DOCSLIB.ORG

Structural Chronology of the Alleghanian Orogeny in Southeastern West Virginia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Structural chronology of the Alleghanian orogeny in southeastern West Virginia STUART L. DEAN Department of Geology, University of Toledo, Toledo, Ohio 43606 BYRON R. KULANDER Department of Geosciences, Wright State University, Dayton, Ohio 45435 JEFFREY M. SKINNER Wintershall Oil and Gas Corporation, 5 Post Oak Park, Suite 2000, Houston, Texas 77027 ABSTRACT The trend change between central and southern Appalachian extension of this same line of structural discontinuity, the Covington lin- structures is sharply defined in southeastern West Virginia. There, eament (Dean and others, 1979), extends into the Valley and Ridge of N30°-35°E trends coincident with major central Appalachian folds, Virginia at least to the Rich Patch anticline and possibly into the Shenan- such as the Browns Mountain anticline, end abruptly at N60°E- doah Valley (Fig. 1). The Covington lineament thus serves as the northern trending southern Appalachian structures along the St. Clair fault. boundary to the Roanoke sector recess and as the principal boundary Analysis of local and regional folds, cleavage, bedding-perpendicular between the central and southern Appalachians. stylolite seams and bedding, and fault slickenlines reveals that layer- The abrupt changes in trend and discontinuous nature of structures parallel shortening, directed N10°-30°W, occurred in nonfolded across the boundaries of the central-southern Appalachian juncture have Greenbrier Group (Mississippian) carbonates well into the present suggested to Rodgers (1970) that folds and faults of the southern sector Appalachian Plateau area. This structural event is early and is asso- predated deformation in the central sector. It is the intention of the present ciated with the evolution of southern Appalachian folds and faults study to clarify Alleghanian deformational chronology in this region south of the St. Clair fault. Central Appalachian folds and mesoscopic through structural analysis of Greenbrier Group carbonates (Mississippian) structures were superimposed on this early layer-parallel shortening in West Virginia. Folds, bedding-perpendicular stylolite seams, cleavage, fabric. This structural chronology indicates that southern Appalachian and slickenlines have been analyzed on a regional basis and in detail at two folds and faults predated the development of central Appalachian locations in the study area in West Virginia (Fig. 1, locations A and B). structures in the region. FOLDS AND CLEAVAGE INTRODUCTION With the exception of the Abbs Valley anticline and Hurricane Ridge Appalachian Plateau and Valley and Ridge structures show abrupt syncline, central Appalachian folds in Monroe County, West Virginia, changes in trend and continuity at the boundaries of, and within, the plunge out into the line of Appalachian juncture (southwestern extension V-shaped recess north and northwest of Roanoke, Virginia (Fig. I). The of the Covington lineament). The exact nature of the relationship of these northern boundary of this recess marks the junction between the central two structures to the trend change is unclear. The West Virginia Geologi- Appalachians, where folds dominate the structural framework with cal Survey county report for Mercer, Summers, and Monroe Counties N30°-35°E trends, and the southern Appalachians, where southeast- (Reger, 1925) shows virtually no structural relief at the Avis Limestone dipping thrust faults, with N60°E trends, are the major features. The (Upper Mississippian) level on these folds that is continuous from central southern boundary of this V-shaped sector is a linear zone marking the to southern Appalachian trends. Recent work by McDowell (1982) also abrupt termination of the Catawba syncline, Saltville fault, and Sinking suggests a lack of continuity of these structures across the trend change. It Creek anticline and the change in trend of the Pulaski fault. Rodgers seems clear that previous positioning of the axial traces is speculative (1970) and Lowry (1971) have discussed in detail the contrasting aspects across the trend change and that any interpretation of synchronism of between central and southern Appalachian structures. structural development across the trend change, based on this continuity, is To the northwest, the Roanoke sector recess converges in eastern inconclusive. Monroe County, West Virginia, to the position of the St. Clair fault. This South of the extension of the Covington lineament in Monroe thrust fault and the Glen Lyn syncline (McDowell, 1982), which has the County, Appalachian structures such as the St. Clair fault strike N60°E same trend and is immediately to the northwest, serve as the approximate parallel to this line of trend change. Particularly significant north of the boundary between the central and southern Appalachians in southeastern Covington lineament extension is the series of small folds, east of the West Virginia as well as marking the position of the Allegheny structural community of Union, that are developed on the southern terminus of the front. The trace of the St. Clair fault ends just across the West Virginia- Browns Mountain anticline (Fig. 1, area A; Fig. 2). None of these struc- Virginia state line in Alleghany County, Virginia, but the northeastern tures carries through into the southern Appalachians. Some larger folds Geological Society of America Bulletin, v. 100, p. 299-310,10 figs., February 1988. 