Impact Cratering: Processes and Products

Impact cratering is arguably the most ubiquitous geological process in the Solar System. It has played an important role in Earth’s history, shaping the geological landscape, affecting the evolution of life, and generating economic resources. However, it was only in the latter half of the 20th century that the importance of impact cratering as a geological process was recognized and only during the past couple of decades that the study of meteorite impact structures has moved into the mainstream. This book seeks to fill a critical gap in the literature by providing an overview text covering broad aspects of the impact cratering process and aimed at graduate students, professionals and researchers alike. It introduces readers to the threat and nature of impactors, the impact cratering process, the products, and the effects – both destructive and beneficial. A series of chapters on the various techniques used to study impact craters provide a foundation for anyone studying impact craters for the first time.

Table of Contents:
Preface xi List of contributors xii 1 Impact cratering: processes and products 1 Gordon R. Osinski and Elisabetta Pierazzo 1.1 Introduction 1 1.2 Formation of hypervelocity impact craters 3 1.3 Morphology and morphometry of impact craters 8 1.4 Impactites 12 1.5 Recognition of impact craters 14 1.6 Destructive effects of impact events 15 1.7 Benefi cial effects of impact events 15 1.8 When a crater does not exist: other evidence for impact events 16 1.9 Concluding remarks 16 References 17 2 Population of impactors and the impact cratering rate in the inner Solar System 21 Patrick Michel and Alessandro Morbidelli 2.1 Introduction 21 2.2 Population of impactors in the inner Solar System 22 2.3 Impact frequency of NEOs with the Earth 24 2.4 Comparison with the impact record on terrestrial planets 25 2.5 Variability of the impact frequency during the last 3 Ga 26 2.6 The early cratering history of the Solar System 27 2.7 Conclusions 28 References 29 3 The contact and compression stage of impact cratering 32 H. Jay Melosh 3.1 Introduction 32 3.2 Maximum pressures during contact and compression 35 3.3 Jetting during contact and compression 37 3.4 The isobaric core 38 3.5 Oblique impact 39 3.6 The end of contact and compression 40 References 42 4 Excavation and impact ejecta emplacement 43 Gordon R. Osinski, Richard A. F. Grieve and Livio L. Tornabene 4.1 Introduction 43 4.2 Excavation 43 4.3 Impact plume 46 4.4 Generation of continuous ejecta blankets 47 4.5 Rayed craters 51 4.6 Generation of multiple ejecta layers 52 4.7 Distal impact ejecta 56 4.8 Depth of excavation 57 References 57 5 The modification stage of crater formation 60 Thomas Kenkmann, Gareth S. Collins and Kai Wünnemann 5.1 Introduction 60 5.2 Morphology and morphometry of simple and complex impact craters 62 5.3 Kinematics of crater collapse 64 5.4 Subsurface structure of complex impact craters 66 5.5 Mechanics of cavity collapse: what makes the target so weak? 69 5.6 Effects of oblique impact incidences on cavity collapse 71 5.7 Effects of rheologically complex targets on cavity modifi cation 71 References 73 6 Impact-induced hydrothermal activity 76 Kalle Kirsimäe and Gordon R. Osinski 6.1 Introduction 76 6.2 Formation and development of the post-impact thermal field 76 6.3 Composition and evolution of the hydrothermal fluids and mineralization 79 6.4 Implications for extraterrestrial impacts and microbial life 85 References 87 7 Impactites: their characteristics and spatial distribution 90 Richard A. F. Grieve and Ann M. Therriault 7.1 Introduction 90 7.2 Autochthonous impactites 90 7.3 Parautochthonous impactites 91 7.4 Allochthonous impactites 92 7.5 Concluding remarks 101 References 102 8 Shock metamorphism 106 Ludovic Ferrière and Gordon R. Osinski 8.1 Introduction 106 8.2 Shock metamorphic features 108 8.3 Post-shock thermal features 119 8.4 Concluding remarks 120 References 121 9 Impact melting 125 Gordon R. Osinski, Richard A. F. Grieve, Cassandra Marion and Anna Chanou 9.1 Introduction 125 9.2 Why impact melting occurs 125 9.3 Terrestrial impact melt products 126 9.4 Planetary impact melt products 139 9.5 Impactor contamination 141 9.6 Concluding remarks 142 References 142 10 Environmental effects of impact events 146 Elisabetta Pierazzo and H. Jay Melosh 10.1 Introduction 146 10.2 The impact hazard 146 10.3 The impact cratering process 147 10.4 Shock wave effects 148 10.5 Ejecta launch 150 10.6 Long-term atmospheric perturbation 151 10.7 The response of the Earth system to large impacts 152 10.8 Environmental impact effects favourable for life 153 10.9 Concluding remarks 153 References 154 11 The geomicrobiology of impact structures 157 Charles S. Cockell, Gordon R. Osinski and Mary A. Voytek 11.1 Introduction 157 11.2 Physical changes 158 11.3 Chemical changes 165 11.4 Impact events and weathering 166 11.5 Impoverishment or enrichment? 171 11.6 Astrobiological implications 172 11.7 Concluding remarks 172 References 172 12 Economic deposits at terrestrial impact structures 177 Richard A. F. Grieve 12.1 Introduction 177 12.2 Progenetic deposits 177 12.3 Syngenetic deposits 182 12.4 Epigenetic deposits 186 12.5 Hydrocarbon accumulations 186 12.6 Concluding remarks 189 References 190 13 Remote sensing of impact craters 194 Shawn P. Wright, Livio L. Tornabene and Michael S. Ramsey 13.1 Introduction 194 13.2 Background 194 13.3 Photogeology 196 13.4 Morphometry, altimetry, topography 196 13.5 Composition derived from remote sensing 196 13.6 Physical properties derived from remote sensing 201 13.7 General spectral enhancement and mapping techniques 202 13.8 Case studies 203 13.9 Concluding remarks 207 References 207 14 Geophysical studies of impact craters 211 Joanna Morgan and Mario Rebolledo-Vieyra 14.1 Introduction 211 14.2 Geophysical signature of terrestrial impacts 211 14.3 The resolution of geophysical data 215 14.4 Modelling geophysical data 216 14.5 Case studies 217 References 220 15 Projectile identification in terrestrial impact structures and ejecta material 223 Steven Goderis, François Paquay and Philippe Claeys 15.1 Introduction 223 15.2 Current situation: projectile identification at impact craters and ejecta layers 223 15.3 Methodology 226 15.4 Review of identified projectiles 234 15.5 Concluding remarks 235 References 235 16 The geochronology of impact craters 240 Simon P. Kelley and Sarah C. Sherlock 16.1 Introduction 240 16.2 Techniques used for dating terrestrial impact craters 241 16.3 Impact craters at the K–Pg boundary 246 16.4 Geochronology of impacts, flood basalts and mass extinctions 247 16.5 Using geochronology to identify clusters of impacts in the geological record 248 16.6 Concluding remarks 250 References 251 17 Numerical modelling of impact processes 254 Gareth S. Collins, Kai Wünnemann, Natalia Artemieva and Elisabetta Pierazzo 17.1 Introduction 254 17.2 Fundamentals of impact models 256 17.3 Material models 262 17.4 Validation, verifi cation and benchmarking 267 17.5 Concluding remarks 267 References 268 18 Comparison of simple impact craters: a case study of Meteor and Lonar Craters 271 Horton E. Newsom, Shawn P. Wright, Saumitra Misra and Justin J. Hagerty 18.1 Introduction 271 18.2 Meteor Crater, Arizona 271 18.3 Lonar Crater 274 18.4 Comparisons and planetary implications 283 18.5 Summary and concluding remarks 285 Acknowledgements 285 References 286 19 Comparison of mid-size terrestrial complex impact structures: a case study 290 Gordon R. Osinski and Richard A. F. Grieve 19.1 Introduction 290 19.2 Overview of craters 290 19.3 Comparisons and implications 301 19.4 Comparisons with lunar and Martian impact craters 302 19.5 Concluding remarks 303 References 303 20 Processes and products of impact cratering: glossary and definitions 306 Gordon R. Osinski 20.1 Introduction 306 20.2 General definitions 306 20.3 Morphometric definitions and equations 307 20.4 Impactites 308 References 308 Index 310

