MAP of NORMAL FAULTS and EXTENSIONAL FOLDS in the TENDOY MOUNTAINS and BEAVERHEAD RANGE, SOUTHWEST MONTANA and EASTERN IDAHO Endorsement by the U.S

Total Page:16

File Type:pdf, Size:1020Kb

MAP of NORMAL FAULTS and EXTENSIONAL FOLDS in the TENDOY MOUNTAINS and BEAVERHEAD RANGE, SOUTHWEST MONTANA and EASTERN IDAHO Endorsement by the U.S U.S. DEPARTMENT OF THE INTERIOR MISCELLANEOUS FIELD STUDIES MAP MF–2362 U.S. GEOLOGICAL SURVEY Version 1.0 OVERVIEW 6.62-Ma tuff of Blacktail (age from Morgan and others, 1998) and DISCUSSION AND REGIONAL IMPLICATIONS Geological Society of America Abstracts with Programs, v. 113°45' MAP EXPLANATION overlying undated gravel deposits (Skipp, 1984; Skipp and others, 32, no. 5, p. A-12. 45°05' 113°30' Compilation of a 1:100,000-scale map of normal faults and 1979). Skipp (1984) assigned a Pliocene to early Pleistocene(?) The history of Tertiary extension in the Tendoy and Beaver- Janecke, S.U., VanDenburg, C.J., and Blankenau, J.J., 1998, age to these gravel deposits. Altogether the data suggest a latest head Mountains is complex, but detailed mapping and analysis Geometry, mechanisms and significance of extensional folds 113°15' extensional folds in southwest Montana and adjacent Idaho reveals Miocene to Pleistocene(?) age for the normal faults of set 5. from examples in the Rocky Mountain Basin and Range prov- Salmon a complex history of normal faulting that spanned at least the last show that the seemingly random array of normal faults represents ° 113 FAULTS, FOLDS, AND LINEAMENTS 50 m.y. and involved six or more generations of normal faults. The east-west-striking normal faults are parallel to the Centen- a fairly orderly sequence of more than six temporal and geometric ince, U.S.A.: Journal of Structural Geology, v. 20, no. 7, p. 45°05' The map is based on both published and unpublished mapping nial normal fault (Witkind, 1975) to the east of the map area and sets of normal faults (Janecke, 2000). Within each phase of nor- 841–856. basin Low-angle normal fault—Tics on hanging wall. Dashed where approximate; dotted where concealed and shows normal faults and extensional folds between the valley probably have a common origin (Janecke and others, 2000a). mal faulting a consistent extension direction prevails. Extension Janecke, S.U., VanDenburg, C.J., Blankenau, J.J., and Grasshopper Normal faults with east-west strikes are currently active in a 100- was northeast-southwest during phases 1, 3, and 6, whereas M’Gonigle, J.W., 2000c, Long-distance longitudinal transport Bloody Dick Creek fault of the Red Rock River of southwest Montana and the Lemhi and to 150-km-wide belt west of the Yellowstone caldera, in a region northwest-southeast extension characterized phases 2 and 4. The of gravel across the Cordilleran thrust belt of Montana and Normal fault that cuts out or reactivates a thrust fault—Fault places older rocks on younger rocks. Birch Creek valleys of eastern Idaho between latitudes 45°05' N. directly east of the map area (Janecke and others, 2000a). Far- newly identified fifth phase of extension accommodated north- Idaho: Geology, v. 28, no. 5, p. 439–442. basin Sawteeth on hanging wall. Dashed where approximate; dotted where concealed and 44°15' N. in the Tendoy and Beaverhead Mountains. Some Salmon of the unpublished mapping has been compiled in Lonn and oth- ther to the west and northwest, east-west-striking normal faults are south extension during latest Miocene to Pleistocene(?) time. Kiilsgaard, T.H., Fisher, F.S., and Bennett, E.H., 1986, The no longer active. Instead, the active normal faults strike northwest The largest normal faults to form in the region accommodated Trans-Challis fault system and associated precious metal de- Muddy-Grasshopper ers (2000). Many traces of the normal faults parallel the generally Lemhi Moderately or steeply dipping normal fault—Bar and ball on downthrown side; opposed arrows show northwest to north-northwest structural grain of the preexisting (set 6) and appear to record “typical” northeast-southwest Basin northeast-southwest extension during phases 1, 3, and 