DOCSLIB.ORG

Durham E-Theses

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Durham E-Theses Durham E-Theses Shock metamorphism of potassic feldspars Robertson, P. B. How to cite: Robertson, P. B. (1973) Shock metamorphism of potassic feldspars, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/8594/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk SHOCK METAMORPHISM OF POTASSIC FELDSPARS A thesis submitted for the degree of Doctor of Philosophy in the University of Durham P.B. Robertson Graduate Society October, 1973 ABSTRACT Hypervelocity meteorite impact produces transient pressures as high as several megabars and temperatures in excess of 1500°C. Shock metamorphism describes the effects upon the target rocks, effects most distinctive in the range approximately 100-600kb. Shock deformation produced in potassic feldspars at three terrestrial craters and in experimentally shocked K-spar have been examined. Pressures in natural material were estimated from deformation of coexisting quartz and plagioclase, and in experiments pressures were calculated using impedance matching. At Charlevoix crater, Quebec, pressures above 170kb have induced chemical remobilization partially converting film perthite to spindle microperthite in orthoclase and microcline. In ortho- clase, shock produced cleavages form parallel to (210) and (120) at 170kb, and above 300kb parallel to (112), (031), (Oil) and (101). Planar deformation features resulting from lattice gliding, form initially at 200kb, and are well developed at 230-270kb. In orthoclase they are generally parallel to (241) and (241), and (131), (110) and (120) in microcline. Above 300kb some sets become glide twins. Structural state of the feldspars is apparently not affected in the pressure range examined (<_ 360kb). In the breccias of Lac Couture crater, Quebec, strong deformation twins and planar features develop in microcline above 150kb, and some of the twins may obey a 'diagonal' twin law. Single crystal microcline was experimentally shocked at pressures from 37 to 417kb. Three shock regions were recognized: Regime I (<100kb) normal elastic compression, Regime II (100-300kb) mixed phase region, Regime III (>300kb) high pressure phase region. Shock cleavages, (111), (111) and (hkO), developed initially below 60kb, contain glass at highest pressures. Planar features, generally parallel to (111) and (111) also, appear at 154kb becoming more pronounced with increasing pressure, with poorly defined deformation twins occurring above 175kb. X-ray patterns show that long range structural order diminishes above 150kb accompanied by formation of a low-birefringent, unidentified phase, possibly a high-pressure, disordered modification of K-feldspar. Differences in the pressure required for formation of particular shock effects between craters, and between natural and experimental systems are due to differences in structural state of the feldspars. At Brent crater, Ontario, partially recrystallized alkali feldspars in shocked basement gneisses show compositional variations due to incomplete homogenization. This is not a shock effect but results from thermal metamorphism by the overlying melt layer. A similar thermal effect has produced chemical variations in some highly shocked orthoclases at Charlevoix. TABLE OF CONTENTS Page CHAPTER I INTRODUCTION 1 1.1 Meteorite Impact Phenomena 1 1.1.1 Terrestrial Meteorite Craters 1 1.1.2 Shock Metamorphism 3 I.1.2A Shock Environments 3 I.1.2B Typical Shock Effects 4 I.1.2C Shock Effects in K-feldspars 10 1.2 Research Objectives 14 1.3 Acknowledgements 16 CHAPTER II STRUCTURAL DEFORMATION IN ORTHOCLASE AND MICROCLINE 18 II. 1 Charlevoix 