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During Neoproterozoic Glaciations with Evolutionary Implications
Geosciences 2012, 2, 90-108; doi:10.3390/geosciences2020090 OPEN ACCESS geosciences ISSN 2076-3263 www.mdpi.com/journal/geosciences Review The Location and Styles of Ice-Free “Oases” during Neoproterozoic Glaciations with Evolutionary Implications Daniel Paul Le Heron Department of Earth Sciences, Royal Holloway University of London, Queen’s Building, Egham TW200EX, UK; E-Mail: [email protected]; Tel.: +0044-1784-443615; Fax: +0044-1784-471780 Received: 13 March 2012; in revised form: 10 April 2012 / Accepted: 17 May 2012 / Published: 29 May 2012 Abstract: Evidence based on molecular clocks, together with molecular evidence/biomarkers and putative body fossils, points to major evolutionary events prior to and during the intense Cryogenian and Ediacaran glaciations. The glaciations themselves were of global extent. Sedimentological evidence, including hummocky cross-stratification (representing ice-free seas affected by intra-glacial storms), dropstone textures, microbial mat-bearing ironstones, ladderback ripples, and wave ripples, militates against a “hard” Snowball Earth event. Each piece of sedimentological evidence potentially allows insight into the shape and location, with respect to the shoreline, of ice-free areas (“oases”) that may be viewed as potential refugia. The location of such oases must be seen in the context of global paleogeography, and it is emphasized that continental reconstructions at 600 Ma (about 35 millions years after the “Marinoan” ice age) are non-unique solutions. Specifically, whether continents such as greater India, Australia/East Antarctica, Kalahari, South and North China, and Siberia, were welded to a southern supercontinent or not, has implications for island speciation, faunal exchange, and the development of endemism. -
Neoproterozoic Glaciations in a Revised Global Palaeogeography from the Breakup of Rodinia to the Assembly of Gondwanaland
Sedimentary Geology 294 (2013) 219–232 Contents lists available at SciVerse ScienceDirect Sedimentary Geology journal homepage: www.elsevier.com/locate/sedgeo Invited review Neoproterozoic glaciations in a revised global palaeogeography from the breakup of Rodinia to the assembly of Gondwanaland Zheng-Xiang Li a,b,⁎, David A.D. Evans b, Galen P. Halverson c,d a ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia b Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, USA c Earth & Planetary Sciences/GEOTOP, McGill University, 3450 University St., Montreal, Quebec H3A0E8, Canada d Tectonics, Resources and Exploration (TRaX), School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia article info abstract Article history: This review paper presents a set of revised global palaeogeographic maps for the 825–540 Ma interval using Received 6 January 2013 the latest palaeomagnetic data, along with lithological information for Neoproterozoic sedimentary basins. Received in revised form 24 May 2013 These maps form the basis for an examination of the relationships between known glacial deposits, Accepted 28 May 2013 palaeolatitude, positions of continental rifting, relative sea-level changes, and major global tectonic events Available online 5 June 2013 such as supercontinent assembly, breakup and superplume events. This analysis reveals several fundamental ’ Editor: J. Knight palaeogeographic features that will help inform and constrain models for Earth s climatic and geodynamic evolution during the Neoproterozoic. First, glacial deposits at or near sea level appear to extend from high Keywords: latitudes into the deep tropics for all three Neoproterozoic ice ages (Sturtian, Marinoan and Gaskiers), al- Neoproterozoic though the Gaskiers interval remains very poorly constrained in both palaeomagnetic data and global Rodinia lithostratigraphic correlations. -
A Community Effort Towards an Improved Geological Time Scale