299 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/100/2/299/3380083/i0016-7606-100-2-299.pdf by guest on 02 October 2021 STRUCTURES CITIES A.V. A. Abbs Valley Anticline R. P. A. Rich Patch Anticline C Covington B.V.A. Back Valley Anticline SC.A. Sinking Creek Anticline M Mar 1 in ton B.D. Bane Dome W.S.A. Warm Springs Anticline R Roa noke B.M.A. Browns Mt. Anticline W.A. Williamsburg Anticline U Union C.S. Caldwell Syncline W.M.A. Wills Mt. Anticline CT. S Catawba Syncline N.F. Narrows Fault G.L.S. Glen Lyn Syncline P. F. Pulaski Fault H.R.S. Hurricane Ridge Syncline S.F. Saltville Fault MM.A. Mann Mt. Anticline S C F. S t. C 1 a i r Fault P. S. Pedro Syncline Figure 1. Area of investigation, showing major tectonic elements, specific locations of areas A and B, the extent of the Roanoke recess, and the position of the Covington lineament. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/100/2/299/3380083/i0016-7606-100-2-299.pdf by guest on 02 October 2021 STRUCTURAL CHRONOLOGY OF ALLEGHANIAN OROGENY, WEST VIRGINIA 301 Figure 1. (Continued). such as the Pedro syncline, just to the east of the Browns Mountain trending folds are present north of the Covington lineament in Monroe structure, appear to swing into alignment with the N60°E trend of the County. The low amplitude and short wave length of Greenbrier Group extension of the Covington lineament. The verification of the continuity of folds in Monroe County also indicate that these structures are rooted this structure to the southwest as an extension of McDowell's (1982) Glen primarily at a Middle Devonian (lower Millboro-Marcellus) shale Lyn syncline requires additional field work, however. No major N60°E- décollement level, as postulated for the region by Roeder and others Figure 2. Fold and solution cleavage trends, southeastern Monroe County, West Virginia (area A, Fig. 1). Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/100/2/299/3380083/i0016-7606-100-2-299.pdf by guest on 02 October 2021 Figure 3. (a) Lower hemisphere, equal-area plot of poles to solution cleavage, southeastern Monroe County, West Vir- ginia (area A, Fig. 1). Maxima reveal trends of N62°E and N10°E. (b) Lower hemisphere, equal-area plot of poles to stylo- lite seams, southeastern Monroe County, West Virginia (area A, Fig. 1). Maximum shows a trend of N56°E. (c) Lower hemisphere, equal-area plot of stylolite teeth trends, southeastern Monroe County, West Virginia (area A, Fig. 1). Major maximum occurs at N13°W. Minor maximum also at N85°W. (d) Lower hemisphere, equal-area plot of bedding slick- enline trends, southeastern Monroe County, West Virginia (area A, Fig. 1). Maxima occur at N15°W, N42°W, and N85°W. (e) Lower hemisphere, equal-area plot of slickenline n = 275 n =240 trends on small, low-dipping bedding reverse faults, south- Contour Interval Contour Interval eastern Monroe County, West Virginia (area A, Fig. 1). Max- ima occur at N15°W, N40°W, and N77°W. 1-9% >9% 1-12% >12% N13W N 1 5 W N15 W N42 W N 77 W N85 W n=320 n = 180 n = 180 Contour Interval Contour Interval Contour Interval VP. y za A 1-1É >16% 1-9% >9% 1-6% Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/100/2/299/3380083/i0016-7606-100-2-299.pdf by guest on 02 October 2021 STRUCTURAL CHRONOLOGY OF ALLEGHANIAN OROGENY, WEST VIRGINIA 303 (1978), Dean and others (1979), Perry (1980), and Perry and others (1979). Solution cleavage is present in Greenbrier limestone throughout the Greenbrier outcrop belt of southeastern West Virginia (regional location map, Fig. 1) and is especially well developed near the trend change in Monroe County (Fig. 2). Figure 3a reveals trends of N62°E and N10°E at this locale that are attributable to southern and central Appalachian de- formational stresses, respectively, if deformational stresses are considered to be normal to structural trends. Figure 2 reveals that the N62°E-trending cleavage is only locally developed within the prominent central Appala- chian grain north of the Covington lineament and has been found no farther north than the community of Union, ~5 km north of this trend 5 10 15 MILES Figure 4. Trends of stylolite seams throughout the Greenbrier Valley in southeastern West Virginia. Long lines represent major regional systematic trends, and short lines represent the orthogonal stylolite set. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/100/2/299/3380083/i0016-7606-100-2-299.pdf by guest on 02 October 2021 304 DEAN AND OTHERS change.
Recommended publications
  • GEO 2008 Conference Abstracts, Bahrain GEO 2008 Conference Abstracts

