Structural and Stratigraphic Framework of the Giles County Area, a Part of the Appalachian Basin of Virginia and West Virginia Late Paleozoic Depositional Trends in the Central Appalachian Basin U.S. GEOLOGICAL SURVEY BULLETIN 1839-E, F Structural and Stratigraphic Framework of the Giles County Area, a Part of the Appalachian Basin of Virginia and West Virginia By ROBERT C. McDOWELL and ARTHUR P. SCHULTZ Late Paleozoic Depositional Trends in the Central Appalachian Basin By KENNETH J. ENGLUND and ROGER E. THOMAS U.S. GEOLOGICAL SURVEY BULLETIN 1839-E, F EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN DEPARTMENT OF THE INTERIOR MANUEL LUJAN, Jr., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government UNITED STATES GOVERNMENT PRINTING OFFICE: 1990 For sale by the Books and Open-File Reports Section U.S. Geological Survey Federal Center, Box 25425 Denver, CO 80225 Library of Congress Cataloging in Publication Data (Revised for ch. E, F) Evolution of sedimentary basins Appalachian basin. (U.S. Geological Survey bulletin ; 1839 A- ) Includes bibliographies. Supt. of Docs, no.: I 19.3:1839A-D Contents: ch. A. Horses and fensters of the Pulaski thrust sheet, southwestern Virginia/ by Arthur P. Schultz [etc.] ch. E. Structural and stratigraphic framework of the Giles County area, a part of the Appalachian basin of Virginia and West Virginia / by Robert C. McDowell and Arthur P. Schultz ch. F. Late Paleozoic depositional trends in the central Appala­ chian basin / by Kenneth J, Englund and Roger E. Thomas. 1. Geology- Appalachian basin. I. Series. QE75.B9no. 1839 A-D 557.3 s [557.4] 88-600224 [QE78.3] Chapter E Structural and Stratigraphic Framework of the Giles County Area, a Part of the Appalachian Basin of Virginia and West Virginia By ROBERT C. McDOWELL and ARTHUR P. SCHULTZ A description of the bedrock geology of a part of the Appalachian foreland U.S. GEOLOGICAL SURVEY BULLETIN 1839 EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN CONTENTS Abstract El Introduction El Stratigraphy E2 Cambrian System E2 Rome Formation (Lower Cambrian) E2 Honaker Dolomite (Middle and Upper Cambrian) E3 Nolichucky Shale (Upper Cambrian) E4 Cambrian and Ordovician Systems E4 Ordovician System E8 Middle Ordovician limestones E8 Martinsburg Formation E8 Juniata Formation E9 Silurian System E9 Tuscarora Quartzite E9 Rose Hill Formation E9 Keefer Sandstone E9 Tonoloway Limestone E10 Devonian System E10 Rocky Gap Sandstone E10 Huntersville Chert E10 Millboro Shale E10 Brallier Shale Ell Chemung Formation Ell Mississippian System Ell Price Formation Ell Maccrady Shale Ell Greenbrier Limestone E12 Mauch Chunk Group E12 Bluefield Formation E12 Hinton Formation E12 Princeton Sandstone E13 Bluestone Formation E13 Structural Geology and Seismicity E13 Structural Setting E13 Regional Structures E13 Tectonic Evolution E17 Seismicity E18 Mineral Resources E19 Iron E19 Manganese E19 Nonmetallic Resources E19 Fossil Fuels E19 Geologic Hazards E20 References Cited E20 Contents III PLATE 1. Geologic map of Giles County, Virginia, and adjacent areas in Virginia and West Virginia [In pocket] FIGURES 1-4. Maps showing: 1. Structural provinces of the Appalachians of Virginia and West Virginia E2 2. Regional structural setting of the Giles County area of Virginia and West Virginia E3 3. Index to previous mapping in the Giles County area of Virginia and West Virginia E4 4. Index to l:24,000-scale quadrangles in the Giles County area of Virginia and West Virginia E4 5. Generalized columnar section for rocks in the Giles County area of Virginia and West Virginia E5 6. Map showing major structural features in the Giles County area of Virginia and West Virginia E14 7. Diagrams showing interpretation of structures along line of section A-A'(pl. 1) by various authors E15 TABLE 1. Stratigraphic nomenclature used in this study and other studies in the Giles County area of Virginia and West Virginia E6 CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE To convert from To Multiply by Feet (ft) Meters (m) 0.3048 Miles (mi) Kilometers (km) 1.609 Pounds (Ib) Kilograms (kg) .4536 Degrees Fahrenheit (°F) Degrees (°C) Temp °C=(temp °F-32)/1.8 IV Contents EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN Structural and Stratigraphic Framework of the Giles County Area, a Part of the Appalachian Basin of Virginia and West Virginia By Robert C. McDowell and Arthur P. Schultz Abstract INTRODUCTION The Giles County area is in the western part of the The area of this report includes Giles County in Valley and Ridge province, just south of the Appalachian southwestern Virginia and adjacent parts of the surrounding bend near Roanoke, Va. The area is underlain by rocks of counties in Virginia and West Virginia (figs. 1,2). The map the eastern central Appalachian basin that range in age area is in the eastern central Appalachian basin and is from Early Cambrian to Late Mississippian and occur in mainly in the western part of the Valley