18 II. 1.1 Introduction 18 II. 1.2 Chamockitic Rocks 27 11.1.3 Levels of Shock Metamorphism Preserved 36 11.1.4 Shock Metamorphism of Potassic Feldspars 42 II.1.4A Structural State 42 II.1.4B Microscopic Evidence for Deformation 70 11.2 Lac Couture Crater 101 11.2.1 Introduction 101 11.2.2 Shock Metamorphism of Microcline 104 11.3 Discussion 114 CHAPTER III THE EFFECT OF SHOCK METAMORPHISM ON THE COMPOSITIONS OF ALKALI FELDSPARS, CHIEFLY AT BRENT CRATER 127 111.1 Introduction 127 111.2 Brent Crater 129 III.2.1 Geology 129 111.3 Petrography, Composition and Genesis of the Igneous Rocks of Brent Crater 135 :•y..:. III.3.1 Composition of Feldspars Beneath the Brent Crater 139 III. 4 Discussion 156 CHAPTER IV SHOCK-LOADING EXPERIMENTS ON MICROCLINE 170 IV. 1 Introduction 170 IV.1.1 Equation of State and Recovery Shock Experiments 170 IV.1.2 Experimental Deformation of Feldspars 172 IV.1.2A Static Deformation 172 IV.1.2B Shock Deformation. 173 IV.2 Recovery Shock Experiments on Microcline 183 IV.2.1 Procedure 183 IV.2.2 Post-Shock Examination 189 TABLE OF CONTENTS (CONT'D) .IV.2. 2A General Observations 189 IV.2.2B Microscopic Observations 190 IV.2. 2C Shock Deformation Effects 199 IV.2.2D X-ray Examination 228 IV.2. 2E Electron Microprobe Analysis 238 IV.3 Discussion and Summary 242 IV.3.1 Regime - Stage Subdivisions of Shock Effects 243 IV.3.2 Comparison with Observations of Others on Shocked Feldspars 250 IV.3.3 High-Pressure Phase 251 CHAPTER V CONCLUSIONS 255 V.l Changes in Outward Physical Appearance, Visible either in Hand Specimen or Microscopically 256 V.l.l Fracturing 256 V.l.2 Planar Deformation Features 258 V.l. 3 Deformation Twinning 261 V.l.4 Colour Changes 263 V.2 Crystal Structure Changes 263 V.2.1 Disordering 264 V.2.2 Phase Transformations, Disordering and Diaplectic Glass 265 V.2.3 Densityu 267 V.3 Changes in Optical Properties 267 V.3.1 Refractive Index 268 V.3.2 Birefringence 269 V.3.3 Optic Axial Angle 269 V.4 Chemical Changes 269 V.5 Experimental vs. Natural Shock Deformation 271 V.6 Loose Ends 274 APPENDIX A STRUCTURAL PARAMETERS OF CHARLEVOIX K-FELDSPARS 277 APPENDIX B "BEST FIT" METHOD 278 APPENDIX C RECOVERY SHOCK EXPERIMENTS 283 APPENDIX D HUGONIOT EQUATION OF STATE 291 REFERENCES 308 LIST OF FIGURES Figure Page 11.1 Location of Charlevoix, Lac Couture and Brent craters 20 11.2 Topography of the Charlevoix crater 22 11.3 Geology of the Charlevoix crater 25 11.4 Sample localities, Charlevoix crater 31 11.5 Optic angle vs_. composition for potassic feldspars 51 11.6 Standard deviation of 2Va vs_. distance from crater centre 54 11.7 202o4 vs* 2^060 for potassic feldspars 59 11.8 b vs. £ for potassic feldspars 63 11.9 Per cent ordering of potassic feldspars 67 11.10 Shock-induced cleavages in potassic feldspars 80 11.11 Planar deformation features in orthoclase, Charlevoix 394 11.12 Planar deformation features in microcline, Charlevoix 98 11.13 Lac Couture crater 103 11.14 Planar deformation features in microcline, Lac Couture 111 111.1 Geology of the Brent crater 132 111.2 Cross-section of the. Brent crater 134 111.3 Composition of feldspars beneath Brent crater 153 111.4 Compositions of feldspars in melt layer, Brent 158 111.5 Compositions of feldspars, sample 94, Charlevoix 167 IV.1 Partial Hugoniot of microcline 176 IV.2 Composite feldspar Hugoniot 179 IV. 3 Shock pressure vs_. shock temperature of tectosilicates 181 IV.4 Shock experiment design 185 IV.5 Target and projectile assembly 187 IV.6 Density of shocked microcline vs_. pressure 193 IV. 7 Refractive index of shocked microcline vs_. pressure 197 IV.8 Cleavages in experimentally shocked microcline 208 IV.9 Twins in experimentally shocked microcline 