DOCSLIB.ORG

Subduction Zone Backarcs, Mobile Belts, and Orogenic Heat

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Subduction Zone Backarcs, Mobile Belts, and Orogenic Heat VVOL.OL. 115,5, NNO.O. 2 A PPUBLICATIONUBLICATION OFOF TTHEHE GGEOLOGICALEOLOGICAL SSOCIETYOCIETY OOFF AAMERICAMERICA FFEBRUARYEBRUARY 22005005 Subduction zone backarcs, mobile belts, and orogenic heat Inside: Subduction zone backarcs, mobile belts, and orogenic heat, ROY D. HYNDMAN, CLAIRE A. CURRIE, AND STEPHANE P. M AZZOTTI, p. 4 2004–2005 Division Officers and Past Chairs, p. 11 GeoVentures™ 2005, p. 29 An Earth Scientist’s Periodic Table of the Elements and Their Ions by L. Bruce Railsback An Earth Scientist’s Periodic Table of the Elements and form as ions rather than in elemental form. The immediate Their Ions is a new periodic table designed to contextualize result is a completely rearranged table in which many trends in geochemistry, mineralogy, aqueous chemistry, elements appear multiple times, because many elements and other natural sciences. First published as an insert assume different charge under different natural conditions. in the September 2003 issue of Geology, this version is The practical result is that many trends in mineralogy, updated and supersized—36" by 76"! seawater chemistry, soil chemistry, the chemistry of This new periodic table of the elements is more useful Earth’s crust and mantle, the chemistry of sediments, and to earth scientists than the conventional periodic table nutrient chemistry become apparent in ways that are not used by chemists. The periodic table presented here recognizable on conventional, elementally constructed, acknowledges that most natural matter occurs in charged periodic tables. MCH092F, 1 folded sheet (36" × 76"), 7 p. text $25.00, member price $20.00—folded MCH092R, 1 rolled sheet (36" × 76"), 7 p. text $30.00, member price $24.00—rolled Order online at: GSA Sales and Service P.O. Box 9140, Boulder, CO 80301-9140 (303) 357-1000, option 3 www.geosociety.org/bookstore 1-888-443-4472 • fax 303-357-1071 Volume 15, Number 2 FEBRUARY 2005 Cover: The North America Cordillera GSA TODAY publishes news and information for more than mobile belt illustrating the high elevation 18,000 GSA members and subscribing libraries. GSA Today and complex tectonics characteristic of hot, lead science articles should present the results of exciting new thin backarc lithospheres. Backarcs remain research or summarize and synthesize important problems weak enough to be deformed by plate or issues, and they must be understandable to all in the earth margin forces for long geological periods. science community. Submit manuscripts to science editors Keith A. Howard, [email protected], or Gerald M. Ross, Right: Heat flow and thermal-tectonic cross [email protected]. section for N. Cascadia backarc illustrating uniform high heat flow and inferred GSA TODAY (ISSN 1052-5173 USPS 0456-530) is published 11 shallow asthenosphere convection. See times per year, monthly, with a combined April/May issue, by The “Subduction zone backarcs, mobile belts, Geological Society of America, Inc., with offices at 3300 Penrose Place, Boulder, Colorado. Mailing address: P.O. Box 9140, and orogenic heat,” by R.D. Hyndman et Boulder, CO 80301-9140, USA. Periodicals postage paid at al., p. 4–10. Boulder, Colorado, and at additional mailing offices. Postmaster: Send address changes to GSA Today, GSA Sales and Service, P.O. Box 9140, Boulder, CO 80301-9140. Copyright © 2005, The Geological Society of America, Inc. (GSA). All rights reserved. Copyright not claimed on content prepared SCIENCE ARTICLE wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, 4 Subduction zone backarcs, mobile belts, and orogenic heat, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in other subsequent ROY D. HYNDMAN, CLAIRE A. CURRIE, AND STEPHANE P. MAZZOTTI works and to make unlimited photocopies of items in this journal for noncommercial use in classrooms to further education and science. For any other use, contact Copyright Permissions, GSA, P.O. Box 9140, Boulder, CO 80301-9140, USA, Fax 303- 11 Meeting Wrap-up—Denver 2004: Geoscience in a Changing World 357-1073, [email protected]; reference GSA Today, ISSN 1052-5173. Permission is granted to authors to post the abstracts only of their articles on their own or their organization’s Web site 11 2004–2005 Division Officers and Past Chairs providing the posting includes this reference: “The full paper was published in the Geological Society of America’s journal GSA 2004 GSA Medals and Awards Today, [include year, month, and page numbers if known, where 12 the article will appear].” GSA provides this and other forums for the presentation of diverse opinions and positions by scientists 13 2004 Honorary Fellows worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. 