Gravity and Magnetic Signatures of Meteorite Impact Structures
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3-D Seismic Characterization of a Cryptoexplosion Structure
Cryptoexplosion structure 3-D seismic characterization of a eryptoexplosion structure J. Helen Isaac and Robert R. Stewart ABSTRACT Three-quarters of a circular structure is observed on three-dimensional (3-D) seismic data from James River, Alberta. The structure has an outer diameter of 4.8 km and a raised central uplift surrounded by a rim synform. The central uplift has a diameter of 2.4 km and its crest appears to be uplifted about 400 m above regional levels. The structure is at a depth of about 4500 m. This is below the zone of economic interest and the feature has not been penetrated by any wells. The disturbed sediments are interpreted to be Cambrian. We infer that the structure was formed in Late Cambrian to Middle Devonian time and suffered erosion before the deposition of the overlying Middle Devonian carbonates. Rim faults, probably caused by slumping of material into the depression, are observed on the outside limb of the synform. Reverse faults are evident underneath the feature and the central uplift appears to have coherent internal reflections. The amount of uplift decreases with increasing depth in the section. The entire feature is interpreted to be a cryptoexplosion structure, possibly caused by a meteorite impact. INTRODUCTION Several enigmatic circular structures, of different sizes and ages, have been observed on seismic data from the Western Canadian sedimentary basin (WCSB) (e.g., Sawatzky, 1976; Isaac and Stewart, 1993) and other parts of Canada (Scott and Hajnal, 1988; Jansa et al., 1989). The structures present startling interruptions in otherwise planar seismic features. -
Show Your Parents
Show your parents Saxby and William Pridmore Show your parents is a series of short chapters aimed at helping children (under 12 years) master a little general knowledge and science. Some of this material may need input from an adult – some words and ideas may be a bit difficult. But, the need for a bit of adult/parent input is not a bad thing – such interaction between the generations may be helpful to both. See what you think. It is a not-for-profit endeavour. Editorial Board Rachel & Amelia Allan, Eve Porter, Layla Tanner, Dempsey & Isaac O’Neil, and Julia & Claude Glaetzer Dedicated to Helen Stephen [pictured] [William’s pre-school teacher; many thanks to Sarah Stephen for the photograph] Contents 1. Start here… 2. Here, pussy, pussy… 3. Bones 4. Space opportunity 5. Rainbows 6. Where is New Zealand? 7. The narwhal 8. Kangaroos, what they do… 9. Planets and volcanos 10. Optical illusions 11. First and surprising 12. The marsupials 13. Tree rings and things 14. Flowers and honey 15. Evolution and waterfalls 16. Catalogue 17. Magnets and unrelated 18. Cakes first 19. Take a breath 20. Dolphins and 21. Getting around 22. Geography special 23. Speak up 24. Going around 25. Dragon’s blood 26. Larry 27. More atoms 28. Flags 29. Moscow 30. Some carbon 31. More carbon 32. Photosynthesis 33. Pisa 34. Toes and energy 35. Water and energy 36. Craters 37. Animals, mainly 38. Old rocks Show your parents Chapter 1. [‘Show your parents’ is a series of short chapters aimed at helping children (with input from their parents) learn some stuff. -
Cross-References ASTEROID IMPACT Definition and Introduction History of Impact Cratering Studies
18 ASTEROID IMPACT Tedesco, E. F., Noah, P. V., Noah, M., and Price, S. D., 2002. The identification and confirmation of impact structures on supplemental IRAS minor planet survey. The Astronomical Earth were developed: (a) crater morphology, (b) geo- 123 – Journal, , 1056 1085. physical anomalies, (c) evidence for shock metamor- Tholen, D. J., and Barucci, M. A., 1989. Asteroid taxonomy. In Binzel, R. P., Gehrels, T., and Matthews, M. S. (eds.), phism, and (d) the presence of meteorites or geochemical Asteroids II. Tucson: University of Arizona Press, pp. 298–315. evidence for traces of the meteoritic projectile – of which Yeomans, D., and Baalke, R., 2009. Near Earth Object Program. only (c) and (d) can provide confirming evidence. Remote Available from World