Arguments and Evidence Against a Younger Dryas Impact Event
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Lunar and Planetary Science XXX 1753.Pdf
Lunar and Planetary Science XXX 1753.pdf INTERSTELLAR DIAMOND. II. GROWTH AND IDENTIFICATION. Andrew W. Phelps, University of Dayton Research Institute, Materials Engineering Division (300 College Park, Dayton OH, 45469-0130, [email protected]). likely form clumps of carbon that look much like the Introduction: The first abstract in this series starting material – hydrogen rich sp3 bound clusters. suggested that many types of diamond are found in many types of meteoritic material and that the The compounds that fit the requirements above variation in polytype abundance appears to reflect the include the cycloalkanes such as adamantane [21-30] nature of the host. How the diamonds got there and (C10H16) and bicyclooctane (C6H8) (BCO) . what they mean will now be examined. Opinions These compounds ‘look’ like small cubic diamonds regarding the formation mechanism(s) of meteoritic and lonsdaleite respectively. If these particular and interstellar diamond grains have changed over compounds are suggested as models for diamond the years as new methods of making synthetic nuclei then a number of structural and diamond were developed[1,2]. Meteoritic diamonds thermodynamic predictions can be made about the were once believed to be the result of high pressure - types of diamond that can form and its relative temperature processes in the interior of planetary abundance with regard to the physics and chemistry bodies[3,4]. Impact formation of diamond became of its growth environment. A few examples of this popular after the development of shock wave are: Adamantane is a lower energy form and would diamond synthesis[5] because shock synthesis was tend to form in an environment of sufficient thermal able to form lonsdaleite and meteorites were full of energy to allow the molecule to organize into this lonsdaleite. -
A Detrital Zircon and Apatite Provenance Study of the Stac Fada Member and Wider St
On the track of a Scottish impact structure: a detrital zircon and apatite provenance study of the Stac Fada Member and wider Stoer Group, northwest Scotland Gavin G. Kenny1,2*, Gary J. O’Sullivan1, Stephen Alexander1, Michael J. Simms3, David M. Chew1 and Balz S. Kamber1,4 1Department of Geology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland 2Department of Geosciences, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden 3Department of Natural Sciences, National Museums Northern Ireland, Cultra, BT18 0EU Northern Ireland, UK 4School of Earth, Environmental and Biological Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001, Australia *[email protected] Abstract The Stac Fada Member of the Stoer Group, within the Torridonian succession of northwest Scotland, is a melt-rich, impact-related deposit that has not been conclusively correlated with any known impact structure. However, a gravity low approximately 50 km east of the preserved Stac Fada Member outcrops has recently been proposed as the associated impact site. Here we aimed to shed light on the location of the impact structure through a provenance study of detrital zircon and apatite in five samples from the Stoer Group. Our zircon U-Pb data is dominated by Archaean grains (>2.5 Ga), consistent with earlier interpretations that the detritus was derived largely from local Lewisian Gneiss Complex, whereas the apatite data (the first for the Stoer Group) display a single major peak at ca. 1.7 Ga, consistent with regional Laxfordian metamorphism. The almost complete absence of Archaean-aged apatite is best explained by later heating of the >2.5 Ga Lewisian basement (the likely source region) above the closure temperature of the apatite U-Pb system (~375-450°C). -
Impact−Cosmic−Metasomatic Origin of Microdiamonds from Kumdy−Kol Deposit, Kokchetav Massiv, N
