DOCSLIB.ORG

The Håkåneset Rockslide, Tinnsjø

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Håkåneset Rockslide, Tinnsjø The Håkåneset rockslide, Tinnsjø Stability analysis of a potentially rock slope instability. Inger Lise Sollie Geotechnology Submission date: June 2014 Supervisor: Bjørn Nilsen, IGB Norwegian University of Science and Technology Department of Geology and Mineral Resources Engineering I II ABSTRACT The Håkåneset rockslide is located on the west shore of Lake Tinnsjø (191 m.a.s.l), a fjordlake stretching 32 km with a SSE-NNW orientation in Telemark, southern Norway. The instability extends from 550 m.a.s.l. and down to approximately 300 m depth in the lake, making up a surface area of 0.54 km2 under water and 0.50 km2 on land. The rockslide comprises an anisotropic metavolcanic rock that is strongly fractured. Five discontinuity sets are identified with systematic field mapping supported by structural analysis of terrestrial laser scan (TLS) data. These are interpreted as gravitationally reactivated inherited tectonic structures. At the northern end the instability is limited by a steep south-east dipping joint (JF3 (~133/77)) that is one direction of a conjugate strike slip fault set (JF3, JF2 (~358/65)). Towards the south the limit to the stable bedrock is transitional. A back scarp is defined by a north-east dipping J1 (~074/59) surface that is mapped out at 550 m.a.s.l. Kinematic analysis indicates that planar sliding, wedge sliding and toppling are feasible. However, because the joint sets are steeply dipping these failure mechanisms can only occur for small rock volumes and are limited to steep slope sections only. Large scale rock slope deformation can only be justified by assuming deformation along a combination of several anisotropies. This assumption is based on the presence of the ~50-65 degrees NE dipping J1 and the up to 19 degrees NNE dipping foliation, making bi-planar sliding a feasible mechanism in case of a massive failure of the entire slope instability. Numerical modelling using Phase2 support assumption of bi-planar failure and indicate that significant rock damage by retrogressive failure mechanism is most likely for a stepped development of a basal sliding surface. The modeling results indicate that this sliding surface may daylight at a depth of ~100 m in the lake. By sensitivity tests for groundwater and different joint- and rock mass properties it is assumed that the instability is, besides the main structures, controlled principally by topography and rock strength conditions. III IV SAMMENDRAG Det ustabile fjellpartiet ved Håkåneset er lokalisert på vestsiden av Tinnsjø (191 moh.) i Telemark i Sør-Norge. Innsjøen strekker seg 32 km i SSØ-NNV retning. Ustabiliteten starter på 550 moh. og går ned til omtrent 300m dybde i Tinnsjø, og tilsvarer 0,54 km2 under vann og 0,50 km2 på land. Bergmassen i området består av en en anisotropisk metavulkansk bergart som er sterkt oppsprukket. Fem sprekkesett er identifisert ved systematisk feltkartlegging, og har blitt bekreftet med strukturell analyse av "terrestrial laser scan" (TLS). Disse er tolket som gravitativt reaktiverte tektoniske strukturer. Den nordlige avgrensingen av ustabiliteten er definert av et bratt sør-øst fallende sprekksett (JF3 (~133/77)) som er tolket som en retning av et konjugert "strike-slip" forkastningssystem (JF3, JF2(~358/65)). Mot sør er det anslått å være en gradvis overgang til stabilt fjell. I bakkant er ustabiliteten avgrenset av en bakvegg med samme orientering som sprekkesettet J1 (~074/59), og reiser seg fra ca. 550 m.o.h.. Kinematisk analyse av diskontinuitetene antyder at planær utgliding, kileformet utgliding og blokktopling er mulig. På grunn av at det bratte fallet på samtlige sprekkesett er disse bruddmekanismene mulig kun for små volum og kan kun forekomme i de bratteste delene av skråningen. For å forklare en massive utglidning av hele fjellpartiet må det antas at deformasjonen skjer langs en kombinasjon av flere anisotropier. I dette tilfellet er J1 som faller ~50-65 grader i NØ retning og det opp til 19 grader bratte NNØ fallende foliasjonen to sprekkesett som gjør bi-planar utgliding av et stort volum av fjell til en mulig bruddmekanisme. Numerisk modeliering i Phase2 støtter antakelsen om bi-planær utglidning og indikerer at utviklingen av et nedre bruddplan vil involvere betydeling ødeleggelser av intakt berg ved en retrogressiv bruddmekanisme. Resultatet fra modeleringen antyder at en sannsynlig lokalisering av et bruddplanet vil være på et nivå på ca. 100 m dybde i Tinnsjø. Sensitivitetstest av grunnvann og ulike sprekke- og bergmassestyrkeegenskaper antyder at stabiliteten av fjellsiden er kontrollert av diskontinuitetene, topografien og bergmassestyrke paramtre. V VI PREFACE AND ACKNOWLEDGEMENT This thesis is the final work of my master degree at the Department of Geology and Mineral Resource Engineering at the Norwegian University of Science and Technology (NTNU), Trondheim. The master thesis is written in collaboration with the Norwegian Geological Survey (NGU). Reginald Hermanns (head of the landslide department at NGU) and Bjørn Nilsen (professor at the Department of Geology and Mineral Resource Engineering, NTNU) have been my supervisors. I would like to thank Bjørn Nilsen and Reginald Hermanns for guiding me through the work with this master thesis. Thank you for always being so friendly set time for a meeting, to answer my questions and for all interesting discussions about geology - I have really learned a lot! I am also very grateful for the help I have got from Gro Sandøy and Thierry Oppikofer at NGU and Nghia Quoc Trinh at SINTEF