Wide Web: http://neo.jpl.nasa.gov/ sensing, including morphological observations, as well programs. as geophysical studies, cannot provide confirming evi- dence – which requires the study of actual rock samples. Cross-references Impacts influenced the geological and biological evolu- tion of our own planet; the best known example is the link Albedo between the 200-km-diameter Chicxulub impact structure Asteroid Impact Asteroid Impact Mitigation in Mexico and the Cretaceous-Tertiary boundary. Under- Asteroid Impact Prediction standing impact structures, their formation processes, Torino Scale and their consequences should be of interest not only to Earth and planetary scientists, but also to society in general. ASTEROID IMPACT History of impact cratering studies In the geological sciences, it has only recently been recog- Christian Koeberl nized how important the process of impact cratering is on Natural History Museum, Vienna, Austria a planetary scale. -
Detecting and Avoiding Killer Asteroids
Target Earth! Detecting and Avoiding Killer Asteroids by Trudy E. Bell (Copyright 2013 Trudy E. Bell) ARTH HAD NO warning. When a mountain- above 2000°C and triggering earthquakes and volcanoes sized asteroid struck at tens of kilometers (miles) around the globe. per second, supersonic shock waves radiated Ocean water suctioned from the shoreline and geysered outward through the planet, shock-heating rocks kilometers up into the air; relentless tsunamis surged e inland. At ground zero, nearly half the asteroid’s kinetic energy instantly turned to heat, vaporizing the projectile and forming a mammoth impact crater within minutes. It also vaporized vast volumes of Earth’s sedimentary rocks, releasing huge amounts of carbon dioxide and sulfur di- oxide into the atmosphere, along with heavy dust from both celestial and terrestrial rock. High-altitude At least 300,000 asteroids larger than 30 meters revolve around the sun in orbits that cross Earth’s. Most are not yet discovered. One may have Earth’s name written on it. What are engineers doing to guard our planet from destruction? winds swiftly spread dust and gases worldwide, blackening skies from equator to poles. For months, profound darkness blanketed the planet and global temperatures dropped, followed by intense warming and torrents of acid rain. From single-celled ocean plank- ton to the land’s grandest trees, pho- tosynthesizing plants died. Herbivores starved to death, as did the carnivores that fed upon them. Within about three years—the time it took for the mingled rock dust from asteroid and Earth to fall out of the atmosphere onto the ground—70 percent of species and entire genera on Earth perished forever in a worldwide mass extinction. -
The Future of Continental Scientific Drilling U.S
THE FUTURE OF CONTINENTAL SCIENTIFIC DRILLING U.S. PERSPECTIVE Proceedings of a workshop | June 4-5, 2009 | Denver, Colorado DOSECC WORKSHOP PUBLICATION 1 Front Cover: Basalts and rhyolites of the Snake River Plain at Twin Falls, Idaho. Project Hotspot will explore the interaction of the Yellowstone hotspot with the continental crust by sampling the volcanic rocks underlying the plain. Two 1.5 km holes will penetrate both the surficial basalt and the underlying rhyolite caldera-fill and outflow depos- its. A separate drill hole will explore the paleoclimate record in Pliocene Lake Idaho in the western Snake River Plain. In addition to the understanding of continent-mantle interaction that develops and the paleoclimate data collected, the project will study water-rock interaction, gases emanating from the deeper curst, and the geomicro- biology of the rocks of the plain. Once scientific objectives and set, budgets are developed, and funding is granted, successful implementation of projects requires careful planning, professional on-site staff, appropriate equip- ment, effective logistics, and accurate accounting. Photo by Tony Walton The authors gratefully acknowledge support of the National Science Foundation (NSF EAR 0923056 to The University of Kansas) and DOSECC, Inc. of Salt Lake City, Utah. Anthony W. Walton, University of Kansas, Lawrence, Kansas Kenneth G. Miller, Rutgers University, New Brunswick, N.J. Christian Koeberl, University of Vienna, Vienna, Austria John Shervais, Utah State University, Logan, Utah Steve Colman, University of Minnesota, Duluth, Duluth, Minnesota edited by Cathy Evans. Stephen Hickman, US Geological Survey, Menlo Park, California covers and design by mitch favrow. Will Clyde, University of New Hampshire, Durham, New Hampshire document layout by Pam Lerow and Paula Courtney. -
