DOCSLIB.ORG

Subglacial Lake Ellsworth CEE V2.Indd

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Subglacial Lake Ellsworth CEE V2.Indd Proposed Exploration of Subglacial Lake Ellsworth Antarctica Draft Comprehensive Environmental Evaluation February 2011 1 The cover art was created by first, second, and third grade students at The Village School, a Montessori school located in Waldwick, New Jersey. Art instructor, Bob Fontaine asked his students to create an interpretation of the work being done on The Lake Ellsworth Project and to create over 200 of their own imaginary microbes. This art project was part of The Village School’s art curriculum that links art with ongoing cultural work. 2 Contents Non Technical Summary .................................................4 Personnel ............................................................................................ 26 Chapter 1: Introduction ...................................................6 Power generation and fuel calculations ....................................... 27 Chapter 2: Description of proposed activity..................7 Vehicles ................................................................................................ 28 Background and justification ..............................................................7 Water and waste ...............................................................................28 The site ...................................................................................................8 Communications ............................................................................... 28 Chapter 3: Baseline conditions of Lake Ellsworth .........9 Transport of equipment and personnel .......................................28 Location..................................................................................................9 Equipment and personnel removal ............................................... 28 Geophysical surveys and available data ...........................................9 Contingency plans .............................................................................29 Radio-echo sounding surveys .........................................................10 Safe Site Procedures .........................................................................29 Ice sheet surface ................................................................................ 11 Chapter 6: Identification or prediction of impacts, Lake surface and extent ................................................................... 11 including preventative or mitigating measures ...........30 Bed topography ................................................................................. 11 Methods and data used to predict impacts and mitigation measures ............................................................................................. 30 Englacial layering ................................................................................12 Impact on native flora and fauna within Lake Ellsworth........... 30 Lake-water depth ..............................................................................12 Microbial control at design stage ................................................... 31 Water circulation and lake hydrological balance........................ 12 Microbial control during construction, transport and Basal sediments.................................................................................. 13 deployment on site ...........................................................................31 Ice flow ................................................................................................13 Population Reduction Methods ..................................................... 32 Ice cores and lake geochemistry ................................................... 14 Verification and assessment ............................................................33 Surface accumulation ........................................................................ 14 Analytical methods ........................................................................... 34 Meteorological conditions .............................................................. 15 Developments planned by the Lake Ellsworth Consortium ... 34 Summary of lake access site ........................................................... 15 Impact to air .......................................................................................34 Microbial content of the lake ......................................................... 15 Impact to ice ...................................................................................... 35 Microbial content of the snow .......................................................16 Impact to native flora and fauna (on the ice surface) ...............37 Fauna and Flora ................................................................................. 16 Non recovery of equipment ...........................................................37 Protected Areas ................................................................................. 16 Impact on wilderness and aesthetics ............................................37 Chapter 4: Description of the technologies .................16 Cumulative impacts .......................................................................... 37 Hot Water Drill ................................................................................. 16 Programme and site management .................................................37 Deployment of instruments ............................................................ 21 Impact matrices .................................................................................38 Probe description .............................................................................. 