DOCSLIB.ORG

Continental Collision Structures and Post-Orogenic Geological History Of

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Continental Collision Structures and Post-Orogenic Geological History Of Geosciences 2014, 4, 316-334; doi:10.3390/geosciences4040316 OPEN ACCESS geosciences ISSN 2076-3263 www.mdpi.com/journal/geosciences Review Continental Collision Structures and Post-Orogenic Geological History of the Kangerlussuaq Area in the Southern Part of the Nagssugtoqidian Orogen, Central West Greenland Jon Engström 1,* and Knud Erik S. Klint 2 1 Geological Survey of Finland, P.O. Box 96, SF-02151 Espoo, Finland 2 Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +358-29-503-2624; Fax: +358-29-503-2901. External Editors: Ken McCaffrey and Jesus Martinez-Frias Received: 29 August 2014; in revised form: 23 November 2014 / Accepted: 2 December 2014 / Published: 10 December 2014 Abstract: Deep-seated continental collision sutures, formed at a depth of more than 20 km, are exposed near Kangerlussuaq, close to the Greenland ice cap, on the southern margin of the Nagssugtoqidian orogen in Central West Greenland, thus offering a rare opportunity to study the tectonic deformation style of such an orogen. This paper adds new information on the tectonic history of the southern flank of the Nagssugtoqidian orogen. It focuses on (1) the results of a detailed structural investigation of lineament zones revealed from remote sensing of geophysical and topographic data and aerial photo interpretation, (2) detailed geological mapping at key locations and (3) a tectonic structural model describing the geological development of the area. The area has undergone several episodes of deformation, which have been compiled into an event succession that recognizes eight tectonic events overprinting each other: Two stages of folding (F1 and F2) have been identified along with one major episode of intrusion of the Kangâmiut mafic dyke swarm (2.05 Ga) into the Archaean continent. These dyke intrusions are very important, since by examining the style of deformation for these intrusions it is possible to define the transition from the North Atlantic Craton in the south to the mobile belts in the Nagssugtoqidian orogen in the north. Five different types of pronounced lineaments and one less pronounced lineament post-dating the Kangâmiut dykes extending from ductile deformation shearing events to brittle deformation with extensive faulting. These lineaments cover both the collisional and post-collisional Geosciences 2014, 4 317 tectonic history of the area. The study focused on two types of lineaments: one semi-ductile type trending E–W with a dextral sense of shear and a second, a pronounced lineament outlining the Kangerlussuaq–Russell thrust fault. These two features are interpreted to be related to the Nagssugtoqidian orogeny, while the latter lineaments have a more brittle appearance and are regarded to be considerably younger and probably related to post-orogenic tectonic events. Keywords: continental collision structures; Kangerlussuaq–Russell thrust fault; tectonic structural model; Nagssugtoqidian orogeny; West Greenland 1. Introduction The Nagssugtoqidian orogeny of West Greenland mainly occurred between 1.92 and 1.75 Ga [1], as a consequence of the convergence and collision of the North Atlantic Craton and a poorly defined craton to the north [2]. The Palaeoproterozoic reworking during the orogeny extends from Kangerlussuaq to southern Disko Bugt [3–5]. Several studies have been performed in the central and northern areas of the Nagssugtoqidian orogen (e.g., [1,6]), while the southern end of the orogen at the northern margin of the North Atlantic Craton, in the proximity of Kangerlussuaq, has largely remained unexplored. However, since 2008, the international Greenland Analogue Project (GAP) has been conducting intensive research in the area around Kangerlussuaq [7]. The main goal of the GAP has been to investigate the deep groundwater in a glaciated terrain. In order to study and model the hydrogeology, a detailed geological investigation and a conceptual geological 3D model of the fault/fracture zones was required. The GAP also drilled three cored boreholes in the vicinity of the ice margin, which provided data for the 3D geological interpretation. The geological survey revealed a number of structures formed in a plate tectonic collision zone, and the main goal of this paper is to add complementary information to aid in understanding the formation of the Nagssugtoqidian orogen in central West Greenland. 