A community effort towards an improved geological time scale 1 This manuscript is a preprint of a paper that was submitted for publication in Journal 2 of the Geological Society. Please note that the manuscript is now formally accepted 3 for publication in JGS and has the doi number: 4 5 https://doi.org/10.1144/jgs2020-222 6 7 The final version of this manuscript will be available via the ‘Peer reviewed Publication 8 DOI’ link on the right-hand side of this webpage. Please feel free to contact any of the 9 authors. We welcome feedback on this community effort to produce a framework for 10 future rock record-based subdivision of the pre-Cryogenian geological timescale. 11 1 A community effort towards an improved geological time scale 12 Towards a new geological time scale: A template for improved rock-based subdivision of 13 pre-Cryogenian time 14 15 Graham A. Shields1*, Robin A. Strachan2, Susannah M. Porter3, Galen P. Halverson4, Francis A. 16 Macdonald3, Kenneth A. Plumb5, Carlos J. de Alvarenga6, Dhiraj M. Banerjee7, Andrey Bekker8, 17 Wouter Bleeker9, Alexander Brasier10, Partha P. Chakraborty7, Alan S. Collins11, Kent Condie12, 18 Kaushik Das13, Evans, D.A.D.14, Richard Ernst15, Anthony E. Fallick16, Hartwig Frimmel17, Reinhardt 19 Fuck6, Paul F. Hoffman18, Balz S. Kamber19, Anton Kuznetsov20, Ross Mitchell21, Daniel G. Poiré22, 20 Simon W. Poulton23, Robert Riding24, Mukund Sharma25, Craig Storey2, Eva Stueeken26, Rosalie 21 Tostevin27, Elizabeth Turner28, Shuhai Xiao29, Shuanhong Zhang30, Ying Zhou1, Maoyan Zhu31 22 23 1Department -
The History of Ice on Earth by Michael Marshall
The history of ice on Earth By Michael Marshall Primitive humans, clad in animal skins, trekking across vast expanses of ice in a desperate search to find food. That’s the image that comes to mind when most of us think about an ice age. But in fact there have been many ice ages, most of them long before humans made their first appearance. And the familiar picture of an ice age is of a comparatively mild one: others were so severe that the entire Earth froze over, for tens or even hundreds of millions of years. In fact, the planet seems to have three main settings: “greenhouse”, when tropical temperatures extend to the polesand there are no ice sheets at all; “icehouse”, when there is some permanent ice, although its extent varies greatly; and “snowball”, in which the planet’s entire surface is frozen over. Why the ice periodically advances – and why it retreats again – is a mystery that glaciologists have only just started to unravel. Here’s our recap of all the back and forth they’re trying to explain. Snowball Earth 2.4 to 2.1 billion years ago The Huronian glaciation is the oldest ice age we know about. The Earth was just over 2 billion years old, and home only to unicellular life-forms. The early stages of the Huronian, from 2.4 to 2.3 billion years ago, seem to have been particularly severe, with the entire planet frozen over in the first “snowball Earth”. This may have been triggered by a 250-million-year lull in volcanic activity, which would have meant less carbon dioxide being pumped into the atmosphere, and a reduced greenhouse effect. -
Stream Sediment and Stream Water OG SU Alberta Geological Survey (MITE) ICAL 95K 85J 95J 85K of 95I4674 85L
Natural Resources Ressources naturelles Canada Canada CurrentCurrent and and Upcoming Upcoming NGR NGR Program Program Activities Activities in in British British Columbia, Columbia, NationalNational Geochemical Geochemical Reconnaissance Reconnaissance NorthwestNorthwest Territories, Territories, Yukon Yukon Territory Territory and and Alberta, Alberta, 2005-06 2005-06 ProgrProgrammeamme National National de de la la Reconnaissance Reconnaissance Géochimique Géochimique ActivitésActivités En-cours En-cours et et Futures Futures du du Programme Programme NRG NRG en en Colombie Colombie Britannique, Britannique, P.W.B.P.W.B. Friske, Friske,S.J.A.S.J.A. Day, Day, M.W. M.W. McCurdy McCurdy and and R.J. R.J. McNeil McNeil auau Territoires Territoires de du Nord-Ouest, Nord-Ouest, au au Territoire Territoire du du Yukon Yukon et et en en Alberta, Alberta, 2005-06 2005-06 GeologicalGeological Survey Survey of of Canada Canada 601601 Booth Booth St, St, Ottawa, Ottawa, ON ON 11 Area: Edéhzhie (Horn Plateau), NT 55 Area: Old Crow, YT H COLU Survey was conducted in conjunction with Survey was conducted in conjunction with and funded by IS M EUB IT B and funded by NTGO, INAC and NRCAN. NORTHWEST TERRITORIES R I the Yukon Geological Survey and NRCAN. Data will form A 124° 122° 120° 118° 116° B Alberta Energy and Utilities