13 2004 GSA Division Awards SUBSCRIPTIONS for 2005 calendar year: Society Members: GSA Today is provided as part of membership dues. Contact 15 Call for Nominations: Fourteenth Annual Biggs Award for GSA Sales and Service at 1-888-443-4472, (303) 357-1000, Excellence in Earth Science Teaching for Beginning Professors option 3, or [email protected] for membership information. Nonmembers & Institutions: Free with paid subscription to both GSA Bulletin and Geology, otherwise 15 Mann Mentor Programs—Careers in Hydrogeology and $75. Contact Subscription Services at (800) 627-0629 or Hydrology [email protected]. Also available on an annual CD-ROM (together with GSA Bulletin, Geology, GSA Data Repository, and an Electronic Retrospective Index to journal articles from 1972); 16 Final Announcement and Call for Papers: North-Central Section $99 to GSA Members, others call GSA Subscription Services for prices and details. Claims: For nonreceipt or for damaged copies, members contact GSA Sales and Service; all others 19 GSA Section Meetings contact Subscription Services. Claims are honored for one year; please allow sufficient delivery time for overseas copies, up to 22 Mentor Programs—Students: Mark your calendars! six months. GSA TODAY STAFF: 23 Final Announcement and Call for Papers: Rocky Mountain Section Executive Director: John W. Hess Science Editors: Keith A. Howard, U.S. Geological Survey, MS 919, Menlo Park, CA 94025, USA, [email protected]; 28 Upcoming Deadlines and Gerald M. Ross, Kupa’a Farm, Box 458, Kula, HI 96790, [email protected]. GeoCorps™ America—Summer application deadline is just days away! Director of Publications: Jon Olsen 28 Managing Editor: Kristen E. Asmus, [email protected] Editorial Staff: Matt Hudson 29 GeoVentures™ 2005—Australia; New Zealand; Montana, USA; and Production Coordinator: Margo Y. Sajban Graphics Production: Margo Y. Sajban Golden, Colorado, USA ADVERTISING: Classifieds & Display: Ann Crawford, 1-800-472-1988, ext. 1053, 32 GSA Foundation Update (303) 357-1053, Fax 303-357-1070; [email protected] GSA ONLINE: www.geosociety.org 33 Announcements Printed in the USA using pure soy inks. 35 Classified Advertising 37 Journal Highlights 50% Total Recovered Fiber 38 GeoMart Geoscience Directory 10% Postconsumer Subduction zone backarcs, mobile belts, and orogenic heat Roy D. Hyndman, Pacific Geoscience Centre, Geological Survey of Canada, P.O. Box 6000, Sidney, British Columbia V8L4B2, Canada, and School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W3P6, Canada, [email protected]; Claire A. Currie, School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8W3P6, Canada; and Stephane P. Mazzotti, Pacific Geoscience Centre, Geological Survey of Canada, P.O. Box 6000, Sidney, British Columbia V8L4B2, Canada ABSTRACT hot backarc lithosphere, not from the Two important problems of continental orogenic deformation process itself. tectonics may be resolved by recogniz- INTRODUCTION ing that most subduction zone backarcs The model of plate tectonics with have hot, thin, and weak lithospheres narrow plate boundaries provides an Figure 1. The North America Cordillera mobile over considerable widths. These are (1) excellent first-order description of global the origin of long-lived active “mobile belt. The high elevation and complex current tectonics. Plate tectonics also provides tectonics illustrate the hot, weak, backarc belts” contrasted to the stability of cra- an elegant explanation for orogenic lithosphere deformed by variable margin forces. tons and platforms, and (2) the origin crustal shortening and thickening in of the heat of continental collision orog- terms of continental or terrane colli- eny. At