2. Background: The Development of the Nagssugtoqidian Orogen and the Study Area The Nagssugtoqidian orogen is interpreted as a collisional orogenic setting where juvenile Palaeoproterozoic igneous rocks intruded Archaean units and where Palaeoproterozoic sedimentary volcanic rocks were deposited. The orogen is now seen as an approximately 250-km-wide, south- to southeastward-trending belt that includes diverse Archaean and Palaeoproterozoic rocks affected by polyphase deformation and high-grade metamorphism [8]. Along the northern margin of the North Atlantic craton, within the southern Nagssugtoqidian orogen, Archaean dioritic, granodioritic, tonalitic and granitic orthogneiss of the North Atlantic craton predominate, albeit in a reworked state [2,9–12]. The orthogneisses have been dated to 2.87–2.81 Ga, with the plutonic protoliths deformed and metamorphosed between 2.81 and 2.72 Ga, immediately after their emplacement [11,12]. The orthogneisses are cut by several sets of mafic dykes, the most voluminous of which is the E–W- to NE–SW-trending, 2.05–2.04 Ga Kangâmiut dyke swarm [13–21]. The Kangâmiut dyke swarm, which extends from the Archaean foreland into the centre of the orogen, has become reworked across a sharp transition at the southern Geosciences 2014, 4 318 Nagssugtoqidian front. Its northern extent is abruptly terminated by the Ikertoôq thrust zone (Figure 1), which is a south-vergent ductile shear zone [2]. Dykes from the Kangâmiut swarm occur in the Archaean gneiss complex for approximately 150 km south of the thrust zones traditionally taken as marking the southern Nagssugtoqidian front in SW Greenland, and continue as deformed bodies in the reworked Archaean gneisses for approximately 50–100 km to the north of the front [17]. The granulite-facies thermal peak of metamorphism in the core of the orogen was dated at ca. 1.86–1.84 Ga [11,20,22,23]. This age interval coincides with the timing of thrusting and is interpreted as documenting the main phase of collision across the Nagssugtoqidian orogen. The Nagssugtoqidian orogen is interpreted as being associated with the closure of two south-dipping Palaeoproterozoic sutures [6,24,25]: (1) a northern suture, the Disko Bugt suture, which separates the lower plate Rae craton from the middle Aasiaat domain; and (2) a southern suture rooting in the Nordre Isortoq steep belt that separates the southerly-located North Atlantic Craton from the Aasiaat domain [26]. This model was further developed by Garde and Hollis [1], who concluded there are two south- to SSE-dipping subduction zones in the central and northern Nagssugtoqidian orogen, which were separated by the previously unidentified Aasiaat domain or microcontinent. Figure 1. (A) Geological map of the central West Greenland and the Nagssugtoqidian orogen, indicating the location of Kangerlussuaq. Map modified from van Gool et al. [2]. (B) A lineament and geological map of the study area, in front of the Greenland ice sheet. Map modified from Garde and Marker [27]. The Study Area The study area is located at the southern end of the orogen in the vicinity of the North Atlantic Craton (Figure 1). It covers a domain of 60 km × 80 km with a special focus on an area at the front of the Geosciences 2014, 4 319 Greenland ice sheet (Figure 1A). Most of the mapping, including the drilling of three deep boreholes, was conducted in area A (Figure 1B) during field campaigns in 2008–2009, while area B was surveyed during mapping campaigns in 2010–2011. A geological 3D model close to the boreholes was constructed for groundwater modelling purposes. The mapping at other locations primarily focused on the nature of the lineaments and their crosscutting relations in order to identify lineaments with potential for hydraulically conductive fractures/faults. A preliminary geological event succession based on lineament interpretation of the area was presented by Klint et al. [28] in 2013, complementary data were collected in the field, and this paper presents an updated geological model of the Kangerlussuaq area. The study area, extending from Kangerlussuaq Airport to the ice sheet, is dominated by primarily felsic banded gneisses and mafic garnet-rich orthogneisses, intruded in places by pronounced 1–25-m-wide Kangâmiut dykes, especially in the southwestern part of the study area. Detailed geological mapping focused on selected sites from Kangerlussuaq Airport to the margin of the ice sheet (Figures 1B and 2). The Nagssugtoqidian structures reflect the general ductile nature of the regional deformation and include a penetrative gneissic fabric, macro-scale folds, and evidence of shearing in pronounced shear zones. Brittle structures such as faults and fractures are abundant and were probably formed in a younger, shallow, colder and hence more rigid environment. Figure 2. Geological map illustrating the distribution of the lineaments in the ice-margin valley area as well as the main general structures and rock fabric. Seven key locations were investigated in 2011 and three more (Figures 3–5) in 2013. The key locations described below are highlighted along with the different lineament systems defined by Klint et al. [28]. Geosciences 2014, 4 320 Figure 3. Geological map illustrating the geology around the two boreholes, DH-GAP03 and DH-GAP04. The cross-section illustrates how the folding pattern changes from a larger open fold in the E towards tight to isoclinal folding in the W. The same can be observed in the stereographic plots. Geosciences 2014, 4 321 Figure 4. Location B. Overview of the BBQ location. Detailed measurements of faults and fractures were conducted along 3 transects, BBQ 1–3.