21 Chapter 7: Alternatives ..................................................42 Probe mounted corer ......................................................................21 Lake access technique ......................................................................42 Instrumentation ................................................................................. 21 Alternative lakes ................................................................................42 Topside equipment ............................................................................ 22 Microbial control ...............................................................................42 Sediment corer ..................................................................................22 Not proceeding ................................................................................. 43 Thermistor string ..............................................................................22 Chapter 8: Assessment and verification of impacts Sampling strategy .............................................................................. 22 and monitoring ...............................................................44 Fieldwork analysis ............................................................................. 23 Monitoring .......................................................................................... 44 Laboratory analysis ...........................................................................24 Environmental Audit ......................................................................... 44 Microbiology ...................................................................................... 24 Chapter 9: Gaps in knowledge and uncertainties .......45 Biological analysis ..............................................................................24 Chapter 10: Conclusions ................................................45 Organic geochemistry ...................................................................... 25 References .......................................................................................... 47 Hydrochemistry ................................................................................ 25 Appendix 1: Access to Lake Ellsworth: blowout likelihood, risk analysis and mitigation.............................................................. 50 Sedimentology and palaeo-analysis ............................................... 26 Annex 1: Engineering Blowout Prevention Strategies ............... 55 Integration of in situ and laboratory data .................................... 26 Appendix 2: Subglacial Lake Ellsworth Program – Advisory Chapter 5: Description of the camp and the logistics 26 Committee ......................................................................................... 58 Camp overview and location ......................................................... 26 Non Technical Summary Introduction • To build a hot water drill capable of drilling cleanly through A draft Comprehensive Environmental Evaluation (CEE) has up to 3.5 km ice. been carried out by the British Antarctic Survey (BAS) for the • To construct a sampling probe capable of measuring and proposed investigation of Ellsworth Subglacial Lake in West sampling the water column and surface sediment. Antarctica (referred to hereafter as Lake Ellsworth). • To construct a sediment corer capable of retrieving a 1 m to This draft CEE has been prepared in accordance with 3 m sediment core. Annex I of the Protocol on Environmental Protection to the • To develop a communications tether that can be used to Antarctic Treaty (1998). The guidelines for Environmental lower the probe / corer and guide its measurement and Impact assessment in Antarctica (Resolution 4, ATCM XXVIII, sampling strategy. 2005) were also consulted. This draft CEE describes the • To design and
Load more

Recommended publications
  • Dustin M. Schroeder
    Dustin M. Schroeder Assistant Professor of Geophysics Department of Geophysics, School of Earth, Energy, and Environmental Sciences 397 Panama Mall, Mitchell Building 361, Stanford University, Stanford, CA 94305 [email protected], 440.567.8343 EDUCATION 2014 Jackson School of Geosciences, University of Texas, Austin, TX Doctor of Philosophy (Ph.D.) in Geophysics 2007 Bucknell University, Lewisburg, PA Bachelor of Science in Electrical Engineering (B.S.E.E.), departmental honors, magna cum laude Bachelor of Arts (B.A.) in Physics, magna cum laude, minors in Mathematics and Philosophy PROFESSIONAL EXPERIENCE 2016 – present Assistant Professor of Geophysics, Stanford University 2017 – present Assistant Professor (by courtesy) of Electrical Engineering, Stanford University 2020 – present Center Fellow (by courtesy), Stanford Woods Institute for the Environment 2020 – present Faculty Affiliate, Stanford Institute for Human-Centered Artificial Intelligence 2021 – present Senior Member, Kavli Institute for Particle Astrophysics and Cosmology 2016 – 2020 Faculty Affiliate, Stanford Woods Institute for the Environment 2014 – 2016 Radar Systems Engineer, Jet Propulsion Laboratory, California Institute of Technology 2012 Graduate Researcher, Applied Physics Laboratory, Johns Hopkins University 2008 – 2014 Graduate Researcher, University of Texas Institute for Geophysics 2007 – 2008 Platform Hardware Engineer, Freescale Semiconductor SELECTED AWARDS 2021 Symposium Prize Paper Award, IEEE Geoscience and Remote Sensing Society 2020 Excellence in Teaching Award, Stanford School of Earth, Energy, and Environmental Sciences 2019 Senior Member, Institute of Electrical and Electronics Engineers 2018 CAREER Award, National Science Foundation 2018 LInC Fellow, Woods Institute, Stanford University 2016 Frederick E. Terman Fellow, Stanford University 2015 JPL Team Award, Europa Mission Instrument Proposal 2014 Best Graduate Student Paper, Jackson School of Geosciences 2014 National Science Olympiad Heart of Gold Award for Service to Science Education 2013 Best Ph.D.