when applying the different software techniques. Finally, I would like to speak to my classmates at NTNU. Thank you for early mornings and late night at "Lesesalen", ice cream in the sun, dancing in T-Town, good memories from field excursions and the years we have had together in Trondheim. You rock! Trondheim, 10.06.2014 Inger Lise Sollie VII VIII TABLE OF CONTENTS Abstract ................................................................................................................................... III Sammendrag ............................................................................................................................. V Preface and acknowledgement ............................................................................................. VII Table of Contents ..................................................................................................................... IX 1 Introduction ....................................................................................................................... 1 1.1 Systematic mapping approach of large unstable rock slopes in Norway ........................ 1 1.2 Background .......................................................................................................................... 3 1.3 Aim and restrictions of the study........................................................................................ 3 1.4 Available data and site specific literature .......................................................................... 6 1.5 Previous work ....................................................................................................................... 7 1.5.1 Gvålviknatten rock fall monitoring project, Norwegian Public Roads Administration (Statens Vegvesen) ...................................................................................................................................................... 7 1.5.2 Periodic monitoring with terrestrial laser scan (TLS), NGU ........................................................... 7 1.5.3 dGNSS displacement measurements (NGU, UiO) .......................................................................... 8 1.5.4 Student project assignment: Geological investigation of Håkåneset ............................................... 8 2 Site information: Regional and geological settings ......................................................... 9 2.1 Location and topography .................................................................................................... 9 2.2 Climate and hydrogeological conditions .......................................................................... 11 2.3 Geology ............................................................................................................................... 14 2.4 Historical events ................................................................................................................. 15 3 General background about large natural rock slope instabilities ................................. 17 3.1 Development and definition of rockslide ......................................................................... 17 3.2 Causes and controlling factors of rock slope instability ................................................. 19 3.3 A case study of a subaerial-subaquatic rockslide: The Hochmais–Atemkopf rockslide system, Austria ................................................................................................................................ 19 4 Methods used of stability assessment of the Håkåneset rockslide ................................. 21 4.1 Digital elevation model (DEM) analysis ........................................................................... 21 IX 4.2 Terrestrial Laser scan (TLS) analyses ............................................................................. 21 4.2.1 Structural analysis in Coltop-3D ................................................................................................... 22 4.2.2 Displacement
Load more

Recommended publications
  • Hydrogeology and Simulation of Ground-Water Flow in the Thick Regolith-Fractured Crystalline Rock Aquifer System of Indian Creek
    Hydrogeology and Simulation of Ground-Water Flow in the Thick Regolith-Fractured Crystalline Rock Aquifer System of Indian Creek Basin, North Carolina AVAILABILITY OF BOOKS AND MAPS OF THE US. GEOLOGICAL SURVEY Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the current- year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Survey publica­ tions released prior to the current year are listed in the most recent annual "Price and Availability List." Publications that may be listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability List" may be no longer available. Order U.S. Geological Survey publications by mail or over the counter from the offices given below. BY MAIL OVER THE COUNTER Books Books and Maps Professional Papers, Bulletins, Water-Supply Papers, Tech­ Books and maps of the U.S. Geological Survey are available niques of Water-Resources Investigations, Circulars, publications over the counter at the following U.S. Geological Survey Earth Sci­ of general interest (such as leaflets, pamphlets, booklets), single ence Information Centers (ESIC's), all of which are authorized copies of Preliminary Determination of Epicenters, and some mis­ agents of the Superintendent of Documents: cellaneous reports, including some of the foregoing series that have gone out of print at the Superintendent of Documents, are obtain­ ANCHORAGE, Alaska Rm. 101, 4230 University Dr. able by mail from LAKEWOOD, Colorado Federal Center, Bldg.