Load more

Recommended publications
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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)
    [Show full text]
  • 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).
    [Show full text]
  • THE GROWTH of SHEEP MOUNTAIN ANTICLINE: COMPARISON of FIELD DATA and NUMERICAL MODELS Nicolas Bellahsen and Patricia E
    THE GROWTH OF SHEEP MOUNTAIN ANTICLINE: COMPARISON OF FIELD DATA AND NUMERICAL MODELS Nicolas Bellahsen and Patricia E. Fiore Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 e-mail: [email protected] be explained by this deformed basement cover interface Abstract and does not require that the underlying fault to be listric. In his kinematic model of a basement involved We study the vertical, compression parallel joint compressive structure, Narr (1994) assumes that the set that formed at Sheep Mountain Anticline during the basement can undergo significant deformations. Casas early Laramide orogeny, prior to the associated folding et al. (2003), in their analysis of field data, show that a event. Field data indicate that this joint set has a basement thrust sheet can undergo a significant heterogeneous distribution over the fold. It is much less penetrative deformation, as it passes over a flat-ramp numerous in the forelimb than in the hinge and geometry (fault-bend fold). Bump (2003) also discussed backlimb, and in fact is absent in many of the forelimb how, in several cases, the basement rocks must be field measurement sites. Using 3D elastic numerical deformed by the fault-propagation fold process. models, we show that early slip along an underlying It is noteworthy that basement deformation often is thrust fault would have locally perturbed the neglected in kinematic (Erslev, 1991; McConnell, surrounding stress field, inducing a compression that 1994), analogue (Sanford, 1959; Friedman et al., 1980), would inhibit joint formation above the fault tip. and numerical models. This can be attributed partially Relating the absence of joints in the forelimb to this to the fact that an understanding of how internal stress perturbation, we are able to constrain the deformation is delocalized in the basement is lacking.
    [Show full text]
  • Deepwater Fold-And-Thrust Belt Along New Caledonia's Western Margin
    Deepwater fold-and-thrust belt along New Caledonia’s western margin: relation to post-obduction vertical motions J. Collot, M. Patriat, S. Etienne, P. Rouillard, F. Soetaert, C Juan, B. Marcaillou, Giulia Palazzin, Camille Clerc, P. Maurizot, et al. To cite this version: J. Collot, M. Patriat, S. Etienne, P. Rouillard, F. Soetaert, et al.. Deepwater fold-and-thrust belt along New Caledonia’s western margin: relation to post-obduction vertical motions. Tectonics, American Geophysical Union (AGU), 2017, 36, pp.2108-2122. 10.1002/2017TC004542. insu-01614136 HAL Id: insu-01614136 https://hal-insu.archives-ouvertes.fr/insu-01614136 Submitted on 24 Oct 2017 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. PUBLICATIONS Tectonics RESEARCH ARTICLE Deepwater Fold-and-Thrust Belt Along New 10.1002/2017TC004542 Caledonia’s Western Margin: Relation Key Points: to Post-obduction Vertical Motions • New deepwater fold-and-thrust belt discovered off New Caledonia’s J. Collot1 , M. Patriat1,2 , S. Etienne1,3 , P. Rouillard1,3,4, F. Soetaert1,2, C. Juan1, western margin 5 6 7 1 1,3 1,3 1 • Origin of the deepwater B. Marcaillou , G. Palazzin , C.
    [Show full text]
  • Collision Orogeny
    Downloaded from http://sp.lyellcollection.org/ by guest on October 6, 2021 PROCESSES OF COLLISION OROGENY Downloaded from http://sp.lyellcollection.org/ by guest on October 6, 2021 Downloaded from http://sp.lyellcollection.org/ by guest on October 6, 2021 Shortening of continental lithosphere: the neotectonics of Eastern Anatolia a young collision zone J.F. Dewey, M.R. Hempton, W.S.F. Kidd, F. Saroglu & A.M.C. ~eng6r SUMMARY: We use the tectonics of Eastern Anatolia to exemplify many of the different aspects of collision tectonics, namely the formation of plateaux, thrust belts, foreland flexures, widespread foreland/hinterland deformation zones and orogenic collapse/distension zones. Eastern Anatolia is a 2 km high plateau bounded to the S by the southward-verging Bitlis Thrust Zone and to the N by the Pontide/Minor Caucasus Zone. It has developed as the surface expression of a zone of progressively thickening crust beginning about 12 Ma in the medial Miocene and has resulted from the squeezing and shortening of Eastern Anatolia between the Arabian and European Plates following the Serravallian demise of the last oceanic or quasi- oceanic tract between Arabia and Eurasia. Thickening of the crust to about 52 km has been accompanied by major strike-slip faulting on the rightqateral N Anatolian Transform Fault (NATF) and the left-lateral E Anatolian Transform Fault (EATF) which approximately bound an Anatolian Wedge that is being driven westwards to override the oceanic lithosphere of the Mediterranean along subduction zones from Cephalonia to Crete, and Rhodes to Cyprus. This neotectonic regime began about 12 Ma in Late Serravallian times with uplift from wide- spread littoral/neritic marine conditions to open seasonal wooded savanna with coiluvial, fluvial and limnic environments, and the deposition of the thick Tortonian Kythrean Flysch in the Eastern Mediterranean.