    [Show full text]
  • Air and Shipborne Magnetic Surveys of the Antarctic Into the 21St Century
    TECTO-125389; No of Pages 10 Tectonophysics xxx (2012) xxx–xxx Contents lists available at SciVerse ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Air and shipborne magnetic surveys of the Antarctic into the 21st century A. Golynsky a,⁎,R.Bellb,1, D. Blankenship c,2,D.Damasked,3,F.Ferracciolie,4,C.Finnf,5,D.Golynskya,6, S. Ivanov g,7,W.Jokath,8,V.Masolovg,6,S.Riedelh,7,R.vonFresei,9,D.Youngc,2 and ADMAP Working Group a VNIIOkeangeologia, 1, Angliysky Avenue, St.-Petersburg, 190121, Russia b LDEO of Columbia University, 61, Route 9W, PO Box 1000, Palisades, NY 10964-8000, USA c University of Texas, Institute for Geophysics, 4412 Spicewood Springs Rd., Bldg. 600, Austin, Texas 78759-4445, USA d BGR, Stilleweg 2 D-30655, Hannover, Germany e BAS, High Cross, Madingley Road, Cambridge, CB3 OET, UK f USGS, Denver Federal Center, Box 25046 Denver, CO 80255, USA g PMGE, 24, Pobeda St., Lomonosov, 189510, Russia h AWI, Columbusstrasse, 27568, Bremerhaven, Germany i School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH, 43210, USA article info abstract Article history: The Antarctic geomagnetics' community remains very active in crustal anomaly mapping. More than 1.5 million Received 1 August 2011 line-km of new air- and shipborne data have been acquired over the past decade by the international community Received in revised form 27 January 2012 in Antarctica. These new data together with surveys that previously were not in the public domain significantly Accepted 13 February 2012 upgrade the ADMAP compilation.
    [Show full text]
  • Office of Polar Programs
    DEVELOPMENT AND IMPLEMENTATION OF SURFACE TRAVERSE CAPABILITIES IN ANTARCTICA COMPREHENSIVE ENVIRONMENTAL EVALUATION DRAFT (15 January 2004) FINAL (30 August 2004) National Science Foundation 4201 Wilson Boulevard Arlington, Virginia 22230 DEVELOPMENT AND IMPLEMENTATION OF SURFACE TRAVERSE CAPABILITIES IN ANTARCTICA FINAL COMPREHENSIVE ENVIRONMENTAL EVALUATION TABLE OF CONTENTS 1.0 INTRODUCTION....................................................................................................................1-1 1.1 Purpose.......................................................................................................................................1-1 1.2 Comprehensive Environmental Evaluation (CEE) Process .......................................................1-1 1.3 Document Organization .............................................................................................................1-2 2.0 BACKGROUND OF SURFACE TRAVERSES IN ANTARCTICA..................................2-1 2.1 Introduction ................................................................................................................................2-1 2.2 Re-supply Traverses...................................................................................................................2-1 2.3 Scientific Traverses and Surface-Based Surveys .......................................................................2-5 3.0 ALTERNATIVES ....................................................................................................................3-1
    [Show full text]
  • Englacial Architecture and Age‐Depth Constraints Across 10.1029/2019GL086663 the West Antarctic Ice Sheet Key Points: David W
    RESEARCH LETTER Englacial Architecture and Age‐Depth Constraints Across 10.1029/2019GL086663 the West Antarctic Ice Sheet Key Points: David W. Ashmore1 , Robert G. Bingham2 , Neil Ross3 , Martin J. Siegert4 , • We measure and date individual 5 1 isochronal radar internal reflection Tom A. Jordan , and Douglas W. F. Mair horizons across the Weddell Sea 1 2 sector of the West Antarctic Ice School of Environmental Sciences, University of Liverpool, Liverpool, UK, School of GeoSciences, University of Sheet Edinburgh, Edinburgh, UK, 3School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne, • – – Horizons dated to 1.9 3.2, 3.5 6.0, UK, 4Grantham Institute and Department of Earth Science and Engineering, Imperial College London, London, UK, and 4.6–8.1 ka are widespread and 5British Antarctic Survey, Cambridge, UK linked to previous radar surveys of the Ross and Amundsen Sea sectors • These form the basis for a wider database of ice sheet architecture for Abstract The englacial stratigraphic architecture of internal reflection horizons (IRHs) as imaged by validating and calibrating ice sheet ice‐penetrating radar (IPR) across ice sheets reflects the cumulative effects of surface mass balance, basal models of West Antarctica melt, and ice flow. IRHs, considered isochrones, have typically been traced in interior, slow‐flowing regions. Here, we identify three distinctive IRHs spanning the Institute and Möller catchments that cover 50% of Supporting Information: • Supporting Information S1 West Antarctica's Weddell Sea Sector and are characterized by a complex system of ice stream tributaries. We place age constraints on IRHs through their intersections with previous geophysical surveys tied to Byrd Ice Core and by age‐depth modeling.
