Detachment Folds Above a Passive-Roof Duplex: an Example from the Northeastern Brooks Range
Total Page:16
File Type:pdf, Size:1020Kb

Load more
Recommended publications
-
326-97 Lab Final S.D
Geol 326-97 Name: KEY 5/6/97 Class Ave = 101 / 150 Geol 326-97 Lab Final s.d. = 24 This lab final exam is worth 150 points of your total grade. Each lettered question is worth 15 points. Read through it all first to find out what you need to do. List all of your answers on these pages and attach any constructions, tracing paper overlays, etc. Put your name on all pages. 1. One way to analyze brittle faults is to calculate and plot the infinitesimal shortening and extension directions on a lower hemisphere, stereographic projection. These principal axes lie in the “movement plane”, which contains the pole to the fault plane and the slickensides, and are at 45° to the pole. The following questions apply to a single fault described in part (a), below: (a) A fault has a strike and dip of 250, 57 N and the slickensides have a rake of 63°, measured from the given strike azimuth. Plot the orientations of the fault plane and the slickensides on an equal area projection. (b) Bedding in the vicinity of the fault is oriented 37, 42 E. Assuming that the fault formed when the bedding was horizontal, determine and plot the original geometry of the fault and the slickensides. (c) Determine the original (pre-rotation)orientation of the infinitesimal shortening and extension axes for fault. 2. All of the following questions apply to the map shown on the next page. In all of the rocks with cleavage, you may assume that both cleavage and bedding strike 024°. -
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). -
Pacific Petroleum Eology
Pacific Petroleum Geology NEWSLETTER Pacific Section • American Association of Petroleum Geologists September & October• 2010 School of Rock Ridge Basin CONTENTS 2010-2011 OFF I C E RS EV E RY ISSU E President Cynthia Huggins 661.665.5074 [email protected] 4 Message from the President • C. Huggins President-Elect John Minch 805.898.9200 6 Editor’s Corner • E. Washburn [email protected] Vice President Jeff Gartland 7 PS-AAPG News 661.869.8204 [email protected] 13 Publications Secretary Tony Reid 661.412.5467 17 Member Society News [email protected] Treasurer 2009-2011 Cheryl Blume TH I S ISSU E 661.864.4722 [email protected] 8 Sharktooth Hill Fossil Fund • K. Hancharick Treasurer 2010-2012 Jana McIntyre 661.869.8231 [email protected] 10 AAPG Young Professionals • J. Allen Past President Scott Hector 11 Serpentine: The Rest of the Story • Mel 707.974.6402 [email protected] Erskine Editor-in-Chief Ed Washburn 661.654.7182 [email protected] ST AFF Web Master Bob Countryman 661.589.8580 [email protected] Membership Chair Brian Church 661.654.7863 [email protected] Publications Chair Larry Knauer 661.392.2471 [email protected] [email protected] Advisory Council Representative Kurt Neher 661.412.5203 [email protected] Cover photo of Ridge Basin outcrop courtesy Jonathan Allen Page 3 Pacific Petroleum Geologist Newsletter September & October • 2010 MESSAGE FRO M THE PRESIDENT CYNTHIA HUGGINS Do you know what Marilyn Bachman, Mike Fillipow, Peggy Lubchenco, and Jane Justus Frazier have in common? They were all recipients of the Teacher of the Year Award from AAPG, and they all came from the Pacific Section! Of the 13 recipients of this award, four have been from PSAAPG. -
Chapter 01.Pdf
Mathematical Background in Aircraft Structural Mechanics CHAPTER 1. Linear Elasticity SangJoon Shin School of Mechanical and Aerospace Engineering Seoul National University Active Aeroelasticityand Rotorcraft Lab. Basic equation of Linear Elasticity Structural analysis … evaluation of deformations and stresses arising within a solid object under the action of applied loads - if time is not explicitly considered as an independent variable → the analysis is said to be static → otherwise, structural dynamic analysis or structural dynamics Small deformation Under the assumption of { Linearly elastic material behavior - Three dimensional formulation → a set of 15 linear 1st order PDE involving displacement field (3 components) { stress field (6 components) strain