6. These posits, Idaho: Economic Geology, v. 81, no. 3, p. 721–724. oblique-slip movement. Dashed where approximate; dotted where concealed basin Sevier fold and thrust belt and dip west-southwest, but northeast- and Range extension. The east-west-striking normal faults proba- three phases also appear to be the most protracted phases of ex- Landis, C.A., Jr., 1963, Geology of the Graphite Mountain–Tepee and east-striking normal faults are also prominent. Northeast- bly reflect transient stress reorientation in the vicinity of the Yel- tension. Phase 3, which produced among the largest faults in the Mountain area Montana-Idaho: University Park, Pa., Pennsyl- Pass Anticline—Arrow indicates plunge direction. Dashed where approximate; dotted where concealed lowstone hot spot due to subsidence toward the growing eastern area, persisted from the waning phases of Challis volcanism (about vania State University M.S. thesis, 153 p. detachment striking normal faults are subparallel to the traces of southeast-di- fault ? rected thrusts that shortened the foreland during the Laramide or- Snake River Plain. The inactive east-west-striking normal faults in 45 Ma) into early Miocene time (about 20 Ma) (VanDenburg and Lonn, J.D., Skipp, Betty, Ruppel, E.T., Janecke, S.U., Perry, Syncline—Arrow indicates plunge direction. Dashed where approximate; dotted where concealed ogeny. It is unlikely that the northeast-striking normal faults reac- the Tendoy and Beaverhead Mountains may have formed when others, 1998; Janecke and others, 1999), possibly until about 15 W.J., Jr., Sears, J.W., Bartholomew, M.J., Stickney, M.C., tivated fabrics in the underlying Precambrian basement, as has the Yellowstone hot spot was southwest of its current position (Ja- Ma (S.U. Janecke and M. Perkins, unpublished data). Fritz, W.J., Hurlow, H.A., and Thomas, R.C., 2000, Prelimi- Arm necke and others, 2000a). The overall parallelism between the largely southwest-dipping nary geologic map of the Lima 30' x 60' quadrangle, south- fault (M.G.F.) Monocline—Arrow on steep limb of the fold been documented elsewhere in southwestern Montana (Schmidt and others, 1984), because exposures of basement rocks in the normal faults of sets 1, 3, and 6 and the preexisting contractional west Montana: Montana Bureau of Mines and Geology Open- stead fault Fault set 4. Early to middle Miocene northwest-dipping structures of the Sevier belt (Janecke and others, 1999) suggests Lineament—Dashed where uncertain map area exhibit north-northwest- to northwest-striking deforma- File Report MBMG 408, scale 1:100,000, includes pam- ° normal faults (shown in magenta on the map) 45 tional fabrics (Lowell, 1965; M’Gonigle, 1993, 1994; M’Gonigle that all three sets are due to gravitational collapse of the Sevier phlet. and Hait, 1997; M’Gonigle and others, 1991). The largest nor- orogenic belt. Royse and others (1975) and Constenius (1996) Lowell, W.R., 1965, Geologic map of the Bannack-Grayling area Normal faults of fault set 4 strike northeast, at a high angle to mal faults in the area are southwest-dipping normal faults that lo- documented the strong structural control of thrust belt structures Beaverhead County, Montana: U.S. Geological Survey Mis- AGES OF NORMAL FAULTS the overall northwest structural grain of the fold and thrust belt cally reactivate thrust faults (fig. 1). Normal faulting began before on younger normal faults in the Basin and Range province. Gravi- cellaneous Geologic Investigations Map I–433, scale and to most of the normal faults of the region, but parallel to the tational collapse of the fold and thrust belt cannot explain the ? middle Eocene Challis volcanism and continues today. The exten- 1:31,680, includes 6-page pamphlet. 