    GEO 2008 Conference Abstracts, Bahrain GEO 2008 Conference Abstracts

    GEO 2008 conference abstracts, Bahrain GEO 2008 Conference Abstracts he abstracts of the GEO 2008 Conference presentations (3-5 March 2008, Bahrain) are published in Talphabetical order based on the last name of the first author. Only those abstracts that were accepted by the GEO 2008 Program Committee are published here, and were subsequently edited by GeoArabia Editors and proof-read by the corresponding author. Several names of companies and institutions to which presenters are affiliated have been abbreviated (see page 262). For convenience, all subsidiary companies are listed as the parent company. (#117804) Sandstone-body geometry, facies existing data sets and improve exploration decision architecture and depositional model of making. The results of a recent 3-D seismic reprocessing Ordovician Barik Sandstone, Oman effort over approximately 1,800 square km of data from the Mediterranean Sea has brought renewed interest in Iftikhar A. Abbasi (Sultan Qaboos University, Oman) deep, pre-Messinian structures. Historically, the reservoir and Abdulrahman Al-Harthy (Sultan Qaboos targets in the southern Mediterranean Sea have been the University, Oman <[email protected]>) Pliocene-Pleistocene and Messinian/Pre-Messinian gas sands. These are readily identifiable as anomalousbright The Lower Paleozoic siliciclastics sediments of the amplitudes on the seismic data. The key to enhancing the Haima Supergroup in the Al-Haushi-Huqf area of cen- deeper structure is multiple and noise attenuation. The tral Oman are subdivided into a number of formations Miocene and older targets are overlain by a Messinian- and members based on lithological characteristics of aged, structurally complex anhydrite layer, the Rosetta various rock sequences.
  • Deformation Mechanisms, Rheology and Tectonics Geological Society Special Publications Series Editor J

    Deformation Mechanisms, Rheology and Tectonics Geological Society Special Publications Series Editor J