many continental margin plate sion. However, a number of large-scale deformation over long geological peri- boundaries, there are broad belts with tectonic problems are not explained by ods. They have some characteristic that a long history of distributed deforma- the simple rigid plate and continental allows them to maintain an especially tion. These regions are mobile because collision models. In this article, we pre- thick, strong lithosphere, such as a more the lithosphere is sufficiently weak to sent explanations for two such tectonic refractory mantle composition (Jordan, be deformed by the forces developed problems: the origin of long-lived active 1978; Forte and Perry, 2000). The rea- at plate boundaries. We conclude that “mobile belts” that lie along a number son for the long histories of tectonic mobile belts are weak because they are of continental
Load more

Recommended publications
  • Topic B - Geologic Processes on Earth
    Topic B - Geologic Processes on Earth 1 Chapter 6 - ELEMENTS OF GEOLOGY 6-1 The Original Planet Earth Planet Earth formed out of the original gas and dust that prevailed at the origin of the solar system some 4.6 billion years ago. It is the only known habitable planet so far. This is due to the concurrence of special conditions such as its position with respect to the Sun giving it the right temperature range, the preponderance of necessary gases and a shielding atmosphere that protects it from lethal solar radiation. Early Earth has however not always been so welcoming to life. Initially Earth was rich in silicon, iron and magnesium oxide. Heat trapped inside Earth along with radioactive decay which tends to produce more heat helped heavier elements to sink to the depths leaving lighter elements closer to the surface. Within the first 500 million years, an inner core formed of mostly solid iron surrounded by a molten iron outer core. The mantle formed of rocks that can deform. The thin outer crust that sustains life is composed mostly of silicate rocks. The various natural processes inside and on the surface of Earth make it a dynamic system which has evolved into what we know now. These include the oceans and the continents, the volcanoes that form the mountains and erosion that erodes the landscape, earthquakes that shape the topography and the movement of earth’s crust through the plate tectonics process. mantle outer core crust inner core 35 700 2885 5155 6371 Depth in km Figure 6-1: Schematics showing the Earth’s solid inner core, liquid outer core, mantle and curst.
    [Show full text]
  • AGAP Antarctic Research Project Http
    AGAP Antarctic Research Project Image by Zina Deretsky, NSF Image from - http- //news.bbc.co.uk/1/hi/sci/tech/6145642 Build Your Gamburtsev Mountain Formation Mountain Building: Remember mountain ranges can be built in different ways. With the Gamburtsev Mountains there are several possible theories, but with the mountains under ice, there is little data available. Let’s focus on the two main theories, collision and hot spot volcanic activity. Select one theory to support. Your task is to create a model of your mountain building event and explain why you picked it, how your model supports your theory, and what ‘tools of the trade’ from our geophysical tools you could use to test your theory. The Gamburtsevs, the Result of a Collision? Mountain belts are formed along boundaries between the Earth’s crustal (lithospheric) plates. Remember, the Earth’s outside crust is made up of plates (or sections) with pieces that are slowly moving. When the different plates collide they can push or fold the land up forming raised areas, or mountains. The European Alps and the Himalayas formed this way. The sections of Earth’s continental crust are constantly shifting. During the Cambrian Period, a time between ~500 and 250 Ma, the piece of crust that would become Antarctica (we will call this proto-Antarctica) was on the move! Early in the Cambrian it was located close to the equator, a much Proto Antarctica Other Continent milder climate than its current location, but as the Cambrian Period advanced proto-Antarctica moved slowly south. The collision theory suggests that as these pieces of continent moved, like bumper cars they collided with each other.
