Characteristics of Some Paleozoic Clastic Sediments of the Central Appalachians

MASTER'S THESIS M-1128 EISENHARD, Robert M. CHARACTERISTICS OF SOME PALEOZOIC CLASTIC SEDIMENTS OF THE CENTRAL APPALACHIANS. The American University, M.S., 1966 Geology University Microfilms. Inc., Ann Arbor, Michigan Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHARACTERISTICS OF SOME PALEOZOIC CLASTIC SEDIMENTS OF THE CENTRAL APPALACHIANS by Robert M. Eisenhard Submitted to the Faculty of the College of Arts and Sciences of The American University in Partial Fulfillment of the Requirements for the Degree of Master of Science Signatures of Committee: ' y- ^ ChairmaytT-y^ y ' J - ^ > Dean of the College Date : (Lf - Date: ^ __/<^y / 1966 The American University Washington, D. C. AMERICAN utiv,? Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 11 CONTENTS I General Geology, Stratigraphie Section And Area Map ................................. 1 II Collection of Samples (including description of Formations) ........................... 5 III Preparation of Samples ............................ 8 IV Analysis of Samples and Characteristics of Heavy Minerals ........................... 9 V Summary and Conclusions ........................... 15 VI Appendix .......................................... 20 Graph I Distribution by Weight Percent of Sieve Fractions .......................... 21 Graph II Cumulative Percent of Sieve Fractions by Weight Oriskany, Tuscarora and Conococheague ... 22 Graph III Gumulative Percent of Sieve Fractions by Weight Weverton, Antietam, Martinsburg, Bloomsburg ........ 2.3 Graph IV Heavy Minerals as Percent of Size Fraction ................................. 24 Tables I - VII Sieve Fraction Data ................ 25 Table VIII Grain Size and Heavy Mineral Distribu tion ................................... 32 References .............................................. 33 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. I. General Geology The clastic rock samples for this study were taken from the northernmost portion of the Appalachian Valley in Virginia. The Appalachian Valley Province (also known as the Valley and Ridge Province) is a subdivision of the Appalachian Highlands. To the southeast of the Appalachian Valley is the Blue Ridge Province and to the northwest, the Appalachian Plateau. Surface exposures in the area show folded and thrust faulted Cambrian, Ordovician, Silurian and Devonian sedimentary rocks which were deposited in the Appalachian geosyncline. Here, essentially continuous sedimentation produced an average of 30,000 feet and a maximum of perhaps 50,000 feet of section. (Butts, 1940, p. 3.) The folding and faulting in some cases make measurements of the stratigraphie thicknesses at best somewhat questionable. The eastern half of the area studied varies from nearly flat to rolling topography. The formations present here are the Tomstown dolomite, Waynesboro formation, Elbrook, Conococheague, and Beckmantown limestones, and the Martinsburg shale. The valley floor is at an altitude of 700' at Winchester rising westward to 1000 feet at the base of Little North Mountain, rising southwest- ward to 1400 feet at Harrisonburg and decreasing eastward to 500 feet at the Shenandoah River (Butts, 1940, p. 7). In the Massanutten Mountain region and in the western half of the area, the tough resistant Tuscarora quartzite along with the Oriskany sandstone support long ridges rising 1000 to 1500 feet above the valley floor. Inside the Tuscarora ridges of the Massanutten syncline, the Romney shale forms the valley. In the western Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. portion of the area, the Jennings and Romney formations form the valley floors. On the eastern margin the Cambrian Weverton formation and Antietam quartzite underlie the eastern ridge. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. GENERALIZED STRATIGRAPHIC SECTION FOR THE APPALACHIAN VALLEY IN NORTHERN VIRGINIA (after Cloos, Butts, Stose and others) Formations in CAPITALS are those studied Catskill formation Juniata formation Jennings formation MARTINSBURG SHALE Romney shale Chambersburg limestone % I ORISKANY SANDSTONE St. Paul group Q a > Helderburg limestone o Beekmantown limestone Rockdale Run formation Keyser limestone Stonehenge limestone Tondcway limestone Wills Creek shale CONOCOCHEAGUE LIMESTONE BLOOMSBURG FORMATION Elbrook limestone formation McKenzie formation Waynesboro formation TUSCARORA QUARTZITE Tomstown dolomite § ANTIETAM QUARTZITE Pi Harpers shale Ü WEVERTON FORMATION Loudoun formation Catoctin