The Origin of the Circular K Anomalies at the Bosumtwi Impact Structure
Large Meteorite Impacts VI 2019 (LPI Contrib. No. 2136) 5008.pdf THE ORIGIN OF THE CIRCULAR K ANOMALIES AT THE BOSUMTWI IMPACT STRUCTURE. C.A.B. Niang1,2,3, D. Baratoux3, D.P. Diallo1, R. Braucher4, P. Rochette4, C. Koeberl5, M.W. Jessell6, W.U. Reimold7, D. Boamah8, G. Faye9, M.S. Sapah10, O. Vanderhaeghe3, S. Bouley11. 1Département de Géologie, Université Cheikh Anta Diop, Dakar, Senegal, [email protected], 2Institut Fon- damental d’Afrique Noire Cheikh Anta Diop, Dakar, Senegal. 3Géosciences Environnement Toulouse, University of Toulouse, CNRS & IRD, 14, Avenue Edouard Belin, 31400, Toulouse, France. 4Centre Européen de Recherche et d’Enseignement des Géosciences et de l’Environnement, Aix-Marseille Université, CNRS, IRD, CEREGE UM34, Aix en Provence, France, 5Department of Lithospheric Research, University of Vienna, 1090 Vienna, Austria, and Natural History Museum 1010 Vienna, Austria. 6Centre for Exploration Targeting, The University of Western Aus- tralia, 35 Stirling Highway, Crawley, WA 6009, Australia. 7Institute of Geosciences, Laboratory of Geodynamics, Geochronology and Environmental Science, University of Brasília, Brasília, Brazil. 8Geological Survey Department, Accra, Ghana. 9Institut des Sciences de la Terre, Université Cheikh Anta Diop de Dakar, Sénégal.10Department of Earth Science, University of Ghana, Accra, Ghana. 11GEOPS - Géosciences Paris Sud, Univ. Paris-Sud, CNRS, Université Paris-Saclay, Rue du Belvédère, Bât. 504-509, 91405 Orsay, France Introduction: Radiometric data are commonly to weathering, erosional and transport processes. Sev- used for geological mapping in mineral exploration, eral samples were also taken at surface and combined particularly in tropical regions where outcrop condi- with samples from shallow boreholes used for cosmo- tions are poor. -
Extraordinary Rocks from the Peak Ring of the Chicxulub Impact Crater: P-Wave Velocity, Density, and Porosity Measurements from IODP/ICDP Expedition 364 ∗ G.L
Earth and Planetary Science Letters 495 (2018) 1–11 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl Extraordinary rocks from the peak ring of the Chicxulub impact crater: P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition 364 ∗ G.L. Christeson a, , S.P.S. Gulick a,b, J.V. Morgan c, C. Gebhardt d, D.A. Kring e, E. Le Ber f, J. Lofi g, C. Nixon h, M. Poelchau i, A.S.P. Rae c, M. Rebolledo-Vieyra j, U. Riller k, D.R. Schmitt h,1, A. Wittmann l, T.J. Bralower m, E. Chenot n, P. Claeys o, C.S. Cockell p, M.J.L. Coolen q, L. Ferrière r, S. Green s, K. Goto t, H. Jones m, C.M. Lowery a, C. Mellett u, R. Ocampo-Torres v, L. Perez-Cruz w, A.E. Pickersgill x,y, C. Rasmussen z,2, H. Sato aa,3, J. Smit ab, S.M. Tikoo ac, N. Tomioka ad, J. Urrutia-Fucugauchi w, M.T. Whalen ae, L. Xiao af, K.E. Yamaguchi ag,ah a University of Texas Institute for Geophysics, Jackson School of Geosciences, Austin, USA b Department of Geological Sciences, Jackson School of Geosciences, Austin, USA c Department of Earth Science and Engineering, Imperial College, London, UK d Alfred Wegener Institute Helmholtz Centre of Polar and Marine Research, Bremerhaven, Germany e Lunar and Planetary Institute, Houston, USA f Department of Geology, University of Leicester, UK g Géosciences Montpellier, Université de Montpellier, France h Department of Physics, University of Alberta, Canada i Department of Geology, University of Freiburg, Germany j SM 312, Mza 7, Chipre 5, Resid. -
Terrestrial Impact Structures Provide the Only Ground Truth Against Which Computational and Experimental Results Can Be Com Pared