    [Show full text]
  • Tectonic Features of the Precambrian Belt Basin and Their Influence on Post-Belt Structures
    ... Tectonic Features of the .., Precambrian Belt Basin and Their Influence on Post-Belt Structures GEOLOGICAL SURVEY PROFESSIONAL PAPER 866 · Tectonic Features of the · Precambrian Belt Basin and Their Influence on Post-Belt Structures By JACK E. HARRISON, ALLAN B. GRIGGS, and JOHN D. WELLS GEOLOGICAL SURVEY PROFESSIONAL PAPER X66 U N IT ED STATES G 0 V ERN M EN T P R I NT I N G 0 F F I C E, \VAS H I N G T 0 N 19 7 4 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress catalog-card No. 74-600111 ) For sale by the Superintendent of Documents, U.S. GO\·ernment Printing Office 'Vashington, D.C. 20402 - Price 65 cents (paper cO\·er) Stock Number 2401-02554 CONTENTS Page Page Abstract................................................. 1 Phanerozoic events-Continued Introduction . 1 Late Mesozoic through early Tertiary-Continued Genesis and filling of the Belt basin . 1 Idaho batholith ................................. 7 Is the Belt basin an aulacogen? . 5 Boulder batholith ............................... 8 Precambrian Z events . 5 Northern Montana disturbed belt ................. 8 Phanerozoic events . 5 Tectonics along the Lewis and Clark line .............. 9 Paleozoic through early Mesozoic . 6 Late Cenozoic block faults ........................... 13 Late Mesozoic through early Tertiary . 6 Conclusions ............................................. 13 Kootenay arc and mobile belt . 6 References cited ......................................... 14 ILLUSTRATIONS Page FIGURES 1-4. Maps: 1. Principal basins of sedimentation along the U.S.-Canadian Cordillera during Precambrian Y time (1,600-800 m.y. ago) ............................................................................................... 2 2. Principal tectonic elements of the Belt basin reentrant as inferred from the sedimentation record ............
    [Show full text]
  • GY 112 Lecture Notes D
    GY 112 Lecture Notes D. Haywick (2006) 1 GY 112 Lecture Notes Archean Geology Lecture Goals: A) Time frame (the Archean and earlier) B) Rocks and tectonic elements (shield/platform/craton) C) Tectonics and paleogeography Textbook reference: Levin 7th edition (2003), Chapter 6; Levin 8th edition (2006), Chapter 8 A) Time frame Up until comparatively recently (start of the 20th century), most geologists focused their discussion of geological time on two eons; the “Precambrian” and the Phanerozoic. We now officially recognize 4 eons and the Precambrian is just used as a come-all term for all time before the Phanerozoic: Eon Time Phanerozoic 550 MA to 0 MA Proterozoic 2.5 GA to 550 MA Archean 3.96 GA to 2.5 GA Hadean 4.6 GA to 3.96 GA The “youngest” of these two new eons, the Archean, was first introduced by field geologists working in areas where very old rocks cropped out. One of these geologists was Sir William Logan (pictured at left; ess.nrcan.gc.ca ) one of the most respected geologists working with the Geological Survey of Canada. His study area was the Canadian Shield. Logan was able to identify two major types of rocks; 1) layered sedimentary and volcanic rocks and 2) highly metamorphosed granitic gneisses (see image at the top of the next page from http://www.trailcanada.com/images/canadian-shield.jpg). Logan found evidence that the gneisses mostly underlayed the layered rocks and hence, they had to be older than the layered rocks. The layered rocks were known to be Proterozoic in age.