    [Show full text]
  • Antarctic Primer
    Antarctic Primer By Nigel Sitwell, Tom Ritchie & Gary Miller By Nigel Sitwell, Tom Ritchie & Gary Miller Designed by: Olivia Young, Aurora Expeditions October 2018 Cover image © I.Tortosa Morgan Suite 12, Level 2 35 Buckingham Street Surry Hills, Sydney NSW 2010, Australia To anyone who goes to the Antarctic, there is a tremendous appeal, an unparalleled combination of grandeur, beauty, vastness, loneliness, and malevolence —all of which sound terribly melodramatic — but which truly convey the actual feeling of Antarctica. Where else in the world are all of these descriptions really true? —Captain T.L.M. Sunter, ‘The Antarctic Century Newsletter ANTARCTIC PRIMER 2018 | 3 CONTENTS I. CONSERVING ANTARCTICA Guidance for Visitors to the Antarctic Antarctica’s Historic Heritage South Georgia Biosecurity II. THE PHYSICAL ENVIRONMENT Antarctica The Southern Ocean The Continent Climate Atmospheric Phenomena The Ozone Hole Climate Change Sea Ice The Antarctic Ice Cap Icebergs A Short Glossary of Ice Terms III. THE BIOLOGICAL ENVIRONMENT Life in Antarctica Adapting to the Cold The Kingdom of Krill IV. THE WILDLIFE Antarctic Squids Antarctic Fishes Antarctic Birds Antarctic Seals Antarctic Whales 4 AURORA EXPEDITIONS | Pioneering expedition travel to the heart of nature. CONTENTS V. EXPLORERS AND SCIENTISTS The Exploration of Antarctica The Antarctic Treaty VI. PLACES YOU MAY VISIT South Shetland Islands Antarctic Peninsula Weddell Sea South Orkney Islands South Georgia The Falkland Islands South Sandwich Islands The Historic Ross Sea Sector Commonwealth Bay VII. FURTHER READING VIII. WILDLIFE CHECKLISTS ANTARCTIC PRIMER 2018 | 5 Adélie penguins in the Antarctic Peninsula I. CONSERVING ANTARCTICA Antarctica is the largest wilderness area on earth, a place that must be preserved in its present, virtually pristine state.
