Abstract

Structural style variations across the Tennessee segment of the Valley and Ridge thrust belt are correlated with two facies changes in important structural/stratigraphic units. The Middle and Upper Cambrian Conasauga Group and the Middle Ordovician Chickamauga Group change their internal stratigraphy regionally at oblique angles to the trend of this segment of the thrust belt. These stratigraphic variations correlate geographically with structural style changes within individual thrust sheets, whereas other variables, such as temperature, pressure, and magnitude of tectonic transport, do not. In the Conasauga, the east to west, limestone to shale facies transition coincides with areas where structural styles change along thrusts at the Conasauga level. The shale-dominated and carbonate-dominated facies show simple frontal imbricate thrusts, whereas in the shale/carbonate zone of interlayering, duplexes occur. In the Chickamauga, an east-west change from basinal shale to shelfal limestone controlled the regional presence of a middle-level glide zone in the paths of eastern thrusts and its absence to the west. This stratigraphic inhomogeneity also controlled a change in the Knoxville area from surficial folding in the northeast to surficial thrusting in the southwest. The terminology of structural lithic units and their subsidiary predominant and conforming members is applied in dividing the stratigraphic section into structurally significant packages.

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