11th International Kimberlite Conference Extended Abstract No. 11IKC-4506, 2017 Impact−Cosmic−Metasomatic Origin of Microdiamonds from Kumdy−Kol Deposit, Kokchetav Massiv, N. Kazakhstan L. I. Tretiakova1 and A. M. Lyukhin2 1St. Petersburg Branch Russian Mineralogical Society. RUSSIA, [email protected] 2Institute of remote ore prognosis, Moscow, RUSSIA, [email protected] Introduction Any collision extraterrestrial body and the Earth had left behind the “signature” on the Earth’s surface. We are examining a lot of signatures of an event caused Kumdy-Kol diamond-bearing deposit formation, best- known as “metamorphic” diamond locality among numerous UHP terrains around the world. We are offering new impact-cosmic-metasomatic genesis of this deposit and diamond origin provoked by impact event followed prograde and retrograde metamorphism with metasomatic alterations of collision area rocks that have been caused of diamond nucleation, growth and preserve. Brief geology of Kumdy-Kol diamond-bearing deposit Kumdy-Kol diamond-bearing deposit located within ring structure ~ 4 km diameter, in the form and size compares with small impact crater (Fig. 1). It is important impact event signature. Figure1: Cosmic image of Kumdy-Kol deposit area [http://map.google.ru/]. Diamond-bearing domain had been formed on the peak of UHP metamorphism provoked by comet impact under oblique angle on the Earth surface. As a result, steep falling system of tectonic dislocations, which breakage and fracture zones filling out of impact and host rock breccia with blastomylonitic and blastocataclastic textures have been created. Diamond-bearing domain has complicated lenticular-bloc structure (1300 x 40-200 m size) and lens out with deep about 300 m. -
Handbook of Iron Meteorites, Volume 2 (Canyon Diablo, Part 2)
Canyon Diablo 395 The primary structure is as before. However, the kamacite has been briefly reheated above 600° C and has recrystallized throughout the sample. The new grains are unequilibrated, serrated and have hardnesses of 145-210. The previous Neumann bands are still plainly visible , and so are the old subboundaries because the original precipitates delineate their locations. The schreibersite and cohenite crystals are still monocrystalline, and there are no reaction rims around them. The troilite is micromelted , usually to a somewhat larger extent than is present in I-III. Severe shear zones, 100-200 J1 wide , cross the entire specimens. They are wavy, fan out, coalesce again , and may displace taenite, plessite and minerals several millimeters. The present exterior surfaces of the slugs and wedge-shaped masses have no doubt been produced in a similar fashion by shear-rupture and have later become corroded. Figure 469. Canyon Diablo (Copenhagen no. 18463). Shock The taenite rims and lamellae are dirty-brownish, with annealed stage VI . Typical matte structure, with some co henite crystals to the right. Etched. Scale bar 2 mm. low hardnesses, 160-200, due to annealing. In crossed Nicols the taenite displays an unusual sheen from many small crystals, each 5-10 J1 across. This kind of material is believed to represent shock annealed fragments of the impacting main body. Since the fragments have not had a very long flight through the atmosphere, well developed fusion crusts and heat-affected rim zones are not expected to be present. The energy responsible for bulk reheating of the small masses to about 600° C is believed to have come from the conversion of kinetic to heat energy during the impact and fragmentation. -
Evidence from Polymict Ureilite Meteorites for a Disrupted and Re-Accreted Single Ureilite Parent Asteroid Gardened by Several Distinct Impactors