214 IV. 10 Planar deformation features in experimentally shocked microcline 223 IV.11 Lattice changes in experimentally shocked microcline 227 IV. 12 Schematic Debije-Scherrer pattern of shocked microcline 235 B.l Stereograms using optic directions as axes 281 D.l Typical Hugoniot curves 294 D.2 Hugoniot typical of some geologic materials 296 D.3 Propagation of shock waves in experiments 299 D.4 Graphical method of impedance matching method 303 D.5 Shock-wave propagation and impedance matching solution in Recovery experiments 306 LIST OF TABLES Table Page 11.1 Modal analyses of charnockitic rocks of Charlevoix 33 11.2 Shock metamorphism of quartz of Charlevoix 41 11.3 Composition and 2Va of K-feldspars of Charlevoix 48 11.4 Triclinicity of K-feldspars of Charlevoix 56 11.5 Normal and anomalous K-feldspars of Charlevoix 60 11.6 Per cent order of K-feldspars of Charlevoix 68 11.7 Deformation planes in K-feldspars of Charlevoix 81 11.8 Shock metamorphism of quartz from Lac Couture 106 11.9 Planar deformation features in microcline from Lac Couture 113 111.1 K20.and Na20 (wt%) in Brent crater rocks 138 111.2 Composition of potassic feldspar beneath Brent crater 147 111.3 Composition of plagioclase in mesoperthites beneath Brent 148 111.4 Composition of plagioclase beneath Brent crater 149 111.5 Composition of feldspars in impact melt, Brent crater 163 111.6 Composition of potassic feldspar, sample MBP 94, Charlevoix 165 IV.1 Characteristics of Shock Regimes § Shock Stages for tecto- silicates 182 IV. 2 Density and. triclinicity of experimentally shocked microcline 191 IV.3 Optical properties of experimentally shocked microcline 195 IV.4 Planar deformations in experimentally shocked microcline 224 IV.5 Interplanar spacing for reflections from high-pressure phases 237 IV.
Load more

Recommended publications
  • Hydrothermal Alteration at the Lonar Lake Impact Structure, India: Implications for Impact Cratering on Mars
    Meteoritics & Planetary Science 38, Nr 3, 365–381 (2003) Abstract available online at http://meteoritics.org Hydrothermal alteration at the Lonar Lake impact structure, India: Implications for impact cratering on Mars Justin J. HAGERTY* and Horton E. NEWSOM Institute of Meteoritics, Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA *Corresponding author. E-mail: [email protected] (Received 12 June 2002; revision accepted 20 February 2003) Abstract–The 50,000 year old, 1.8 km diameter Lonar crater is one of only two known terrestrial craters to be emplaced in basaltic target rock (the 65 million year old Deccan Traps). The composition of the Lonar basalts is similar to martian basaltic meteorites, which establishes Lonar as an excellent analogue for similarly sized craters on the surface of Mars. Samples from cores drilled into the Lonar crater floor show that there are basaltic impact breccias that have been altered by post-impact hydrothermal processes to produce an assemblage of secondary alteration minerals. Microprobe data and X-ray diffraction analyses show that the alteration mineral assemblage consists primarily of saponite, with minor celadonite, and carbonate. Thermodynamic modeling and terrestrial volcanic analogues were used to demonstrate that these clay minerals formed at temperatures between 130°C and 200°C. By comparing the Lonar alteration assemblage with alteration at other terrestrial craters, we conclude that the Lonar crater represents a lower size limit for impact-induced hydrothermal activity. Based on these results, we suggest that similarly sized craters on Mars have the potential to form hydrothermal systems, as long as liquid water was present on or near the martian surface.
