\ I I I i NUREG/CR-1621 A Characterization of Faults in the Appalachian Foldbelt Prepared by A. L. Odom, R. D. Hatcher, Jr. ' Florida State University Prepared for U.S. Nucle~r Regulatory Commission ,,/! NOTICE This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. Available from GPO Sales Program Division of Technical Information and Document Control U.S. Nuclear Regulatory Cormnission Washington, D. C. 20555 and National Technical Information Service Springfield, Virginia 22161 I I . I NUREG/CR-1621 i: i I .f , A Characterization of Faults in the Appalachian Foldbelt Manuscript Completed: July 1980 Date .Published: September 1980 Prepared by A. L. Odom, R. D. Hatcher, Jr. Contributing Authors: D. E. Dunn - University of New Orleans · \. T. J. Engelder - Lamont-Doherty Geologic Observatory P. A. Geiser - University of Connecticut S. A. Kish - University of North Carolina S. Schamel - Lafayette College . D. U. Wise - University of Massachusetts Florida State University Tallahassee, FL 32306 Prepared for Division of Siting, Health and_ Safeguards Standards Office of Standards Development U.S. Nuclear Regulatory Commission Washington, D.C. 20555 NRC FIN No. 81053-8 ABSTRACT The characterization is a synthesis of available data on geologic faults in the Appalachian foldbelt regarding their description, generic implications, rate of movement, and potentiaJ as geologic-seismic hazards. It is intended to assist applicants and reviewers in evaluating faults at sites for nuclear facilities. Appalachian faults were found to fall into 13 groups which can be defined on either their temporal, generic, or descriptive.properties. They are as follows: Group 1, faults with demonstrable Cenozoic movement; Group 2, Wildflysch type thrust sheets; Group 3, bedding plane thrusts - decollements; Group A, pre- to synmetamorphic thrusts in medium to high grade terranes; Group 5, post-metamorphic thrusts in medium to high grade terranes; Group 6, thrusts rooted in low crystalline basement; Group 7, high angle reverse faults; Group 8, strike'slip faults; Group. 9, .normal (block) faults; Group 10, compound faults; Group 11, structural lineaments; Group 12, faults associated with local centers; and Group 13, faults related to geomorphic phenomena. Unhealed faults (Groups 1, 6, 8, 9, and 12) must be considered candidates for reactivation. Heated brittle or auctile faults (Groups 4, 5, and 10)· are not places of mechanical discontinuity and are unlikely candidates for reacti~ation. The remaining groups (2, 3, 7, 11, and 13) should be . individually assessed as to their potential for reactivation. iii '\ CONTENTS Page I. Introduction .....................•......•....... ~....... .... 1 A. Purpose .......•.........•.....•....•..••.... ~ ! ••••••••••••• B. Rat i ona I e ... ~ ....•........•.•.•.......••....•...•.......... ~ · 2 I I. Summary of Characteristics and Distribution of Faul-rs in The App a I ach i an Fo Id be It . • • . .. • . • . • • . • . • . • . 5 IIJ. fa.u.lt Reactivation .o •• ~ ••••••••.••••.•• o.· ••• , •• 111................ 37 A. Fa1.:.11,-t c I asses most subject to reactivation • • • • • • • • • • • • • ••. • 37 8. Faul;t cl'asses least subject to reactivation • • • • • • • • • • • • • • • 37 c.. Successfu I techniques for dati:ng I ast motion • . • • • . • . • • • • . • 38 D,, Relati.on of seismicity to surface breaks •. • • •• ••• ••• •• • • • • 39 IV. De:f i"nition o·f Key Terms . • • • • • • • • . • • . • • • • • • • • • • • • • • • • • • . • • . • • • 40 A. Fa. u. I, t . .. .. .. 40 I • Ductile fault . ......................................... 40 Brittle • •••••••••••••••••••••• 2. fault ~ ••• 0 ••••••••••••• 40 a. Unhealed ...•... ·....•.......•.........•.....•...... 40 b. Fi 11.ed . .. '.' ....................................... 40 Healed • •••••••• ! ••••••. c. • ••••••••••••••••••••• 0 • , •••• 40 B. SI ip Versus G ••••••••••••••••••• Separation .· ...... • ••••••••• 42 C. Fa u It Zone Mater i a Is . • . 42 I. Prodycts of cataclasis ••••••••••••••••••• -............. 42 2. Products of mylonitization •••••.•••••.•••••.••••••••••• 42 V. Faults With Demonstrable Cenozoic Movement (Group I) •••.•••• ~. 43 VI. Wi I df I ysche Type Sheets (Group 2) ........................... .. 59 VI I. Bedding Plane Thrusts -- Decol lements (Group 3) .......... .•••• 81 V VIII. Pre-to Synmetamorphic Faults in Medium to High Grade Terrane CGroup 4 ) ••• ~ •· • • • • • • • • •• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • . • I• I I IX. Postmetamorph,ic Thrusts in Medium to High Grade Terranes (Group 5) ••..