Date of Award
Doctor of Philosophy
The Parksville quadrangle is structurally located at a salient in the Blue Ridge front. The Great Smoky fault divides the quadrangle such that the southeastern one-third consists of Blue Ridge rocks and northwestern two-thirds of Valley and Ridge rocks.
The Blue Ridge consists of Precambrian Ocoee and Lower Cambrian Chilhowee rocks. The Ocoee Series is represented by both the Wilhite and Sandsuck formations, although previous maps had not indicated the presence of any Wilhite rocks. A mappable unit of Wilhite containing paragonite has served to divide the Formation into an Upper and a Lower Member. All of the fine-grained Wilhite rocks possess slaty cleavage.
Valley and Ridge rocks consist of, in ascending order: Conasauga Shale, Maynardville Limestone, Knox Group carbonates, Athens Shale, and an Upper Middle Ordovician sandy calcarenite resembling the Tellico and Chota formations. They show little or no metamorphic effects. The metamorphic boundary separating the provinces is sharp and corresponds to the Great Smoky fault.
To monitor the increase in metamorphic grade within the Blue Ridge rocks, a method utilizing the sharpness of the 10 Å illite peak proved generally unsuccessful. A method was developed for comparing the relative intensities of two peaks, one for 1M and the other for 2M muscovite, which proved somewhat more successful. The ratio I O25(2M) / I 112(IM) increases with increasing metamorphic grade to the southeast.
The Wilhite rocks have been metamorphosed to the quartz-albite-muscovite-chlorite subfacies; the principle assemblages are: quartz-muscovite; quartz-muscovite-chlorite; quartz-muscovite-chlorite-paragonite.
The constancy of mineral assemblages suggests that the rocks are of uniform chemical composition and the simplicity of assemblages suggests the attainment of chemical equilibrium during metamorphism. Semiquantitative analyses show the atom ratio Fe/Mg ≂ 1 which may account for the absence of chloritoid as a phase, or its absence may be due to a high f₀₂ and P total during metamorphism.
The dominant Valley and Ridge structure is a syncline, nonplunging in the north and south-plunging in the south. A low-angle thrust fault, the Cookson Creek fault, brings a flap, mainly of Knox, over the north segment of the east limb of the syncline. The Cookson Creek fault is compared to the Pulaski fault.
The Blue Ridge rocks have been tightly folded and faulted. Topographic trends generally reflect the underlying structure. A convergence of linear trends in the southwest and northeast suggest a squeezing of the structural block at either end, causing the Parksville synclinorium to doubly plunge toward the center. Local disruption of the trends suggests minor flexures which occurred later than the main period of deformation.
The tight folding and faulting was produced by compressional forces from the southeast which slightly preceded the main pulse of thermal metamorphism, previously dated at about 360 m.y. The minor flexures accompanied the emplacement of the Great Smoky thrust sheet, dated at about 225 m.y.
Sutton, Thomas Culver, "Relationship Between Metamorphism and Geologic Structure Along the Great Smoky Fault System, Parksville Quadrangle, Polk and Bradley Counties, Tennessee. " PhD diss., University of Tennessee, 1971.