DOCSLIB.ORG

Pamphlet to Accompany Scientific Investigations Map 3163

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Pamphlet to Accompany Scientific Investigations Map 3163 Prepared for the National Aeronautics and Space Administration Geologic Map of the Hecate Chasma Quadrangle (V–28), Venus By Ellen R. Stofan, John E. Guest, and Antony W. Brian Pamphlet to accompany Scientific Investigations Map 3163 75° 75° V–1 50° V–5 V–7 50° V–6 V–14 V–19 V–15 V–18 V–16 V–17 25° 25° V–26 V–31 V–27 V–30 V–28 V–29 180° 210° 240° 270° 300° 330° 360° 0° 0° V–40 V–41 V–39 V–42 V–38 V–43 –25° –25° V–52 V–53 V–51 V–54 V–50 V–55 V–60 ° ° –50 V–59 V–61 –50 V–62 2012 –75° –75° U.S. Department of the Interior U.S. Geological Survey This page intentionally left blank Contents The Magellan Mission ..................................................................................................................................1 Magellan Radar Data ..........................................................................................................................1 Introduction ....................................................................................................................................................1 Mapping Techniques ....................................................................................................................................2 General Geology ............................................................................................................................................2 Mappable Units ....................................................................................................................................2 Tessera Material .........................................................................................................................2 Plains Material ............................................................................................................................2 Volcanic Edifice and Flow Material .........................................................................................4 Corona Material ..........................................................................................................................5 Crater Material ............................................................................................................................7 Surficial Material .................................................................................................................................7 Structure ................................................................................................................................................7 Geologic History ............................................................................................................................................8 References Cited ...........................................................................................................................................9 Tables 1. Coronae of V–28 .....................................................................................................................................12 2. Impact craters of V–28 ..........................................................................................................................12 Figures 1. Magellan topographic map of quadrangle V–28, extending from lat 0°–25° N., long 240°–270° E. (map sheet) 2. Magellan RMS slope roughness map of quadrangle V–28, extending from lat 0°–25° N., long 240°–270° E. (map sheet) 3. Magellan emissivity map of quadrangle V–28, extending from lat 0°–25° N., long 240°–270° E. (map sheet) 4. Portion of Hinemoa edifice plains material (unit peH) illustrating high concentration of small edifices within the unit, and the closely spaced lineaments that deform the unit (map sheet) 5. Edifice field material (unit ef), characterized by small edifices surrounded by radar-dark flow deposits (map sheet) 6. The volcano Kono Mons is cut in half by Zverine Chasma; the dashed lines indicate the location of the Zverine trough rim (map sheet) i This page intentionally left blank The Magellan Mission above which high-dielectric minerals or coatings are thought to be present. This leads to very bright SAR echoes from virtually The Magellan spacecraft orbited Venus from August 10, all areas above that critical elevation. 1990, until it plunged into the Venusian atmosphere on October The measurements of passive thermal emission from 12, 1994. Magellan Mission objectives included (1) improving Venus, though of much lower spatial resolution than the SAR the knowledge of the geological processes, surface properties, data, are more sensitive to changes in the dielectric constant and geologic history of Venus by analysis of surface radar char- of the surface than to roughness. They can be used to augment acteristics, topography, and morphology and (2) improving the studies of the surface and to discriminate between roughness knowledge of the geophysics of Venus by analysis of Venusian and reflectivity effects. Observations of the near-nadir back- gravity. scatter power, collected using a separate smaller antenna on The Magellan spacecraft carried a 12.6-cm radar system to the spacecraft, were modeled using the Hagfors expression map the surface of Venus. The transmitter and receiver systems for echoes from gently undulating surfaces to yield estimates were used to collect three data sets: (1) synthetic aperture radar of planetary radius, Fresnel reflectivity, and root-mean-square (SAR) images of the surface, (2) passive microwave thermal (rms) slope. The topographic data produced by this technique emission observations, and (3) measurements of the backscat- have