    [Show full text]
  • Multiple Fluvial Reworking of Impact Ejecta—A Case Study from the Ries Crater, Southern Germany
    Multiple fluvial reworking of impact ejecta--A case study from the Ries crater, southern Germany Item Type Article; text Authors Buchner, E.; Schmieder, M. Citation Buchner, E., & Schmieder, M. (2009). Multiple fluvial reworking of impact ejecta—A case study from the Ries crater, southern Germany. Meteoritics & Planetary Science, 44(7), 1051-1060. DOI 10.1111/j.1945-5100.2009.tb00787.x Publisher The Meteoritical Society Journal Meteoritics & Planetary Science Rights Copyright © The Meteoritical Society Download date 06/10/2021 20:56:07 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/656594 Meteoritics & Planetary Science 44, Nr 7, 1051–1060 (2009) Abstract available online at http://meteoritics.org Multiple fluvial reworking of impact ejecta—A case study from the Ries crater, southern Germany Elmar BUCHNER* and Martin SCHMIEDER Institut für Planetologie, Universität Stuttgart, 70174 Stuttgart, Germany *Corresponding author. E-mail: [email protected] (Received 21 July 2008; revision accepted 12 May 2009) Abstract–Impact ejecta eroded and transported by gravity flows, tsunamis, or glaciers have been reported from a number of impact structures on Earth. Impact ejecta reworked by fluvial processes, however, are sparsely mentioned in the literature. This suggests that shocked mineral grains and impact glasses are unstable when eroded and transported in a fluvial system. As a case study, we here present a report of impact ejecta affected by multiple fluvial reworking including rounded quartz grains with planar deformation features and diaplectic quartz and feldspar glass in pebbles of fluvial sandstones from the “Monheimer Höhensande” ~10 km east of the Ries crater in southern Germany.
    [Show full text]
  • Magnetic, Gravity and Seismic Constraints on the Nature of the Wanapitei Lake Impact Crater
    Large Meteorite Impacts (2003) 4016.pdf MAGNETIC, GRAVITY AND SEISMIC CONSTRAINTS ON THE NATURE OF THE WANAPITEI LAKE IMPACT CRATER. E. L’Heureux1, H. Ugalde2, B. Milkereit2, N. Eyles3, J. Boyce4 and W. Morris4,1Dept. of Physics, Univ. Toronto, 60 St. George, Toronto, Ontario, Canada, [email protected], 2Dept. of Physics, Univ. Toronto, 60 St. George, Toronto, Ontario, Canada, 3University of Toronto at Scarborough, Toronto, Canada, 4School of Geography and Geology, McMaster Univ., 1280 Main street West, Hamilton, Canada Introduction: The Wanapitei Lake impact crater fects (quartzite fragments and the presence of glass) (46°45’N, 80°45’W) is located in Northern Ontario, that have been found in glacial drift on the southern bounded on its West side by the deformed East rim of shores of the lake [1, 3, 4]. These include boulders of the 1.85 b.y. old Sudbury impact structure. The crater suevite and glassy breccia as well as samples of coesite is believed to be of medium size (with a diameter of [3]. Dressler [2] observed deformation lamellae in a ~7.5 km) and lies entirely within the central, circular few quartz grains at only three locations in the south- portion of the 9 km diameter Wanapitei Lake [1]. Be- western region of the lake. cause the crater lies underwater, there are few con- straints on its actual size: its suggested diameter is based solely on one gravity survey. There are only few samples presenting shock metamorphic features in proximity of the lake, all of which come from glacial drift South of Wanapitei.
    [Show full text]
  • Remove This Report from Blc8. 25
    .:WO _______CUfe\J-&£sSU -ILtXJZ-.__________ T REMOVE THIS REPORT FROM BLC8. 25 UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY This report is preliminary and has not been edited or reviewed for conformity with U.S. Geological Survey standards and nomenclature. Prepared by the Geological Survey for the National Aeronautics and Space Administration U )L Interagency Report: 43 GUIDE TO THE GEOLOGY OF SUDBURY BASIN, ONTARIO, CANADA (Apollo 17 Training Exercise, 5/23/72-5/25/72) by I/ 2/ Michael R. Dence , Eugene L. Boudette 2/ and Ivo Lucchitta May 1972 Earth Physics Branch Dept. of Energy, Mines & Resources Ottawa, Canada 21 Center of Astrogeology U. S. Geological Survey Flagstaff, Arizona 86001 ERRATA Guide to the geology of Sudbury Basin, Ontario, Canada by Michael R. Dence, Eugene L. Boudette, and Ivo Lucchitta Page ii. Add "(photograph by G. Mac G. Boone) 11 to caption. iii. P. 2, line 5; delete "the" before "data", iv. P. 1, line 3; add "of Canada, Ltd." after "Company", iv. P. 1, line 7; delete "of Canada" after "Company". v. Move entire section "aerial reconnaissance....etc..." 5 spaces to left margin. 1. P. 2, line 6; add "moderate to" after "dips are". 1. P. 2, line 13; change "strike" to "striking". 2. P. 1, line 2; change "there" to "these". 2. P. 2, line 7; change "(1) breccias" to "breccias (1)". 2. P. 3, line 3; add "slate" after "Onwatin". 4. P. 1, line 7; change "which JLs" to "which are". 7. P. 1, line 9; add "(fig. 3)" after "surveys". 7. P.
