Geometry, Kinematics, and Displacement
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Linking Megathrust Earthquakes to Brittle Deformation in a Fossil Accretionary Complex
ARTICLE Received 9 Dec 2014 | Accepted 13 May 2015 | Published 24 Jun 2015 DOI: 10.1038/ncomms8504 OPEN Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex Armin Dielforder1, Hauke Vollstaedt1,2, Torsten Vennemann3, Alfons Berger1 & Marco Herwegh1 Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. 1 Institute of Geological Sciences, University of Bern, Baltzerstrasse 1 þ 3, Bern CH-3012, Switzerland. 2 Center for Space and Habitability, University of Bern, Sidlerstrasse 5, Bern CH-3012, Switzerland. 3 Institute of Earth Surface Dynamics, University of Lausanne, Geˆopolis 4634, Lausanne CH-1015, Switzerland. Correspondence and requests for materials should be addressed to A.D. (email: [email protected]). NATURE COMMUNICATIONS | 6:7504 | DOI: 10.1038/ncomms8504 | www.nature.com/naturecommunications 1 & 2015 Macmillan Publishers Limited. -
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. -
Tectonics of the Musandam Peninsula and Northern Oman Mountains: from Ophiolite Obduction to Continental Collision
GeoArabia, 2014, v. 19, no. 2, p. 135-174 Gulf PetroLink, Bahrain Tectonics of the Musandam Peninsula and northern Oman Mountains: From ophiolite obduction to continental collision Michael P. Searle, Alan G. Cherry, Mohammed Y. Ali and David J.W. Cooper ABSTRACT The tectonics of the Musandam Peninsula in northern Oman shows a transition between the Late Cretaceous ophiolite emplacement related tectonics recorded along the Oman Mountains and Dibba Zone to the SE and the Late Cenozoic continent-continent collision tectonics along the Zagros Mountains in Iran to the northwest. Three stages in the continental collision process have been recognized. Stage one involves the emplacement of the Semail Ophiolite from NE to SW onto the Mid-Permian–Mesozoic passive continental margin of Arabia. The Semail Ophiolite shows a lower ocean ridge axis suite of gabbros, tonalites, trondhjemites and lavas (Geotimes V1 unit) dated by U-Pb zircon between 96.4–95.4 Ma overlain by a post-ridge suite including island-arc related volcanics including boninites formed between 95.4–94.7 Ma (Lasail, V2 unit). The ophiolite obduction process began at 96 Ma with subduction of Triassic–Jurassic oceanic crust to depths of > 40 km to form the amphibolite/granulite facies metamorphic sole along an ENE- dipping subduction zone. U-Pb ages of partial melts in the sole amphibolites (95.6– 94.5 Ma) overlap precisely in age with the ophiolite crustal sequence, implying that subduction was occurring at the same time as the ophiolite was forming. The ophiolite, together with the underlying Haybi and Hawasina thrust sheets, were thrust southwest on top of the Permian–Mesozoic shelf carbonate sequence during the Late Cenomanian–Campanian. -
The Confusion Range, West-Central Utah: Fold-Thrust Deformation and a Western Utah Thrust Belt in the Sevier Hinterland
The Confusion Range, west-central Utah: Fold-thrust deformation and a western Utah thrust belt in the Sevier hinterland David C. Greene* Department of Geosciences, Denison University, Granville, Ohio 43023, USA ABSTRACT INTRODUCTION tions together while delineating the lateral and oblique thrust ramps that form a signifi cant The Confusion Range in west-central Utah The Confusion Range is a collection of ridges complicating factor in the structure of the fold- has been considered a broad structural trough and small ranges that together form a low moun- thrust system. Together, these fi ve cross sections or synclinorium with little overall shorten- tain range in western Utah, between the more total almost 300 km in map length. Enlarged ing. However, new structural studies indicate imposing Snake Range on the west and House versions of the cross sections at a scale of that the Confusion Range is more accurately Range on the east (Figs. 1 and 2). The range is 1:50,000, along with a discussion of the petro- characterized as an east-vergent, fold-thrust named for its “rugged isolation and confusing leum potential of the region, may be found in system with ~10 km of horizontal shortening topography” (Van Cott, 1990). The Confusion Greene and Herring (2013). during Late Jurassic to Eocene Cordilleran Range exposes ~5000 m of Ordovician through Similar structural style and fold-thrust struc- contractional deformation. For this study, Triassic strata in what has been considered a tures are continuous southward throughout the four balanced and retrodeformable cross broad structural trough or synclinorium (e.g., length of the originally proposed synclinorium, sections across the Confusion Range and Hose, 1977; Anderson, 1983; Hintze and Davis, forming a fold-thrust belt more than 130 km in adjacent Tule Valley were constructed using 2003; Rowley et al., 2009). -
