mound impact debris bed has not been identified yet in Ohio’s Pennsylvanian-Permian succession.
Iowa’s Manson Crater does have an ejecta bed 100 km away. The Manson Crater is 30-50 km in size.
The Serpent Mound cores are still at the Ohio Geological Survey core barn. Folks are invited to look for microdiamonds in Serpent Mound rocks.
The Serpent Mound Crater is now gone - we’ve got the roots left.
Coesite has not yet been found associated with Serpent Mound. To find coesite, it's suggested that one looks in sandstone or quartz grains in Ohio Shale.
Impact diamonds perhaps may be found in the pseudotachylite.