THE DUTCH JOHN ANTICLINE IN THE CAROLINA TERRANE, MONTGOMERY COUNTY, NORTH CAROLINA

The Dutch John anticline is a small fold on the eastern limb of the regional New London syncline (or synclinorium) in the Carolina terrane of central North Carolina. This anticline mainly affects rocks in the Cambrian Albemarle volcanic arc, which include argillite and felsic volcanic rocks of the Tillery Formation and felsic and mafic volcanic rocks of the overlying Cid Formation. We have previously described the Dutch John anticline as a periclinal fold, trending northeast-southwest. The first-order architecture of the fold is inclined, gently plunging, asymmetric, and verging southeast. The fold has a wavelength of about 5km. Axial planar cleavage has a mean attitude of 225°,67° (RHR). Measurements in sedimentary parts of the Tillery and Cid formations dominate bedding attitudes. Bedding attitudes have a maximum eigenvector of 32°,133° (SD 223°,58° RHR), which approximates the synthetic northwest limb of the Dutch John anticline. The intermediate eigenvector is 56°, 289°, representing the synthetic southeast limb. The minimum eigenvector of 11°,36° is the hinge line orientation of the anticline assuming a cylindrical fold. However, the plane normal to that eigenvector does not perfectly conform to the visual distribution of poles to bedding on a spherical projection. Given the large fold closures within the study area, this would be consistent with a non-cylindrical distribution. Contours on the bedding stereo plot show a weak circular distribution that can be inferred to represent folding around steeply northwest- and southeast-plunging axes. The speculative axial surface orientation for those folds would be northwest-southeast. That trend parallels a strong fracture orientation in the region, including Jurassic diabase dikes. A few minor (cms) kink folds, some with small offset faults, have been observed to deform bedding in the Tillery Formation. The Dutch John anticline is a complex accretionary structure in the Carolina terrane.