field (6 components) plane stress problem → simpler, 2-D formulations { plane strain problem For most situations, not possible to develop analytical solutions → analysis of structural components … bars, beams, plates, shells 1-2 Active Aeroelasticity and Rotorcraft Lab., Seoul National University 1.1 The concept of Stress 1.1.1 The state of stress at a point State of stress in a solid body… measure of intensity of forces acting within the solid - distribution of forces and moments appearing on the surface of the cut … equipollent force F , and couple M - Newton’s 3rd law → a force and couple of equal magnitudes and opposite directions acting on the two forces created by the cut Fig. 1.1 A solid body cut by a plane to isolate a free body 1-3 Active Aeroelasticity and Rotorcraft -
Folds and Folding
Chapter ................................ 11 Folds and folding Folds are eye-catching and visually attractive structures that can form in practically any rock type, tectonic setting and depth. For these reasons they have been recognized, admired and explored since long before geology became a science (Leonardo da Vinci discussed them some 500 years ago, and Nicholas Steno in 1669). Our understanding of folds and folding has changed over time, and the fundament of what is today called modern fold theory was more or less consolidated in the 1950s and 1960s. Folds, whether observed on the micro-, meso- or macroscale, are clearly some of our most important windows into local and regional deformation histories of the past. Their geometry and expression carry important information about the type of deformation, kinematics and tectonics of an area. Besides, they can be of great economic importance, both as oil traps and in the search for and exploitation of ores and other mineral resources. In this chapter we will first look at the geometric aspects of folds and then pay attention to the processes and mechanisms at work during folding of rock layers. 220 Folds and folding 11.1 Geometric description (a) Kink band a a It is fascinating to watch folds form and develop in the laboratory, and we can learn much about folds and folding by performing controlled physical experiments and numerical simulations. However, modeling must always be rooted in observations of naturally folded Trace of Axial trace rocks, so geometric analysis of folds formed in different bisecting surface settings and rock types is fundamental. Geometric analy- (b) Chevron folds sis is important not only in order to understand how various types of folds form, but also when considering such things as hydrocarbon traps and folded ores in the subsurface. -
The Role of Flexural Slip in the Development of Chevron Folds
Scholars' Mine Masters Theses Student Theses and Dissertations Spring 2018 The role of flexural slip in the development of chevron folds Yuxing Wu Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses Part of the Petroleum Engineering Commons Department: Recommended Citation Wu, Yuxing, "The role of flexural slip in the development of chevron folds" (2018). Masters Theses. 7788. https://scholarsmine.mst.edu/masters_theses/7788 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. i THE ROLE OF FLEXURAL SLIP IN THE DEVELOPMENT OF CHEVRON FOLDS by YUXING WU A THESIS Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE IN PETROLEUM ENGINEERING 2018 Approved by Andreas Eckert, Advisor John Patrick Hogan Jonathan Obrist Farner ii 2018 Yuxing Wu All Rights Reserved iii ABSTRACT Chevron folds are characterized by straight limbs and narrow hinge zones. One of the conceptual models to initiate and develop chevron folds involves flexural slip during folding. While some kinematical models show the necessity for slip to initiate during chevron folding, recent numerical modeling studies of visco-elastic effective single layer buckle folding have shown that flexural slip does not result in chevron folds. In this study, several 2D finite element analysis models are run, distinguished by 1) geometry of the initial perturbation (sinusoidal and white noise), 2) varying thewavelength of the initial perturbation (10%, 50%, and 100% of the dominant wavelength) and 3) variation of the friction coefficient (high and low friction coefficient between interlayers). -