and Ridge structural linear folds cut by thrust faults. The rocks, well exposed along the New River, represent a relatively continuous province, just southwest of a 30° bend in the trend of the succession of carbonate platform and clastic basinal Appalachian erogenic belt near Roanoke, Va. (figs. 1,2). deposits that is about 15,000 ft thick. The northwestern part of the area is west of the Allegheny Major structures in the area trend about N. 65° E., Front in the Allegheny Plateau province. The study area is typical of the northern part of the southern Appalachians. underlain by sedimentary rocks of Early Cambrian to Late Thrust faults and axial surfaces of folds dip to the south­ Mississippian age that have been deformed into long, linear east. The major thrust faults are the Pulaski, Saltville, fold belts cut by several major thrust faults. Narrows, and St. Clair, and the surface traces of the latter The Giles County area is of special geologic interest three terminate just northeast of the study area, in the because the epicenter of the largest earthquake recorded in Roanoke bend. The Narrows fault block contains several Virginia (Modified Mercalli intensity (MMI) of VIII), major synclines and anticlines, notably the doubly plung­ which occurred in 1897, was near Pearisburg (Campbell, ing Bane anticline of problematic origin, which is the site 1898; Hopper and Bollinger, 1971, p. 54-66). Recent work of an exploratory test well. Recent studies conclusively has identified a seismogenic zone within Giles County that show that the area was deformed in a thin-skin style may be associated with that event (Bollinger and Wheeler, without direct involvement of Precambrian basement 1980, 1983; Bollinger, 1981). rocks. In the Giles County area, the New River turns from The largest earthquake known to have occurred in Virginia took place near Pearisburg in 1897. Minor earth­ its northeastward course, along strike, and cuts northwest­ quakes have persisted in the Giles County area. Although ward across the grain of the Appalachian foreland. Exten­ their origin is not well understood, they appear to origi­ sive exposures of bedrock along its course across the folded nate at great depth in basement rocks. and faulted Valley and Ridge belt make the area particularly Mineral resources in the Giles County area include useful for interpreting the geology and geologic evolution iron, manganese, limestone, and various sources of aggre­ (see, for example, Butts and others, 1932; Cooper, 1961, gate. Limestone is the main resource currently being 1964, 1968; Bartholomew and others, 1980). In this report, developed. Geologic hazards include landslides, flooding, we provide details of the stratigraphy and structural geology earthquakes, and karst terrain. None appears to represent of this important area, discuss the development of ideas on a major problem, although the potential for a major its tectonic evolution, and describe the economic aspects earthquake is not yet well known. (including hazards) of the geology. The area was selected for study because of its relatively high levels of historical Manuscript approved for publication May 18, 1989. and present-day seismicity. Numerous investigations and Structural and Stratigraphic Framework, Giles County, Virginia and West Virginia E1 PENNSYLVANIA 37' COASTAL TENNESSEE NORTHCAROLINAX Figure 1. Structural provinces of the Appalachians of Virginia and West Virginia. Location of area of plate 1 is also shown. extensive geologic mapping within the area by various posits from the Lower Cambrian Rome Formation to the workers in recent years, as well as those done for this study, Upper Mississippian Bluestone Formation, a composite make it possible to characterize the geology in considerable thickness of about 15,000 ft. These strata are shown on the detail and provide an exceptional opportunity to analyze the generalized columnar section (fig. 5). Stratigraphic nomen­ geologic evolution of this part of the Appalachian foreland. clature used in this report is compared in table 1 to that used The map of Giles County and vicinity (pi. 1) was in Giles County and nearby areas by other workers. The prepared by compiling the geologic maps in numerous following brief descriptions of the units are based in part on published and unpublished reports between 1944 and 1986, descriptions by Butts (1940), Cooper (1961), and Lesure supplemented by field checking and detailed and reconnais­ and others (1982). sance mapping by the authors between 1979 and 1987. Figure 3 indicates the source and coverage of most of the previous mapping; other reports used in the compilation include maps of Mercer and Monroe Counties, West Vir­ ginia (Reger, 1926), and geologic maps by Cooper (1944a, Cambrian System pi. 3; 1963, pi. 2.1) and Houser (1980, pi. 1). Giles County itself occupies about one-half of the map area, and an Rome Formation (Lower Cambrian) unpublished map of the county compiled by W.