Available online at www.sciencedirect.com Geochimica et Cosmochimica Acta 72 (2008) 4825–4844 www.elsevier.com/locate/gca Evidence from polymict ureilite meteorites for a disrupted and re-accreted single ureilite parent asteroid gardened by several distinct impactors Hilary Downes a,b,*, David W. Mittlefehldt c, Noriko T. Kita d, John W. Valley d a School of Earth Sciences, Birkbeck University of London, Malet Street, London WC1E 7HX, UK b Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058, USA c Mail Code KR, NASA/Johnson Space Center, Houston, TX 77058, USA d Department of Geology and Geophysics, University of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706, USA Received 25 July 2007; accepted in revised form 24 June 2008; available online 17 July 2008 Abstract Ureilites are ultramafic achondrites that exhibit heterogeneity in mg# and oxygen isotope ratios between different meteor- ites. Polymict ureilites represent near-surface material of the ureilite parent asteroid(s). Electron microprobe analyses of >500 olivine and pyroxene clasts in several polymict ureilites reveal a statistically identical range of compositions to that shown by unbrecciated ureilites, suggesting derivation from a single parent asteroid. Many ureilitic clasts have identical compositions to the anomalously high Mn/Mg olivines and pyroxenes from the Hughes 009 unbrecciated ureilite (here termed the ‘‘Hughes cluster”). Some polymict samples also contain lithic clasts derived from oxidized impactors. The presence of several common distinctive lithologies within polymict ureilites is additional evidence that ureilites were derived from a single parent asteroid. In situ oxygen three isotope analyses were made on individual ureilite minerals and lithic clasts, using a secondary ion mass spectrometer (SIMS) with precision typically better than 0.2–0.4& (2SD) for d18O and d17O. -
POSTER SESSION 5:30 P.M
Monday, July 27, 1998 POSTER SESSION 5:30 p.m. Edmund Burke Theatre Concourse MARTIAN AND SNC METEORITES Head J. W. III Smith D. Zuber M. MOLA Science Team Mars: Assessing Evidence for an Ancient Northern Ocean with MOLA Data Varela M. E. Clocchiatti R. Kurat G. Massare D. Glass-bearing Inclusions in Chassigny Olivine: Heating Experiments Suggest Nonigneous Origin Boctor N. Z. Fei Y. Bertka C. M. Alexander C. M. O’D. Hauri E. Shock Metamorphic Features in Lithologies A, B, and C of Martian Meteorite Elephant Moraine 79001 Flynn G. J. Keller L. P. Jacobsen C. Wirick S. Carbon in Allan Hills 84001 Carbonate and Rims Terho M. Magnetic Properties and Paleointensity Studies of Two SNC Meteorites Britt D. T. Geological Results of the Mars Pathfinder Mission Wright I. P. Grady M. M. Pillinger C. T. Further Carbon-Isotopic Measurements of Carbonates in Allan Hills 84001 Burckle L. H. Delaney J. S. Microfossils in Chondritic Meteorites from Antarctica? Stay Tuned CHONDRULES Srinivasan G. Bischoff A. Magnesium-Aluminum Study of Hibonites Within a Chondrulelike Object from Sharps (H3) Mikouchi T. Fujita K. Miyamoto M. Preferred-oriented Olivines in a Porphyritic Olivine Chondrule from the Semarkona (LL3.0) Chondrite Tachibana S. Tsuchiyama A. Measurements of Evaporation Rates of Sulfur from Iron-Iron Sulfide Melt Maruyama S. Yurimoto H. Sueno S. Spinel-bearing Chondrules in the Allende Meteorite Semenenko V. P. Perron C. Girich A. L. Carbon-rich Fine-grained Clasts in the Krymka (LL3) Chondrite Bukovanská M. Nemec I. Šolc M. Study of Some Achondrites and Chondrites by Fourier Transform Infrared Microspectroscopy and Diffuse Reflectance Spectroscopy Semenenko V. -
The Eltanin Impact and Its Tsunami Along the Coast of South America: Insights for Potential Deposits
Earth and Planetary Science Letters 409 (2015) 175–181 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl The Eltanin impact and its tsunami along the coast of South America: Insights for potential deposits Robert Weiss a, Patrick Lynett b, Kai Wünnemann c a Department of Geosciences, Virginia Tech, VA 24061, USA b Sonny Astani Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089-2531, USA c Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany a r t i c l e i n f o a b s t r a c t Article history: The Eltanin impact occurred 2.15 million years ago in the Bellinghausen Sea in the southern Pacific. Received 21 June 2014 While a crater was not formed, evidence was left behind at the impact site to prove the impact origin. Received in revised form 10 October 2014 Previous studies suggest that a large tsunami formed, and sedimentary successions along the coast of Accepted 19 October 2014 