45° foreland uplifts to the east. These faults appear as widely spaced Fault set Color Magnitude of this Relative and absolute age constraints sion direction flipped by about 90° four times. northeast-southwest extension that is affecting the foreland farther Lucchitta, B.K., 1966, Structure of the Hawley Creek area, Idaho- fault zones. Faults of set 4 formed in early to middle Miocene Lemhi extensional event to the east, in the Ruby Mountains and adjacent areas. It is note- Montana: University Park, Pa., Pennsylvania State University ? Lemhi Pass fault time (for example, Fritz and Sears, 1993; Sears and Fritz, 1998), worthy that the same northeast-southwest extension direction per- Ph.D. dissertation, 235 p. fault INTRODUCTION and are relatively rare in the Tendoy and Beaverhead Mountains. Youngest 6 Green Moderate Active or potentially active normal faults in the current tectonic sists into the Ruby Range in the foreland east of the Sevier fold McBride, B.C., 1988, Geometry and kinematics of the central Similar normal faults to the northeast bound the southeast margin and thrust belt during the current tectonic regime (set 6) (Stickney Pass regime. The age of initial slip is uncertain. Snowcrest Range—A Rocky Mountain foreland uplift in Normal faults in southwest Montana and adjacent Idaho were of the Miocene Ruby and Beaverhead half grabens and appear to and Bartholomew, 1987; Fritz and Sears, 1993). southwestern Montana: Kalamazoo, Mich., Western Michigan divided into distinct fault sets where cross-cutting relationships with reactivate southeast-vergent basement-cored thrust sheets of the Two sets of normal faults show an especially strong relation- University M.S. thesis, 267 p., 8 plates. 5 Brown Uncertain Many of the east-west striking normal faults cut the Paleogene datable features indicated the approximate age of slip across them. foreland (McBride, 1988; Fritz and Sears, 1993; Sears and Fritz, Agency-Yearian ship with preexisting contractional structures. Both the prevolcan- McDowell, R.J., 1992, Effects of synsedimentary basement tec- normal faults (blue) and are cut by the active Basin and Range faults Absolute and relative ages of normal faults are best constrained at 1998). Three northwest-dipping normal faults were included in ic normal faults of set 1 and the basin-forming normal faults of set tonics on fold-thrust belt geometry, southwestern Montana: (green).
Recommended publications
  • Deformation Pattern During Normal Faulting: a Sequential Limit Analysis
    Originally published as: Yuan, X., Maillot, B., Leroy, Y. M. (2017): Deformation pattern during normal faulting: A sequential limit analysis. ‐ Journal of Geophysical Research, 122, 2, pp. 1496—1516. DOI: http://doi.org/10.1002/2016JB013430 Journal of Geophysical Research: Solid Earth RESEARCH ARTICLE Deformation pattern during normal faulting: 10.1002/2016JB013430 A sequential limit analysis Key Points: • New 2-D mechanically balanced X. P. Yuan1,2 , B. Maillot3, and Y. M. Leroy1,4 model of formation and evolution of half-grabens above low-angle normal 1Laboratoire de Géologie, CNRS UMR, École Normale Supérieure, Paris, France, 2Now at Helmholtz Centre Potsdam, detachment 3 • Tectonic extensional and gravitational German Research Center for Geosciences (GFZ), Potsdam, Germany, Laboratoire Géosciences et Environnement Cergy, 4 modes of deformation in frictional Université de Cergy-Pontoise, Cergy-Pontoise, France, Now at Total, CSTJF, Pau, France wedges are well captured • Fault weakening and sedimentation control number of fault-bounded Abstract We model in 2-D the formation and development of half-graben faults above a low-angle blocks in hanging wall normal detachment fault. The model, based on a “sequential limit analysis” accounting for mechanical equilibrium and energy dissipation, simulates the incremental deformation of a frictional, cohesive, and Supporting Information: fluid-saturated rock wedge above the detachment. Two modes of deformation, gravitational collapse and • Supporting Information S1 tectonic collapse, are revealed which compare well with the results of the critical Coulomb wedge theory. •MovieS1 •MovieS2 We additionally show that the fault and the axial surface of the half-graben rotate as topographic •MovieS3 subsidence increases. This progressive rotation makes some of the footwall material being sheared and •MovieS4 entering into the hanging wall, creating a specific region called foot-to-hanging wall (FHW).
