The structural geology of Crums Knob and vicinity Greene County, Tennessee
A detailed study of a portion of the Valley and Ridge Province in eastern Tennessee was conducted to decipher its geologic nature and relation to surroundings and the Blountian phase of deformation. This area known as Crums Knob and is located nine miles south of Greenville, TN. Locally, the area owes its anomalous topography to inherited geologic structures. Crums Knob is bound in the north and south by tear faults and the main topographic feature represents a series of SW plunging folds. Deformation in three phases: folding, thrust faulting, and refolding. Stratigraphic relations show facies changes which affect the mechanical behavior of the Tellico Sandstone. When the sandstone is Underlain by the Lower Shale Unit or Lenoir Limestone, minor folds and thrust faulting occur within the Tellico Sandstone. But when it is underlain by the Knox Group, it deforms in the same way as the Knox Group forming broader folds.In a regional context, the following may be concluded: 1) The Blountian phase occurred from Upper Cambrian to the Middle Ordovician times, resulting in uplift of the terrain to the southeast. 2) The Middle Ordovician basin was developed as an isostatic response to the uplift. 3) Isostatic movements took place along fractures that were oriented W-NW and E-NE. As a result eroded limestone clasts were deposited along these fractures preserving the fractures' initial orientation. 4) During the Alleghanian Orogeny (?), there was a reactivation of these fractures moving blocks either: A) upward to form ramps as a response to the back load of advancing thrust sheets, or B) downward as a response to the direct load of the transported sheets. 5) Either of these movements controlled the pattern of tear faults in the Middle Ordovician basin in terms of their distribution density and length. 6) The Blountian Phase is diachronous, and its effects in the southeast were earlier than those in the northern regions.This area has not been mapped in detail and it merits a more intensive study regarding its petrographic and stratigraphic nature.