    [Show full text]
  • The Petroleum Potential of the Riphean–Vendian Succession of Southern East Siberia
    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/253369249 The petroleum potential of the Riphean–Vendian succession of southern East Siberia CHAPTER in GEOLOGICAL SOCIETY LONDON SPECIAL PUBLICATIONS · MAY 2012 Impact Factor: 2.58 · DOI: 10.1144/SP366.1 CITATIONS READS 2 95 4 AUTHORS, INCLUDING: Olga K. Bogolepova Uppsala University 51 PUBLICATIONS 271 CITATIONS SEE PROFILE Alexander P. Gubanov Scandiz Research 55 PUBLICATIONS 485 CITATIONS SEE PROFILE Available from: Olga K. Bogolepova Retrieved on: 08 March 2016 Downloaded from http://sp.lyellcollection.org/ by guest on March 25, 2013 Geological Society, London, Special Publications The petroleum potential of the Riphean-Vendian succession of southern East Siberia James P. Howard, Olga K. Bogolepova, Alexander P. Gubanov and Marcela G?mez-Pérez Geological Society, London, Special Publications 2012, v.366; p177-198. doi: 10.1144/SP366.1 Email alerting click here to receive free e-mail alerts when service new articles cite this article Permission click here to seek permission to re-use all or request part of this article Subscribe click here to subscribe to Geological Society, London, Special Publications or the Lyell Collection Notes © The Geological Society of London 2013 Downloaded from http://sp.lyellcollection.org/ by guest on March 25, 2013 The petroleum potential of the Riphean–Vendian succession of southern East Siberia JAMES P. HOWARD*, OLGA K. BOGOLEPOVA, ALEXANDER P. GUBANOV & MARCELA GO´ MEZ-PE´ REZ CASP, West Building, 181a Huntingdon Road, Cambridge CB3 0DH, UK *Corresponding author (e-mail: [email protected]) Abstract: The Siberian Platform covers an area of c.
    [Show full text]
  • Sedimentological Constraints on the Initial Uplift of the West Bogda Mountains in Mid-Permian
    www.nature.com/scientificreports OPEN Sedimentological constraints on the initial uplift of the West Bogda Mountains in Mid-Permian Received: 14 August 2017 Jian Wang1,2, Ying-chang Cao1,2, Xin-tong Wang1, Ke-yu Liu1,3, Zhu-kun Wang1 & Qi-song Xu1 Accepted: 9 January 2018 The Late Paleozoic is considered to be an important stage in the evolution of the Central Asian Orogenic Published: xx xx xxxx Belt (CAOB). The Bogda Mountains, a northeastern branch of the Tianshan Mountains, record the complete Paleozoic history of the Tianshan orogenic belt. The tectonic and sedimentary evolution of the west Bogda area and the timing of initial uplift of the West Bogda Mountains were investigated based on detailed sedimentological study of outcrops, including lithology, sedimentary structures, rock and isotopic compositions and paleocurrent directions. At the end of the Early Permian, the West Bogda Trough was closed and an island arc was formed. The sedimentary and subsidence center of the Middle Permian inherited that of the Early Permian. The west Bogda area became an inherited catchment area, and developed a widespread shallow, deep and then shallow lacustrine succession during the Mid- Permian. At the end of the Mid-Permian, strong intracontinental collision caused the initial uplift of the West Bogda Mountains. Sedimentological evidence further confrmed that the West Bogda Mountains was a rift basin in the Carboniferous-Early Permian, and subsequently entered the Late Paleozoic large- scale intracontinental orogeny in the region. The Central Asia Orogenic Belt (CAOB) is the largest accretionary orogen on Earth, which was formed by the amalgamation of multiple micro-continents, island arcs and accretionary wedges1–5.