    [Show full text]
  • Dicionarioct.Pdf
    McGraw-Hill Dictionary of Earth Science Second Edition McGraw-Hill New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto Copyright © 2003 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be repro- duced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-141798-2 The material in this eBook also appears in the print version of this title: 0-07-141045-7 All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please contact George Hoare, Special Sales, at [email protected] or (212) 904-4069. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw- Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decom- pile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent.
    [Show full text]
  • Lund, Sweden, January 8–10 2014
    31st Nordic Geological Winter Meeting. Lund, Sweden. January 8-10, 2014 31st Nordic Sponsors Hosted by the Geological Society of Sweden Lund, Sweden, January 8–10 2014 Abiskojokk canyon, Abisko Sweden Photo: Mark Johnson, 2012 Main sponsors Table of Contents Welcome ______________________________________________________ 2 Organizing committee __________________________________________ 3 Scientific program committee ___________________________________ 3 Program Overview _____________________________________________ 4 Social Program ________________________________________________ 5 Scientific Program______________________________________________ 6 - Oral presentations __________________________________________ 7 - Posters ___________________________________________________ 22 Abstracts1 ________________________________________________ 34 - Plenary talks ________________________________________________ 35 - HYD-ENV Hydrogeology/Environmental Geology _______________ 37 - ENG-GEO Engineering Geology ______________________________ 46 - ECON-OIL Economic and Petroleum Geology __________________ 50 - LUNDPAL Lundadagarna i Historisk Geologi och Paleontologi ____________________________________________ 64 - PET Petrology ______________________________________________ 77 - STR-TEC Structural Geology/Tectonics ________________________ 104 - MOR-GLA Geomorphology and Glacial Geology ______________ 126 - QUAT Quaternary Geology _________________________________ 148 - GEOBIO Geobiology and Astrobiology _______________________ 156 - GEOP Geophysics
    [Show full text]
  • Sheeting Joints and Polygonal Patterns in the Navajo Sandstone, Southern Utah: Controlled by Rock Fabric, Tectonic Joints, Buckling, and Gullying David B
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Papers in the Earth and Atmospheric Sciences Earth and Atmospheric Sciences, Department of 2018 Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, tectonic joints, buckling, and gullying David B. Loope University of Nebraska, Lincoln, [email protected] Caroline M. Burberry University of Nebraska - Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/geosciencefacpub Part of the Earth Sciences Commons Loope, David B. and Burberry, Caroline M., "Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, tectonic joints, buckling, and gullying" (2018). Papers in the Earth and Atmospheric Sciences. 532. https://digitalcommons.unl.edu/geosciencefacpub/532 This Article is brought to you for free and open access by the Earth and Atmospheric Sciences, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in the Earth and Atmospheric Sciences by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Research Paper GEOSPHERE Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, tectonic joints, buckling, GEOSPHERE, v. 14, no. 4 and gullying https://doi.org/10.1130/GES01614.1 David B. Loope and Caroline M. Burberry 14 figures; 1 table Department of Earth and Atmospheric Sciences, University of Nebraska,
    [Show full text]
  • Factors Contributing to the Formation of Sheeting Joints
