Structural geology and geometries of the Denton Duplex along the frontal Blue Ridge, near Hartford, Tennessee

The frontal Blue Ridge in east Tennessee is marked in many places by narrow-discontinuous exposures of Lower-Cambrian Chilhowee Group rocks (+/- Shady Dolomite and Rome Formation). The Denton duplex is one of these exposures that until now has not been mapped in detail. It is complexly faulted into eight separate thrust blocks. The stratigraphy and structure of each block are described in detail.

Several reports in the past describe the thrusting of the area as hindward progressive (i.e., progressing from northwest to southeast). In addition, Keller (1980) interpreted the Great Smoky fault as a late - cross-cutting fault that offsets pre-existing thrust sheets.

Mapping of the study area shows that the Denton duplex consists of individual horse blocks that are part of a complex fault system of which the Great Smoky fault is the principal fault. Each horse block was plucked from the footwall of the fault as it ramped through the Chilhowee Group. Balanced cross-sections show that the average angle at which the fault cut up-section is between 15 and 20 degrees.

Fault contour maps and balanced cross-sections show that the successive stacking of these horse blocks, combined with progressive deformation in lower-younger sheets of the Valley and Ridge rocks, folded the overlying Great Smoky thrust sheet into a broad anticline-syncline pair. The cross-sections and restored sections also show that the English Mountain thrust block (also composed largely of Chilhowee Group rocks), to the northwest of the study area, has a "flat" geometry and therefore must restore to the southeast of the Denton duplex.

Late high-angle extensional normal faults cut earlier structures (thrusts), locally placing younger rocks on older ones.