horizontal footprint sizes of about 10 km near periapsis tered power at small angles of incidence, which were processed and a vertical resolution on the order of 100 m. The Fresnel to yield altimetric data. Radar imaging and altimetric and radio- reflectivity data provide a comparison to the emissivity maps, metric mapping of the Venusian surface were accomplished in and the rms slope parameter is an indicator of the surface tilts, mission cycles 1, 2, and 3 from September 1990 until Septem- which contribute to the quasi-specular scattering component. ber 1992. Ninety-eight percent of the surface was mapped with radar resolution on the order of 120 m. The SAR observations were projected to a 75-m nominal horizontal resolution, and Introduction these full-resolution data compose the image base used in geologic mapping. The primary polarization mode was hori- The Hecate Chasma quadrangle (V–28) extends from lat 0° zontal-transmit, horizontal-receive (HH), but additional data for to 25° N. and from long 240° E. to 270° E. The quadrangle was selected areas were collected for the vertical polarization sense. mapped at 1:5,000,000 scale as part of the National Aeronautics Incidence angles varied between about 20° and 45°. and Space Administration (NASA) Planetary Geologic Mapping High-resolution Doppler tracking of the spacecraft took Program. place from September 1992 through October 1994 (mission Hecate Chasma is an extensive rift system consisting of cycles 4, 5, 6). Approximately 950 orbits of high-resolution multiple branches (for example, Hamilton and Stofan, 1996) gravity observations were obtained between September 1992 that lies in the lowland region of Hinemoa Planitia in the and May 1993 while Magellan was in an elliptical orbit with a northern hemisphere of Venus. Here, we use the term “rift” periapsis near 175 km and an apoapsis near 8,000 km. An addi- and “chasma” (plural “chasmata”) to designate the trough and tional 1,500 orbits were obtained following orbit-circularization fracture zones that make up the Hecate system. Lineaments in mid-1993. These data exist as a 75° by 75° harmonic field. within the Hecate rift system that define Hecate, Zverine, and Hanwi Chasmata are mapped in red for emphasis. The system Magellan Radar Data consists of several rifts and fracture belts, low-lying plains units, coronae and numerous small volcanic edifices including Radar backscatter power is determined by (1) the morphol- shields, domes and cones. The three branches of the Hecate rift ogy of the surface at a broad range of scales and (2) the intrinsic system in this quadrangle are Hecate Chasma (centered at lat reflectivity, or dielectric constant, of the material. Topography at 18.2° N., long 254.3° E.), Zverine Chasma (centered at lat 18.5° scales of several meters and larger can produce quasi-specular N., long 271° E.), and Hanwi Chasma (centered at lat 10.5° N., echoes, and the strength of the return is greatest when the local long 247° E.). The quadrangle also contains many intermedi- surface is perpendicular to the incident beam. This type of ate to large volcanoes, including Polik-mana Mons and Nazit scattering is most important at very small angles of incidence, Mons. Eighteen coronae are located in the quadrangle (table 1), because natural surfaces generally have few large tilted facets the largest of which is the 525 km across Taranga Corona, along at high angles. The exception is in areas of steep slopes, such as with fourteen impact craters (table 2). Corona maximum widths ridges or rift zones, where favorably tilted terrain can produce are measured to the outer edge of the annulus (for example, very bright signatures in the radar image. For most other areas, Stofan and others, 1992). Lineaments that form the corona diffuse echoes from roughness at scales comparable to the radar annulus are mapped in green for emphasis. wavelength are responsible for variations in the SAR return. In The overall topography of V–28 consists of plains located either case,
Load more

Recommended publications
  • Evidence for Volcanism in and Near the Chaotic Terrains East of Valles Marineris, Mars
    43rd Lunar and Planetary Science Conference (2012) 1057.pdf EVIDENCE FOR VOLCANISM IN AND NEAR THE CHAOTIC TERRAINS EAST OF VALLES MARINERIS, MARS. Tanya N. Harrison, Malin Space Science Systems ([email protected]; P.O. Box 910148, San Diego, CA 92191). Introduction: Martian chaotic terrain was first de- ple chaotic regions are visible in CTX images (Figs. scribed by [1] from Mariner 6 and 7 data as a “rough, 1,2). These fractures have widened since the formation irregular complex of short ridges, knobs, and irregular- of the flows. The flows overtop and/or bank up upon ly shaped troughs and depressions,” attributing this pre-existing topography such as crater ejecta blankets morphology to subsidence and suggesting volcanism (Fig. 2c). Flows are also observed originating from as a possible cause. McCauley et al. [2], who were the fractures within some craters in the vicinity of the cha- first to note the presence of large outflow channels that os regions. Potential lava flows are observed on a por- appeared to originate from the chaotic terrains in Mar- tion of the floor as Hydaspis Chaos, possibly associat- iner 9 data, proposed localized geothermal melting ed with fissures on the chaos floor. As in Hydraotes, followed by catastrophic release as the formation these flows bank up against blocks on the chaos floor, mechanism of chaotic terrain. Variants of this model implying that if the flows are volcanic in origin, the have subsequently been detailed by a number of au- volcanism occurred after the formation of Hydaspis thors [e.g. 3,4,5]. Meresse et al.