Board Data will form the basis of a mineral potential GEOSCIENCE 95N 85O the basis of a mineral potential evaluation as part of a 95O 85N evaluation as part of a larger required 95P 85M larger required Resource Assessment. OFFICE .Wrigley RESEARCH ANALYSIS INFORMATION Resource Assessment. .Wha Ti G 63° YUKON 63° Metals in the Environment (MITE) E Y AGS ESS Program: O E ESS Program: Metals in the Environment V .Rae-Edzo L R GSEOLOGICAL URVEY Survey Type: Stream Sediment and Stream Water OG SU Alberta Geological Survey (MITE) ICAL 95K 85J 95J 85K OF 95I4674 85L Survey Type: Stream Sediment, stream M Year of Collection: 2004 and 2005 A C K ENZI E R 2 62° I V water, bulk stream sediment (HMCs and KIMs). -
Timing and Tempo of the Great Oxidation Event
Timing and tempo of the Great Oxidation Event Ashley P. Gumsleya,1, Kevin R. Chamberlainb,c, Wouter Bleekerd, Ulf Söderlunda,e, Michiel O. de Kockf, Emilie R. Larssona, and Andrey Bekkerg,f aDepartment of Geology, Lund University, Lund 223 62, Sweden; bDepartment of Geology and Geophysics, University of Wyoming, Laramie, WY 82071; cFaculty of Geology and Geography, Tomsk State University, Tomsk 634050, Russia; dGeological Survey of Canada, Ottawa, ON K1A 0E8, Canada; eDepartment of Geosciences, Swedish Museum of Natural History, Stockholm 104 05, Sweden; fDepartment of Geology, University of Johannesburg, Auckland Park 2006, South Africa; and gDepartment of Earth Sciences, University of California, Riverside, CA 92521 Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved December 27, 2016 (received for review June 11, 2016) The first significant buildup in atmospheric oxygen, the Great situ secondary ion mass spectrometry (SIMS) on microbaddeleyite Oxidation Event (GOE), began in the early Paleoproterozoic in grains coupled with precise isotope dilution thermal ionization association with global glaciations and continued until the end of mass spectrometry (ID-TIMS) and paleomagnetic studies, we re- the Lomagundi carbon isotope excursion ca. 2,060 Ma. The exact solve these uncertainties by obtaining accurate and precise ages timing of and relationships among these events are debated for the volcanic Ongeluk Formation and related intrusions in because of poor age constraints and contradictory stratigraphic South Africa. These ages lead to a more coherent global per- correlations. Here, we show that the first Paleoproterozoic global spective on the timing and tempo of the GOE and associated glaciation and the onset of the GOE occurred between ca. -
March 21–25, 2016
FORTY-SEVENTH LUNAR AND PLANETARY SCIENCE CONFERENCE PROGRAM OF TECHNICAL SESSIONS MARCH 21–25, 2016 The Woodlands Waterway Marriott Hotel and Convention Center The Woodlands, Texas INSTITUTIONAL SUPPORT Universities Space Research Association Lunar and Planetary Institute National Aeronautics and Space Administration CONFERENCE CO-CHAIRS Stephen Mackwell, Lunar and Planetary Institute Eileen Stansbery, NASA Johnson Space Center PROGRAM COMMITTEE CHAIRS David Draper, NASA Johnson Space Center Walter Kiefer, Lunar and Planetary Institute PROGRAM COMMITTEE P. Doug Archer, NASA Johnson Space Center Nicolas LeCorvec, Lunar and Planetary Institute Katherine Bermingham, University of Maryland Yo Matsubara, Smithsonian Institute Janice Bishop, SETI and NASA Ames Research Center Francis McCubbin, NASA Johnson Space Center Jeremy Boyce, University of California, Los Angeles Andrew Needham, Carnegie Institution of Washington Lisa Danielson, NASA Johnson Space Center Lan-Anh Nguyen, NASA Johnson Space Center Deepak Dhingra, University of Idaho Paul Niles, NASA Johnson Space Center Stephen Elardo, Carnegie Institution of Washington Dorothy Oehler, NASA Johnson Space Center Marc Fries, NASA Johnson Space Center D. Alex Patthoff, Jet Propulsion Laboratory Cyrena Goodrich, Lunar and Planetary Institute Elizabeth Rampe, Aerodyne Industries, Jacobs JETS at John Gruener, NASA Johnson Space Center NASA Johnson Space Center Justin Hagerty, U.S. Geological Survey Carol Raymond, Jet Propulsion Laboratory Lindsay Hays, Jet Propulsion Laboratory Paul Schenk, -
Impact Melt Emplacement on Mercury