Describe the Geometry of a Fault (1) Orientation of the Plane (Strike and Dip) (2) Slip Vector
Learning goals - January 16, 2012 You will understand how to: Describe the geometry of a fault (1) orientation of the plane (strike and dip) (2) slip vector Understand concept of slip rate and how it is estimated Describe faults (the above plus some jargon weʼll need) Categories of Faults (EOSC 110 version) “Normal” fault “Thrust” or “reverse” fault “Strike-slip” or “transform” faults Two kinds of strike-slip faults Right-lateral Left-lateral (dextral) (sinistral) Stand with your feet on either side of the fault. Which side comes toward you when the fault slips? Another way to tell: stand on one side of the fault looking toward it. Which way does the block on the other side move? Right-lateral Left-lateral (dextral) (sinistral) 1992 M 7.4 Landers, California Earthquake rupture (SCEC) Describing the fault geometry: fault plane orientation How do you usually describe a plane (with lines)? In geology, we choose these two lines to be: • strike • dip strike dip • strike is the azimuth of the line where the fault plane intersects the horizontal plane. Measured clockwise from N. • dip is the angle with respect to the horizontal of the line of steepest descent (perpendic. to strike) (a ball would roll down it). strike “60°” dip “30° (to the SE)” Profile view, as often shown on block diagrams strike 30° “hanging wall” “footwall” 0° N Map view Profile view 90° W E 270° S 180° Strike? Dip? 45° 45° Map view Profile view Strike? Dip? 0° 135° Indicating direction of slip quantitatively: the slip vector footwall • let’s define the slip direction (vector) -
Position, Displacement, Velocity Big Picture
Position, Displacement, Velocity Big Picture I Want to know how/why things move I Need a way to describe motion mathematically: \Kinematics" I Tools of kinematics: calculus (rates) and vectors (directions) I Chapters 2, 4 are all about kinematics I First 1D, then 2D/3D I Main ideas: position, velocity, acceleration Language is crucial Physics uses ordinary words but assigns specific technical meanings! WORD ORDINARY USE PHYSICS USE position where something is where something is velocity speed speed and direction speed speed magnitude of velocity vec- tor displacement being moved difference in position \as the crow flies” from one instant to another Language, continued WORD ORDINARY USE PHYSICS USE total distance displacement or path length traveled path length trav- eled average velocity | displacement divided by time interval average speed total distance di- total distance divided by vided by time inter- time interval val How about some examples? Finer points I \instantaneous" velocity v(t) changes from instant to instant I graphically, it's a point on a v(t) curve or the slope of an x(t) curve I average velocity ~vavg is not a function of time I it's defined for an interval between instants (t1 ! t2, ti ! tf , t0 ! t, etc.) I graphically, it's the \rise over run" between two points on an x(t) curve I in 1D, vx can be called v I it's a component that is positive or negative I vectors don't have signs but their components do What you need to be able to do I Given starting/ending position, time, speed for one or more trip legs, calculate average -
Along Strike Variability of Thrust-Fault Vergence
