Geology and coal resources of the Elk Valley area, Tennessee and Kentucky

Abstract

The 240-square-mile area described in this report includes the Ivydell, Jellico 'Vest, Ketchen, and Pioneer 7lh-minute quadrangles in Scott and Campbell Counties, Tenn., and McCreary and Whitley Counties, Ky. Elk Yalle.y, the source of the area name, is centrally located.The quadrangles of this report are in the Cumberland Mountain section of the Appalachian Plate-aus province, except for the southeast co•rner of the Ivydell quadrangle which is in the Valley and Ridge province. That part of the area in the Cumberland Mountain section lies within the gently folded Cumberland overthrust sheet where the principal streams flow parallel to ridges that fringe the blunt southwest end of the Middlesboro syncline. Northwest and •southwest of the Cumberland overthrust sheet, the Cumberland Mountain section is characterized by dendritic drainage patterns that were incised into relatively flat-lying rocks.The rock formations exposed in the Elk Valley area range from the Newala Dolomite of Early Ordovician age to the Hignite Formation of Middle Pennsylvanian age. Approximately the lower third of this sequence consists of ca•rbonate rocks of Early and Middle Ordovician age that crop out in the extreme southeast corner of the area. The middle third of the sequence is composed of alternating beds of shale and carbonate rocks of Late Ordovician to Early Mississippian age that crop out in narrow belts of upturned beds on the limbs of the MiddleSJboro syncline and along the Pine Mountain fault zone. Strata in the upper third of the section consist principally of sandstone, siltstone, shale, and coal of Late Mississippian and Pennsylvanian age, which are at the surface in most of the report area. These upper strata are largely of continental origin and vary more laterally than do the underlying formations of marine origin. The sequence totals a'bout 8,300 feet in thickness and haSI been divided into 25 mapped formations. An additional 3,500 feet of underlying strata in the subsurface has been assigned to six formations that range in age from Early Cambrian to Early Ordovician. Unconsolidated surficial deposits of Quaternary age locally cover the bedrock.The gentle southeasterly dip of strata, away from the Cincinnati arch, is terminated in the Elk Valley area by faulting and folding at the pe.riphery of the Cumberland overthrust sheet. During late-or post-Paleozoic deformation of the Appalachian geosyncline the overthrust sheet was di>splaced northwestward by overthrusting on the Pine Mountain fault and by strike-slip movement along the Jacksboro fault. The thickness and character of formations on opposite sides of the Jacksboro fault indicate approximately 11 miles of movement at the southwest end of the overthrust sheet. Because of southeastward thickening of the stratigraphic section, northwestward movement of the overthrust sheet has placed a relatively thicker ,section of rocks opposite its counterpart across the Jacksboro fault. As a result of this thickening and subsequent displacement, 'beds cropping out in the Middlesboro ....

A mechanical model for thrust sheet deformation at a ramp

“…Perhaps the first aspect of Pine Mountain block deformation to strike anyone looking for deformation features is the lack of them. Despite the fact that bedding dips as steeply as 70 ø in places (northwest of Powell Valley anticline, southwest end of block), outcrop-scale folding and faulting are restricted almost exclusively to within about 100 m of the major faults [Miller and Fuller, 1954;Englund, 1968;Wiltschko, 1977]. Table 1 summarizes the inferred conditions and nature of the deformation in the upper plate.…”

“…Greater displacement of the fault produced a broader anticline with the same structural relief [Rich, 1934]. Powell Valley anticline narrows to the northeast, and Englund [1968,1971] and Harris [1970] have also shown that displacement decreases from 18 to 7 km in that direction [Englund, 1968, Figure 19, 1971Harris, 1970, p. 163]. The Pine Mountain block has both rotational and translational components to its movement.…”

Revised stratigraphy and nomenclature for the Middle Pennsylvanian Kanawha Formation in southwestern West Virginia

“…On the basis of their common stratigraphic position with respect to the Dingess Shale Member and certain extensively mined coal beds, the Winifrede has been correlated with the Magoffin Member of the Breathitt Formation in Kentucky by Wanless (1939, p. 53), Outerbridge (1976), and Blake et al (1989). The Winifrede Member and its correlatives are probably among the most widely recognized and mapped Middle Pennsylvanian units in the central part of the Appalachian basin, extending from east-central West Virginia to Scott County, Tennessee (Englund, 1968). In Kentucky, this horizon was earlier referred to as the "Fossil Limestone" by Wanless (1946).…”

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“…Although the Fire Clay tonstein has been traced from West Virginia across Virginia and Kentucky to Tennessee, both on the Cumberland overthrust sheet and in the autochthonous portion of the basin northwest of the overthrust sheet (Wanless, 1946), there is an area that is stratigraphically and structurally isolated at the southwestern end of the Cumberland overthrust sheet where the identity of the tonstein has been questioned. Rice (1984) determined that the stratigraphic position of the Fire Clay tonstein in that area was in the Walnut Mountain coal bed, about 80 m higher in the Pennsylvanian section than had been previously indicated by Glenn (1925) and Englund (1968). We collected sample RI of the tonstein in Glenn's (1925) type Walnut Mountain coal bed on Walnut Mountain in Campbell county, Tennessee, for 40 Ar/ 39 Ar age spectrum dating and for a comparison of its phenocryst mineralogy with that of other samples of the Fire Clay tonstein dated in this study.…”