    [Show full text]
  • Accommodation of Penetrative Strain During Deformation Above a Ductile Décollement
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Earth and Atmospheric Sciences, Department Papers in the Earth and Atmospheric Sciences of 2016 Accommodation of penetrative strain during deformation above a ductile décollement Bailey A. Lathrop Caroline M. Burberry Follow this and additional works at: https://digitalcommons.unl.edu/geosciencefacpub Part of the Earth Sciences Commons 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. Accommodation of penetrative strain during deformation above a ductile décollement Bailey A. Lathrop* and Caroline M. Burberry* DEPARTMENT OF EARTH AND ATMOSPHERIC SCIENCES, UNIVERSITY OF NEBRASKA-LINCOLN, 214 BESSEY HALL, LINCOLN, NEBRASKA 68588, USA ABSTRACT The accommodation of shortening by penetrative strain is widely considered as an important process during contraction, but the distribu- tion and magnitude of penetrative strain in a contractional system with a ductile décollement are not well understood. Penetrative strain constitutes the proportion of the total shortening across an orogen that is not accommodated by the development of macroscale structures, such as folds and thrusts. In order to create a framework for understanding penetrative strain in a brittle system above a ductile décollement, eight analog models, each with the same initial configuration, were shortened to different amounts in a deformation apparatus. Models consisted of a silicon polymer base layer overlain by three fine-grained sand layers. A grid was imprinted on the surface to track penetra- tive strain during shortening.
    [Show full text]
  • Bivergent Thrust Wedges Surrounding Oceanic Island Arcs: Insight from Observations and Sandbox Models of the Northeastern Caribbean Plate
    Downloaded from gsabulletin.gsapubs.org on February 8, 2010 Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern Caribbean plate Uri S. ten Brink1,†, Stephen Marshak2, and José-Luis Granja Bruña3 1U.S. Geological Survey, Woods Hole, Massachusetts 02543, USA 2Department of Geological Sciences, University of Illinois, Urbana, Illinois 61801, USA 3Geodynamics Department, Universidad Complutense de Madrid, Madrid 28040, Spain ABSTRACT modated entirely within the prowedge and 1993; Beaumont and Quinlan, 1994; Fig. 1A). the arc—the retrowedge hosts only dip-slip The material incorporated in bivergent orogens At several localities around the world, faulting (“frontal thrusting”). The existence is primarily crustal, therefore such orogens are thrust belts have developed on both sides of of large retrowedges and the distribution of also called “bivergent crustal wedges.” oceanic island arcs (e.g., Java-Timor, Pan- faulting in an island arc may, therefore, be There are several examples of island arcs in ama, Vanuatu, and the northeastern Carib- evidence that the arc is relatively rigid. The which a thrust belt with vergence opposite to that bean). In these localities, the overall vergence rigidity of an island arc may arise from its of the accretionary prism develops in the back- of the backarc thrust belt is opposite to that mafi c composition and has implications for arc region, so that bivergent thrusting involves of the forearc thrust belt. For example, in seismic-hazard analysis. the entire island arc (e.g., Banda, Vanuatu, the northeastern Caribbean, a north-verging and Panama arcs; Fig. 2). The Eastern Greater accretionary prism lies to the north of the INTRODUCTION Antilles arc (Hispaniola and Puerto Rico) of the Eastern Greater Antilles arc (Hispaniola and northeastern Caribbean illustrates this geom etry.