    Deformation Mechanisms, Rheology and Tectonics Geological Society Special Publications Series Editor J. BROOKS J/iLl THIS VOLUME IS DEDICATED TO THE WORK OF HENDRIK JAN ZWART GEOLOGICAL SOCIETY SPECIAL PUBLICATION NO. 54 Deformation Mechanisms, Rheology and Tectonics EDITED BY R. J. KNIPE Department of Earth Sciences Leeds University UK & E. H. RUTTER Department of Geology Manchester University UK ASSISTED BY S. M. AGAR R. D. LAW Department of Earth Sciences Department of Geological Sciences Leeds University Virginia University UK USA D. J. PRIOR R. L. M. VISSERS Department of Earth Sciences Institute of Earth Sciences Liverpool University University of Utrceht UK Netherlands 1990 Published by The Geological Society London THE GEOLOGICAL SOCIETY The Geological Society of London was founded in 1807 for the purposes of 'investigating the mineral structures of the earth'. It received its Royal Charter in 1825. The Society promotes all aspects of geological science by means of meetings, speeiat lectures and courses, discussions, specialist groups, publications and library services. It is expected that candidates for Fellowship will be graduates in geology or another earth science, or have equivalent qualifications or experience. Alt Fellows are entitled to receive for their subscription one of the Society's three journals: The Quarterly Journal of Engineering Geology, the Journal of the Geological Society or Marine and Petroleum Geology. On payment of an additional sum on the annual subscription, members may obtain copies of another journal. Membership of the specialist groups is open to all Fellows without additional charge. Enquiries concerning Fellowship of the Society and membership of the specialist groups should be directed to the Executive Secretary, The Geological Society, Burlington House, Piccadilly, London W1V 0JU.
  • Detrital Zircon Provenance and Lithofacies Associations Of

    Detrital Zircon Provenance and Lithofacies Associations Of

    geosciences Article Detrital Zircon Provenance and Lithofacies Associations of Montmorillonitic Sands in the Maastrichtian Ripley Formation: Implications for Mississippi Embayment Paleodrainage Patterns and Paleogeography Jennifer N. Gifford 1,*, Elizabeth J. Vitale 1, Brian F. Platt 1 , David H. Malone 2 and Inoka H. Widanagamage 1 1 Department of Geology and Geological Engineering, University of Mississippi, Oxford, MS 38677, USA; [email protected] (E.J.V.); [email protected] (B.F.P.); [email protected] (I.H.W.) 2 Department of Geography, Geology, and the Environment, Illinois State University, Normal, IL 61790, USA; [email protected] * Correspondence: jngiff[email protected]; Tel.: +1-(662)-915-2079 Received: 17 January 2020; Accepted: 15 February 2020; Published: 22 February 2020 Abstract: We provide new detrital zircon evidence to support a Maastrichtian age for the establishment of the present-day Mississippi River drainage system. Fieldwork conducted in Pontotoc County,Mississippi, targeted two sites containing montmorillonitic sand in the Maastrichtian Ripley Formation. U-Pb detrital zircon (DZ) ages from these sands (n = 649) ranged from Mesoarchean (~2870 Ma) to Pennsylvanian (~305 Ma) and contained ~91% Appalachian-derived grains, including Appalachian–Ouachita, Gondwanan Terranes, and Grenville source terranes. Other minor source regions include the Mid-Continent Granite–Rhyolite Province, Yavapai–Mazatzal, Trans-Hudson/Penokean, and Superior. This indicates that sediment sourced from the Appalachian Foreland Basin (with very minor input from a northern or northwestern source) was being routed through the Mississippi Embayment (MSE) in the Maastrichtian. We recognize six lithofacies in the field areas interpreted as barrier island to shelf environments. Statistically significant differences between DZ populations and clay mineralogy from both sites indicate that two distinct fluvial systems emptied into a shared back-barrier setting, which experienced volcanic ash input.
  • 129 the Use of Joint Patterns for Understanding The