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. -
The Structure and Kinematics of the Southeastern Zagros Fold-Thrust Belt, Iran : from Thin-Skinned to Thick-Skinned Tectonics M
The structure and kinematics of the southeastern Zagros fold-thrust belt, Iran : From thin-skinned to thick-skinned tectonics M. Molinaro, Pascale Leturmy, Jean-Claude Guezou, Dominique Frizon de Lamotte To cite this version: M. Molinaro, Pascale Leturmy, Jean-Claude Guezou, Dominique Frizon de Lamotte. The struc- ture and kinematics of the southeastern Zagros fold-thrust belt, Iran : From thin-skinned to thick- skinned tectonics. Tectonics, American Geophysical Union (AGU), 2005, 24 (3), pp.TC3007. 10.1029/2004TC001633. hal-00022420 HAL Id: hal-00022420 https://hal.archives-ouvertes.fr/hal-00022420 Submitted on 20 May 2021 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. TECTONICS, VOL. 24, TC3007, doi:10.1029/2004TC001633, 2005 The structure and kinematics of the southeastern Zagros fold- thrust belt, Iran: From thin-skinned to thick-skinned tectonics M. Molinaro, P. Leturmy, J.-C. Guezou, and D. Frizon de Lamotte De´partement des Sciences de la Terre et de l’Environnement, UMR 7072, CNRS, Universite´ de Cergy-Pontoise, Cergy, France S. A. Eshraghi Geological Survey of Iran, Tehran, Iran Received 17 February 2004; revised 14 February 2005; accepted 11 March 2005; published 15 June 2005. -
Joints, Folds, and Faults
Structural Geology Rocks in the Crust Are Bent, Stretched, and Broken … …by directed stresses that cause Deformation. Types of Differential Stress Tensional, Compressive, and Shear Strain is the change in shape and or volume of a rock caused by Stress. Joints, Folds, and Faults Strain occurs in 3 stages: elastic deformation, ductile deformation, brittle deformation 1 Type of Strain Dependent on … • Temperature • Confining Pressure • Rate of Strain • Presence of Water • Composition of the Rock Dip-Slip and Strike-Slip Faults Are the Most Common Types of Faults. Major Fault Types 2 Fault Block Horst and Graben BASIN AND Crustal Extension Formed the RANGE PROVINCE Basin and Range Province. • Decompression melting and high heat developed above a subducted rift zone. • Former margin of Farallon and Pacific plates. • Thickening, uplift ,and tensional stress caused normal faults. • Horst and Graben structures developed. Fold Terminology 3 Open Anticline – convex upward arch with older rocks in the center of the fold (symmetrical) Isoclinal Asymmetrical Overturned Recumbent Evolution Simple Folds of a fold into a reverse fault An eroded anticline will have older beds in the middle An eroded syncline will have younger beds in middle Outcrop patterns 4 • The Strike of a body of rock is a line representing the intersection of A layer of tilted that feature with the plane of the horizon (always measured perpendicular to the Dip). rock can be • Dip is the angle below the horizontal of a geologic feature. represented with a plane. o 30 The orientation of that plane in space is defined with Strike-and- Dip notation. Maps are two- Geologic Map Showing Topography, Lithology, and dimensional Age of Rock Units in “Map View”. -
Thesis-Reproduction (Electronic)
A synopsis of the geologic and structural history of the Randsburg Mining District Item Type text; Thesis-Reproduction (electronic) Authors Morehouse, Jeffrey Allen, 1953-1985 Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 27/09/2021 08:53:56 Link to Item http://hdl.handle.net/10150/558085 Call No. BINDING INSTRUCTIONS INTERUBRARY INSTRUCTIONS Dept. E9791 Author: Morehouse, J. 1988 245 Title: RUSH___________________ PERMABIND____________ PAMPHLET._____________ GIFT____________________ COLOR: M,S* POCKET FOR MAP______ COVERS Front_______Both Special Instructions - Bindery or Repair REFERENCE____ i________ O th er--------------------------- 3 /2 /9 0 A SYNOPSIS OF THE GEOLOGIC AND STRUCTURAL HISTORY OF THE RANDSBURG MINING DISTRICT by Jeffrey Allen Morehouse A Thesis Submitted to the Faculty of the DEPARTMENT OF GEOSCIENCES In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 19 8 8 THE UNIVERSITY OF ARIZONA TUCSON, ARIZONA 85721 DEPARTMENT OF GEOSCIENCES BUILDING *77 GOULD-SIMPSON BUILDING TEL (602) 621-6024 To the reader of Jeff Morehouse's thesis: Jeff Morehouse's life was lamentably cut short by a hiking-rock climbing accident in the Santa Catalina Mountains near Tucson, Arizona, on March 24, 1985. Those who knew Jeff will always regret that accident, not only because it abbreviated what would certainly have been an uncommonly productive geological career but also because it snuffed an effervescent, optimistic,, charming personality. -