    [Show full text]
  • Northwestern Superior Craton Margin, Manitoba: an Overview of Archean
    GS-7 Northwestern Superior craton margin, Manitoba: an overview of Archean and Proterozoic episodes of crustal growth, erosion and orogenesis (parts of NTS 54D and 64A) by R.P. Hartlaub1, C.O. Böhm, L.M. Heaman2, and A. Simonetti2 Hartlaub, R.P., Böhm, C.O., Heaman, L.M. and Simonetti, A. 2005: Northwestern Superior craton margin, Manitoba: an overview of Archean and Proterozoic episodes of crustal growth, erosion, and orogenesis (parts of NTS 54D and 64A); in Report of Activities 2005, Manitoba Industry, Economic Development and Mines, Manitoba Geological Survey, p. 54–60. Summary xenocrystic zircon, and in the The northwestern margin of the Superior Province in isotopic signature of Neoarchean Manitoba represents a dynamic boundary zone with good granite bodies (Böhm et al., 2000; potential for magmatic, sedimentary-hosted, and structur- Hartlaub et al., in press). The ALCC extends along the ally controlled mineral deposits. The region has a history Superior margin for at least 50 km, and may have a com- that commences in the early Archean with the formation mon history with other early Archean crustal fragments of the Assean Lake Crustal Complex. This fragment of in northern Quebec and Greenland (Hartlaub et al., in early to middle Archean crust was likely accreted to the press). Superior Province between 2.7 and 2.6 Ga, a major period South of the ALCC, the Split Lake Block repre- of Superior Province amalgamation. Sediments derived sents a variably retrogressed and shear zone–bounded from this amalgamation process were deposited at granulite terrain that is dominated by plutonic rocks and numerous locations along the northwestern margin of mafic granulite (Hartlaub et al., 2003, 2004).
    [Show full text]
  • Part 629 – Glossary of Landform and Geologic Terms
    Title 430 – National Soil Survey Handbook Part 629 – Glossary of Landform and Geologic Terms Subpart A – General Information 629.0 Definition and Purpose This glossary provides the NCSS soil survey program, soil scientists, and natural resource specialists with landform, geologic, and related terms and their definitions to— (1) Improve soil landscape description with a standard, single source landform and geologic glossary. (2) Enhance geomorphic content and clarity of soil map unit descriptions by use of accurate, defined terms. (3) Establish consistent geomorphic term usage in soil science and the National Cooperative Soil Survey (NCSS). (4) Provide standard geomorphic definitions for databases and soil survey technical publications. (5) Train soil scientists and related professionals in soils as landscape and geomorphic entities. 629.1 Responsibilities This glossary serves as the official NCSS reference for landform, geologic, and related terms. The staff of the National Soil Survey Center, located in Lincoln, NE, is responsible for maintaining and updating this glossary. Soil Science Division staff and NCSS participants are encouraged to propose additions and changes to the glossary for use in pedon descriptions, soil map unit descriptions, and soil survey publications. The Glossary of Geology (GG, 2005) serves as a major source for many glossary terms. The American Geologic Institute (AGI) granted the USDA Natural Resources Conservation Service (formerly the Soil Conservation Service) permission (in letters dated September 11, 1985, and September 22, 1993) to use existing definitions. Sources of, and modifications to, original definitions are explained immediately below. 629.2 Definitions A. Reference Codes Sources from which definitions were taken, whole or in part, are identified by a code (e.g., GG) following each definition.
    [Show full text]
  • Pan-African Orogeny 1
    Encyclopedia 0f Geology (2004), vol. 1, Elsevier, Amsterdam AFRICA/Pan-African Orogeny 1 Contents Pan-African Orogeny North African Phanerozoic Rift Valley Within the Pan-African domains, two broad types of Pan-African Orogeny orogenic or mobile belts can be distinguished. One type consists predominantly of Neoproterozoic supracrustal and magmatic assemblages, many of juvenile (mantle- A Kröner, Universität Mainz, Mainz, Germany R J Stern, University of Texas-Dallas, Richardson derived) origin, with structural and metamorphic his- TX, USA tories that are similar to those in Phanerozoic collision and accretion belts. These belts expose upper to middle O 2005, Elsevier Ltd. All Rights Reserved. crustal levels and contain diagnostic features such as ophiolites, subduction- or collision-related granitoids, lntroduction island-arc or passive continental margin assemblages as well as exotic terranes that permit reconstruction of The term 'Pan-African' was coined by WQ Kennedy in their evolution in Phanerozoic-style plate tectonic scen- 1964 on the basis of an assessment of available Rb-Sr arios. Such belts include the Arabian-Nubian shield of and K-Ar ages in Africa. The Pan-African was inter- Arabia and north-east Africa (Figure 2), the Damara- preted as a tectono-thermal event, some 500 Ma ago, Kaoko-Gariep Belt and Lufilian Arc of south-central during which a number of mobile belts formed, sur- and south-western Africa, the West Congo Belt of rounding older cratons. The concept was then extended Angola and Congo Republic, the Trans-Sahara Belt of to the Gondwana continents (Figure 1) although West Africa, and the Rokelide and Mauretanian belts regional names were proposed such as Brasiliano along the western Part of the West African Craton for South America, Adelaidean for Australia, and (Figure 1).