    [Show full text]
  • Constraining the Tectonic Evolution of Extensional Fault Systems in the Cyclades (Greece) Using Low-Temperature Thermochronology Stephanie Brichau
    Constraining the tectonic evolution of extensional fault systems in the Cyclades (Greece) using low-temperature thermochronology Stephanie Brichau To cite this version: Stephanie Brichau. Constraining the tectonic evolution of extensional fault systems in the Cyclades (Greece) using low-temperature thermochronology. Applied geology. Université Montpellier II - Sciences et Techniques du Languedoc; Johannes Gutenberg Universität Mainz, 2004. English. tel- 00006814 HAL Id: tel-00006814 https://tel.archives-ouvertes.fr/tel-00006814 Submitted on 3 Sep 2004 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Universität Mainz “Johannes Gutenberg” and Université de Montpellier II “Sciences et techniques du Languedoc” Dissertation zur Erlangung des Grades “DOKTOR DER NATURWISSENSCHAFTEN” am Fachbereich Geowissenschaften der Johannes Gutenberg-Universität Mainz THESE Pour obtenir le grade de “DOCTEUR DE L’UNIVERSITÉ MONTPELLIER II” Discipline: Terre solide, géodynamique Formation Doctorale: Structure et Evolution de la Lithosphère Ecole Doctorale: Science de la Terre et de l’Eau Presented and publicly defended at Mainz by Stéphanie Brichau June 29th, 2004 Title: Constraining the tectonic evolution of extensional fault systems in the Cyclades (Greece) using low-temperature thermochronology JURY M. Stephen Foley GP, Mainz President M. Michel Faure IST, Orléans Reviewer M.
    [Show full text]
  • "Extension Layer-Parallel Shear and Normal Faulting."
    * * A/H6 Extensional layer-parallel shear and normal faulting DAVID A. FERRILL Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 ALAN P. MORRIS Division of Earth and Physical Sciences, University of Texas at San Antonio, San Antonio, Texas 78249 SIDNEY M. JONES and JOHN A. STAMATAKOS Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 Abstract-An extensional fault system in Bare Mountain, Nevada, contains abundant evidence of layer-parallel shear deformation contemporaneous with faulting. Layer-parallel shear is manifest by deformation of pre-existing fabrics such as teeth on bedding-parallel stylolites and shape fabrics in fossiliferous and oolitic limestone that all indicate shear in the down-dip direction, perpendicular to fault-bedding intersections. Cleavage at a low angle to bedding has the same vergence, indicating development and/or modification during shear parallel to bedding with a down-dip sense. Localized layer-parallel shear along discrete bedding planes has locally offset normal faults, and shear distributed within layers has reoriented block-bounding normal faults. These observations of internal deformation within fault blocks indicate that layer-parallel shear contributes to fault block deformation. In simple rigid-block models of extension accommodated by normal faults above a low-angle detachment or decollement zone, extension causes faults to rotate to progressively lower dips, while originally horizontal beds rotate to steeper dips. These rotations reorient faults away from originally optimum conditions for slip 2 into orientations of a lower slip tendency, whereas bedding rotates to steeper dips with progressively higher slip tendency.