    129 the Use of Joint Patterns for Understanding The

    129 THE USE OF JOINT PATTERNS FOR UNDERSTANDING THE ALLEGHANIAN OROGENY IN THE UPPER DEVONIAN APPALACHIAN BASIN, FINGER LAKES DISTRICT, NEW YORK TERRY ENGELDER Department of Geosciences, Pennsylvania State University University Park, Pennsylvania 16802 REGIONAL SIGNIFICANCE Abundantevidence (deformed fo ssils) for layer parallel shortening in western New York indicates the extent to which the Alleghanian Orogeny affected the Appalachian Plateau (Engelder and Engelder, 1977). In addition to low amplitude ( 100 m) long wave length ( 15 km) folds the Upper Devonian sediments of western New York contain many< mesoscopic-scale structures< including joints that can be systematically related to the Alleghanian Orogeny. Based on the nonorthogonality of cleavage and joints, the Alleghanian Orogeny in the Finger Lakes District of New York consists of at least two phases which Geiser and Engelder (1983) correlate with folding and cross-cutting cleavages in the Appalachian Valley and Ridge. To the southeast of the Finger Lakes District the earlier Lackawanna Phase is manifested by formation of the Lackawanna syncline and Green Pond outlier and the development of a northeast-striking disjunctive cleavage within the Appalachian Valley and Ridge mainly fromthe Kingston Arch of the Hudson Valley southwestward beyond Port Jervis, Pennsylvania (Fig. 1). Within the Finger Lakes Distric� New York, a Lackawanna Phase cleavage is absent; and one fm ds instead a cross-fold joint set which is consistent in orientation with a Lackawanna Phase compression. In bedded siltstone-shale sequences (i.e. the Genesee Group) this cross-fold joint set favors development in the siltstones 1# 2#). Main Phase (stops and The is seen as the refolding of the Lackawanna syncline and Green Pond outlier, as well as the development of the major folds in central Pennsylvania.
  • Mechanical Stratigraphic Controls on Natural Fracture Spacing and Penetration

    Mechanical Stratigraphic Controls on Natural Fracture Spacing and Penetration

    Journal of Structural Geology 95 (2017) 160e170 Contents lists available at ScienceDirect Journal of Structural Geology journal homepage: www.elsevier.com/locate/jsg Mechanical stratigraphic controls on natural fracture spacing and penetration * Ronald N. McGinnis a, , David A. Ferrill a, Alan P. Morris a, Kevin J. Smart a, Daniel Lehrmann b a Department of Earth, Material, and Planetary Sciences, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166, USA b Geoscience Department, Trinity University, One Trinity Place, San Antonio, TX 78212, USA article info abstract Article history: Fine-grained low permeability sedimentary rocks, such as shale and mudrock, have drawn attention as Received 20 July 2016 unconventional hydrocarbon reservoirs. Fracturing e both natural and induced e is extremely important Received in revised form for increasing permeability in otherwise low-permeability rock. We analyze natural extension fracture 21 December 2016 networks within a complete measured outcrop section of the Ernst Member of the Boquillas Formation Accepted 7 January 2017 in Big Bend National Park, west Texas. Results of bed-center, dip-parallel scanline surveys demonstrate Available online 8 January 2017 nearly identical fracture strikes and slight variation in dip between mudrock, chalk, and limestone beds. Fracture spacing tends to increase proportional to bed thickness in limestone and chalk beds; however, Keywords: Mechanical stratigraphy dramatic differences in fracture spacing are observed in mudrock. A direct relationship is observed be- Natural fractures tween fracture spacing/thickness ratio and rock competence. Vertical fracture penetrations measured Fracture spacing from the middle of chalk and limestone beds generally extend to and often beyond bed boundaries into Fracture penetration the vertically adjacent mudrock beds.
  • The Role of Pressure Solution Seam and Joint Assemblages In