South America have been attributed to the Eltanin impact tsunami. They are characterized by large clasts, Available online xxxx often several meters in diameter. Our state-of-the-art numerical modeling of the impact process and its Editor: J. Lynch-Stieglitz coupling with non-linear wave simulations allows for quantifying the initial wave characteristic and the Keywords: propagation of tsunami-like waves over large distances. We find that the tsunami attenuates quickly with −1.2 Eltanin impact η(r) ∝ r resulting in maximum wave heights similar to those observed during the 2004 Sumatra tsunamis and 2011 Tohoku-oki tsunamis. -
6Th Annual Jackson School of Geosciences Student Research Symposium February 4, 2017
6th Annual Jackson School of Geosciences Student Research Symposium February 4, 2017 Jackson School of Geosciences GSEC Graduate Student Executive Committee Welcome to the 6th Annual Jackson School Research Symposium It is with great pleasure we welcome you all to the 6th Annual Jackson School Research Symposium at UT-Austin! This symposium would not have been possible without the hard work of student volunteers, the support of faculty/research scientists, and generous support from ConocoPhillips. Thank you for taking part in supporting our students and growing research program within the Jackson School. Enjoy the posters! Schedule of Presentations and Events Breakfast, A.M. session poster set-up...............................................8:30 a.m. Early Career Graduate (ECG) posters......................................9:00-11:30 a.m. Late Career Masters (LCM) posters.........................................9:00-11:30 a.m. Lunch, A.M. session poster take-down.............................................11:30 a.m. P.M. session poster set-up................................................................12:30 p.m. Undergraduate (U) posters….....................................................1:00-3:30 p.m. Late Career PhD (LCPhD) posters.............................................1:00-3:30 p.m. Happy hour/judging............................................................................3:30 p.m. Awards/closing....................................................................................4:00 p.m. ii Table of Contents Program -
Impact Structures and Events – a Nordic Perspective
107 by Henning Dypvik1, Jüri Plado2, Claus Heinberg3, Eckart Håkansson4, Lauri J. Pesonen5, Birger Schmitz6, and Selen Raiskila5 Impact structures and events – a Nordic perspective 1 Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern, NO 0316 Oslo, Norway. E-mail: [email protected] 2 Department of Geology, University of Tartu, Vanemuise 46, 51014 Tartu, Estonia. 3 Department of Environmental, Social and Spatial Change, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark. 4 Department of Geography and Geology, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark. 5 Division of Geophysics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki, Finland. 6 Department of Geology, University of Lund, Sölvegatan 12, SE-22362 Lund, Sweden. Impact cratering is one of the fundamental processes in are the main reason that the Nordic countries are generally well- the formation of the Earth and our planetary system, as mapped. reflected, for example in the surfaces of Mars and the Impact craters came into the focus about 20 years ago and the interest among the Nordic communities has increased during recent Moon. The Earth has been covered by a comparable years. The small Kaalijärv structure of Estonia was the first impact number of impact scars, but due to active geological structure to be confirmed in northern Europe (Table 1; Figures 1 and processes, weathering, sea floor spreading etc, the num- 7). First described in 1794 (Rauch), the meteorite origin of the crater ber of preserved and recognized impact craters on the field (presently 9 craters) was proposed much later in 1919 (Kalju- Earth are limited. -
Early Fracturing and Impact Residue Emplacement: Can Modelling Help to Predict Their Location in Major Craters?