    [Show full text]
  • The Shumagin Seismic Gap Structure and Associated Tsunami Hazards, Alaska Convergent Margin GEOSPHERE, V
    Research Paper THEMED ISSUE: Subduction Top to Bottom 2 GEOSPHERE The Shumagin seismic gap structure and associated tsunami hazards, Alaska convergent margin GEOSPHERE, v. 15, no. 2 Roland von Huene1,*,†, John J. Miller2,*,†, and Anne Krabbenhoeft3 https://doi.org/10.1130/GES01657.1 1U.S. Geological Survey, 800 Blossom Hill Road, Los Gatos, California 95032, USA 2U.S. Geological Survey, Denver Federal Center, Denver, Colorado 80225, USA 3 14 figures; 1 set of supplemental files GEOMAR Helmholz Centre for Ocean Research, D-24148, Kiel, Germany CORRESPONDENCE: rhuene@ mindspring .com ABSTRACT ruptured in the 1964 great earthquake, the Semidi segment that broke in a CITATION: von Huene, R., Miller, J.J., and Krabben‑ 1938 earthquake, and the Unimak segment that ruptured in 1946. In contrast, hoeft, A., 2019, The Shumagin seismic gap structure and associated tsunami hazards, Alaska convergent The potential for a major earthquake in the Shumagin seismic gap, and the the Shumagin segment has no historic great earthquake and is constrained by margin: Geosphere, v. 15, no. 2, p. 324–341, https:// tsunami it could generate, was reported in 1971. However, while potentially its neighboring segments rather than its own aftershocks. Since Sykes (1971) doi .org /10 .1130 /GES01657.1. tsunamigenic splay faults in the adjacent Unimak and Semidi earthquake seg- first drew attention to the Shumagin segment, it has been a proposed seismic ments are known, such features along the Shumagin segment were undoc- gap. Earthquakes in the adjacent segments have produced tsunamis. To the Science Editor: Shanaka de Silva umented until recently. To investigate margin structure and search for splay southwest, during the 1946 M8.6 earthquake, the Unimak segment generated Associate Editor: Laura M.
    [Show full text]
  • Styles of Positive Inversion Tectonics in the Central Apennines and in the Adriatic Foreland: Implications for the Evolution of the Apennine Chain (Italy)
    ARTICLE IN PRESS Journal of Structural Geology xxx (2009) 1–19 Contents lists available at ScienceDirect Journal of Structural Geology journal homepage: www.elsevier.com/locate/jsg Styles of positive inversion tectonics in the Central Apennines and in the Adriatic foreland: Implications for the evolution of the Apennine chain (Italy) Vittorio Scisciani* Dipartimento di Scienze della Terra, Universita` ‘‘G. D’Annunzio’’ Chieti-Pescara, Campus Universitario Madonna delle Piane, Via dei Vesini, 30, 68013 Chieti Scalo (CH), Italy article info abstract Article history: Integration of new field structural and geophysical data with existing information from the Apennines Received 22 February 2008 chain in Italy and its adjacent Adriatic foreland indicates that the styles of positive inversion tectonics Received in revised form and the modes of interaction between the extensional and the subsequent compressive structures vary. 19 February 2009 Starting from the Cretaceous, the contractional deformation induced by the mainly north-directed Accepted 27 February 2009 convergence of Africa/Adria with respect to the European plate promoted the closure of various arms of Available online xxx the Atlantic and the Neo-Tethys oceans, which opened in different times and with distinct orientations. The mosaic of continental blocks, carbonate platforms, rift basins and oceanic domains with several Keywords: Positive inversion tectonics geometries and orientations with respect to the axis of the subsequent compression, and the resulting Extensional and contractional deformation heterogeneities within the shallow sedimentary cover and the overall lithosphere, strongly influenced Thick-skinned tectonics both the structural evolution of the Apennine orogenic belt and the intra-continental deformation within Fault reactivation the Adriatic foreland.