volcanics Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. f V CD N. ■D X / O Q. / Luray % C \ ^ / p A G E ^ g / Q. /‘■'s . » V roch INGHAM^, o ! ■D yMonterVy^.f Harrisonburg CD J h i g h l a n i ^ AREA STUDIED C/) C/) ^ —( A U G U TA y Staunton 80^ BATH X CD V / Warm°Springs/ \ 38“ 8 38* • 7 \ / wuv> 10 50 MILES ÂLLEOr AN W 7 Lexington/ CD 3. > f\BOTETOURT'" \ v^^^>/ ' 3" «Newcastle CD * ° / X C R A I G / Fincastle y~^, CD ■D V I R G O Q. 81® ^ C Y a V“*“ O r, T/X Grun(|y\_ >, 3 ^<%0NT60MERlf|^-- ^ “' V - "O ^ ‘ySUCH/vNAN y \ O j _ A PULASKI3UL '^^^fcigllvvood \ ,-^t"Â2^-'T AZ EW tw E tL uL. I- 0 0L AI NA N| W»^ y af -Pu<rPuW6ki— 37* ^ 'ÎCKENSOI^^ jM \V Tazewell,— O ., '/ Blando ^ CD Q. X ) . ) y - ^ \ \ V -3 7 ® \ X 3?y-37%^ WÜWi^— ■] \ wylh^vmeWytheville , \ \ ,. ) W I ' s r u s s «> 83' < /----- \"lebanor^ 81° V' ' v O . ■D V . - . / \ r M anon \ ' CD XVASH N6T0N ' 61® C/) T T V Abinpdon C/) Gate^City \ , . v - ,o 02® 83® r ~ E N' N II. Collection of Samples; During the summer of 1962, samples were collected in the Appalachian Valley in northwestern Virginia. Sites were chosen in Frederick, Clarke, and Shenandoah Counties where typical expo sures of the desired clastic Paleozoic sediments were to be found. At all locations, multiple samples of the formations were made with an effort to collect a representative set of samples based on grain size, color, mineral content, cementation, induration and structural position. Weverton Quartzite, -6wg, Lower Cambrian: The Weverton quartzite was named by Keith (1892, p. 365; 1893, p. 329; 1894) with a type section at Weverton, Maryland. It is described by Nickelsen (1956, p. 248) as three quartzite members with two intermediate phyllite members with thin quartzite inter beds. It is light gray to dark gray to vitreous bluish-black in the quartzite members. The upper member is poorly sorted with much cross bedding while the lower member is the best sorted with only local small-scale cross bedding. Samples were taken along a .3 mile stretch east from the horseshoe curve at Snickers Gap on Rt. 7. Approaching this location from the east, the Weverton exposure begins about 1.4 mile after the first road to Bluemont. Antietam Quartzite, -fia. Lower Cambrian: The Antietam quartzite was named by Keith (1893, p. 335) and Williams and Clark (1893, p. 68). The type section is Antietam Creek, Maryland. The Antietam consists of light gray to medium gray and light tan, fine to very fine grained massive quartzite. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Some beds darker and more poorly sorted are described as sericitic quartzite or silty phyllite by Nickelsen (1956, p. 251). Outcrops were sampled starting 3.4 miles west of the Bluemont Road on Rt. 7 and continuing down the hill for several hundred feet toward the Shenandoah River. Conococheague Limestone,-€c, Upper Cambrian: The Conococheague limestone was named by Stose (1908, p. 701). The type section was from Conococheague Creek in Franklin County, Pennsylvania. Stose originally included the present Conococheague in the Knox formation and described the distinctive basal sand beds. The Conococheague consists of medium gray limestone, calcareous sandstone, dolomite and dolomitic siltstone. Oolites, limestone pebble conglomerates, and cryptozoon algae are present in this for mation in many places. The sandy beds in this formation were sampled approximately 3% miles west of Winchester, on Rt. 50, 1 mile east of the Little North Mountain Gap where the Conococheague is exposed in a road cut through an orchard. Martinsburg, Omb, Ordovician: The Martinsburg shale was named by Geiger & Keith (1891) for a belt of shale east of Martinsburg, West Virginia. The Martinsburg consists of nearly black, chippy, fissile shale, medium brown siltstones and various gray graywackes, with lesser low grade slates, thin limestones, dolomite, chert, and conglomerates. Weathering in many cases produces a yellow-brown hue. Samples were first taken 1.8 mile west of Opequon Creek on Rt. 7 east of Winchester. Additional samples were taken at exposures in readouts east of Winchester and south of Winchester on Rt. 522. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Tuscarora, Stc, Silurian: The Tuscarora was named by Darton in 1896 (Darton and Taff, 1896; Darton, 1896) from Tuscarora Mountain, Pennsylvania. The Tuscarora is a very fine to medium grained quartzite. The degree of diagenesis varies so that a few layers are nearly friable and others massive. All samples, though, had at least some grains that show typical quartzitic

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