Brigham Young University BYU ScholarsArchive Theses and Dissertations 2014-06-11 Along Strike Variability of Thrust-Fault Vergence Scott Royal Greenhalgh Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Geology Commons BYU ScholarsArchive Citation Greenhalgh, Scott Royal, "Along Strike Variability of Thrust-Fault Vergence" (2014). Theses and Dissertations. 4095. https://scholarsarchive.byu.edu/etd/4095 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Along Strike Variability of Thrust-Fault Vergence Scott R. Greenhalgh A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Science John H. McBride, Chair Brooks B. Britt Bart J. Kowallis John M. Bartley Department of Geological Sciences Brigham Young University April 2014 Copyright © 2014 Scott R. Greenhalgh All Rights Reserved ABSTRACT Along Strike Variability of Thrust-Fault Vergence Scott R. Greenhalgh Department of Geological Sciences, BYU Master of Science The kinematic evolution and along-strike variation in contractional deformation in over- thrust belts are poorly understood, especially in three dimensions. The Sevier-age Cordilleran overthrust belt of southwestern Wyoming, with its abundance of subsurface data, provides an ideal laboratory to study how this deformation varies along the strike of the belt. We have per- formed a detailed structural interpretation of dual vergent thrusts based on a 3D seismic survey along the Wyoming salient of the Cordilleran overthrust belt (Big Piney-LaBarge field). -
Development of the Rocky Mountain Foreland Basin: Combined Structural
University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2007 DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION, ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA Emily Geraghty Ward The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Ward, Emily Geraghty, "DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION, ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA" (2007). Graduate Student Theses, Dissertations, & Professional Papers. 1234. https://scholarworks.umt.edu/etd/1234 This Dissertation is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. DEVELOPMENT OF THE ROCKY MOUNTAIN FORELAND BASIN: COMBINED STRUCTURAL, MINERALOGICAL, AND GEOCHEMICAL ANALYSIS OF BASIN EVOLUTION ROCKY MOUNTAIN THRUST FRONT, NORTHWEST MONTANA By Emily M. Geraghty Ward B.A., Whitman College, Walla Walla, WA, 1999 M.S., Washington State University, Pullman, WA, 2002 Dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geology The University of Montana Missoula, MT Spring 2007 Approved by: Dr. David A. Strobel, Dean Graduate School James W. Sears, Chair Department of Geosciences Julia A. Baldwin Department of Geosciences Marc S. Hendrix Department of Geosciences Steven D. -
Contractional Tectonics: Investigations of Ongoing Construction of The
Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2014 Contractional Tectonics: Investigations of Ongoing Construction of the Himalaya Fold-thrust Belt and the Trishear Model of Fault-propagation Folding Hongjiao Yu Louisiana State University and Agricultural and Mechanical College, [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Earth Sciences Commons Recommended Citation Yu, Hongjiao, "Contractional Tectonics: Investigations of Ongoing Construction of the Himalaya Fold-thrust Belt and the Trishear Model of Fault-propagation Folding" (2014). LSU Doctoral Dissertations. 2683. https://digitalcommons.lsu.edu/gradschool_dissertations/2683 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. CONTRACTIONAL TECTONICS: INVESTIGATIONS OF ONGOING CONSTRUCTION OF THE HIMALAYAN FOLD-THRUST BELT AND THE TRISHEAR MODEL OF FAULT-PROPAGATION FOLDING A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Geology and Geophysics by Hongjiao Yu B.S., China University of Petroleum, 2006 M.S., Peking University, 2009 August 2014 ACKNOWLEDGMENTS I have had a wonderful five-year adventure in the Department of Geology and Geophysics at Louisiana State University. I owe a lot of gratitude to many people and I would not have been able to complete my PhD research without the support and help from them. -
Structural and Kinematic Analyses of the Basement Window Within the Hinterland Fold-And-Thrust Belt of the Zagros Orogen, Iran