    [Show full text]
  • Characteristics of Earthquake Ruptures and Dynamic Off-Fault Deformation on Propagating Faults
    Solid Earth, 11, 1333–1360, 2020 https://doi.org/10.5194/se-11-1333-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Characteristics of earthquake ruptures and dynamic off-fault deformation on propagating faults Simon Preuss1, Jean Paul Ampuero2, Taras Gerya1, and Ylona van Dinther3 1Geophysical Fluid Dynamics, Institute of Geophysics, Department of Earth sciences, ETH Zürich, 8092 Zürich, Switzerland 2Géoazur Laboratory, Institut de Recherche pour le Développement – Université Côte d’Azur, Campus Azur du CNRS, 06560 Valbonne, France 3Tectonics, Department of Earth Sciences, Utrecht University, Princetonlaan 4, 3584 CB, Utrecht, the Netherlands Correspondence: Simon Preuss ([email protected]) Received: 8 February 2020 – Discussion started: 25 February 2020 Revised: 16 June 2020 – Accepted: 26 June 2020 – Published: 22 July 2020 Abstract. Natural fault networks are geometrically complex tures range from fan-shaped distributed deformation to local- systems that evolve through time. The evolution of faults ized splay faults. We observe that the fault-normal width of and their off-fault damage patterns are influenced by both the outer damage zone saturates with increasing fault length dynamic earthquake ruptures and aseismic deformation in due to the finite depth of the seismogenic zone. We also ob- the interseismic period. To better understand each of their serve that dynamically and statically evolving stress fields contributions to faulting we simulate both earthquake rup- from neighboring fault strands affect primary and secondary ture dynamics and long-term deformation in a visco-elasto- fault growth and thus that normal stress variations affect plastic crust subjected to rate- and state-dependent friction.
    [Show full text]
  • Extensional Tectonics and Gravitational Collapse in an Ordovician Passive Margin: the Western Argentine Precordillera ⁎ J.L
    Available online at www.sciencedirect.com Gondwana Research 13 (2008) 204–215 www.elsevier.com/locate/gr Extensional tectonics and gravitational collapse in an Ordovician passive margin: The Western Argentine Precordillera ⁎ J.L. Alonso a, , J. Gallastegui a, J. García-Sansegundo a, P. Farias a, L.R. Rodríguez Fernández b, V.A. Ramos c a Department of Geology, University of Oviedo, c/ Arias de Velasco s/n, 33005 Oviedo, Spain b Instituto Geológico y Minero de España, c/ La Calera, 1, 28740, Tres Cantos, Madrid, Spain c Laboratorio de Tectónica Andina, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires 1428, Buenos Aires, Argentina Received 29 September 2006; accepted 28 May 2007 Available online 7 June 2007 Abstract The paper describes ubiquitous extensional structures developed in a passive margin of Ordovician age in the Argentine Precordillera. These extensional structures include normal faults and boudinaged sequences. In some places the boudinage reaches very high extension values, giving rise to block-in-matrix formations. Most of these extensional structures developed when sediments were not well lithified, as recorded by hydroplastic fractures, slump folds and pinch-and-swell structures. The presence of slump folds coeval with the extensional deformation, the variable extension directions obtained from the kinematic analysis and a weak cleavage recording layer-perpendicular shortening support the interpretation that gravitational collapse related to submarine sliding was the cause for extensional deformation. Well-consolidated rocks, located at the lower part of the stratigraphic sequence, also display scarce extensional faults. These extensional faults predate folding because they were breached by flexural-slip faults and, as a result of their passive rotation in fold limbs, these initial normal faults may now appear as reverse faults, particularly in steep and overturned limbs.
