DOCSLIB.ORG

Styles of Deformation in Ishtar Terra and Their Implications

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Styles of Deformation in Ishtar Terra and Their Implications JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 97, NO. El0, PAGES 16,085-16,120, OCTOBER 25, 1992 Stylesof Deformationin IshtarTerra and Their Implications Wn.T.TAMM. KAU•A,• DOAN•L. BINDSCHAD•-R,l ROBERT E. GPaM•,2'3 VICKIL. HANSEN,2KARl M. ROBERTS,4AND SUZANNE E. SMREr,AR s IshtarTerra, the highest region on Venus, appears to havecharacteristics of both plume uplifts and convergent belts.Magellan imagery over longitudes 330ø-30øE indicates a great variety of tectonicand volcanic activity, with largevariations within distances of onlya few 100km. Themost prominent terrain types are the volcanic plains of Lakshmiand the mountain belts of Maxwell,Freyja, and Danu. Thebelts appear to havemarked variations in age. Thereare also extensive regions of tesserain boththe upland and outboard plateaus, some rather featureless smoothscarps, flanking basins of complexextensional tectonics, and regions of gravitationalor impactmodifica- tion.Parts of Ishtarare the locations of contemporaryvigorous tectonics and past extensive volcanism. Ishtar appearsto be the consequence of a history of several100 m.y., in whichthere have been marked changes in kinematic patternsand in whichactivity at any stage has been strongly influenced by the past. Ishtar demonstrates three general propertiesof Venus:(1) erosionaldegradation is absent,leading to preservationof patternsresulting from past activity;(2) manysurface features are the responses ofa competentlayer less than 10 km thick to flowsof 100km orbroaderscale; and (3) thesebroader scale flows are controlled mainly by heterogeneities inthe mantle. Ishtar Terra doesnot appear to bethe result of a compressionconveyed by anEarthlike lithosphere. But there is stilldoubt as to whetherIshtar is predominantlythe consequence of a mantleupflow or downflow.Upflow is favoredby the extensivevolcanic plain of Lakshmiand the high geoid: topography ratio; downflow is favoredby the intense deformationof themountain belts and the absence of majorrifts. Both could be occurring, or have recently occurred, withLakshmi the most likely locus of upflowand Maxwell the main locus of downflow.But doubts about the causes of Ishtarwill probablynever be resolvedwithout circularization of the Magellanorbit to obtaina moredetailed gravityfield. 1. INTRODUCTION superiorconjunction hiatus. If we takethe 3-km elevationcontour as IshtarTerra is of specialinterest as the mostprominent departure the limit, then the latitudinal bounds would be about 55øN to 78øN. fromhydrostatic equilibrium on Venus. The peak of MaxwellMontes However,tectonic patterns associated with IshtarTerra extendto is ! 0 km abovethe mean planetary radius (MPR), whichoutstrips the superiorconjunction hiatus. If we takethe 3-km elevationcontour as secondhighest feature, Maat Mons in Atla Regio,by morethan a the limit, then the latitudinal bounds would be about 55øN to 78øN. kilometer.This promontory is partof a generaluplands more than 3 However, tectonicpatterns associated with Ishtar Terra extendto km high in topographyand morethan 20 m high in geoid,with a lowerelevations in manyplaces. Within these longitude and latitude horizontalextent of about4000 km: about1% of theplanet's surface boundaries,we identify sevenmajor provinces:Lakshmi, Danu, area.These uplands have sharply defined boundaries in mostplaces Freyja,North Scarp and Basin, South Scarp and Basin, Maxwell, and and significantvariations in characteron scalesof 200 to 1000 km. WesternFortuna. Each province is namedafter its dominant feature, Thevariety of terrainsis evidentin theimagery, of whichFigure ! is but the province includesother named featuresthat have close a mosaic. The immediate causes of most of these variations are relationshipto the dominantfeature: e.g., the province"Danu" evident:lava flows for thesmooth plains of LakshmiPlanurn, conver- includesnot only Danu Montes but also VestaRupes, Clotho Tessera, gentmotions for thesurrounding mountain belts of Maxwell,Freyja, andparts of LakshmiPlanurn and Sedna Planitia. Akna, andDanu [Masurskyet al., 1980;Barsukov et al., 1986]. But Importantto interpretation of theimagery are topographic altitudes thereare differences among these physiographic provinces of varying andgravity variations. Figure 3 givesthe Magellan