    FACTORS CONTRIBUTING TO THE FORMATION OF SHEETING JOINTS: A STUDY OF SHEETING JOINTS ON A DOME IN YOSEMITE NATIONAL PARK A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI„I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE IN GEOLOGY AND GEOPHYSICS AUGUST 2010 By Kelly J. Mitchell Thesis Committee: Steve Martel, Chairperson Fred Duennebier Paul Wessel Keywords: sheeting joints, exfoliation joints, topographic stresses, curvature, mechanics, spectral filtering, Yosemite Acknowledgements I would like to extend my sincerest gratitude to those who helped make this thesis possible. Thanks to the National Science Foundation for funding this research. Thank you to my graduate advisor, Dr. Steve Martel, for your advice and support through the past few years. This has been a long and difficult project but you have been patient and supportive through it all. Special thanks to my committee, Dr. Fred Duennebier and Dr. Paul Wessel for their advice and contributions; without your help I do not think this project would have been possible. I appreciate the time all of you have spent discussing the project with me. Thank you to Chris Hurren, Shay Chapman, and Carolyn Parcheta for your hard work and moral support in the field; you kept a great attitude during the field season. Special thanks to the National Park Service staff in Yosemite, particularly Dr. Greg Stock and Brian Huggett for their assistance. I wish to thank NCALM, Ole Kaven, Nicholas VanDerElst, and Emily Brodsky for LIDAR data collection. Thank you to Carolina Anchietta Fermin, Lisa Swinnard, and Darwina Griffin for their moral support.
    [Show full text]
  • Rockfall Triggering by Cyclic Thermal Stressing of Exfoliation Fractures
    ARTICLES PUBLISHED ONLINE: 28 MARCH 2016 | DOI: 10.1038/NGEO2686 Rockfall triggering by cyclic thermal stressing of exfoliation fractures Brian D. Collins1* and Greg M. Stock2 Exfoliation of rock deteriorates clis through the formation and subsequent opening of fractures, which in turn can lead to potentially hazardous rockfalls. Although a number of mechanisms are known to trigger rockfalls, many rockfalls occur during periods when likely triggers such as precipitation, seismic activity and freezing conditions are absent. It has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces, which can cause outward expansion. Here we use data from 3.5 years of field monitoring of an exfoliating granite cli in Yosemite National Park in California, USA, to assess the magnitude and temporal pattern of thermally induced rock deformation. From a thermodynamic analysis, we find that daily, seasonal and annual temperature variations are sucient to drive cyclic and cumulative opening of fractures. Application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock. Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the ecacy of other, more typical rockfall triggers. ockfalls are common and hazardous in steep terrains around thermally induced deformation occurs in unstable rock masses, the world1–4, and are primary agents of landscape erosion whether by long-term creep of detached blocks or by short-term in many environments4–8. In exfoliating landscapes (Fig. 1a), fracture propagation in competent rock27–30.
    [Show full text]
  • Dictionary of Geology and Mineralogy
    McGraw-Hill Dictionary of Geology and Mineralogy Second Edition McGraw-Hill New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto All text in the dictionary was published previously in the McGRAW-HILL DICTIONARY OF SCIENTIFIC AND TECHNICAL TERMS, Sixth Edition, copyright ᭧ 2003 by The McGraw-Hill Companies, Inc. All rights reserved. McGRAW-HILL DICTIONARY OF GEOLOGY AND MINERALOGY, Second Edi- tion, copyright ᭧ 2003 by The McGraw-Hill Companies, Inc. All rights reserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 1234567890 DOC/DOC 09876543 ISBN 0-07-141044-9 This book is printed on recycled, acid-free paper containing a mini- mum of 50% recycled, de-inked fiber. This book was set in Helvetica Bold and Novarese Book by the Clarinda Company, Clarinda, Iowa. It was printed and bound by RR Donnelley, The Lakeside Press. McGraw-Hill books are available at special quantity discounts to use as premi- ums and sales promotions, or for use in corporate training programs. For more information, please write to the Director of Special Sales, McGraw-Hill, Professional Publishing, Two Penn Plaza, New York, NY 10121-2298. Or contact your local bookstore. Library of Congress Cataloging-in-Publication Data McGraw-Hill dictionary of geology and mineralogy — 2nd. ed. p. cm. “All text in this dictionary was published previously in the McGraw-Hill dictionary of scientific and technical terms, sixth edition, —T.p.
