Wolfgang Frisch /Martin Meschede /

Plate TectonicsRonald Blakey

Wolfgang Frisch /Martin Meschede /

Plate TectonicsRonald Blakey

123

Continental D riftand Mountain Building

ISBN 978-3-540-76503-5 e-ISBN 978-3-540-76504-2DOI 10.1007/978-3-540-76504-2Springer Heidelberg Dordrecht London New York

c© Springer-Verlag Berlin Heidelberg 2011This work is subject to copyright. All rights are reserved, whether the whole or part of the mate-rial is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Dupli-cation of this publication or parts thereof is permitted only under the provisions of the GermanCopyright Law of September 9, 1965, in its current version, and permission for use must alwaysbe obtained from Springer. Violations are liable to prosecution under the German Copyright Law.The use of general descriptive names, registered names, trademarks, etc. in this publication doesnot imply, even in the absence of a specific statement, that such names are exempt from the rele-vant protective laws and regulations and therefore free for general use.

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Prof. Dr. Wolfgang FrischDepartment of GeosciencesUniversity of TübingenGermanyfrisch@uni-tuebingen.de

Prof. Dr. Martin MeschedeUniversity of GreifswaldInstitute of Geography and GeologyFriedrich-Ludwig-Jahn-Str. 17AD-17487 GreifswaldGermanymeschede@uni-greifswald.de

Prof. Dr. Ronald BlakeyNorthern Arizona UniversityDept. GeologyCenter for EnvironmentalSciences & EducationPO Box 409986011-4099 Flagstaff ArizonaUSARonald.Blakey@nau.edu

Content

Preface XII

1 Contractional theory, continental drift and plate tectonics 1

Plate tectonics – a change in the paradigm of the geosciences 1

Early history of geodynamic thought 1

From continental drift to plate tectonics 2

Th e plate tectonic concept 4

Th e pattern of magnetic polarity stripes 8

Plate motions and earthquake zones 8

Two kinds of continental margins 11

Magmatism and plate tectonics 11

What drives the plates and what slows them down? 12

Collision and mountain building 12

2 Plate movements and their geometric relationships 15

Helpful transform faults 15

Relative movements and triple junctions 16Two RTF triple junctions off North America 18

Relative plate velocities – past and present 20

Direct measurement of plate movements 21

Apparent contradictions in the plate motion pattern 22

Fault-plane-solutions of earthquakes 23Seismic tomography 25

3 Continental graben structures 27

Active and passive graben structures 28Symmetric and asymmetric crustal extension 28

Sediments and ore deposits in graben structures 29

Volcanism in graben structures 30

Th e Upper Rhine Graben in Germany 31

Th e history of the Upper Rhine Graben 32Th e Upper Rhine Graben in the Middle European stress fi eld 33

Magmatism and heat fl ow in the Upper Rhine Graben 34

Th e large East African rift system 34

Th e Afar Depression 37Th e Red Sea – from rift to drift 37Th e extensional area of the Basin and Range Province 39

Th e development of metamorphic domes 40

A brief history of the Basin and Range Province 41

4 Passive continental margins and abyssal plains 43

Continuous subsidence of the continental margins 43

Th e sedimentary trap at a passive continental margin 44

Tracts of sequence stratigraphy 45Processes on continental margins 46

Petroleum deposits – the economic signifi -cance of passive continental margins 48

Th e Atlantic – an ocean opens in an intricate manner 48

Pangaea and Panthalassa 49Th e large abyssal plains 51

Sediments of the abyssal plains 52Manganese nodules from the deep sea 54

Facies changes on the large oceanic conveyor belt 55

Th e Bengal deep sea fan 56

VI

5 Mid-ocean ridges 59

Topography of the ridges 59

Generation of oceanic lithosphere 60

Rocks of the oceanic crust 61Pillow lavas 62Seismic layers 64

Basalts of mid-ocean ridges 65

Fast and slow spreading ridges and rocks of the lithospheric mantle 65

Segmentation of ridges by faults 67

Graben formation in the Atlantic 67An oceanic crustal profi le in the Atlantic Ocean 68