altimetry for the subtlety,and for somefeatures (e.g., the smoothnessof the scarps areadiscussed in theform of contoursat 0.5-kmintervals. Superim- borderingeastern Lakshmi) the proximate cause is not at all evident. posedon it is thegeoid from the 36th degree field of SmithandNerem Nearlyall papersin thisspecial issue are devoted to particular feature [1992],based on PioneerVenus tracking data. The spacecraftwas types;it isour belief that one directed to anarea markedly anomalous, 700-2200km highat theselatitudes, so the signalis bland,and the but widelyranging in character,would be a valuablecomplement. geoidhigh probably shifted toward the pericenter, i.e., southward.A The main physiographicprovinces of westernIshtar Terra are regionalgravity solution by Grimmand Phillips [1991] alsoobtains shownin Figure2. Our discussionwill be confined,however, to the a geoidhigh to thesouth of Ishtarbut somewhat west of thatin Figure partsof IshtarTerra between 330øE and 30øE: i.e., those imaged by the 3. For interpretationof IshtarTerra, circularization of theMagellan Magellanradar between the start of themission and the start of thefirst orbiterto an altitudeof about250 km is required. IshtarTerra' s greatheight, broad extent, and particularly its large geoidanomaly require appreciable support from mantle convection. •DapartmentofEarth and Space Sciences, University of California, Buteven the first-order nature of thisdependence (upflow or downflow, Los Angeles. or combinationsthereof) is debated[Pronin, 1986; Bindschadleret 2Dapartmentof Geological Sciences, Southern Methodist Universi- ty, Dallas, Texas. al., 1990; Grimm and Phillips, 1990, 1991; Roberts and Head, 3Nowa• Department of Geology, Arizona State University, Tempe. 1990a,b;Lenardic et al.., 1991]. Examinationof the Magellan 4Dopartmentof GeologicalSciences, Brown University, Provi- imageryshould help to addressthese questions. Ideally, suchan dence, Rhode Island. SDapartmentof Earth, Atmospheric,and PlanetarySciences, examinationwould result in a kinematicmap of the surface,analo- MassachusettsInstitute of Technology,Cambridge. gousto thoseinferred on Earth from remanentmagnetism, dated offsets of interfaces, and other devices. The clues to motions on Copyright1992 by the American GeophyscialUnion. Venus are much more limited. Furthermore, the immediate causesof Paper number92JE01643. surfacefeatures often are quite indirect in theirrelationships to any 0148-0227/92/92JE-01643505.00 mantleflow pattern.This indirectnessis most evidentfor the lava 16,085 16,086 KAULA ET AL.' STYLES OF DEFORMATION IN ISHTAR TERRA Fig. 1. WesternIshtar Terra. Latitudes55ø-80øN, longitudes 300ø-30øE. From C2-MIDRP.60N333E. flows coveringthe Lakshmi plateau,but it is also true for the projectionis sinusoidal.Twenty-one F-MIDRPs are availablefor variationson a 10-km scalein the mountainbelts, arising from the IshtarTerra. The imagesprinted in thispaper are nearly all segments weaknessof the lower crust,as occurringin many partsof Venus of F-MIDRPs. However,they offer a ratherselective view, so the [Zuber, 1987; Solomonet al., tthis issue]. seriousreader is urgedto consultthe original F-MIDRPs, obtainable The varietyof featuresin IshtarTerra compelsa somewhatseg- on compactdiscs from the NSSDC at NASA GoddardSpace Flight mentedapproach. Section 2 is the majorpart of this paper,which Centeror from a PlanetaryData Center. containsdetailed description and interpretation for eachof theseven 2. Theradar altimetry by Magellan is conveyed through 1:4,500,000 provinces.Section 3 drawson section2 to identifyand interpret contourplots of 500-m interval;see Figure 3. characteristicfeature types. Section4 attemptsto infer the contem- 3. The gravimetryfor Ishtar Terra is of low resolutionbut porarystructure and kinematics of IshtarTerra, plus the evolution nonethelesshas a stronginfluence on our interpretations;see Figure leadingthereto. 