    [Show full text]
  • Aqueous Minerals from Arsia Chasmata of Arsia Mons, Tharsis Region: Implications for Aqueous Alteration Processes on Mars
    45th Lunar and Planetary Science Conference (2014) 1826.pdf AQUEOUS MINERALS FROM ARSIA CHASMATA OF ARSIA MONS, THARSIS REGION: IMPLICATIONS FOR AQUEOUS ALTERATION PROCESSES ON MARS. N. Jain*, S. Bhattacharya, P. Chauhan, Space Applications Centre (ISRO), Ahmedabad, Gujarat, India ([email protected]/ Fax: +91-079- 26915825). Introduction: The Arsia Chasmata is a complex help of high resolution data such as MGS-MOC (Mars collapsed region located at the northeastern flank of Global Surveyor-Mars Orbiter Camera), Viking orbiter Arsia Mons (figure 1 A and B) within Tharsis region [3], fresh appearing lava flows [4], graben and glaciers of planet Mars and is the most important region for the on flanks of Arsia Mons [5], young lava flows [6] study of minerals like phyllosilicate and pyroxene. The small shields at floor of caldera [7]. reflectance data of MRO-CRISM (figure 1 C D) has Present study mainly focuses on the mineralogy of confirmed above mentioned minerals in the study area. Arsia Chasmata which interestingly contains The presence of these minerals at the Arsia Chasmata absorption features of aqueous altered minerals such as on Mars provides the evidence of its past watery serpentine (phyllosilicate). This mineral is also located environment and their processes of formation. In the in Nili Fossae region which is long, narrow depression present study the absorption features of serpentine present on Mars [8]. But in the present study (phyllosilicate) are obtained at 2.32 µm, 1.94 µm and occurrence of this mineral at high altitude region raise 2.51 µm. Previous studies on Mars show that the curiosity to know about their formation processes.
    [Show full text]
  • Volcanism on Mars
    Author's personal copy Chapter 41 Volcanism on Mars James R. Zimbelman Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC, USA William Brent Garry and Jacob Elvin Bleacher Sciences and Exploration Directorate, Code 600, NASA Goddard Space Flight Center, Greenbelt, MD, USA David A. Crown Planetary Science Institute, Tucson, AZ, USA Chapter Outline 1. Introduction 717 7. Volcanic Plains 724 2. Background 718 8. Medusae Fossae Formation 725 3. Large Central Volcanoes 720 9. Compositional Constraints 726 4. Paterae and Tholi 721 10. Volcanic History of Mars 727 5. Hellas Highland Volcanoes 722 11. Future Studies 728 6. Small Constructs 723 Further Reading 728 GLOSSARY shield volcano A broad volcanic construct consisting of a multitude of individual lava flows. Flank slopes are typically w5, or less AMAZONIAN The youngest geologic time period on Mars identi- than half as steep as the flanks on a typical composite volcano. fied through geologic mapping of superposition relations and the SNC meteorites A group of igneous meteorites that originated on areal density of impact craters. Mars, as indicated by a relatively young age for most of these caldera An irregular collapse feature formed over the evacuated meteorites, but most importantly because gases trapped within magma chamber within a volcano, which includes the potential glassy parts of the meteorite are identical to the atmosphere of for a significant role for explosive volcanism. Mars. The abbreviation is derived from the names of the three central volcano Edifice created by the emplacement of volcanic meteorites that define major subdivisions identified within the materials from a centralized source vent rather than from along a group: S, Shergotty; N, Nakhla; C, Chassigny.