    [Show full text]
  • Relationship Between Exfoliation Dome Geometry and Topography on Cadillac Mountain, Mount Desert Island, Maine
    RELATIONSHIP BETWEEN EXFOLIATION DOME GEOMET... http://gsa.confex.com/gsa/2009NE/finalprogram/abstract_155922.htm Northeastern Section - 44th Annual Meeting (22–24 March 2009) Paper No. 9-7 Presentation Time: 8:00 AM-12:00 PM RELATIONSHIP BETWEEN EXFOLIATION DOME GEOMETRY AND TOPOGRAPHY ON CADILLAC MOUNTAIN, MOUNT DESERT ISLAND, MAINE VOLLMER, Frederick W., Geology, SUNY New Paltz, New Paltz, NY 12561, [email protected] Exfoliation joints are generally associated with topographic domes, and there appears to be a direct mechanical relationship between topography and exfoliation joint formation. One question that has been raised is what is the age of the topography that the joints are related to, for example, present day topography or pre-glacial topography. Exfoliation joints exposed on Cadillac Mountain, and adjacent Pemetic and Dorr Mountains on Mount Desert Island provide an excellent data set to test these alternate hypotheses. The three adjacent mountains lie within the homogeneous Silurian Cadillac Mountain granite. This is also of interest for risk assessment associated with rock slides and falls initiated on the sloping joint surfaces, in 2006 earthquake damage closed several trails in the park. Measurements of joint orientations were taken across the area, with UTM coordinates recorded using a GPS unit. The absence of mineral infillings suggest the joints form in response to near-surface tensile stresses. A grid of orientation matrixes was calculated from the orientation data, and a dip line field was determined from the grid. The surface normals were used to create a pseudo-shaded relief map using standard illumination angles (45-315) and bilinear interpolation of the calculated light intensities.
    [Show full text]
  • Weathering and Erosion Notes
    9/30/2014 Mechanical Weathering Earth’s surface processes • Mechanical weathering – breaking of rocks into smaller pieces Weathering – Physical breakdown and chemical alteration of rock at Earth’s 1) Frost Wedging surface 2) Abrasion 3) Plant/Animal Activity 2 kinds of Weathering – 4) Gravity/Pressure mechanical and chemical 5) Wetting/Drying 6) Exfoliation / Joint Sheeting 7) Thermal Stress Rockfall caused by frost wedging Frost wedging – freezing and thawing of water in cracks disintegrates rocks Abrasion Plant/Animal Activity Scraping of the surface by moving particles during their transport by wind, glacier, • The activity of organisms, waves, gravity, running water or erosion. including plants, burrowing Glacial Abrasion Geology.com animals, and humans, can also cause mechanical weathering. Sandblasting abrasion National Geographic.com 1 9/30/2014 Gravity/Pressure Wetting/Drying • Bedrock is under pressure from overlying • Wetting and drying causes clay minerals rock. When overlying rock layers are to expand and contract, and salts may removed, the pressure on bedrock is dissolve and re-precipitate. reduced and it expands and cracks. Picture to demonstrate Shale (mostly clay) shrink/swell potential of clay weathering from www.agronomy.lsu.udu Wetting/Drying cycles www.sandatlas.org www.geologycafe.com Mechanical Exfoliation / Joint Sheeting Reduced pressure caused by “unloading” on igneous Thermal Stress rock causes it to expand and allows slabs of outer rock Heating up and cooling down makes to break off in layers in a process called exfoliation. rocks swell and shrink until they break. Chemical Weathering Dissolution of Soluble Compounds • CO 2 mixed with water forms • Breaks down rock and minerals by carbonic acid.
