4 Structural Geology and Tectonics (Posters)

Thursday, 5 April 2001
8:00 AM - 12:00 PM

SWANNANOA TRENCH VALLEY LINEAMENT IN THE BLUE RIDGE MOUNTANS NEAR CANTON, NC

Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

As previously identified by Hack (1982), Dennison and others (1997), and Gay (1999), eighteen major lineaments cutting across lithologic trends exist in the Great Smoky-Blue Ridge region. These lineaments, with orientations trending in three general directions, are marked by quite straight depressions approximately 8-240 km long; their origins are unknown. This study concentrates on the Canton Quadrangle, which is crossed by the longest lineament, the Swannanoa trench valley, which trends E-W and stretches from Fontana Lake through Canton to Black Mountain and into the Piedmont near Hickory. Near Canton, the narrow bottom of the trench valley is 0.2-0.3 km wide, is incised 110 m into the broader trench, and is very pronounced and straight topographically. The early Nineteenth Century toll road, the railroad, Hominy Creek, and locally the Pigeon River follow this narrow valley.

The Canton location contains gneisses and schists mapped by Merschat and Wiener (1988) as Precambrian Y Richard Russell Formation and Precambrian Z Ashe Metamorphic Suite. These Proterozoic rocks provide an opportunity to develop an age relationship between the trench and the preexisting structures. Studies are now underway to determine if joint patterns indicate evidence concerning the formation of the Swannanoa lineament near Canton. My preliminary joint measurements indicate two general joint patterns, one striking NE-SW and the other NW-SE, and both dipping steeply. Merschat and Weiner (1988) classify these joints as Mesozoic-Cenozoic age and they credit the diversity of joint orientations to the “non-homogenous nature of the area.” In this study the possible relationship between the joints and the lineament is tested, and early observations indicate that the joints may be bending into the lineament with increasing proximity to it.