    [Show full text]
  • Timothy O. Nesheim
    Timothy O. Nesheim Introduction Superior Craton Kimberlites Beneath eastern North Dakota lays the Superior Craton and the To date, over a hundred kimberlites have been discovered across potential for continued diamond exploration as well as diamond the Superior Craton, more than half of which were discovered mine development. The Superior Craton is a large piece of Earth’s within the past 15 years. Most of these kimberlites occur as crust that has been tectonically stable for over 2.5 billion years. clusters within the Canadian provinces of Ontario and Quebec The long duration of tectonic stability has allowed the underlying (figs. 1 and 2). Moorhead et al. (2000) noted that the average mantle to cool enough to develop the necessary temperature and distance between kimberlite fields/clusters across the Canadian pressure conditions to form diamonds at depths of more than 50 Shield is similar to the typical global average distance of 250 miles miles below the surface. Diamonds are transported to the surface (400 km) between large kimberlite fields. Globally, only 14% through kimberlitic eruptions, which are volcanic eruptions that of kimberlites are diamondiferous (contain diamonds), most in originate tens of miles below the surface and typically erupt concentrations too low for commercial mining. The percentage along zones of weakness in Earth’s crust such as faults and of diamondiferous Superior kimberlites appears to be higher than fractures. The resulting eruption commonly forms a pipe-shaped the global average, including 1) the Attawapiskat cluster – 16 of 18 geologic feature called a kimberlite. Kimberlites typically occur kimberlites (89%) are diamondiferous and so far one kimberlite in groups referred to as either fields or clusters.
    [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]
  • Deep Structure, Tectonics and Petroleum Potential of the Western Sector of the Russian Arctic
    Journal of Marine Science and Engineering Article Deep Structure, Tectonics and Petroleum Potential of the Western Sector of the Russian Arctic Alexey S. Egorov 1, Oleg M. Prischepa 2, Yury V. Nefedov 2,* , Vladimir A. Kontorovich 3 and Ilya Y. Vinokurov 4 1 The Faculty of Geology, Federal State Budget Educational Institution of Higher Education, Saint-Petersburg Mining University, 199106 Saint-Petersburg, Russia; [email protected] 2 Oil and Gas Geology Department, Federal State Budget Educational Institution of Higher Education, Saint-Petersburg Mining University, Saint-199106 Petersburg, Russia; [email protected] 3 Siberian Branch, Russian Academy of Science, The Trofimuk Institute of Petroleum Geology and Geophysics, 630090 Novosibirsk, Russia; [email protected] 4 Deep Geophysics Department, Russian Geological Research Institute, 199106 Saint-Petersburg, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-911-230-56-36 Abstract: The evolutionary-genetic method, whereby modern sedimentary basins are interpreted as end-products of a long geological evolution of a system of conjugate palaeo-basins, enables the assessment of the petroleum potential of the Western sector of the Russian Arctic. Modern basins in this region contain relics of palaeo-basins of a certain tectonotype formed in varying geodynamic regimes. Petroleum potential estimates of the Western Arctic vary broadly—from 34.7 to more than 100 billion tons of oil equivalent with the share of liquid hydrocarbons from 5.3 to 13.4 billion tons of oil equivalent. At each stage of the development of palaeo-basins, favourable geological, geochemical and thermobaric conditions have emerged and determined the processes of oil and gas formation, Citation: Egorov, A.S.; Prischepa, migration, accumulation, and subsequent redistribution between different complexes.
    [Show full text]