Ann. Rev. Earth Planet. Sci. 1987. 15:245-70 Copyright([;; /987 by Annual Reviews Inc. All rights reserved TERRESTRIAL IMI!ACT STRUCTURES ··- Richard A. F. Grieve Geophysics Division, Geological Survey of Canada, Ottawa, Ontario KIA OY3, Canada INTRODUCTION Impact structures are the dominant landform on planets that have retained portions of their earliest crust. The present surface of the Earth, however, has comparatively few recognized impact structures. This is due to its relative youthfulness and the dynamic nature of the terrestrial geosphere, both of which serve to obscure and remove the impact record. Although not generally viewed as an important terrestrial (as opposed to planetary) geologic process, the role of impact in Earth evolution is now receiving mounting consideration. For example, large-scale impact events may hav~~ been responsible for such phenomena as the formation of the Earth's moon and certain mass extinctions in the biologic record. The importance of the terrestrial impact record is greater than the relatively small number of known structures would indicate. Impact is a highly transient, high-energy event. It is inherently difficult to study through experimentation because of the problem of scale. In addition, sophisticated finite-element code calculations of impact cratering are gen erally limited to relatively early-time phenomena as a result of high com putational costs. Terrestrial impact structures provide the only ground truth against which computational and experimental results can be com pared. These structures provide information on aspects of the third dimen sion, the pre- and postimpact distribution of target lithologies, and the nature of the lithologic and mineralogic changes produced by the passage of a shock wave. -
La Ronge Lynn Lake Bridge Project: Geology of the Southern Reindeer Lake Area
Saskatchewan Open File Report 2003-1 Industry and Resources Saskatchewan Geological Survey _ La Ronge Lynn Lake Bridge Project: Geology of the Southern Reindeer Lake Area Executive Summary (part of CD1) R.O. Maxeiner, C.T. Harper, D. Corrigan, and D.G. MacDougall 2004 Saskatchewan Open File Report 2003-1 Industry and Resources Saskatchewan Geological Survey La Ronge–Lynn Lake Bridge Project: Geology of the Southern Reindeer Lake Area Executive Summary (part of CD1) R.O. Maxeiner, C.T. Harper, D. Corrigan, and D.G. MacDougall 2004 19 48 Printed under the authority of the Minister of Industry and Resources Although the Department of Industry and Resources has exercised all reasonable care in the compilation, interpretation, and production of this report, it is not possible to ensure total accuracy, and all persons who rely on the information contained herein do so at their own risk. The Department of Industry and Resources and the Government of Saskatchewan do not accept liability for any errors, omissions or inaccuracies that may be included in, or derived from, this report. Cover: Garnet-anthophyllite alteration assemblage from the Numabin Bay area (Reindeer Lake). This report is available for viewing and additional copies are available for purchase at: Publications Office Saskatchewan Industry and Resources 2101 Scarth Street, 3rd floor Regina, SK SA4P 3V7 (306) 787-2528 or FAX (306) 787-2488 E-mail: [email protected] and the Resident Geologists’ offices in La Ronge and Creighton Parts of this publication may be quoted if credit is given. It is recommended that reference to this report be made as follows: Maxeiner, R.O., Harper, C.T., Corrigan, D., and MacDougall, D.G. -
A Study of the Brushy Creek Feature, Saint Helena Parish, Louisiana Andrew Schedl
Open-File Series No. 18-01 Fall 2018 A Study of the Brushy Creek Feature, Saint Helena Parish, Louisiana Andrew Schedl Abstract This study was unable to determine the origin of the Brushy Creek feature. New¯ thin sections were made and new and old thin sections were examined using the opti- cal and scanning electron microscope (SEM). Powdered samples from the center of Brushy Creek were examined using X-ray diffraction (XRD). In sample 16SHPA, a half dozen new grains with probable planar deformation features (PDF) were found with orientations of {1012} and {1011}. Preliminary SEM studies of zircons showed no evidence for PDFs or reidite. Only one grain from the center of Brushy Creek structure showed possible rectangular fracture. XRD analysis found no evidence for high-pressure forms of quartz, coesite