    [Show full text]
  • Final Report Venus Exploration Targets Workshop May 19–21
    Final Report Venus Exploration Targets Workshop May 19–21, 2014, Lunar and Planetary Institute, Houston, TX Conveners: Virgil (Buck) Sharpton, Larry Esposito, Christophe Sotin Breakout Group Leads Science from the Surface Larry Esposito, Univ. Colorado Science from the Atmosphere Kevin McGouldrick, Univ. Colorado Science from Orbit Lori Glaze, GSFC Science Organizing Committee: Ben Bussey, Martha Gilmore, Lori Glaze, Robert Herrick, Stephanie Johnston, Christopher Lee, Kevin McGouldrick Vision: The intent of this “living” document is to identify scientifically important Venus targets, as the knowledge base for this planet progresses, and to develop a target database (i.e., scientific significance, priority, description, coordinates, etc.) that could serve as reference for future missions to Venus. This document will be posted in the VEXAG website (http://www.lpi.usra.edu/vexag/), and it will be revised after the completion of each Venus Exploration Targets Workshop. The point of contact for this document is the current VEXAG Chair listed at ABOUT US on the VEXAG website. Venus Exploration Targets Workshop Report 1 Contents Overview ....................................................................................................................................................... 2 1. Science on the Surface .............................................................................................................................. 3 2. Science within the Atmosphere ...............................................................................................................
    [Show full text]
  • An Overview of Morphological and Compositional Investigation of Melas Chasma of Valles Marineris
    Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089) 6145.pdf An Overview of Morphological and Compositional investigation of Melas Chasma of Valles Marineris. T. Sivasankari1 and S. Arivazhagan2, 1 2 Centre For Applied Geology, Gandhigram Rural Institute - Deemed to be University, Gandhigram, Dindigul-624302, India ([email protected] and [email protected]). Introduction Many studies had been carried out by the primarily by aeolian processes in the recent period of time. researchers for various region of Valles Marineris and has Fig. 2. Shows the geology map of the study area. The geolo- revealed evidence for the presence of sulphate deposits gy map of Melas chasma was derived based on the map giv- namely the Interior Layered Deposits (ILD). The present en by Witbeck et al, 1991. The geological features includes study aims at the identification of mafic minerals High Cal- slope materials on the valley walls, dunes, layered materials, cium Pyroxene [HCP] and Phyllosilicate minerals of Melas fractured sediments, ridged plains, floor materials and crater chasma region of Valles Marineris by using CRISM datasets. fill materials. The topography of Chasma was interpreted by The spectra and the mineral distribution maps are derived the contuor map and DEM derived using the MOLA data. using the spectral summary parameters which helps to under- The contour values shows the highest relief of the study area stand the past geologic events ultimately bringing out the is 4000m and the lowest relief is -3800m. From the DEM origin and evolution of Valles Marineris. The Morphological data it is evident that the chasma has almost smooth valley features of Valles Marineris are compared with the CRISM floor with small isolated patches and a rugged topography as well as the HiRiSE Data.