Early fracturing and impact residue emplacement: Can modelling help to predict their location in major craters? Item Type Proceedings; text Authors Kearsley, A.; Graham, G.; McDonnell, T.; Bland, P.; Hough, R.; Helps, P. Citation Kearsley, A., Graham, G., McDonnell, T., Bland, P., Hough, R., & Helps, P. (2004). Early fracturing and impact residue emplacement: Can modelling help to predict their location in major craters?. Meteoritics & Planetary Science, 39(2), 247-265. DOI 10.1111/j.1945-5100.2004.tb00339.x Publisher The Meteoritical Society Journal Meteoritics & Planetary Science Rights Copyright © The Meteoritical Society Download date 23/09/2021 21:19:20 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/655802 Meteoritics & Planetary Science 39, Nr 2, 247–265 (2004) Abstract available online at http://meteoritics.org Early fracturing and impact residue emplacement: Can modelling help to predict their location in major craters? Anton KEARSLEY,1* Giles GRAHAM,2 Tony McDONNELL,3 Phil BLAND,4 Rob HOUGH,5 and Paul HELPS6 1Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK 2Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, California, USA 3Planetary and Space Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, UK 4Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK 5Museum of Western Australia, Francis Street, Perth, Western Australia 6000, Australia 6School of Earth Sciences and Geography, Kingston University, Kingston-upon-Thames, Surrey, KT1 2EE, UK *Corresponding author. E-mail: [email protected] (Received 30 June 2003; revision accepted 15 December 2003) Abstract–Understanding the nature and composition of larger extraterrestrial bodies that may collide with the Earth is important. -
Appendix a Recovery of Ejecta Material from Confirmed, Probable
Appendix A Recovery of Ejecta Material from Confirmed, Probable, or Possible Distal Ejecta Layers A.1 Introduction In this appendix we discuss the methods that we have used to recover and study ejecta found in various types of sediment and rock. The processes used to recover ejecta material vary with the degree of lithification. We thus discuss sample processing for unconsolidated, semiconsolidated, and consolidated material separately. The type of sediment or rock is also important as, for example, carbonate sediment or rock is processed differently from siliciclastic sediment or rock. The methods used to take and process samples will also vary according to the objectives of the study and the background of the investigator. We summarize below the methods that we have found useful in our studies of distal impact ejecta layers for those who are just beginning such studies. One of the authors (BPG) was trained as a marine geologist and the other (BMS) as a hard rock geologist. Our approaches to processing and studying impact ejecta differ accordingly. The methods used to recover ejecta from unconsolidated sediments have been successfully employed by BPG for more than 40 years. A.2 Taking and Handling Samples A.2.1 Introduction The size, number, and type of samples will depend on the objective of the study and nature of the sediment/rock, but there a few guidelines that should be followed regardless of the objective or rock type. All outcrops, especially those near industrialized areas or transportation routes (e.g., highways, train tracks) need to be cleaned off (i.e., the surface layer removed) prior to sampling. -
Ultrastructural Observations of the Argonaut Shell
Scanning Microscopy Volume 8 Number 1 Article 4 2-15-1994 Ultrastructural Observations of the Argonaut Shell P. R. Mitchell Monash University, Australia P. P. Phakey Monash University, Australia W. A. Rachinger Monash University, Australia Follow this and additional works at: https://digitalcommons.usu.edu/microscopy Part of the Biology Commons Recommended Citation Mitchell, P. R.; Phakey, P. P.; and Rachinger, W. A. (1994) "Ultrastructural Observations of the Argonaut Shell," Scanning Microscopy: Vol. 8 : No. 1 , Article 4. Available at: https://digitalcommons.usu.edu/microscopy/vol8/iss1/4 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Scanning Microscopy by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Scanning Microscopy, Vol. 8, No. 1, 1994 (Pages 35-46) 0891- 7035/94$5. 00 +. 25 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA ULTRASTRUCTURAL OBSERVATIONS OF THE ARGONAUT SHELL P. R. Mitchell, P. P. Phakey*, W. A. Rachinger Department of Physics, Monash University, Wellington Road, Clayton, Victoria 3168, Australia (Received for publication October 6, 1993, and in revised form February 15, 1994) Abstract Introduction An examination of the ultrastructure of the shell of the The Nautilus and the Argonaut are the only two cephalopod Argonauta Nodosa was carried out using scanning cephalopods to possess external shells, however, despite a electron microscopy, transmission electron microscopy and superficial similarity in shape, the shells have very little in polarised light microscopy. The structure of the Argonaut common. The shell of the Argonaut is thin and fragile with shell was found to consist of an inner and outer prismatic no internal partitions or chambers and, in evolutionary terms, layer separated by a thin central zone which was sparsely is a relatively recent addition [Young, 1959, Wells, 1962, occupied by spherulitic crystals.