    [Show full text]
  • An Unusual Occurrence of Coesite at the Lonar Crater, India
    Meteoritics & Planetary Science 52, Nr 1, 147–163 (2017) doi: 10.1111/maps.12745 An unusual occurrence of coesite at the Lonar crater, India 1* 1 2 1 3 Steven J. JARET , Brian L. PHILLIPS , David T. KING JR , Tim D. GLOTCH , Zia RAHMAN , and Shawn P. WRIGHT4 1Department of Geosciences, Stony Brook University, Stony Brook, New York 11794–2100, USA 2Department of Geosciences, Auburn University, Auburn, Alabama 36849, USA 3Jacobs—NASA Johnson Space Center, Houston, Texas 77058, USA 4Planetary Science Institute, Tucson, Arizona 85719, USA *Corresponding author. E-mail: [email protected] (Received 18 March 2016; revision accepted 06 September 2016) Abstract–Coesite has been identified within ejected blocks of shocked basalt at Lonar crater, India. This is the first report of coesite from the Lonar crater. Coesite occurs within SiO2 glass as distinct ~30 lm spherical aggregates of “granular coesite” identifiable both with optical petrography and with micro-Raman spectroscopy. The coesite+glass occurs only within former silica amygdules, which is also the first report of high-pressure polymorphs forming from a shocked secondary mineral. Detailed petrography and NMR spectroscopy suggest that the coesite crystallized directly from a localized SiO2 melt, as the result of complex interactions between the shock wave and these vesicle fillings. INTRODUCTION Although there is no direct observation of nonshock stishovite in nature, a possible post-stishovite phase may High-Pressure SiO2 Phases be a large component of subducting slabs and the core- mantle boundary (Lakshtanov et al. 2007), and Silica (SiO2) polymorphs are some of the simplest stishovite likely occurs in the deep mantle if basaltic minerals in terms of elemental chemistry, yet they are slabs survive to depth.
    [Show full text]
  • Wanapitei Lake Oak Scadding Island Bay
    THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT Your use of this Ontario Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use. Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever. Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”).
    [Show full text]
  • NICKEL by Peter H
    NICKEL By Peter H. Kuck Domestic survey data and tables were prepared by Barbara J. McNair, statistical assistant, and the world production tables were prepared by Glenn J. Wallace, international data coordinator. Stainless steel accounted for more than 60% of primary been storing previously generated wastes there. About 3,600 t nickel consumption in the world. In the United States, however, of shredded nickel scrap was stored at the closed DOE uranium this percentage was only 46% because of the relatively large enrichment facilities in Oak Ridge, TN. Part of the Oak Ridge number of specialty metal industries in the country. Specialty facilities—the K-25 site where the gaseous diffusion plant was uses included superalloys and related aerospace alloys, high- built—has been transformed into the East Tennessee Technology temperature nickel-chromium alloys, electrolytic plating, Park. Ongoing demolition activities at Oak Ridge were electroless plating, cupronickel alloys, and naval brasses. expected to generate an additional 2,400 t of shredded nickel Manufacturers of rechargeable batteries have been using metal scrap. The huge K-25 building shell was not scheduled increasing amounts of nickel metal foam. The foam is produced for demolition until 2008. Future demolition activities at in only four countries—Canada, China, Russia, and the United Oak Ridge, the shuttered facility at Portsmouth, OH, and the Kingdom. operating Paducah facility could generate another 21,000 t of Nickel in excess of 8% is needed to produce the austenitic shredded nickel scrap. The principal contaminants in the Oak microstructure in 300-series stainless steels. The nickel content Ridge and Paducah nickel are technetium-99 (a low-energy of some austenitic grades can be as high as 22%.