    The Role of Pressure Solution Seam and Joint Assemblages In

    THE ROLE OF PRESSURE SOLUTION SEAM AND JOINT ASSEMBLAGES IN THE FORMATION OF STRIKE-SLIP AND THRUST FAULTS IN A COMPRESSIVE TECTONIC SETTING; THE VARISCAN OF SOUTHWESTERN IRELAND Filippo Nenna and Atilla Aydin Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 e-mail: [email protected] scale such as strike-slip faults and thrust-cored folds in Abstract various stages of their development. In this study we focus on the initiation and development of strike-slip The Ross Sandstone in County Clare, Ireland, was faults by shearing of the initial JVs and PSSs and deformed by an approximately north-south compression formation of thrust faults by exploiting weak shale during the end-Carboniferous Variscan orogeny. horizons and the strike-parallel PSSs in the adjacent Orthogonal sets of fundamental structures form the sandstone intervals. initial assemblage; mutually abutting arrays of 170˚ Development of faults from shearing of initial oriented set 1 joints/veins (JVs) and approximately 75˚ fundamental structural elements with either opening or pressure solution seams (PSSs) that formed under the closing modes in a wide range of structural settings has same stress conditions. Orientations of set 2 (splay) JVs been extensively reported. Segall and Pollard (1983), and PSSs suggest a clockwise remote stress rotation of Martel and Pollard (1989) and Martel (1990) have about 35˚ responsible for the contemporaneous described strike-slip faults formed by shearing of shearing of the set 1 arrays. Prominent strike-slip faults thermal fractures in granitic rocks. Myers and Aydin are sub-parallel to set 1 JVs and form by the linkage of (2004) and Flodin and Aydin (2004) reported strike-slip en-echelon segments with broad damage zones faulting formed by shearing of joints formed by an responsible for strike-slip offsets of hundreds of metres.
  • Sedimentary Stylolite Networks and Connectivity in Limestone

    Sedimentary Stylolite Networks and Connectivity in Limestone

    Sedimentary stylolite networks and connectivity in Limestone: Large-scale field observations and implications for structure evolution Leehee Laronne Ben-Itzhak, Einat Aharonov, Ziv Karcz, Maor Kaduri, Renaud Toussaint To cite this version: Leehee Laronne Ben-Itzhak, Einat Aharonov, Ziv Karcz, Maor Kaduri, Renaud Toussaint. Sed- imentary stylolite networks and connectivity in Limestone: Large-scale field observations and implications for structure evolution. Journal of Structural Geology, Elsevier, 2014, pp.online first. <10.1016/j.jsg.2014.02.010>. <hal-00961075v2> HAL Id: hal-00961075 https://hal.archives-ouvertes.fr/hal-00961075v2 Submitted on 19 Mar 2014 HAL is a multi-disciplinary open access L'archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destin´eeau d´ep^otet `ala diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publi´esou non, lished or not. The documents may come from ´emanant des ´etablissements d'enseignement et de teaching and research institutions in France or recherche fran¸caisou ´etrangers,des laboratoires abroad, or from public or private research centers. publics ou priv´es. 1 2 Sedimentary stylolite networks and connectivity in 3 Limestone: Large-scale field observations and 4 implications for structure evolution 5 6 Laronne Ben-Itzhak L.1, Aharonov E.1, Karcz Z.2,*, 7 Kaduri M.1,** and Toussaint R.3,4 8 9 1 Institute of Earth Sciences, The Hebrew University, Jerusalem, 91904, Israel 10 2 ExxonMobil Upstream Research Company, Houston TX, 77027, U.S.A 11 3 Institut de Physique du Globe de Strasbourg, University of Strasbourg/EOST, CNRS, 5 rue 12 Descartes, F-67084 Strasbourg Cedex, France.
  • Stress and Fluid Control on De Collement Within Competent Limestone

