| Summary |
The Pine Mountain Thrust is the northwestern boundary of the Cumberland Mountain over-thrust block that was displaced to the northwest during the Alleghenian Orogeny. The Pine Mountain Thrust intersects the Jacksboro Fault System to make up the western boundary of the Cumberland Mountain over-thrust block in the Pioneer Quadrangle of Tennessee. At this intersection is the southeast end of the Terry Creek Fault. The stratigraphic units exposed in the Pioneer area include the Silurian Rockwood Formation, Devonian Chattanooga Shale, the Fort Payne Chert, Newman Limestone, and Pennington Formation in the Mississippian, and units from the Lower Pennsylvanian Gizzard Group to Vowell Mountain Formation in the Upper Pennsylvanian. Shales and sandstone beds are dominant in most units, except in the Lower and Middle Mississippian units where limestone, chert, and dolomite are present and in the Crab Orchard Group units where conglomerates are present. This study focused on deformation along the Jacksboro Fault System and Pine Mountain Thrust and the relationship between these faults. There is a large anticline along the Jacksboro Fault on the hanging wall. Along the Jacksboro Fault, a series of dropped blocks became thrust slabs when transported because of a lack of friction from the transport of the thrust sheet. On the footwall of the Pine Mountain Thrust is the Woodridge Syncline, which is a compressional structure that formed as the thrust advanced and possibly from the result of duplexing. The Terry Creek Fault is a high angle fault that generally strikes N40W. Transport directions are the most important aspects in understanding the relationships between the Pine Mountain Thrust and the Jacksboro Fault. Regionally there are at least two significant transport directions. The Pine Mountain thrust sheet has been transported towards N40W. At the southeast end of the Jacksboro Fault, the Chattanooga Thrust has a transport direction of N60W. These conditions are the dominant reasons why there these two faults exist in the Pioneer Quadrangle today. |