    [Show full text]
  • Extentional Tectonics
    Extensional Tectonics & Rift systems Where do normal faults occur? i.e. what plate boundaries? What are major sources of stress? (stress drives extension, compression, and transpression!) Extensional Tectonics & Rift systems Where do normal faults occur? i.e. what plate boundaries? • Mid-ocean ridges (divergent plate boundaries) • Continental rift (divergent plate boundaries) i.e. East African Rift, Basin and Range, U.S., à How else could we break up supercontinents! • Convergent plate boundaries i.e. Andes, Himalaya What are major sources of stress? (stress drives extension, compression, and transpression!) • Lithostatic load (vertical!) • Plate tectonics (horizontal) • Fluid pressure • Thermal effects • Buoyancy (vertical) Stress vs. A. B. Map View C. Strain http://earth.leeds.ac.uk/learnstructure/index.htm From: www.uoregon.edu/millerm/LVSS.html From: http://www.nygeo.org/foldedrock.jpg Refresher D. E. F. From: www.fault-analysis-group.ucd.ie From: structuralgeo.files.wordpress.com From: http://www.alexstrekeisen.it/english/meta/boudinage.php Stress Regime Compression Tension Shear Brittle Type of Strain Type Ductile A. B. Map View C. http://earth.leeds.ac.uk/learnstructure/index.htm From: www.uoregon.edu/millerm/LVSS.html From: http://www.nygeo.org/foldedrock.jpg D. E. F. From: www.fault-analysis-group.ucd.ie From: structuralgeo.files.wordpress.com From: http://www.alexstrekeisen.it/english/meta/boudinage.php Compression Tension Shear Reverse Fault Normal Fault Strike-Slip Fault Map View HW FW HW Brittle FW From: structuralgeo.files.wordpress.com
    [Show full text]
  • Rift-Basin Structure and Its Influence on Sedimentary Systems
    STRUCTURE AND SEDIMENTARY SYSTEMS 57 RIFT-BASIN STRUCTURE AND ITS INFLUENCE ON SEDIMENTARY SYSTEMS MARTHA OLIVER WITHJACK AND ROY W. SCHLISCHE Department of Geological Sciences, Rutgers University, Piscataway, New Jersey 08854-8066, U.S.A. e-mail: [email protected]; [email protected] AND PAUL E. OLSEN Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, U.S.A. e-mail: [email protected] ABSTRACT: Rift basins are complex features defined by several large-scale structural components including faulted margins, the border faults of the faulted margins, the uplifted flanks of the faulted margins, hinged margins, deep troughs, surrounding platforms, and large- scale transfer zones. Moderate- to small-scale structures also develop within rift basins. These include: basement-involved and detached normal faults; strike-slip and reverse faults; and extensional fault-displacement, fault-propagation, forced, and fault-bend folds. Four factors strongly influence the structural styles of rift basins: the mechanical behavior of the prerift and synrift packages, the tectonic activity before rifting, the obliquity of rifting, and the tectonic activity after rifting. On the basis of these factors, we have defined a standard rift basin and four end-member variations. Most rift basins have attributes of the standard rift basin and/or one or more of the end-member variations. The standard rift basin is characterized by moderately to steeply dipping basement-involved normal faults that strike roughly perpendicular to the direction of maximum extension. Type 1 rift basins, with salt or thick shale in the prerift and/or synrift packages, are characterized by extensional forced folds above basement-involved normal faults and detached normal faults with associated fault-bend folds.
    [Show full text]
  • Geological and Geophysical Data By
    Segmentation of the Wasatch Fault Zone, Utah­ Summaries, Analyses, and Interpretations of Geological and Geophysical Data By RUSSELL L. WHEELER and KATHERINE B. KRYSTINIK Descriptions, with supporting evidence, of segment boundaries as they are expressed in gravity, aeromagnetic, seismological, fault-geometric, topographic, and structural data U.S. GEOLOGICAL SURVEY BULLETIN 1827 DEPARTMENT OF THE INTERIOR DONALD PAUL HODEL, Secretary U. S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. UNITED STATES GOVERNMENT PRINTING OFFICE: 1988 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 Wheeler, Russell L. Segmentation of the Wasatch fault zone, Utah-summaries, analyses, and interpretations of geological and geophysical data. (U.S. Geological Survey bulletin ; 1827) Bibliography: p. Supt. of Docs. no.: I 19.3:1827 1. Faults (Geology)-Utah. I. Krystinik, Katherine B. II. Title. Ill. Title: Wasatch fault zone, Utah. IV. Series. QE75.B9 no. 1827 557.3 s [551.8' 7' 097922] 87-600430 [QE606.5.U6] CONTENTS Abstract 1 Introduction 1 Criteria that the data must satisfy 2 Bouguer gravity data 3 Introduction 3 Procedures 4 Results 6 Aeromagnetic data 6 Introduction 6 Procedures 7 Results 9 Earthquake epicenters 10 Introduction 10 Procedures 11 Results 12 Salients 13 Introduction 13 Procedures 15 Results 15 Topographic data