    Stress and Fluid Control on De Collement Within Competent Limestone

    Journal of Structural Geology 22 (2000) 349±371 www.elsevier.nl/locate/jstrugeo Stress and ¯uid control on de collement within competent limestone Antonio Teixell a,*, David W. Durney b, Maria-Luisa Arboleya a aDepartament de Geologia, Universitat AutoÁnoma de Barcelona, 08193 Bellaterra, Spain bDepartment of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia Received 5 October 1998; accepted 23 September 1999 Abstract The Larra thrust of the Pyrenees is a bedding-parallel de collement located within a competent limestone unit. It forms the ¯oor of a thrust system of hectometric-scale imbrications developed beneath a synorogenic basin. The fault rock at the de collement is a dense stack of mainly bedding-parallel calcite veins with variable internal deformation by twinning and recrystallization. Veins developed as extension fractures parallel to a horizontal maximum compressive stress, cemented by cavity-type crystals. Conditions during vein formation are interpreted in terms of a compressional model where crack-arrays develop at applied stresses approaching the shear strength of the rock and at ¯uid pressures equal to or less than the overburden pressure. The cracks developed in response to high dierential stress, which was channelled in the strong limestone, and high ¯uid pressure in or below the thrust plane. Ductile deformation, although conspicuous, cannot account for the kilometric displacement of the thrust, which was mostly accommodated by slip on water sills constituted by open cracks. A model of cyclic dierential brittle contraction, stress reorientation, slip and ductile relaxation at a rheological step in the limestone is proposed as a mechanism for episodic de collement movement.
  • Stylolites: Characteristics and Origin

    Stylolites: Characteristics and Origin

    • STYLOLITES: CHARACTERISTICS AND ORIGIN Joseph M. Montello A senior thesis submitted to fulfill the requirements for the degree of B.S. in Geology and Mineralogy • Winter Quarter, 1984 The Ohio State University ~2.~r·Thesis Advisor Department of Geology and Mineralogy Abstract • Stylolites are alternating interpenetrating columns of stone that form irregular interlocking partings or sutures in rock strata. They are most common along bedding planes of limestone but some are oblique or even perpendicular to bedding . Although the vast majority of stylolites occur in calcareous rocks, stylolites have been found in sandstone, quartzite and gypsum. The word "stylolite" refers to each individual column of stone. A cross section of a group of stylolites parallel to their length presents a rough, jagged line called a "stylolite seam" that resembles the sutures of a human skull. Stylolites always have a dark colored "clay" cap at the ends of the columns. The sides of the columns are typically discolored with a thin film of clay and show parallel flutings or striations that parallel their length. The shapes of individual stylolites vary greatly from broad flat­ • topped columns to pointed, jagged and tapering forms. After much controversy concerning the origin of stylolites, it is generally believed that they form by a process of chemical solution under pressure in lithified rock along some crack or seam. The interteething is produced because of differential solubilities and pressures within the rock unit. The clay cap on the stylolites is the non-soluble residue of the dissolved rock. Stylolites are only one of the possible end products in the spectrum of limestone responses to stress.
  • Character of the Alleghanian Orogeny in the Southern Appalachians: Part I

    Character of the Alleghanian Orogeny in the Southern Appalachians: Part I

    Character of the Alleghanian orogeny in the southern Appalachians: Part I. Alleghanian deformation in the eastern Piedmont of South Carolina DONALD T. SECOR, JR. Department of Geology, University of South Carolina, Columbia, South Carolina 29208 ARTHUR W. SNOKE Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071 KENNETH W. BRAMLETT Shell Western E and P, Inc., Box 831, Houston, Texas 77001 OLIVER P. COSTELLO Samson Resources, 801 Travis Street, Suite 1630, Houston, Texas 77002 OLLIE P. KIMBRELL Soil & Material Engineers, Inc., 3025 McNaughton Drive, Columbia, South Carolina 29223 ABSTRACT ward, 1957) is a fundamental problem. This report summarizes results of new field work and outlines interpretations concerning late Paleozoic de- The eastern Piedmont Province in South Carolina contains a formation along the Fall Line in west-central South Carolina. This infor- sequence of Cambrian volcanic and sedimentary rocks that was pene- mation is essential to development of a more general analysis of the tratively deformed (Dj) and regionally metamorphosed (Mi) to the Alleghanian orogeny in the southern Appalachians (Secor and others, greenschist facies during the early and/or middle Paleozoic. The east- 1986). era Piedmont was subsequently affected by late Paleozoic (Allegha- nian) polyphase deformation (D2-D4) and regional metamorphism. The OVERVIEW earliest Alleghanian event (D2) is associated with amphibolite facies regional metamorphism and felsic plutonism in a mid-crustal infra- In the southeastern Piedmont, late Paleozoic deformation events af- structure at ca. 295-315 Ma. The gradational interface between infra- fected a region that had previously been strongly deformed in the early structure and overlying suprastructure contained a steep M2 and/or middle Paleozoic.
  • Stylolite Compaction and Stress Models