3. The main systematicproducts of theseanalyses are geomorphic 2. ANALYSESOF PHYSIOGRAPHICPROVINCES units:characteristic combinations of featuresidentified in theimag- ery and altimetrythat cover sufficientareas to be representedon Theseanalyses are variedin form not only becauseof thediffer- 1:5,000,000-1:20,000,000scale maps. SeeTable 1. encesin characteramong the sevenprovinces (Figure 2) but also For someareas, we presentdelineations of structuralfeatures and becausethe effort was necessarilydivided among coauthors. For histories.But it is difficult to makea systematicmap for asbroad an purposesofdescription, we divide the provinces into 28 regions,some areaas Ishtar Terra, so they have been limited to selectedareas. The of themevident in Figure2, othersdefined on the geomorphicunit ability to infer historiesvaries from oneprovince to another,depen- maps. denton how overwhelminghas been recent activity: tectonic, volca- The followingare principal data sources: nic,or impact.Thus provinces with a varietyof featuresof relatively 1. The radarimagery is conveyedthrough digital images or photo mild relief, suchas SouthScarp and Basinand Danu montes,have printsthat areof theminimum scale at whichthe emulsioncan carry more dues of the past than do LakshmiPlanum, which has been the 75-meter resolution: 1:3,000,000. They are designatedF- largelyflooded by relativelyrecent flows, and Maxwell
Load more

Recommended publications
  • Round 3 Michael Etzkorn • Brad Fischer • Clare Keenan • Mike Laudermith • Lauren Onel Noah Prince • Jacob Simmons • Kristin Strey • Tyler Vaughan
    2017 SCOP MS 8 Round 3 Michael Etzkorn • Brad Fischer • Clare Keenan • Mike Laudermith • Lauren Onel Noah Prince • Jacob Simmons • Kristin Strey • Tyler Vaughan Tossups (1) This astronomical body, which was called Hesperus when it appeared as the Evening Star, has surface features called Maxwell Montes, Lakshmi Planum, and Ishtar Terra that are obscured by a permanent cover of (*) sulfuric acid clouds. A 96% carbon dioxide atmosphere led to a runaway greenhouse effect on, for ten points, what second planet in the Solar System? ANSWER: Venus (2) A holder of this title controversially pushed his people away from polytheism in favor of a solar god worshiped at Amarna. Lord Carnavon funded Howard Carter’s 1922 expedition to discover the burial grounds of one of these people at (*) Luxor, and found a sarcophagus containing a solid gold funerary mask and mummified remains. For ten points, name this title given to Akenhaten, King Tut, and other ancient Egyptian rulers. ANSWER: Egyptian pharaohs (3) A composer from this country wrote about the unlucky servant Ninetta in The Thieving Magpie, and included a “cavalry charge” galop in his (*) William Tell overture. For ten points, name this home country of Gioachino Rossini as well as Giacomo Puccini, who set his opera Tosca in Rome. ANSWER: Italy (accept Italia; accept Italian Republic or Repubblica italiana) (4) The Rydberg formula inspired one model of these objects, and the first sub-parts of these objects were detected by a deflection of cathode rays observed by JJ Thomson. A (*) gold foil experiment determined that these things possess a dense central mass, disproving their “plum pudding” model.
    [Show full text]
  • Investigating Mineral Stability Under Venus Conditions: a Focus on the Venus Radar Anomalies Erika Kohler University of Arkansas, Fayetteville
    University of Arkansas, Fayetteville ScholarWorks@UARK Theses and Dissertations 5-2016 Investigating Mineral Stability under Venus Conditions: A Focus on the Venus Radar Anomalies Erika Kohler University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/etd Part of the Geochemistry Commons, Mineral Physics Commons, and the The unS and the Solar System Commons Recommended Citation Kohler, Erika, "Investigating Mineral Stability under Venus Conditions: A Focus on the Venus Radar Anomalies" (2016). Theses and Dissertations. 1473. http://scholarworks.uark.edu/etd/1473 This Dissertation is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Investigating Mineral Stability under Venus Conditions: A Focus on the Venus Radar Anomalies A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Space and Planetary Sciences by Erika Kohler University of Oklahoma Bachelors of Science in Meteorology, 2010 May 2016 University of Arkansas This dissertation is approved for recommendation to the Graduate Council. ____________________________ Dr. Claud H. Sandberg Lacy Dissertation Director Committee Co-Chair ____________________________ ___________________________ Dr. Vincent Chevrier Dr. Larry Roe Committee Co-chair Committee Member ____________________________ ___________________________ Dr. John Dixon Dr. Richard Ulrich Committee Member Committee Member Abstract Radar studies of the surface of Venus have identified regions with high radar reflectivity concentrated in the Venusian highlands: between 2.5 and 4.75 km above a planetary radius of 6051 km, though it varies with latitude.