    [Show full text]
  • Contents — L Through O
    Large Meteorite Impacts (2003) alpha_l-o.pdf Contents — L through O The Lacustrine Reservoirs in Hellas Impact Basin Region H. Lahtela, V.-P. Kostama, M. Aittola, T. Öhman, and J. Raitala ......................................................... 4073 First Observation of Silicate Hollandite in a Terrestrial Rock F. Langenhorst and B. Dressler ............................................................................................................. 4046 Magnetic, Gravity and Seismic Contraints on the Nature of the Wanapitei Lake Impact Crater E. L’Heureux, H. Ugalde, B. Milkereit, N. Eyles, J. Boyce, and W. Morris........................................... 4016 An Array of Offshore Impact Craters on Mid-Ordovician Baltica M. Lindström.......................................................................................................................................... 4029 On the Decoupling of Microtektites from the Ejecta Plume R. D. Lorenz ........................................................................................................................................... 4114 Origin of Epidote from the Impact Melt of the Chicxulub Crater, Mexico E. Lounejeva, M. Elias-Herrera, F. Ortega-Gutiérrez, and E. Cedillo-Pardo....................................... 4054 Original Diameter and Depth of Erosion of the Popigai Impact Crater, Russia V. L. Masaitis, M. S. Mashchak, and M. V. Naumov.............................................................................. 4039 Numerical Modeling of Large Impacts H. J. Melosh ..........................................................................................................................................
    [Show full text]
  • The Potential of Economic Ore Deposits Related to Meteorite Impact Structures
    Geoscience and Remote Sensing (2018) Vol. 1: 1-8 Clausius Scientific Press, Canada The potential of economic ore deposits related to meteorite impact structures Rui Zhu Department of Applied Geology,WA School of Mines,Curtin Univerisity, Perth, Australia [email protected] Keywords: Impact structure; impact metamorphism; impact signature; economic and geological significance Abstract: At present, research on impact tectonics mainly covers the following aspects: 1. The structure and formation mechanism of the impact crater; 2. The ore-forming mineralization in impact structures; and 3. The economic and geological significance of impact structures. The study of impact structure not only has academic significance but also practical economic and geological significance. Economic deposits associated with impact structures range from world-class to relatively local deposits. There are three types of deposits: progenetic, syngenetic and epigenetic. There is increasing evidence that large-scale impact structures are often associated with economic deposits. Many impact structures can be targets for resource exploration but still need to be discovered. The exploration of impact structures is hindered by technology and sea-land erosion, and a considerable number of craters have been likely buried. Based on the economic deposits associated with these structures, further resource discovery and extraction has great potential. Original article, Published date: 2018-05-22 DOI: 10.23977/geors.2018.11011 ISSN 2523-2592 https://www.clausiuspress.com/journal/GEORS.html 1. Introduction In recent years, the influence of extra-terrestrial objects on Earth geology has been considered as an interesting influence. With the development of planetary exploration, our understanding of the importance of impact cratering has undergone fundamental changes.
    [Show full text]
  • A Geophysical Investigation of a Possible Astrobleme in Southwestern Michigan
    Western Michigan University ScholarWorks at WMU Master's Theses Graduate College 4-1984 A Geophysical Investigation of a Possible Astrobleme in Southwestern Michigan Suhas L. Ghatge Follow this and additional works at: https://scholarworks.wmich.edu/masters_theses Part of the Geophysics and Seismology Commons Recommended Citation Ghatge, Suhas L., "A Geophysical Investigation of a Possible Astrobleme in Southwestern Michigan" (1984). Master's Theses. 1498. https://scholarworks.wmich.edu/masters_theses/1498 This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. A GEOPHYSICAL INVESTIGATION OF A POSSIBLE ASTROBLEME IN SOUTHWESTERN MICHIGAN by Suhas L. Ghatge A Thesis Submitted to the Faculty of The Graduate College in Partial Fulfillment of the requirements for the Degree of Master of Science Department of Geology Western Michigan University Kalamazoo, Michigan April 1984 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. A GEOPHYSICAL INVESTIGATION OF A POSSIBLE ASTROBLEME IN SOUTHWESTERN MICHIGAN Suhas L. Ghatge, M.S. Western Michigan U n iv ers ity , 1984 A circular pattern to the oil production in Calvin Township, Cass County, Michigan, absence o f about 1200 fe e t of Ordovician sediments and uplift indicated by a deep drill hole in the center of the productive area and absence o f anomalies on the regional g ra vity and magnetic maps led to detailed gravity and magnetic surveys over this structure to delineate it and provide information regarding its genesis.
