ROCK DESCRIPTIONS, THE ZIG-ZAG METHOD, AND PETROTECTONIC ASSEMBLAGES: A THANK YOU TO PROFESSOR LOREN RAYMOND FOR HIS SERVICE AND RESEARCH

Accurately estimating the percentage of a millimeter-sized accessory minerals in any rock was not an exception, but an expectation of Loren Raymond for his petrology students at Appalachian State University. In addition to detailed rock descriptions, Loren's tri-colored comments on papers, marathon field trips through the Blue Ridge, and an emphasis on field geology have provided a solid foundation for many young geologists. During my senior thesis, after spending half of a day with Loren in a rhododendron hell hunting float, only to add 1000 feet of contact on the map, I finally grasped the zig-zag method to trace contacts. Since then, I have applied these skills to mapping complex, polydeformed terranes of the Inner Piedmont and Blue Ridge. In the Inner Piedmont, detailed geologic mapping in the Brushy Mountains recognized the Brindle Creek fault —a terrane boundary between Laurentian Tugaloo and mixed affinity Cat Square terranes— and the geometry of several Devonian granitoids. SW-directed shear-sense combined with coaxial L₂ mineral lineations and F₂ folds, and the geometries of the granitoids indicate map-scale sheath folds and SW-directed crustal flow in the Inner Piedmont. Truncation of the ~407 Ma Walker Top granite against the Brindle Creek fault constrains timing of movement of the Brindle Creek fault. The assemblage of pelitic schist, metagraywacke and minor mafic and ultramafic bodies proximal to the central Piedmont suture suggests the Cat Square terrane was deposited on oceanic crust. Palinspastic restoration and mixed Laurentian and peri-Gondwanan affinity of the Cat Square terrane suggests it represents a remnant ocean basin that existed in the Pennsylvania embayment that was closed during the Late Devonian to early Mississippian collision of the Carolina superterrane.