Western University Scholarship@Western Electronic Thesis and Dissertation Repository 7-24-2018 2:00 PM Impact Melt Emplacement on Mercury Jeffrey Daniels The University of Western Ontario Supervisor Neish, Catherine D. The University of Western Ontario Graduate Program in Geology A thesis submitted in partial fulfillment of the equirr ements for the degree in Master of Science © Jeffrey Daniels 2018 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Geology Commons, Physical Processes Commons, and the The Sun and the Solar System Commons Recommended Citation Daniels, Jeffrey, "Impact Melt Emplacement on Mercury" (2018). Electronic Thesis and Dissertation Repository. 5657. https://ir.lib.uwo.ca/etd/5657 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract Impact cratering is an abrupt, spectacular process that occurs on any world with a solid surface. On Earth, these craters are easily eroded or destroyed through endogenic processes. The Moon and Mercury, however, lack a significant atmosphere, meaning craters on these worlds remain intact longer, geologically. In this thesis, remote-sensing techniques were used to investigate impact melt emplacement about Mercury’s fresh, complex craters. For complex lunar craters, impact melt is preferentially ejected from the lowest rim elevation, implying topographic control. On Venus, impact melt is preferentially ejected downrange from the impact site, implying impactor-direction control. Mercury, despite its heavily-cratered surface, trends more like Venus than like the Moon. -
Geologic Map of the Victoria Quadrangle (H02), Mercury
H01 - Borealis Geologic Map of the Victoria Quadrangle (H02), Mercury 60° Geologic Units Borea 65° Smooth plains material 1 1 2 3 4 1,5 sp H05 - Hokusai H04 - Raditladi H03 - Shakespeare H02 - Victoria Smooth and sparsely cratered planar surfaces confined to pools found within crater materials. Galluzzi V. , Guzzetta L. , Ferranti L. , Di Achille G. , Rothery D. A. , Palumbo P. 30° Apollonia Liguria Caduceata Aurora Smooth plains material–northern spn Smooth and sparsely cratered planar surfaces confined to the high-northern latitudes. 1 INAF, Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy; 22.5° Intermediate plains material 2 H10 - Derain H09 - Eminescu H08 - Tolstoj H07 - Beethoven H06 - Kuiper imp DiSTAR, Università degli Studi di Napoli "Federico II", Naples, Italy; 0° Pieria Solitudo Criophori Phoethontas Solitudo Lycaonis Tricrena Smooth undulating to planar surfaces, more densely cratered than the smooth plains. 3 INAF, Osservatorio Astronomico di Teramo, Teramo, Italy; -22.5° Intercrater plains material 4 72° 144° 216° 288° icp 2 Department of Physical Sciences, The Open University, Milton Keynes, UK; ° Rough or gently rolling, densely cratered surfaces, encompassing also distal crater materials. 70 60 H14 - Debussy H13 - Neruda H12 - Michelangelo H11 - Discovery ° 5 3 270° 300° 330° 0° 30° spn Dipartimento di Scienze e Tecnologie, Università degli Studi di Napoli "Parthenope", Naples, Italy. Cyllene Solitudo Persephones Solitudo Promethei Solitudo Hermae -30° Trismegisti -65° 90° 270° Crater Materials icp H15 - Bach Australia Crater material–well preserved cfs -60° c3 180° Fresh craters with a sharp rim, textured ejecta blanket and pristine or sparsely cratered floor. 2 1:3,000,000 ° c2 80° 350 Crater material–degraded c2 spn M c3 Degraded craters with a subdued rim and a moderately cratered smooth to hummocky floor. -
Robert L. Christie (1926 Ð 1999)
ARCTIC VOL. 53, NO. 1 (MARCH 2000) P. 88–91 ROBERT L. CHRISTIE (1926 – 1999) Dr. Robert L. Christie, geologist, naturalist, and explorer, suffered a heart attack on his beloved sailboat in the morning of 1 September 1999 and died a few hours later in hospital in Belleville, Ontario. Some weeks earlier, Bob and Audrey had sold their small farm at nearby Madoc, Ontario, and were preparing to move to Gabriola Island in British Columbia, back to Bob’s home province. Bob will be remembered for a broad range of geological achieve- ments in western and Arctic Canada, as well as in Green- land, achievements documented by nearly 100 maps and reports published in scientific journals. He will be espe- cially remembered for his loving warmth, his infectious laughter, and his limitless generosity. Bob was undoubt- edly the kindest and gentlest man I have ever known, and his family and friends were the special delights in his life. During the early