    [Show full text]
  • Cleopatra Crater on Venus: Happy Solution of the Volcanic Vs
    CLEOPATRA CRATER ON VENUS: HAPPY SOLUTION OF THE VOLCANIC VS. IMPACT CRATER CONTROVERSY; A.T. Basilevsky, A.T. Vernadsky Institute of Geochemistry and Analytical chemistry, Moscow, USSR, and G.G. Schaber, U.S. Geological Survey, Flagstaff AZ 86001 ~ntroduction. Cleopatra is a 100-km-diameter crater on the eastern slope of Maxwell Montes in western Ishtar Terra. For over 12 years, Cleopatra has been the subject of scientific controversy. Discovered during the Pioneer Venus altimetric survey, this feature was initially interpreted as a caldera near the top of a giant volcanic construct, Maxwell Montes [I]. Venera 15/16 data and recent Arecibo radar images show, however, that the Maxwell Montes appear to be more of a tectonic construct, with little or no resemblance to other giant shields known in the Solar System; thus, a nonvolcanic origin of Cleopatra was proposed [2-61. The similarity of the double-ring structure of Cleopatra to those of other multi-ring impact craters of similar size on Venus and the Moon, Mercury, and Mars was more recently given by Basilevsky and Ivanov [7] as the primarily reason to consider this feature an impact crater. At the same time, some characteristics of Cleopatra seemed to contradict an impact origin. For example, Schaber et al. [8], suggestingthat a definitive verification of a volcanic or impact origin would probably require Magellan data, proposed that the evidence from Venera 15/16 and earlier data for a probable volcanic origin for Cleopatra is substantial. They cited, among other points: (1) the absence of a raised rim and highly backscattering ejecta deposits; (2) the crater's association with plains-forming deposits immediately downslope to the east, interpreted as probable lava flows emanating from a distinct breach in the crater's rim; (3) the excessive depth (2.5 km) and depth-to-diameter ratio (0.028) of the crater, (4) the offset of the inner and outer craters; and (5) the crater's position in what was interpreted as a regional tectonic framework.
    [Show full text]
  • Venus' Ishtar Terra: Topographic Analysis of Maxwell, Freyja, Akna
    16th VEXAG Meeting 2018 (LPI Contrib. No. 2137) 8046.pdf Venus’ Ishtar Terra: Topographic Analysis of Maxwell, Freyja, Akna and Danu Montes. Sara Rastegar1 and 2 1 ​ Donna M. Jurdy ,​ C​ ity Colleges of Chicago, Harold Washington College, 30 E. Lake Street, Chicago, IL 60601, ​ ​ 2 [email protected], D​ epartment of Earth and Planetary Sciences, Northwestern University, 2145 Sheridan ​ ​ Rd, Evanston, IL 60208, [email protected] ​ Introduction: Venus’ mountain chains (Figure 1) Analysis: We attempt to address these questions ​ ​ ​ surround Lakshmi Planum, a 3-4 km highland, making with analysis of Magellan topographic data for up Ishtar Terra. No other mountain belts exist on quantitative comparison of Venus' four mountain Venus. Circling Ishtar Terra, Maxwell Montes, ascends chains: Maxwell, Freyja, Akna and Danu. Patterns in to over 11 km, ranking as the location of highest topography may provide clues to the dynamics forming elevation on the planet. Freyja Montes rises to over 7 these Venusian orogenic belts. From topographic km, higher than Akna Montes at about an elevation of profiles across the ec mountain chain, we then 6 km. Danu Montes, ~1.5 km over Lakshmi Planum, determine an average profile for each mountain belt. alone displays a distinctly arcuate form. Next, we correlate these averages to establish a measure of similarity between the chains and terrestrial Tectonic Enigma: The existence of the four analogs. These correlations allow construction of a venusian mountain chains has been attributed to covariance matrix, which can be diagonalized for localized downwelling - analogous to terrestrial eigenvalues, for Principal Component Analysis (PCA) subduction - in response to the proposed upwelling [4].