    Stylolite Compaction and Stress Models

    Geophysical Research Abstracts, Vol. 11, EGU2009-1720, 2009 EGU General Assembly 2009 © Author(s) 2009 Stylolite compaction and stress models D. Koehn (1), M. Ebner (1), F. Renard (2), and R. Toussaint (3) (1) University of Mainz, Department of Geology, Mainz, Germany ([email protected]), (2) LGIT-CNRS-Observatoire, University of Grenoble, France, (3) Institut de Physique du Globe de Strasbourg, University of Strasbourg, France Stylolites are rough dissolution seams that develop during pressure solution in the Earth’s crust. Especially in limestone quarries they exhibit a spectacular roughness with spikes and large columns. They are visible as dark lines of residual clays and other non-dissolvable components in the white limestone. The roughening phenomena seems to be universal since stylolites can also be found in quarzites, mylonites and all kinds of rocks that undergo pressure solution. The genesis of stylolites is not well understood even though they have been used to estimate compaction and to determine the direction of the main compressive stress. We have developed a numerical model to study the dynamic development of the roughness and its dependence on stress. Based on the model we present estimates of finite strain and depth of burial. The numerical stylolites are studied in two ways: the temporal evolution of the roughness on one hand and the fractal characteristics of the roughness on the other hand. In addition we vary the noise in the model and illustrate the importance of the grain size on the roughening process. Surface energies are dominant for small wavelengths and the initial stylolite growth is non-linear and as slow as a diffusive process.
  • Early Jointing in Coal and Black Shale: Evidence for an Appalachian-Wide Stress field As a Prelude to the Alleghanian Orogeny

    Early Jointing in Coal and Black Shale: Evidence for an Appalachian-Wide Stress field As a Prelude to the Alleghanian Orogeny

    Early jointing in coal and black shale: Evidence for an Appalachian-wide stress field as a prelude to the Alleghanian orogeny Terry Engelder* ⎤ ⎥ Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA Amy Whitaker† ⎦ ABSTRACT means of stratigraphically controlled decolle- Early ENE-striking joints (present coordinates) within both Pennsylvanian coal and ment tectonics (Gates et al., 1988; Wise, Devonian black shale of the Central and Southern Appalachians reflect an approximately 2004). rectilinear stress field with a dimension Ͼ1500 km. This Appalachian-wide stress field (AWSF) dates from the time of joint propagation, when both the coal and shale were FRACTURE EVIDENCE FOR THE buried to the oil window during the 10–15 m.y. period straddling the Pennsylvanian- AWSF Permian boundary. The AWSF was generated during the final assembly of Pangea as a Along the Appalachian Mountains an ENE consequence of plate-boundary tractions arising from late-stage oblique convergence, joint set is the first to propagate in many out- where maximum horizontal stress, SH, of the AWSF was parallel to the direction of closure crops of Devonian through Pennsylvanian between Gondwana and Laurentia. After closure, the AWSF persisted during dextral slip rocks (e.g., Nickelsen and Hough, 1967; Nick- of peri-Gondwanan microcontinents, when SH appears to have crosscut plate-scale trans- elsen, 1979; Kulander and Dean, 1993; Pashin current faults at ϳ30؇. Following Ͼ10 m.y. of dextral slip during tightening of Gondwana and Hinkle, 1997). This early joint set strikes against Laurentia, the AWSF was disrupted by local stress fields associated with thrusting parallel to the orientation of the maximum on master basement decollements to produce the local orocline-shaped Alleghanian map horizontal stress, SH, in a stress field that was pattern seen today.