    [Show full text]
  • Characteristics of Thin-Skinned Style of Deformation in the Southern Appalachians, and Potential Hydrocarbon Traps
    Characteristics of Thin-Skinned Style of Deformation in the Southern Appalachians, and Potential Hydrocarbon Traps GEOLOGICAL SURVEY PROFESSIONAL PAPER 1O18 Characteristics of Thin-Skinned Style of Deformation in the Southern Appalachians, and Potential Hydrocarbon Traps By LEONARD D. HARRIS and ROBERT C. MILICI GEOLOGICAL SURVEY PROFESSIONAL PAPER 1018 Description of and field guide to large- and small-scale features of thin-skinned tectonics in the southern Appalachians, and a discussion of hydrocarbon production and potential UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1977 UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Doyle G. Frederick, Acting Director First printing 1977 Second printing 1981 Library of Congress Cataloging in Publication Data Harris, Leonard D. Characteristics of thin-skinned style of deformation in the southern Appalachians, and potential hydrocarbon traps. (Geological Survey professional paper ; 1018) Bibliography: p. Supt. of Docs, no.: I 19.16:1018 1. Rock deformation. 2. Geology Appalachian Mountains. 3. Petroleum -Geology Appalachian Mountains. I. Milici, Robert C., 1931- joint author. II. Title: Characteristics of thin-skinned style of deformation in the southern Appalachians . III. Series: United States. Geological Survey. Professional paper ; 1018. QE604.H37 551.8'7'09768 76-608283 For sale by the Distribution Branch, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 CONTENTS Page Abstract ———_—___________________________——_———————————
    [Show full text]
  • Thrust Faulting and Oil Possibilities in the Plains Adjacent to the Highwood Mountains, Montana ______
    THRUST FAULTING AND OIL POSSIBILITIES IN THE PLAINS ADJACENT TO THE HIGHWOOD MOUNTAINS, MONTANA ______ By FRANK REEVES INTRODUCTION Scope of paper. During May and June, 1926, the writer made a brief study of the geology in the plains adjacent to the High wood Mountains, in north-central Montana, the main purpose of which was the collection of data that would throw light on the origin of the thrust faults that nearly encircle the Bearpaw Mountains an iso­ lated group about 60 miles northeast of the Highwood Mountains. In this investigation it was discovered that thrust faults similar to those adjacent to the Bearpaw Mountains are present north and east of the Highwood Mountains. In the regional study of these faults it became evident that the strata are undisturbed except within a narrow belt, commonly 600 to 700 feet wide, on the upthrown side of the faults, and additional data were obtained in support of the writer's belief that the thrust faulting typical of the region affects only the upper half of the Colorado shale and overlying formations. The principal purpose of this paper is to describe these two features of the faulting, inasmuch as they have an important bearing on the oil and gas possibilities of the area and, to judge from past drilling, have not been recognized by the geologists who have directed the drill­ ing. Consequently, the report will be confined mainly to a description of the formations exposed and penetrated by the drill in the area, a description of the surface expression of the thrust faults, and presen-' tation of the evidence that the thrust faulting does not include the lower half of the Colorado shale and underlying formations, where oil is generally looked for in the region.
    [Show full text]
  • Active Folding and Blind Thrust Faulting Induced by Basin Inversion Processes, Inner California Borderlands, in K
    Rivero, Carlos, and John H. Shaw, 2011, Active folding and blind thrust faulting induced by basin inversion processes, inner California borderlands, in K. McClay, J. Shaw, and J. Suppe, eds., Thrust fault-related folding: AAPG Memoir 94, 9 p. 187 – 214. Active Folding and Blind Thrust Faulting Induced by Basin Inversion Processes, Inner California Borderlands Carlos Rivero1 Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, U.S.A. John H. Shaw Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, U.S.A. ABSTRACT The present bathymetry, basin geometries, and spatial earthquake distribution in the inner California borderlands reflect complex basin inversion processes that reactivated two low- angle Miocene extensional detachments as blind thrust faults during the Pliocene to Holocene. The Oceanside and the Thirtymile Bank detachments comprise the inner California blind thrust system. These low-angle detachments originated during Neogene crustal extension that opened the inner California borderlands, creating a rift system that controlled the deposition of early to late Miocene sedimentary units and the exhumation of the metamorphic Catalina schist. During the Pliocene, a transpressional regime induced by oblique convergence between the Pacific and the North American plates reactivated the Oceanside and the Thirtymile Bank detachments as blind thrust faults. This reactivation generated regional structural wedges cored by faulted basement blocks that inverted the sedimentary basins in the hanging wall of the Miocene extensional detachments and induced contractional fold trends along the coastal plain of Orange and San Diego counties. Favorably oriented high-angle normal faults were also reactivated, creating zones of oblique and strike-slip faulting and folding such as the offshore segments of the Rose Canyon, San Diego, and the Newport-Inglewood fault zones.
    [Show full text]