•.•••••. ~ •.•••••.•••••.•.•••.•.••••••.••••••.••• -. • • • • • . 125 X. Thrusts Rooted in Low Grade To Unmetamorphosed Crystal line Basement (Group 6) .................................................. 139' XI. High Angle Reverse Faults (Group 7) ·····················~··········· 153 XII. Strike - s Ii p Fau Its (Group 8) 162 XI I I. Norma I CB lock) ·Fau Its CG_roup 9) . ........ "' .......................... 190 XIV. Compound Faults With Long, Repeated Movement History (Group fO) .. - .......• ........................... •..................... ·• .. 208 xv. Structural Lineaments (Group II) .•.•••.•••••••.••.••. ~ ••••..•••••.••.• 233 ·XVI. Faults Associated With Local Centers (Group 12) ••••••••••••••••••••• 242 XVII. Geomorph i c Fau I ts (Group 13) . ........................................ 252 . ' . XV II I. Glossary •..............•.....••... • .......•....•..•..•................ 261 . XIX. Suggestions •••••• ! •••••••••••••••••••••••••••••••••••••••••••••••••• 270 XX. Appendices A.· Critical need for in situ .stress measurements ••••••..••..• ; ••••• 275 B.. Prqt.Jems of Distinguishing Between Seismic and Aseismic Faults • • 279 C. Cataclasis versus mylonitization ••••• ·............................ 282 D .. 'Linemanship ••..•..••.....••...•.•••••.••.•.•...•••..••••.••••.••.. .289 I, \ vi 1· List of Illustrations Figure _Page 1-1 Geofectonlc map of the Appalachian Foldbelt •.•••••••••••••• 6 1-2 Map'-Showing Distribution of Group I Faults ••••••••••••••••• 7 1-3 " " " " " 2 ·" • • • • • • • • • • • • • • • • • 8 1-4 11 11 11 II U 3 11· • • • • • • • • • • • • • • • • • 9 1-5 11 11 11 11. II 4 II ••••••••••••••••• 10 1-6' 11 11 11 II 11 5 11 • • • • • • • • • • • • • • • • • II 1-7 11 11 11, II II 6 II • • • • • • • • • • • • •. • • • • 12 1-8 11 11 II II II 8 II • • • • •. • • • • • • • • • • • • 13 1-9 11 11 11 II II 9 II • • • • • • • • • • • • • • • • • 14 1-10 11 11 11 II II 10 II •••••••••••••••• • 15 1-11 · " " " '" " 1 ·2 " ••••••••••••••••• 16 1-12 11 11 11 II II 13 II • • • • • • • • • • • • • • • • • 17· V-1 Relation Between Brittle and Ductile Faults ••••••.••••••••• 41. V-1 Recent Thrusting and Folding of a Syncline ••••••••••••••••• 45 v.:.2 Map of Stafford and Brandywine Fault Systems •••••••••••••.• 48 V-:3 Stratigrafic Variations across Stafford Fault Systems •••••• 50 V-4 Geologic Cross Section in Area of Stafford ••••••••••••••••• 51 VI-I Schematic Representation of Three Types of Submarine Slides.· 60 Vt-2 Eastern North America During.the Ordovician •••••••••••••••• 62 Vl-3 Tectonic Units of tHe Taconic Al lochthon .••••••••••••••••••• 63 Vl-4 Cross Section of Central Taconic Range··~·················· 63 Vl-5- Map of Pennsy I van i a Great Va I Iey and A Ilochthonous Rocks in Martinsburg Fm .•.•..••.••..••••...•••....•..••.•...•. 65 66 Vl-6 Allochthons of Martinsburg Fm, Pennsylvania •••••••••• ~ ••••. Vl-7 Geologic Cross Section Along West Bank of Susquehanna River. 67 Vl-8 Pre-Taconic and Taconian Evolution of North American in Western New Eng I and •••.• ~ ••••.• ~ •••.•.•......•....•... 71 Vl-9 Model for the Evolution of the Appalachian Orogen •••••••••• 72 Vl-10 · Diagram of A ternI at i ve Grav I tat i ona I. Emp I acement Mode.I s •••. n V -11 Schematic Section Showing Emplacement of Thrust Sheets .•••• 74 82 V 1-1 Ramping of Bedding Plane. Fault •••••••••••••••••• ~ •••••.•••• V l-2 Bedding Plane Fault Climbing 83 Section by Decol lement •••••••• 84. V 1-3 Relationship Between Folding and Faulting ••••••••••••••.••• V 1-4 Apparent Violations of Dahlstroms Rules of Thrusting ••••••• 84 V 1-5 Thrust Fau It Anatomy· .•.•...........•..•..•.•... ; .......... 86 -v 1-6 Thrust Fault Terminology •..•. .-..•••........•.•..••......... 86 V 1-7 Complicat-i-ons of Thrust Faulting.Geometry-Leading Edge •••.• 87 11 . 88 V 1-8 11 11 11 11 -Trai I ing 11 V 1-9 Bc>w Thrust •.•...•.......•.. ·.......••••... ~ ••..•.............. 92 92 V 1-10 Rectangu I ar Thrust ..••...••..•.....•..••.•.....•. ~ ........ V 1-11 s·econdary Transverse Tear Fau I ts ••••.••.•••••••••••••••••••. 93 93 V 1-12 Termination of Bedding Plane Thrust into Folds •••••••••• ~ •• V 1-13 Terminations of Bedding Plane Thrust •••• ~ •••••••••••••••••• 94 V 1-14 Relationship Between Detachment Surface and Silurian· · Sa I f Hori zon •.•••••• ·.•.•...••••.••••••.•.. ·.••.•••..•••... 100 VI 1-15 Independence Between Paleo-isotherms and Detachment Surface .........................•.•••..............•.... 103 VI 11-1 Folded, lmbricate Group 4 Thrusts of the Martic Region ••••• 1.13