    [Show full text]
  • Ice-Flow Structure and Ice Dynamic Changes in the Weddell Sea Sector
    Bingham RG, Rippin DM, Karlsson NB, Corr HFJ, Ferraccioli F, Jordan TA, Le Brocq AM, Rose KC, Ross N, Siegert MJ. Ice-flow structure and ice-dynamic changes in the Weddell Sea sector of West Antarctica from radar-imaged internal layering. Journal of Geophysical Research: Earth Surface 2015, 120(4), 655-670. Copyright: ©2015 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. DOI link to article: http://dx.doi.org/10.1002/2014JF003291 Date deposited: 04/06/2015 This work is licensed under a Creative Commons Attribution 4.0 International License Newcastle University ePrints - eprint.ncl.ac.uk PUBLICATIONS Journal of Geophysical Research: Earth Surface RESEARCH ARTICLE Ice-flow structure and ice dynamic changes 10.1002/2014JF003291 in the Weddell Sea sector of West Antarctica Key Points: from radar-imaged internal layering • RES-sounded internal layers in Institute/Möller Ice Streams show Robert G. Bingham1, David M. Rippin2, Nanna B. Karlsson3, Hugh F. J. Corr4, Fausto Ferraccioli4, fl ow changes 4 5 6 7 8 • Ice-flow reconfiguration evinced in Tom A. Jordan , Anne M. Le Brocq , Kathryn C. Rose , Neil Ross , and Martin J. Siegert Bungenstock Ice Rise to higher 1 2 tributaries School of GeoSciences, University of Edinburgh, Edinburgh, UK, Environment Department, University of York, York, UK, • Holocene dynamic reconfiguration 3Centre for Ice and Climate, Niels Bohr Institute, University
    [Show full text]
  • (Antarctica) Glacial, Basal, and Accretion Ice
    CHARACTERIZATION OF ORGANISMS IN VOSTOK (ANTARCTICA) GLACIAL, BASAL, AND ACCRETION ICE Colby J. Gura A Thesis Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 2019 Committee: Scott O. Rogers, Advisor Helen Michaels Paul Morris © 2019 Colby Gura All Rights Reserved iii ABSTRACT Scott O. Rogers, Advisor Chapter 1: Lake Vostok is named for the nearby Vostok Station located at 78°28’S, 106°48’E and at an elevation of 3,488 m. The lake is covered by a glacier that is approximately 4 km thick and comprised of 4 different types of ice: meteoric, basal, type 1 accretion ice, and type 2 accretion ice. Six samples were derived from the glacial, basal, and accretion ice of the 5G ice core (depths of 2,149 m; 3,501 m; 3,520 m; 3,540 m; 3,569 m; and 3,585 m) and prepared through several processes. The RNA and DNA were extracted from ultracentrifugally concentrated meltwater samples. From the extracted RNA, cDNA was synthesized so the samples could be further manipulated. Both the cDNA and the DNA were amplified through polymerase chain reaction. Ion Torrent primers were attached to the DNA and cDNA and then prepared to be sequenced. Following sequencing the sequences were analyzed using BLAST. Python and Biopython were then used to collect more data and organize the data for manual curation and analysis. Chapter 2: As a result of the glacier and its geographic location, Lake Vostok is an extreme and unique environment that is often compared to Jupiter’s ice-covered moon, Europa.
    [Show full text]
  • Subglacial Meltwater Supported Aerobic Marine Habitats During Snowball Earth
    Subglacial meltwater supported aerobic marine habitats during Snowball Earth Maxwell A. Lechtea,b,1, Malcolm W. Wallacea, Ashleigh van Smeerdijk Hooda, Weiqiang Lic, Ganqing Jiangd, Galen P. Halversonb, Dan Asaele, Stephanie L. McColla, and Noah J. Planavskye aSchool of Earth Sciences, University of Melbourne, Parkville, VIC 3010, Australia; bDepartment of Earth and Planetary Science, McGill University, Montréal, QC, Canada H3A 0E8; cState Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, 210093 Nanjing, China; dDepartment of Geoscience, University of Nevada, Las Vegas, NV 89154; and eDepartment of Geology and Geophysics, Yale University, New Haven, CT 06511 Edited by Paul F. Hoffman, University of Victoria, Victoria, BC, Canada, and approved November 3, 2019 (received for review May 28, 2019) The Earth’s most severe ice ages interrupted a crucial interval in Cryogenian ice age. These marine chemical sediments are unique eukaryotic evolution with widespread ice coverage during the geochemical archives of synglacial ocean chemistry. To develop Cryogenian Period (720 to 635 Ma). Aerobic eukaryotes must have sur- a global picture of seawater redox state during extreme glaci- vived the “Snowball Earth” glaciations, requiring the persistence of ation, we studied 9 IF-bearing Sturtian glacial successions across 3 oxygenated marine habitats, yet evidence for these environments paleocontinents (Fig. 1): Congo (Chuos Formation, Namibia), is lacking. We examine iron formations within globally distributed Australia (Yudnamutana Subgroup), and Laurentia (Kingston Cryogenian glacial successions to reconstruct the redox state of the Peak Formation, United States). These IFs were selected for synglacial oceans. Iron isotope ratios and cerium anomalies from a analysis because they are well-preserved, and their depositional range of glaciomarine environments reveal pervasive anoxia in the environment can be reliably constrained.