and stishovite. Suggestions for further study are included. Introduction North-south oriented ridges and ravines dominate the landscape in this part of Louisiana. The Brushy Creek is a “noticeable circular hole” in the ridge/ravine topography (Heinrich, 2003). The feature is about 2 kilometers in diameter and has a relief of 15 meters and Brushy Creek breeches the southeast rim of this feature. Exposed in the rim is the poorly lithified and highly fractured Pliocene Citronelle Formation. Near the Brushy Creek feature, the Citronelle formation consists of cross-bedded, massive, poorly sorted fine to coarse sand 9-12 meters thick underlain by 6 meters of laminated clay and silt. The Kentwood Brick and Tile Company has drilled the center of the feature and have found that the laminated clay and silt is absent. -
Chapter 6 Lawn Hill Megabreccia
Chapter 6 Lawn Hill Megabreccia Chapter 6 Catastrophic mass failure of a Middle Cambrian platform margin, the Lawn Hill Megabreccia, Queensland, Australia Leonardo Feltrin 6-1 Chapter 6 Lawn Hill Megabreccia Acknowledgement of Contributions N.H.S. Oliver – normal supervisory contributions Leonardo Feltrin 6-2 Chapter 6 Lawn Hill Megabreccia Abstract Megabreccia and related folds are two of the most spectacular features of the Lawn Hill Outlier, a small carbonate platform of Middle Cambrian age, situated in the northeastern part of the Georgina Basin, Australia. The megabreccia is a thick unit (over 200 m) composed of chaotic structures and containing matrix-supported clasts up to 260 m across. The breccia also influenced a Mesoproterozoic basement, which hosts the world class Zn-Pb-Ag Century Deposit. Field-studies (undertaken in the mine area), structural 3D modelling and stable isotopic data were used to assess the origin and timing of the megabreccia, and its relationship to the tectonic framework. Previous workers proposed the possible linkage of the structural disruption to an asteroid impact, to justify the extremely large clasts and the conspicuous basement interaction. However, the megabreccia has comparable clast size to some of the largest examples of sedimentary breccias and synsedimentary dyke intrusions in the world. Together with our field and isotope data, the reconstruction of the sequence of events that led to the cratonization of the Centralian Superbasin supports a synsedimentary origin for the Lawn Hill Megabreccia. However, later brittle faulting and veining accompanying strain localisation within the Thorntonia Limestones may represent post-sedimentary, syntectonic deformation, possibly linked to the late Devonian Alice Springs Orogeny. -
Impact Cratering
6 Impact cratering The dominant surface features of the Moon are approximately circular depressions, which may be designated by the general term craters … Solution of the origin of the lunar craters is fundamental to the unravel- ing of the history of the Moon and may shed much light on the history of the terrestrial planets as well. E. M. Shoemaker (1962) Impact craters are the dominant landform on the surface of the Moon, Mercury, and many satellites of the giant planets in the outer Solar System. The southern hemisphere of Mars is heavily affected by impact cratering. From a planetary perspective, the rarity or absence of impact craters on a planet’s surface is the exceptional state, one that needs further explanation, such as on the Earth, Io, or Europa. The process of impact cratering has touched every aspect of planetary evolution, from planetary accretion out of dust or planetesimals, to the course of biological evolution. The importance of impact cratering has been recognized only recently. E. M. Shoemaker (1928–1997), a geologist, was one of the irst to recognize the importance of this process and a major contributor to its elucidation. A few older geologists still resist the notion that important changes in the Earth’s structure and history are the consequences of extraterres- trial impact events. The decades of lunar and planetary exploration since 1970 have, how- ever, brought a new perspective into view, one in which it is clear that high-velocity impacts have, at one time or another, affected nearly every atom that is part of our planetary system.