    [Show full text]
  • E D I T O R I a L
    E D I T O R I A L THE POTENCY OF PREVAILING CONCEPTS In a recent public discussion on a state university campus in the eastern United States, a genetics professor who teaches the basic course in evolution at that institution stated that the developments in molecular biology have established that Charles Darwin was wrong in the mechanism he proposed for an evolutionary development of life. This professor went on to say that although there is at present no evidence that clearly supports an origin and development of life by naturalistic processes, there is no justification for saying that an evolutionary or non-theistic explanation for life is incorrect; the task facing the scientific community is to find new explanations concerning how evolution did occur, not to abandon the concept. Three aspects of these comments deserve consideration. First is the recognition that despite what are often strong claims to the contrary, the accumulation of scientific evidence has been increasingly unfavorable to mechanistic evolutionary concepts of origin. Professor D. E. Green of the Institute for Enzyme Research at the University of Wisconsin and Dr. R. F. Goldberger, chief of the Biosynthesis and Control Section, Laboratory of Chemical Biology, U.S. National Institutes of Health, in their book Molecular Insights Into the Living Process say that “...the macromolecule-to-cell transition is a jump of fantastic dimensions which lies beyond the range of testable hypotheses. In this area all is conjecture. The available facts do not provide a basis for postulating that cells arose on this planet.”1 Dr. John Keosian of the Marine Biological Laboratory at Woods Hole, Massachusetts, at an international conference on the origin of life held in Barcelona, Spain, in June 1973, said “...the simplest heterotrophic [obtains food from outside sources] cell is an intricate structural and metabolic unit of harmoniously coordinated parts and chemical pathways.
    [Show full text]
  • Economic Mineral Deposits in Impact Structures: a Review
    Economic Mineral Deposits in Impact Structures: A Review Wolf Uwe Reimold1, Christian Koeberl2, Roger L. Gibson1, and Burkhard O. Dressler1,3 1Impact Cratering Research Group, School of Geosciences, University of the Witwatersrand, Private Bag 3, P.O. Wits 2050, Johannesburg, South Africa ([email protected]; [email protected]) 2Department of Geological Sciences, University of Vienna, Althanstrasse. 14, A-1090 Vienna, Austria ([email protected]) 3185 Romfield Circuit, Thornhill, Ontario, Canada, L3T 3H7 ([email protected]) Abstract. Many large meteorite impact structures throughout the world host mineral resources that are either currently mined or have the potential to become important economic resources in the future. The giant Vredefort-Witwatersrand and Sudbury impact structures underline this statement, because of their enormous resources in gold and uranium, and nickel, copper, and PGEs, respectively. In relation to impact, three basic types of ore deposits in impact structure settings have been distinguished: (1) progenetic (i.e., pre-impact) deposits that already existed in the target regions prior to an impact event, but may have become accessible as a direct result of the impact; (2) syngenetic (syn-impact) deposits that owe their existence directly to the impact process, and (3) epigenetic (immediately post-impact) deposits that result from impact-induced thermal/hydrothermal activity. In addition to metalliferous ore deposits related to impact structures, impact structure-hosted epigenetic hydrocarbon deposits are reviewed and are shown to make a major contribution to the North American economies. Non-metallic resources, such as minerals derived from crater-lake deposits, dimension stone, and hydrological benefits, may also be derived from impact structures, and the educational and recreational value of many meteorite impact craters can be substantial.
    [Show full text]