    [Show full text]
  • Late Quaternary Volcanic Activity in Marie Byrd Land: Potential 40Ar/39Ar-Dated Time Horizons in West Antarctic Ice and Marine Cores
    Late Quaternary volcanic activity in Marie Byrd Land: Potential 40Ar/39Ar-dated time horizons in West Antarctic ice and marine cores T. I. Wilch* Department of Geological Sciences, Albion College, Albion, Michigan 49224 W. C. McIntosh Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, and New Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico 87801 N. W. Dunbar New Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico 87801 ABSTRACT More than 12 40Ar/39Ar-dated tephra lay- ies is to determine the basal age of the ice sheet. ers, exposed in bare ice on the summit ice cap The 1968 Byrd Station ice core in the West Late Quaternary volcanic activity at three of Mount Moulton, 30 km from their inferred Antarctic Ice Sheet has an inferred basal age of major alkaline composite volcanoes in Marie source at Mount Berlin, range in age from 492 only 74 ka (Hammer et al., 1994). The exten- Byrd Land, West Antarctica, is dominated by to 15 ka. These englacial tephra layers provide sive lateral flow of ice from the ice divide area explosive eruptions, many capable of deposit- a minimum age of 492 ka for the oldest iso- to Byrd Station may have removed or disturbed ing ash layers as regional time-stratigraphic topically dated ice in West Antarctica. This much of the basal ice record. Consequently, the horizons in the West Antarctic Ice Sheet and well-dated section of locally derived glacial ice 74 ka date of the Byrd core provides only a in Southern Ocean marine sediments.
    [Show full text]
  • Report November 1996
    International Council of Scientific Unions No13 report November 1996 Contents SCAR Group of Specialists on Global Change and theAntarctic (GLOCHANT) Report of bipolar meeting of GLOCHANT / IGBP-PAGES Task Group 2 on Palaeoenvironments from Ice Cores (PICE), 1995 1 Report of GLOCHANTTask Group 3 on Ice Sheet Mass Balance and Sea-Level (ISMASS), 1995 6 Report of GLOCHANT IV meeting, 1996 16 GLOCHANT IV Appendices 27 Published by the SCIENTIFIC COMMITTEE ON ANTARCTIC RESEARCH at the Scott Polar Research Institute, Cambridge, United Kingdom INTERNATIONAL COUNCIL OF SCIENTIFIC UNIONS SCIENTIFIC COMMITfEE ON ANTARCTIC RESEARCH SCAR Report No 13, November 1996 Contents SCAR Group of Specialists on Global Change and theAntarctic (GLOCHANT) Report of bipolar meeting of GLOCHANT / IGBP-PAGES Task Group 2 on Palaeoenvironments from Ice Cores (PICE), 1995 1 Report of GLOCHANT Task Group 3 on Ice Sheet Mass Balance and Sea-Level (ISMASS), 1995 6 Report of GLOCHANT IV meeting, 1996 16 GLOCHANT IV Appendices 27 Published by the SCIENTIFIC COMMITfEE ON ANT ARCTIC RESEARCH at the Scott Polar Research Institute, Cambridge, United Kingdom SCAR Group of Specialists on Global Change and the Antarctic (GLOCHANT) Report of the 1995 bipolar meeting of the GLOCHANT I IGBP-PAGES Task Group 2 on Palaeoenvironments from Ice Cores. (PICE) Boston, Massachusetts, USA, 15-16 September; 1995 Members ofthe PICE Group present Dr. D. Raynaud (Chainnan, France), Dr. D. Peel (Secretary, U.K.}, Dr. J. White (U.S.A.}, Mr. V. Morgan (Australia), Dr. V. Lipenkov (Russia), Dr. J. Jouzel (France), Dr. H. Shoji (Japan, proxy for Prof. 0. Watanabe). Apologies: Prof. 0.