    [Show full text]
  • Geology Teacher Guide
    National Park Service Rocky Mountain U.S. Department of Interior Rocky Mountain National Park Geology Teacher Guide Table of Contents Rocky Mountain National Park.................................................................................................1 Teacher Guides..............................................................................................................................2 Rocky Mountain National Park Education Program Goals...................................................2 Geology Background Information Introduction.......................................................................................................................4 Setting.................................................................................................................................5 Tectonics of Rocky Mountain National Park..............................................................10 Glaciers of Rocky Mountain National Park................................................................16 Erosion History of Rocky Mountain National Park...................................................20 Foothills outside Rocky Mountain National Park......................................................21 Climate and Ecology of Rocky Mountain National Park..........................................22 Geology Resources Classroom Book List.......................................................................................................26 Glossary.............................................................................................................................28
    [Show full text]
  • Controlled by Rock Fabric, Tectonic Joints, Buckling, GEOSPHERE, V
    Research Paper GEOSPHERE Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, tectonic joints, buckling, GEOSPHERE, v. 14, no. 4 and gullying https://doi.org/10.1130/GES01614.1 David B. Loope and Caroline M. Burberry 14 figures; 1 table Department of Earth and Atmospheric Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA CORRESPONDENCE: [email protected] ABSTRACT overburden, sheeting joints (like “A-tents” and “pop-ups”; Jahns, 1943; Ro- CITATION: Loope, D.B., and Burberry, C.M., 2018, mani and Twidale, 1999; Twidale and Bourne, 2003) have more recently been Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, Sheeting joints are ubiquitous in outcrops of the Navajo Sandstone on the interpreted as products of compressive stresses parallel to exposed rock sur- tectonic joints, buckling, and gullying: Geosphere, west-central Colorado Plateau, USA. As in granitic terrains, these are open- faces (Holzhausen, 1989; Bahat et al., 1999; Martel, 2011, 2017). These stresses v. 14, no. 4, p. 1818–1836, https://doi.org/10.1130/ ing-mode fractures and form parallel to land surfaces. In our study areas in can be perturbed by local topography, so landscapes have strong influences GES01614.1. south-central Utah, liquefaction during Jurassic seismic events destroyed on the distribution and abundance of fresh, fractured rock (Miller and Dunne, stratification in large volumes of eolian sediment, and first-order sheeting 1996; St. Clair et al., 2015; Slim et al., 2015). At shallow depth, compressive Science Editor: Raymond M. Russo joints are now preferentially forming in these structureless (isotropic) sand- stress parallel to convex land surfaces induces tension perpendicular to the stones.
    [Show full text]
  • Apparent Glacially Induced Structural Controls on Limestone Conduit Development in Ohio Caverns, United States Adrienne Watts* and Ira D
    International Journal of Speleology 45 (1) 59-69 Tampa, FL (USA) January 2016 Available online at scholarcommons.usf.edu/ijs International Journal of Speleology Off icial Journal of Union Internationale de Spéléologie Apparent glacially induced structural controls on limestone conduit development in Ohio Caverns, United States Adrienne Watts* and Ira D. Sasowsky Department of Geosciences, University of Akron, Akron, OH 44235, USA Abstract: Rock discontinuities such as bedding planes and joints are important controls on the form that caves take. We examined structural controls on the development of Ohio Caverns. The cave formed in Devonian limestone underlying a small bedrock knob (Mt. Tabor) within the Interior Lowland province, United States. The area has been overridden by continental glaciation multiple times. The bedrock is pervasively fractured, with many curved and wavy near-vertical fractures showing many different orientations. In the case of Ohio Caverns, it appears that the controlling fractures in map view may not be joints sensu stricto, but rather some combination of tensile and shear (mode-1 and mode-2) fractures, probably forming in the regime transition between tensile and shear fracturing. This is easy to envision in a situation with ice advancing over this topographic high, and would result in the curved fractures that are observed in many places in the cave. It can also explain the numerous fracture directions. However, not all fractures are conduit-significant. The cave initiated on or near a single bedding plane, and the cave passages exhibit strong keyhole or plus-sign cross sections. Passage and fracture orientations are inconsistent with regionally expected directions.
    [Show full text]