Black and white smokers 68

Ocean fl oor metamorphism 70

Chromite deposits 71

Ophiolites 71

Th e ophiolite of the Semail Nappe in Oman 72Metamorphic sole 72

Alpine-Mediterranean ophiolites 72

6 Hot spots 75

Hot spots and mid-ocean ridges 77

Th e mysterious D'' layer and the dented Earth 77

Hot spots of Pangaea 78Hot spot tracks in the ocean 80

A guyot evolves 82Hot spot tracks on the continent 82

Flood and trap basalts 84

Th e Azores – hot, cold or wet spot? 85

Hawaii – a typical oceanic hot spot 86

Iceland 87

Yellowstone 87

Th e superplume event in the Cretaceous 88

7 Subduction zones, island arcs and active continental margins 91

Structure of plate margin systems with subduction zones 91Spontaneous and forced subduction: Mariana- and Chile-type subduction 93

Deep sea trenches as sediment traps 96

Accretionary wedge and outer ridge 97Th e accretionary wedge of the Sunda Arc 99

Subduction erosion instead of accretion 100

Th e forearc basin 103Earthquakes and Benioff zones 103

Th e secret of deep earthquakes 107

High-pressure or subduction metamorphism 109

Ultrahigh-pressure meta morphic rocks 111Rapid burial, rapid uplift 112

Subduction-related magmatism – a paradox? 113

Rocks of the magmatic zone 114

Zonation of magmas in space and time 116Explosive stratovolcanoes as indicators for subduction magmatism 117

Metamorphism in the magmatic belt 119Paired metamorphic belts 119

Ore deposits in the magmatic belt 120

Th e backarc basin 120Splitting of intra-oceanic island arcs 122

Gravity and heat fl ow 122

Subduction and collision 122

What is the reason for the arcuate shape of island arcs? 94

Mud volcanoes 101

Th e Shigatse Flysch in Tibet 104

Isotopic signatures and the infl uence of continental crust 118

VII

8 Transform faults 123

Oceanic transform faults 123

Fracture zones in the ocean fl oor 123

Continental transform faults 125

San Andreas – the infamous transform fault of California 127

Th e North Anatolian Fault in Asia Minor and the Alpine Fault in New Zealand 129

9 Terranes 131

Documenting terranes 132

Terranes in the North American Cordillera 134

Suspect terranes in Mexico and Middle America 138

10 Early Precambrian plate tectonics 139

Th e oldest rocks and minerals 140Greenstone-granite belts 141Granulite-gneiss belts 143

Towards an Archean plate tectonic model 145

Th e growth of continents 146Possible younger equivalents of greenstone-granite belts 147

11 Plate tectonics and mountain building 149

Types of active continental margins within orogenic styles 149

Continent-continent collision 152

Uplift , erosion, and elevation of mountains 154

Collapse and crustal escape 158

12 Old orogens 1592500–2000 million years old ophiolites 159

Th e Wopmay orogen in Canada 160

Th e Grenville orogenic cycle and the formation of the supercontinent Rodinia 160

Th e Panafrican orogeny and the formation of Gondwana 160

Th e Caledonides – a Wilson cycle around the Iapetus Ocean 161

Th e signifi cance of Scotland and the Greek mythology 162

Th e Variscides – a broad mountain belt in central Europe 163

A Variscan suture in the southern Black Forest 165

Th e Variscan orogen in the Alps 165

Paleozoic mountain building in eastern and southern North America 167

How many orogenies? 169

13 Young orogens – the Earth’s loftiest places 171

Th e Himalayas – a mountain range with superlatives 172

Tectonic history of the Himalayas 172Nanga Parbat and Namche Barwa syntaxis 174

Th e Alps – an untypical but classic orogen 174

Brief history of Alpine evolution 176Lateral tectonic extrusion in the Alps 178

Th e North American Cordillera – a diff erent style of orogen 179

Laramide Rocky Mountains – an orogenic mystery solved 185

Epilog 187

Glossary 189References 199Keyword Index 207

Komatiites 144

Th e Great Dike of Zimbabwe 147

VIII

Preface

I n the late 1960’s, Wegener’s theory of continental drift , originally conceived fi ft y years earlier, was merged with the theory of plate tectonics and the