    [Show full text]
  • The Earth-Based Radar Search for Volcanic Activity on Venus
    52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548) 2339.pdf THE EARTH-BASED RADAR SEARCH FOR VOLCANIC ACTIVITY ON VENUS. B. A. Campbell1 and D. B. Campbell2, 1Smithsonian Institution Center for Earth and Planetary Studies, MRC 315, PO Box 37012, Washington, DC 20013-7012, [email protected]; 2Cornell University, Ithaca, NY 14853. Introduction: Venus is widely expected to have geometry comes from shifts in the latitude of the sub- ongoing volcanic activity based on its similar size to radar point, which spans the range from about 8o S Earth and likely heat budget. How lithospheric (2017) to 8o N (2015). Observations in 1988, 2012, and thickness and volcanic activity have varied over the 2020 share a similar sub-radar point latitude of ~3o S. history of the planet remains uncertain. While tessera Coverage of higher northern and southern latitudes may highlands locally represent a period of thinner be obtained during favorable conjunctions (Fig. 1), but lithosphere and strong deformation, there is no current the shift in incidence angle must be recognized in means to determine whether they formed synchronously analysis of surface features over time. The 2012 data on hemispheric scales. Understanding the degree to were collected in an Arecibo-GBT bistatic geometry which mantle plumes currently thin and uplift the crust that led to poorer isolation between the hemispheres. to create deformation and effusive eruptions will better inform our understanding of the “global” versus Searching for Change. Ideally, surface change “localized” timing of heat transport. Ground-based detection could be achieved by co-registering and radar mapping of one hemisphere of Venus over the past differencing any pair of radar maps.
    [Show full text]
  • Testing Evolutionary Models for Venus with the DAVINCI+ Mission
    EPSC Abstracts Vol. 14, EPSC2020-534, 2020 https://doi.org/10.5194/epsc2020-534 Europlanet Science Congress 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Venus, Earth's divergent twin?: Testing evolutionary models for Venus with the DAVINCI+ mission Walter S. Kiefer1, James Garvin2, Giada Arney2, Sushil Atreya3, Bruce Campbell4, Valeria Cottini2, Justin Filiberto1, Stephanie Getty2, Martha Gilmore5, David Grinspoon6, Noam Izenberg7, Natasha Johnson2, Ralph Lorenz7, Charles Malespin2, Michael Ravine8, Christopher Webster9, and Kevin Zahnle10 1Lunar and Planetary Institute/USRA, Houston, Texas, United States of America ([email protected]) 2NASA Goddard Space Flight Center, Greenbelt MD USA 3Planetary Science Laboratory, University of Michigan, Ann Arbor MI USA 4Center for Earth and Planetary Studies, Smithsonian Institution, Washington DC USA 5Dept. of Earth and Environmental Science, Wesleyan University, Middletown CT USA 6Planetary Science Institute, Tucson AZ USA 7Applied Physics Lab, Johns Hopkins University, Laurel MD USA 8Malin Space Science Systems, San Diego CA USA 9Jet Propulsion Laboratory, California Insitute of Technology, Pasadena CA USA 10NASA Ames Research Center, Moffet Field CA USA Understanding the divergent evolution of Venus and Earth is a fundamental problem in planetary science. Although Venus today has a hot, dry atmosphere, recent modeling suggests that Venus may have had a clement surface with liquid water until less than 1 billion years ago [1]. Venus today has a nearly stagnant lithosphere. However, Ishtar Terra’s folded mountain belts, 8-11 km high, morphologically resemble Tibet and the Himalaya mountains on Earth and apparently require several thousand kilometers of surface motion at some time in Venus’s past.
    [Show full text]
  • The Official Journal of the Institute of Science & Technology – The
    The Institute of Science & Technology The Institute of Science & Technology The Journal The Journal Winter 2011 Winter 2011 Kingfisher House 90 Rockingham Street Sheffield S1 4EB Tel: 0114 276 3197 [email protected] www.istonline.org.uk The Official Journal of The Institute of Science & Technology – The Professional Body for Specialist, Technical and Managerial Staff ISSN 2040-1868 The Journal The Official Publication of the Institute of Science & Technology ISSN 2040-1868 CONTENTS – Winter 2011 Editorial Ian Moulson Acting Chairman’s Report Terry Croft Letters to the Editor Rosina K Nyarko Astrobiology Colin Neve An inside view of a Venezuelan shrimp farm Carlos Conroy Origins, part 2: the general theory of relativity Estelle Asmodelle “My Lunar Estate”: the life of Hannah Jackson-Gwilt Alan Gall Teaching Science Christine Thompson Frog trade link to killer fungus Natural Environment Research Council Students to make ship history Arts & Humanities Research Council How parasites modify plants to attract insects Biotechnology & Biological Sciences Research Council Growing computers Engineering & Physical Sciences Research Council HIV study identifies key cellular defence mechanism Medical Research Council Physicists shed light on supernova mystery Science & Technology Facilities Council From the archives Alan Gall Journal puzzle solutions Alan Gall IST new members What is the IST? Cover images credits Front cover bottom left: Image courtesy of NASA Back cover top: Image courtesy of Wikipedia Commons Back cover middle: Image courtesy of NASA The Journal Page 1 Winter 2011 Editorial Welcome I hope that you enjoy this winter edition of the IST’s Journal. There are some really interesting and informative articles inside.
