Paper No. 11-13
Presentation Time: 8:00 AM-12:00 PM
A STRUCTURAL GEOLOGIC TEST OF THE TECTOGRAPHIC ORIGIN OF EDIACARAN SPECIMENS, DURHAM COUNTY, NORTH CAROLINA: UNDERGRADUATE RESEARCH ON NEOPROTEROZOIC LIFE PART II
Seilacher et al. (2000) claimed that Vermiforma antiqua specimens found along the banks of the South Fork of the Little River, Durham County, NC, were “tectographic” pseudo-fossils, and of tectonic rather than biologic origin. These convolute, worm-like features (25-30 cm along their long axes) observed on bedding planes of laminated volcaniclastic strata of the Late Neoproterozoic Hyco arc were proposed to be the result of bedding-plane flexural slip during Late Neoproterozoic Virgilina deformation. Reconstruction of the strain ellipsoid recorded in rocks of the Hyco Formation could be diagnostic as an independent test of this hypothesis. As part of an undergraduate research collaboration between the University of South Carolina and the North Carolina Geological Survey, oriented blocks of volcaniclastic conglomerates interbedded within the Hyco formation were sampled from two separate localities in the vicinity of the S. Fork of the Little River during January 2018. These conglomerates contain cobble- to pebble-sized clasts of primarily intermediate to felsic volcanic material which were likely deposited proximally to the associated volcanic centers of the Hyco arc. Bedding is typically indistinct, and overprinted by a strong, steeply-dipping cleavage. The oriented blocks were slabbed along three orthogonal planes to perform Rf-phi analyses of the clasts. These analyses are compared with similar, previously unpublished analyses from the overlying Aaron Formation (North Carolina State University; J. Hibbard, pers. comm.) to suggest that at both a local and regional scale, the resulting strain ellipsoids appear to be inconsistent in shape and orientation with a tectographic origin for the V. antiqua specimens.