About the Author :
Dr Gordon "Oz" Osinski is the NSERC/MDA/CSA Industrial Research Chair in Planetary Geology in the Departments of Earth Sciences and Physics and Astronomy at Western University, Canada. He holds a B.Sc. (Hons) First Class in Geology from the University of St. Andrews, Scotland (1999) and a Ph.D., also in Geology (2004), from the University of New Brunswick, Canada. His research covers the tectonics of impact crater formation, the generation of impact melts, emplacement of ejecta, and post-impact processes such as impact-associated hydrothermal activity. He has published more than 70 papers in peer-reviewed journals and special papers and has given over 60 conference presentations since 2001. Dr Elisabetta Pierazzo, who tragically died during the preparation of this book, was a Research Scientist at the Planetary Science Institute and an Adjunct Assistant Research Scientist at the Lunar & Planetary Laboratory, University of Arizona, both located in Tucson, Arizona. She held a Laurea in Physics from the University of Padua, Italy (1988) and a Ph.D. in Planetary Sciences from University of Arizona (1997). She was a world renowned expert on the numerical modelling of impact events, focusing on the environmental effects of impact events, oblique impacts, and impact melt production.

Review :
"I fully recommend this book to anyone interested in impacts and their geological influence.  Impact Cratering is first class, fascinating reading to the expert, I am sure, as well as the novice (like your reviewer), and destined to be the standard reference for years to come."  (Geological Journal, 4 April 2014) “This book is now the single best starting point for anyone interested in almost any aspect of impact cratering.  Summing Up: Highly recommended.  Upper-division undergraduates and  above.”  (Choice, 1 November 2013)