    [Show full text]
  • User Guide to the Magellan Synthetic Aperture Radar Images
    https://ntrs.nasa.gov/search.jsp?R=19950018567 2020-06-16T07:22:10+00:00Z User Guide to the Magellan Synthetic Aperture Radar Images Stephen D. Wall Shannon L. McConnell Craig E. Left Richard S. Austin Kathi K. Beratan Mark J. Rokey National Aeronautics and Jet Propulsion Laboratory Space Administration California Institute of Technology Scientific and Technical Pasadena, California Information Branch NASA Reference Publication 1356 March 1995 This publication was prepared at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Contents Iri Introduction .................................................................................................................................................................... 1 I_1 The Spacecraft ................................................................................................................................................................ 2 IB Mission Design ................................................................................................................................................................ 4 D Experiment Description ................................................................................................................................................ 15 B Mission Operations ....................................................................................................................................................... 17 [] Notable Events and Problems .....................................................................................................................................
    [Show full text]
  • Volcanism and Tectonism in Rusalka Planitia and Atla Regio, Venus; M
    LPSC xn/ 767 VOLCANISM AND TECTONISM IN RUSALKA PLANITIA AND ATLA REGIO, VENUS; M. G. Lancaster and J. E. Guest (University of London Observatory, University College London, London, NW7 2QS, U. K.). In order to investigate the relationships between volcanism and tectonism in Rusalka Planitia and Atla Regio, the geology of four adjacent Cycle 1 Magellan ClMIDRs has been mapped (C100N180, C115N180, C115N197, and C100N197). These cover nearly 12 x 106 km2 between latitudes 7.6 S and 22.6 N, and longitudes 171.4 to 206.2 E. This region was chosen because it contains nearly all the types of volcanic and tectonic features observed on Venus, and covers plains as well as highlands. The western half of the region comprises most of the volcanic plains of Rusalka Planitia, which are characterized by a large-scale pervasive fabric of NW-SE trending sinuous ridges that resemble lunar and martian wrinkle ridges [I]. A NW-SE to N-S trending deformation belt occupies the SW comer of C100N180, and contains several coronae including Eigin Corona (5.0 S, 175.0 E). The belt is the source for large, radar-bright, plains forming, flood lava flow fields. A similar collection of corona-like centers and deformation belts composed largely of ridges, is found in the NE comer of C115N197, where an extensive collection of lava flow fields is also present. Other smaller regions of radar-bright lava lie scattered across the plains. A number of N-S to NNW-SSE trending ridge belts occupy the north-central part of these plains.
    [Show full text]
  • Venus Lithograph
    National Aeronautics and and Space Space Administration Administration 0 300,000,000 900,000,000 1,500,000,000 2,100,000,000 2,700,000,000 3,300,000,000 3,900,000,000 4,500,000,000 5,100,000,000 5,700,000,000 kilometers Venus www.nasa.gov Venus and Earth are similar in size, mass, density, composi- and at the surface are estimated to be just a few kilometers per SIGNIFICANT DATES tion, and gravity. There, however, the similarities end. Venus hour. How this atmospheric “super-rotation” forms and is main- 650 CE — Mayan astronomers make detailed observations of is covered by a thick, rapidly spinning atmosphere, creating a tained continues to be a topic of scientific investigation. Venus, leading to a highly accurate calendar. scorched world with temperatures hot enough to melt lead and Atmospheric lightning bursts, long suspected by scientists, were 1761–1769 — Two European expeditions to watch Venus cross surface pressure 90 times that of Earth (similar to the bottom confirmed in 2007 by the European Venus Express orbiter. On in front of the Sun lead to the first good estimate of the Sun’s of a swimming pool 1-1/2 miles deep). Because of its proximity Earth, Jupiter, and Saturn, lightning is associated with water distance from Earth. to Earth and the way its clouds reflect sunlight, Venus appears clouds, but on Venus, it is associated with sulfuric acid clouds. 1962 — NASA’s Mariner 2 reaches Venus and reveals the plan- to be the brightest planet in the sky. We cannot normally see et’s extreme surface temperatures.