    [Show full text]
  • KILOMETER-SIZED CONES on MARS: IGNEOUS OR MUD VOLCANOES?. P. Brož1, P. Fawdon2, and O. Čadek3, 1Institute of Geophysics Of
    Lunar and Planetary Science XLVIII (2017) 1425.pdf KILOMETER-SIZED CONES ON MARS: IGNEOUS OR MUD VOLCANOES?. P. Brož1, P. Fawdon2, and O. Čadek3, 1Institute of Geophysics of the Czech Academy of Science ([email protected]), 2Birkbeck, University of London, Malet St, London WC1E 7HX, 3Faculty of Mathematics and Physics, Department of Geophysics, Charles University in Prague, Czech Republic. Introduction: There is an ongoing debate within scientific community about the formation process of kilometer-sized cones reported from several regions on Mars (e.g., [1-8]). Two of the main mechanisms con- sidered as possible explanations, are (1) small scale igneous volcanism (e.g., [1,4-7]) and (2) mud volcan- ism (e.g., [2,8,10]). It is important to differentiate be- tween these two processes because of the very different implications these processes have for the Martian crust and near surface environment. Small scale igneous activity implies Mars producing magma away from the large Amazonian volcanic centers, whereas mud vol- canism implies pressurized and mobile ground water in the past. Both processes involve key factors of envi- ronmental habitability meaning that understanding the origin of these features is important in our understand- ing of recent habitability of Mars. On Earth small volcanoes and mud volcanism form of morphologically similar landforms (Fig. 1). Both processes form cones with relatively steep flanks and central craters on their tops; often additionally associ- ated with flow-like units spreading around those cones. Consequently, because of this convergence of form, is not readily apparent how to distinguish between these two processes using satellite images.
    [Show full text]
  • Exobiology in the Solar System & the Search for Life on Mars
    SP-1231 SP-1231 October 1999 Exobiology in the Solar System & The Search for Life on Mars for The Search Exobiology in the Solar System & Exobiology in the Solar System & The Search for Life on Mars Report from the ESA Exobiology Team Study 1997-1998 Contact: ESA Publications Division c/o ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands Tel. (31) 71 565 3400 - Fax (31) 71 565 5433 SP-1231 October 1999 EXOBIOLOGY IN THE SOLAR SYSTEM AND THE SEARCH FOR LIFE ON MARS Report from the ESA Exobiology Team Study 1997-1998 Cover Fossil coccoid bacteria, 1 µm in diameter, found in sediment 3.3-3.5 Gyr old from the Early Archean of South Africa. See pages 160-161. Background: a portion of the meandering canyons of the Nanedi Valles system viewed by Mars Global Surveyor. The valley is about 2.5 km wide; the scene covers 9.8 km by 27.9 km centred on 5.1°N/48.26°W. The valley floor at top right exhibits a 200 m-wide channel covered by dunes and debris. This channel suggests that the valley might have been carved by water flowing through the system over a long period, in a manner similar to rivers on Earth. (Malin Space Science Systems/NASA) SP-1231 ‘Exobiology in the Solar System and The Search for Life on Mars’, ISBN 92-9092-520-5 Scientific Coordinators: André Brack, Brian Fitton and François Raulin Edited by: Andrew Wilson ESA Publications Division Published by: ESA Publications Division ESTEC, Noordwijk, The Netherlands Price: 70 Dutch Guilders/ EUR32 Copyright: © 1999 European Space Agency Contents Foreword 7 I An Exobiological View of the
    [Show full text]
  • Neukum.3015.Pdf
    Seventh International Conference on Mars 3015.pdf EPISODICITY IN THE GEOLOGICAL EVOLUTION OF MARS: RESURFACING EVENTS AND AGES FROM CRATERING ANALYSIS OF IMAGE DATA AND CORRELATION WITH RADIOMETRIC AGES OF MARTIAN METEORITES. G. Neukum1, A. T. Basilevsky2, M. G. Chapman3, S. C. Werner1,8, S. van Gasselt1, R. Jaumann4, E. Hauber4, H. Hoffmann4, U. Wolf4, J. W. Head5, R. Greeley6, T. B. McCord7, and the HRSC Co-Investigator Team 1Free University of Berlin, Inst. of Geosciences, 12249 Berlin, Germany ([email protected]), 2Vernadsky Inst. of Geochemistry and Analytical Chemistry, RAS, 119991 Moscow, Russia, 3U.S. Geological Survey, Flagstaff, AZ 86001, USA, 4DLR, Inst. for Planet. Expl., Rutherfordstrasse 2, 12489 Berlin, Germany, 5Brown University, Dept. of Geological Sciences, Providence, R.I. 02912, USA, 6Arizona State Univ., Dept. of Geological Sciences, Box 871404, Tempe, AZ 85287-1404, USA, 7Space Science Institute, Winthrop, WA 98862, USA, 8now at: Geological Survey of Norway (NGU), 7491 Trondheim, Norway Introduction: In early attempts of understanding young meterorite ages. the time-stratigraphic relationships on the martian sur- The early cratering age data were based on post-Vi- face by crater counting techniques and principles of king image data analysis. With the new data from MGS stratigraphic superposition, most of the geological units (MOC) [11], MEX (HRSC) [12,13], and Mars Odyssey and constructs came out as being rather old, in the range (THEMIS) [14], it has become clear by now that the ap- of billions of years; a notable exeption was the Thar- parent discrepancy between the two age sets and the pre- sis province, whose volcanoes were believed to be, at dominance of old ages was a selection effect due to the least partly, relatively young (hundreds of millions of limited Viking resolution showing predominantly large, years) [1-10].