    [Show full text]
  • The Paleoposition of Marie Byrd Land, West Antarctica
    Objectives of the present study are to date the three rock The initial strontium-87/strontium-86 ratio was calcu- units using the Rb-Sr (rubidium-strontium) whole-rock lated as 0.71222 ± .00015. It has been demonstrated by isochron method described by Faure (1977) and to date Faure (1977) that the initial 87Sr/86Sr ratio of mantle-derived mineral separates (biotite, hornblende) using Rb-Sr and rocks would lie between 0.702 and 0.706. Since the calcu- argon-40/argon-39 techniques. This will facilitate an inter- lated initial ratio is well above this range, it suggests that pretation of the cooling history of the area based on the the Carlyon Granodiorite is either a product of re- retention temperature of each mineral for the respective mobilization of crustal material, or has been contaminated isotopes. The analytical data will be used along with field with radiogenic strontium derived from the crust. and petrographic observations to interpret the age, origin, The Carlyon is a medium- to coarse-grained, biotite- and thermal history of these rock suites and to relate this to hornblende-andesine granodiorite. It is commonly porphy- the tectonic evolution of the Transantarctic Mountains. ritic, with a strongly developed foliation, sometimes almost Over the past year we have prepared the rock samples gneissic. These textural and mineralogical criteria suggest for the laboratory analyses, determined rubidium and similarities with the Olympus Granite Gneiss of Wright strontium concentrations of whole-rock samples by X-ray Valley (77°33S 16130E) (Faure, Jones, and Owen 1974) fluorescence, and determined the isotopic composition of and the Lonely Ridge Granodiorite of the Nilsen Plateau strontium using a solid-source mass spectrometer.
    [Show full text]
  • An Inventory of Subglacial Volcanoes in West Antarctica
    Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021 A new volcanic province: an inventory of subglacial volcanoes in West Antarctica MAXIMILLIAN VAN WYK DE VRIES*, ROBERT G. BINGHAM & ANDREW S. HEIN School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK *Correspondence: [email protected] Abstract: The West Antarctic Ice Sheet overlies the West Antarctic Rift System about which, due to the comprehensive ice cover, we have only limited and sporadic knowledge of volcanic activity and its extent. Improving our understanding of subglacial volcanic activity across the province is important both for helping to constrain how volcanism and rifting may have influenced ice-sheet growth and decay over previous glacial cycles, and in light of concerns over whether enhanced geo- thermal heat fluxes and subglacial melting may contribute to instability of the West Antarctic Ice Sheet. Here, we use ice-sheet bed-elevation data to locate individual conical edifices protruding upwards into the ice across West Antarctica, and we propose that these edifices represent subglacial volcanoes. We used aeromagnetic, aerogravity, satellite imagery and databases of confirmed volca- noes to support this interpretation. The overall result presented here constitutes a first inventory of West Antarctica’s subglacial volcanism. We identified 138 volcanoes, 91 of which have not previ- ously been identified, and which are widely distributed throughout the deep basins of West Antarc- tica, but are especially concentrated and orientated along the >3000 km central axis of the West Antarctic Rift System. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.
    [Show full text]