    [Show full text]
  • Size, Scale and the Imaginary in the Work of Land Artists Michael Heizer, Walter De Maria and Dennis Oppenheim
    Larger than life: size, scale and the imaginary in the work of Land Artists Michael Heizer, Walter De Maria and Dennis Oppenheim © Michael Albert Hedger A thesis in fulfillment of the requirements for the degree of Doctor of Philosophy Art History and Art Education UNIVERSITY OF NEW SOUTH WALES | Art & Design August 2014 PLEASE TYPE THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Hedger First name: Michael Other name/s: Albert Abbreviation for degree as given in the University calendar: Ph.D. School: Art History and Education Faculty: Art & Design Title: Larger than life: size, scale and the imaginary in the work of Land Artists Michael Heizer, Walter De Maria and Dennis Oppenheim Abstract 350 words maximum: (PLEASE TYPE) Conventionally understood to be gigantic interventions in remote sites such as the deserts of Utah and Nevada, and packed with characteristics of "romance", "adventure" and "masculinity", Land Art (as this thesis shows) is a far more nuanced phenomenon. Through an examination of the work of three seminal artists: Michael Heizer (b. 1944), Dennis Oppenheim (1938-2011) and Walter De Maria (1935-2013), the thesis argues for an expanded reading of Land Art; one that recognizes the significance of size and scale but which takes a new view of these essential elements. This is achieved first by the introduction of the "imaginary" into the discourse on Land Art through two major literary texts, Swift's Gulliver's Travels (1726) and Shelley's sonnet Ozymandias (1818)- works that, in addition to size and scale, negotiate presence and absence, the whimsical and fantastic, longevity and death, in ways that strongly resonate with Heizer, De Maria and especially Oppenheim.
    [Show full text]
  • VENUS Corona M N R S a Ak O Ons D M L YN a G Okosha IB E .RITA N Axw E a I O
    N N 80° 80° 80° 80° L Dennitsa D. S Yu O Bachue N Szé K my U Corona EG V-1 lan L n- H V-1 Anahit UR IA ya D E U I OCHK LANIT o N dy ME Corona A P rsa O r TI Pomona VA D S R T or EG Corona E s enpet IO Feronia TH L a R s A u DE on U .TÜN M Corona .IV Fr S Earhart k L allo K e R a s 60° V-6 M A y R 60° 60° E e Th 60° N es ja V G Corona u Mon O E Otau nt R Allat -3 IO l m k i p .MARGIT M o E Dors -3 Vacuna Melia o e t a M .WANDA M T a V a D o V-6 OS Corona na I S H TA R VENUS Corona M n r s a Ak o ons D M L YN A g okosha IB E .RITA n axw e A I o U RE t M l RA R T Fakahotu r Mons e l D GI SSE I s V S L D a O s E A M T E K A N Corona o SHM CLEOPATRA TUN U WENUS N I V R P o i N L I FO A A ght r P n A MOIRA e LA L in s C g M N N t K a a TESSERA s U . P or le P Hemera Dorsa IT t M 11 km e am A VÉNUSZ w VENERA w VENUE on Iris DorsaBARSOVA E I a E a A s RM A a a OLO A R KOIDULA n V-7 s ri V VA SSE e -4 d E t V-2 Hiei Chu R Demeter Beiwe n Skadi Mons e D V-5 S T R o a o r LI s I o R M r Patera A I u u s s V Corona p Dan o a s Corona F e A o A s e N A i P T s t G yr A A i U alk 1 : 45 000 000 K L r V E A L D DEKEN t Baba-Jaga D T N T A a PIONEER or E Aspasia A o M e s S a (1 MM= 45 KM) S r U R a ER s o CLOTHO a A N u s Corona a n 40° p Neago VENUS s s 40° s 40° o TESSERA r 40° e I F et s o COCHRAN ZVEREVA Fluctus NORTH 0 500 1000 1500 2000 2500 KM A Izumi T Sekhm n I D .
    [Show full text]