concepts gained global acceptance among geosci-entists. For the fi rst time, a unifying concept, plate tectonics, could reconcile and unify all phenomena in geoscience into a common synthesis. Th e basic tenants have not changed since the 1960’s, although many corrections and refi nements have been added regarding questions of detail. Th e impact of the theory of plate tectonics cannot be overestimated – its importance to geoscience is as basic as Darwin’s theory of evolution is to the biological sciences.

Earth is subject to steady change. Th is can impres-sively be realized in volcanic bursts and earthquakes around the Pacifi c Ocean or in the grandeur of young mountain ranges. Whilst new parts of plates are created along the mid-ocean ridges, older parts of plates disappear in subduction zones. Mountain chains arise from the collisions of plates. Th ese dy-namic processes are driven by the heat that is released from the interior of the Earth; this is what keeps the dynamo running. Continental drift , mountain build-ing, volcanism, earthquakes, and in consequence of quakes, sea waves like the devastating tsunami of 26th December 2004 in the Indian Ocean – all this is the expression of the dynamics of the Earth.

Th is book presents an introduction in the wide fi eld of plate tectonics and is dedicated to a broad audience interested in natural sciences, and students and professionals in geosciences and related subjects. Expertise in tectonics is not a pre-condition; the tech-nical terms and geological processes are explained and reviewed in adequate detail. Many terms are defi ned in the glossary at the end of the book and a keyword index enables quick location of topics and terms in the text. Figures at the inside front-end and back-end covers present concise overviews of the geologic timescale and critical events in Earth history as well as the classifi cation of magmatic and metamorphic rocks. More than 200 references en-able the studious reader to gain deeper insight into special topics.

Th e book begins with an historical introduction concerning early ideas of continental drift and Earth

dynamics that leads into discussion and considera-tion of plate motions and geometry. Th is is followed by several chapters that defi ne, describe in detail, and illustrate the various features, processes, and settings that comprise the plate tectonic realm: graben structures, passive continental margins, ocean basins, mid-ocean ridges, subduction zones, and transform faults. Th e remaining chapters deal with mountain-building processes as a consequence of plate tectonics and the collision of terranes and large continents. Th ese chapters illuminate plate tectonic processes from the early history of the Earth to the present. We examine how plate tec-tonics played a role in the construction of ancient Archean continents and then built large volumes of Proterozoic crust via “modern” plate-tectonic processes. Following the late Proterozoic break-up of the supercontinent Rodinia, we follow the plate tectonic events that generated older and deeply eroded Paleozoic mountains and the formation of Pangaea to the more recent Mesozoic and Ceno-zoic mountains that remain the pinnacles of our modern planet. Examples from across the Earth are presented, including the young and loft y mountain ranges of the Himalayas, the Alps, and the North American Cordilleras. We relate the concepts, pro-cesses, and examples from the earlier chapters of the book to the plate-tectonic evolution discussed in the latter part of the book. In this way the book not only describes the plate tectonic phenomena, but also focuses on the processes behind them and how they have worked in concert to produce the present plate confi guration. Th roughout the book, we strive to communicate to the reader an understanding that the Earth is a body in constant motion and change

– a tectonic machine.Th e present edition has evolved from an earlier

German edition, Plattentektonik (Wissenschaft liche Buchgesellschaft , Darmstadt) by Wolfgang Frisch and Martin Meschede (2005). Although largely a translation of the German edition, it also contains a number of new contributions by Ron Blakey, who especially enriched the text with geological examples from North America and upgraded the English text from an earlier translation.

Wolfgang Frisch, Ron Blakey, and Martin MeschedeVienna, Sedona, and Greifswald, May 2010