The structural geology of a part of the Pulaski thrust sheet near Boone Dam : Sullivan and Washington counties, Tennessee

In the vicinity of Boone Dam, Tennessee, the Pulaski thrust sheet contains the Dunham Ridge and Spurgeon imbricates. The area contains complex structures that include a reentrant in the Dunham Ridge fault, and bifurcation of the Spurgeon fault.

Several reports in the past noted the presence of a broad, northwest-trending lineament zone that extends through the present study area. In addition, Jackson (1982) suggested that the lineament zone was related to a buried, transverse decollement ramp, down to the southwest.

Mapping of the study area suggests that the reentrant in the Dunham Ridge fault is the result of lateral ramping in its footwall. Also, the bifurcation of the Spurgeon fault is a result of imbrication in its footwall.

Fabric data and structural geometries within the area suggest the Pulaski thrust system was originally emplaced at a low angle, in a hinterland to foreland manner. Footwall deformation beneath the Pulaski thrust is modeled as a duplex, with the Pulaski as its roof thrust. Folds associated with emplacement of the large sheet were tightened and modified by minor thrusts during this duplex formation. Rock fabrics are sparse compared to the Valley and Ridge areas along strike, again suggesting dominantly passive folding over underlying structures rather than buckle.folding associated with Pulaski thrust sheet motion and imbricate emplacement.