sixties, Bob and I camped together for three summers in the Arctic Islands, doing fieldwork for the Geological Survey of Canada. When faced with tough conditions in the field, Bob would harden with stoic endurance. But when the sun shone on our little flycamp, he would rise to a rhapsody, and his cheerful yodel would signal that all was well in our little corner of the vast Arctic wilderness. Bob won distinction for his fieldwork, particularly in the Arctic islands, but he eschewed visible signs of pres- tige, particularly those institutionally accepted ones, like the medals that he had won, which he playfully referred to as “gongs.” He felt that his most genuine rewards came from the sense of community and solidarity developed by working closely with people whose opinions and feelings Robert L. -
The Stratigraphic Relationship Between the Shuram Carbon Isotope
Chemical Geology 362 (2013) 250–272 Contents lists available at ScienceDirect Chemical Geology journal homepage: www.elsevier.com/locate/chemgeo The stratigraphic relationship between the Shuram carbon isotope excursion, the oxygenation of Neoproterozoic oceans, and the first appearance of the Ediacara biota and bilaterian trace fossils in northwestern Canada Francis A. Macdonald a,⁎, Justin V. Strauss a, Erik A. Sperling a, Galen P. Halverson b, Guy M. Narbonne c, David T. Johnston a, Marcus Kunzmann b, Daniel P. Schrag a, John A. Higgins d a Department of Earth and Planetary Sciences, Harvard University, 20 Oxford St., Cambridge, MA 02138, United States b Department of Earth and Planetary Sciences/GEOTOP, McGill University, Montreal, QC H3A 2T5, Canada c Department of Geological Sciences and Geological Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada d Princeton University, Guyot Hall, Princeton, NJ 08544, United States article info abstract Article history: A mechanistic understanding of relationships between global glaciation, a putative second rise in atmospher- Accepted 27 May 2013 ic oxygen, the Shuram carbon isotope excursion, and the appearance of Ediacaran-type fossil impressions and Available online 7 June 2013 bioturbation is dependent on the construction of accurate geological records through regional stratigraphic correlations. Here we integrate chemo-, litho-, and sequence-stratigraphy of fossiliferous Ediacaran strata Keywords: in northwestern Canada. These data demonstrate that the FAD of Ediacara-type fossil impressions in north- Ediacaran western Canada occur within a lowstand systems tract and above a major sequence boundary in the infor- Shuram Windermere mally named June beds, not in the early Ediacaran Sheepbed Formation from which they were previously δ13 Carbon-isotope reported. -
The New Nuclear Forensics: Analysis of Nuclear Material for Security
THE NEW NUCLEAR FORENSICS Analysis of Nuclear Materials for Security Purposes edited by vitaly fedchenko The New Nuclear Forensics Analysis of Nuclear Materials for Security Purposes STOCKHOLM INTERNATIONAL PEACE RESEARCH INSTITUTE SIPRI is an independent international institute dedicated to research into conflict, armaments, arms control and disarmament. Established in 1966, SIPRI provides data, analysis and recommendations, based on open sources, to policymakers, researchers, media and the interested public. The Governing Board is not responsible for the views expressed in the publications of the Institute. GOVERNING BOARD Sven-Olof Petersson, Chairman (Sweden) Dr Dewi Fortuna Anwar (Indonesia) Dr Vladimir Baranovsky (Russia) Ambassador Lakhdar Brahimi (Algeria) Jayantha Dhanapala (Sri Lanka) Ambassador Wolfgang Ischinger (Germany) Professor Mary Kaldor (United Kingdom) The Director DIRECTOR Dr Ian Anthony (United Kingdom) Signalistgatan 9 SE-169 70 Solna, Sweden Telephone: +46 8 655 97 00 Fax: +46 8 655 97 33 Email: [email protected] Internet: www.sipri.org The New Nuclear Forensics Analysis of Nuclear Materials for Security Purposes EDITED BY VITALY FEDCHENKO OXFORD UNIVERSITY PRESS 2015 1 Great Clarendon Street, Oxford OX2 6DP, United Kingdom Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries © SIPRI 2015 The moral rights of the authors have been asserted All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of SIPRI, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organizations.