Geol. Mag.: page 1 of 18 c Cambridge University Press 2016 1 doi:10.1017/S0016756816000558 Structural and kinematic analyses of the basement window within the hinterland fold-and-thrust belt of the Zagros orogen, Iran ∗ KHALIL SARKARINEJAD & SOMAYE DERIKVAND Department of Earth Sciences, College of Sciences, Shiraz University, Shiraz 71454, Iran (Received 1 December 2015; accepted 18 May 2016) Abstract – The Zagros hinterland fold-and-thrust belt is located in the central portion of the Zagros Thrust System and consists of the exhumed basement windows associated with NW-striking and NE-dipping flexural duplex structures that contain in-sequence thrusting and related folds. Mylonitic nappes of the basement were exhumed along deep-seated sole thrusts of the Zagros Thrust System. Lattice preferred orientation (LPO) c-axes of quartz show asymmetric type-1 crossed girdles that demonstrate a non-coaxial deformation under plane strain conditions. Based on the opening angles of quartz c-axis fabric skeletons, deformation temperatures vary from 425 ± 50 °C to 540 ± 50 °C, indicating amphibolite facies conditions. The estimated mean kinematic vorticity evaluated from quartz c-axis of the quartzo-feldspathic mylonites (Wm = 0.55 ± 0.06) indicates the degree of non- coaxiality during mylonite exhumation. The estimated angle θ between the maximum instantaneous strain axis (ISA1) and the transpressional zone boundary is 17°, and the angle of oblique convergence is 57° in the M2 nappe of the basement involved. This indicates that the mylonitic nappe was formed by a combination of 62 % pure shear and 38 % simple shear during oblique convergence. Keywords: transpressional zone, mylonitic nappe, vorticity, quartz c-axis, Zagros orogenic belt. -
Redalyc.From Thrust Tectonics to Diapirism. the Role of Evaporites in the Kinematic Evolution of the Eastern South Pyrenean
Geologica Acta: an international earth science journal ISSN: 1695-6133 [email protected] Universitat de Barcelona España Sans, M. From thrust tectonics to diapirism. The role of evaporites in the kinematic evolution of the eastern South Pyrenean front Geologica Acta: an international earth science journal, vol. 1, núm. 3, 2003, pp. 239-259 Universitat de Barcelona Barcelona, España Available in: http://www.redalyc.org/articulo.oa?id=50510301 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Geologica Acta, Vol.1, Nº3, 2003, 239-259 Available online at www.geologica-acta.com From thrust tectonics to diapirism. The role of evaporites in the kinematic evolution of the eastern South Pyrenean front M. SANS Dept. Geodinàmica i Geofísica, Universitat de Barcelona Zona Universitària de Pedralbes, 08028 Barcelona. Spain. E-mail: [email protected] ABSTRACT The South Pyrenean foreland has a buried thrust front geometry where evaporitic levels are present at the sub- surface and are suitable to be detachment horizons. The thrust wedge geometry developed at the externalmost limit of the evaporitic levels permits to define the South Pyrenean Triangle zone. This triangle zone is an excel- lent scenario to study the influence of evaporitic layers in the thrust front geometry of a fold and thrust system and in the development of thrust wedges. Analogue modelling shows different thrust wedge geometries through the deformation history in relation to the different rheological properties of the detachment horizons. -
Oscillations
CHAPTER FOURTEEN OSCILLATIONS 14.1 INTRODUCTION In our daily life we come across various kinds of motions. You have already learnt about some of them, e.g., rectilinear 14.1 Introduction motion and motion of a projectile. Both these motions are 14.2 Periodic and oscillatory non-repetitive. We have also learnt about uniform circular motions motion and orbital motion of planets in the solar system. In 14.3 Simple harmonic motion these cases, the motion is repeated after a certain interval of 14.4 Simple harmonic motion time, that is, it is periodic. In your childhood, you must have and uniform circular enjoyed rocking in a cradle or swinging on a swing. Both motion these motions are repetitive in nature but different from the 14.5 Velocity and acceleration periodic motion of a planet. Here, the object moves to and fro in simple harmonic motion about a mean position. The pendulum of a wall clock executes 14.6 Force law for simple a similar motion. Examples of such periodic to and fro harmonic motion motion abound: a boat tossing up and down in a river, the 14.7 Energy in simple harmonic piston in a steam engine going back and forth, etc. Such a motion motion is termed as oscillatory motion. In this chapter we 14.8 Some systems executing study this motion. simple harmonic motion The study of oscillatory motion is basic to physics; its 14.9 Damped simple harmonic motion concepts are required for the understanding of many physical 14.10 Forced oscillations and phenomena. In musical instruments, like the sitar, the guitar resonance or the violin, we come across vibrating strings that produce pleasing sounds.