Development of a Dilatant Damage Zone Along a Thrust Relay in a Low-Porosity Quartz Arenite
Journal of Structural Geology 28 (2006) 776–792 www.elsevier.com/locate/jsg Development of a dilatant damage zone along a thrust relay in a low-porosity quartz arenite Jennie E. Cook a, William M. Dunne a,*, Charles M. Onasch b a Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1410, USA b Department of Geology, Bowling Green State University, Bowling Green, OH 43403, USA Received 12 August 2005; received in revised form 26 January 2006; accepted 15 February 2006 Available online 18 April 2006 Abstract A damage zone along a backthrust fault system in well-cemented quartz arenite in the Alleghanian foreland thrust system consists of a network of NW-dipping thrusts that are linked by multiple higher-order faults and bound a zone of intense extensional fractures and breccias. The damage zone developed at an extensional step-over between two independent, laterally propagating backthrusts. The zone is unusual because it preserves porous brittle fabrics despite formation at O5 km depth. The presence of pervasive, late-stage fault-normal joints in a fault-bounded horse in the northwestern damage zone indicates formation between two near-frictionless faults. This decrease in frictional resistance was likely a result of increased fluid pressure. In addition to physical effects, chemical effects of fluid also influenced damage zone development. Quartz cements, fluid inclusion data, and Fourier Transform Infrared analysis indicate that both aqueous and methane-rich fluids were present within the damage zone at different times. The backthrust network likely acted as a fluid conduit system, bringing methane-rich fluids up from the underlying unit and displacing resident aqueous fluids. -
Controls on Structural Styles and Decoupling in Stratigraphic Sequences
Manuscript submitted to Journal of Structural Geoloy 1 Controls on structural styles and decoupling in stratigraphic sequences 2 with double décollements during thin-skinned contractional tectonics: 3 insights from numerical modelling 4 Qingfeng Meng*1, David Hodgetts 5 School of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK 6 Abstract 7 Six series of particle-based numerical experiments were performed to simulate thin-skinned 8 contractional tectonics in stratigraphic sequences with double décollements during horizontal 9 shortening. The models were assigned with varying rock competence, depth and thickness of the 10 upper décollement, which resulted in significantly different styles of deformation and decoupling 11 characteristics above and below the upper décollement. The models composed of the least 12 competent material produced distributed sinusoidal detachment folds, with many shallow 13 structures profoundly decoupled from the deep-seated folds. The models composed of a more 14 competent material are dominated by faulted, diapir-cored box folds, with minor disharmonic folds 15 developed in their limbs. Differently, the results of models composed of the most competent 16 material are characterised by localised piggyback thrusts, fault-bend folds and pop-up structures 17 with tensile fractures developed in fold hinges. Depth of the upper décollements also plays an 18 important role in controlling structural decoupling, i.e. the shallower the upper décollements, the 19 higher the degree of decoupling becomes. Thicker upper décollements can provide sufficient 20 mobile materials to fill fold cores, and contribute to the formation of secondary disharmonic folds, 21 helping enhance structural decoupling. Our modelling results are comparable to the structural 1 *Corresponding author.