    [Show full text]
  • Growth of Extensional Faults and Folds During Deposition of an Evaporite-Dominated Half-Graben Basin; the Carboniferous Billefjorden Trough, Svalbard
    University of Nebraska at Omaha DigitalCommons@UNO Geography and Geology Faculty Publications Department of Geography and Geology 2012 Growth of extensional faults and folds during deposition of an evaporite-dominated half-graben basin; the Carboniferous Billefjorden Trough, Svalbard Alvar Braathen Karoline Bælum Harmon Maher Jr. Simon J. Buckley Follow this and additional works at: https://digitalcommons.unomaha.edu/geoggeolfacpub Part of the Geology Commons NORWEGIAN JOURNAL OF GEOLOGY Fault-fold influenced rift system, Billefjorden, Svalbard 137 Growth of extensional faults and folds during deposition of an evaporite-dominated half-graben basin; the Carboniferous Billefjorden Trough, Svalbard Alvar Braathen, Karoline Bælum, Harmon Maher Jr. & Simon J. Buckley Alvar Braathen, Karoline Bælum, Harmon Maher Jr. & Simon Buckley: Growth of extensional faults and folds during deposition of an evaporite- dominated half-graben basin: the Carboniferous Billefjorden Trough, Svalbard. Norwegian Journal of Geology, vol. 91, pp 137-160. Trondheim 2011. ISSN 029-196X. Normal-sense movements along two major strands of the Billefjorden Fault Zone controlled sedimentation in the Carboniferous Billefjorden Trough. The Billefjorden Trough is a more than 2000 meters thick, west-dipping half-graben basin where accommodation was provided by combi nations of extensional faulting and folding throughout the basin history. Whereas previous workers have interpreted several of these folds as due to Tertiary contraction, we argue that they developed during rifting, as extensional forced folds in the style described by other workers from rifts such as the Gulf of Suez. The present basin geometry indicates that accommodation was facilitated by a combination of fault relief and fault-related folds such as extensional fault-propagation monoclines, longitudinal rollover folds and a broad syncline that developed in the hanging wall of the master faults.
    [Show full text]
  • Normal-Fault Development During Two Phases of Non-Coaxial Extension: an Experimental Study
    Journal of Structural Geology 32 (2010) 1656–1667 Contents lists available at ScienceDirect Journal of Structural Geology journal homepage: www.elsevier.com/locate/jsg Normal-fault development during two phases of non-coaxial extension: An experimental study Alissa A. Henza*, Martha O. Withjack, Roy W. Schlische Department of Earth & Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8066, USA article info abstract Article history: We use scaled experimental (analog) models to study the effect of a pre-existing fault fabric on fault Received 29 January 2009 development during extension. In our models, a homogeneous layer of wet clay undergoes two non- Received in revised form coaxial phases of extension whose directions differ by up to 45. The normal faults that develop during 24 June 2009 the first phase create a pronounced fault fabric that influences normal-fault development during the Accepted 26 July 2009 second phase. In all models, the pre-existing faults are reactivated during the second phase of extension. Available online 4 August 2009 Their sense of slip depends on the angle between the first- and second-phase extension directions. Specifically, the component of dip slip relative to strike slip decreases as the angle between the first- and Keywords: Normal faults second-phase extension directions increases. New normal faults also form during the second phase of Experimental modeling extension in all models. The number of new fault segments increases as the angle between the first- and Multiple phases of extension second-phase extension directions increases. The orientations of the new normal-fault segments are Fault reactivation both orthogonal and oblique to the second-phase extension direction, indicating that both the second- phase extension direction and the pre-existing fault fabric control the orientation of new fault segments.
    [Show full text]