    [Show full text]
  • Walter S. Kiefer
    Walter S. Kiefer Lunar and Planetary Institute (281) 486-2110 (Office) 3600 Bay Area Blvd. [email protected] Houston, TX 77058 https://www.lpi.usra.edu/science/staff/kiefer/ Education Ph.D., Planetary Science and Geophysics, California Institute of Technology, 1990 Thesis: Models for the Formation of Highland Regions on Venus M.S., Planetary Science, California Institute of Technology, 1986 B.S., Physics and Astronomy, Texas Christian University, 1984, summa cum laude Honors Thesis: Fourier Transform Infrared Spectroscopy of Clay Minerals and Tar Sands Professional Experience Lunar and Planetary Institute, 1993-present Senior Staff Scientist, 2017-present Manager for Geophysics and Small Bodies Group, 2019-present Staff Scientist, 1997-2016 Research Scientist, 1993-1997 National Research Council Research Associate, Goddard Space Flight Center, 1990-1993 Graduate Research Assistant and Graduate Teaching Assistant, Division of Geological and Planetary Sciences, California Institute of Technology, 1984-1990 Spacecraft Mission and Instrument Development Experience Gravity Recovery and Interior Laboratory (GRAIL) mission Guest Scientist, 2012-2016 DAVINCI+: Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging+ mission proposal Co-I (NASA Discovery program Phase A Concept Study, 2020-2021) NASA representative on European Space Agency’s Science Study Team for the EnVision mission concept Phase A study (Venus remote sensing orbiter), 2018-2021 NASA Venus Landed Platform Science Working Group, 2018-2020 Seismic Atmospheric
    [Show full text]
  • Surface Processes in the Venus Highlands: Results from Analysis of Magellan and a Recibo Data
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 104, NO. E], PAGES 1897-1916, JANUARY 25, 1999 Surface processes in the Venus highlands: Results from analysis of Magellan and A recibo data Bruce A. Campbell Center for Earth and Planetary Studies, Smithsonian Institution, Washington, D.C. Donald B. Campbell National Astronomy and Ionosphere Ceiitei-, Cornell University, Ithaca, New York Christopher H. DeVries Department of Physics and Astronomy, University of Massachusetts, Amherst Abstract. The highlands of Venus are characterized by an altitude-dependent change in radar backscattcr and microwave emissivity, likely produced by surface-atmosphere weathering re- actions. We analyzed Magellan and Arecibo data for these regions to study the roughness of the surface, lower radar-backscatter areas at the highest elevations, and possible causes for areas of anomalous behavior in Maxwell Montes. Arecibo data show that circular and linear radar polarization ratios rise with decreasing emissivity and increasing Fresnel reflectivity, supporting the hypothesis that surface scattering dominates the return from the highlands. The maximum values of these polarization ratios are consistent with a significant component of multiple-bounce scattering. We calibrated the Arecibo backscatter values using areas of overlap with Magellan coverage, and found that the echo at high incidence angles (up to 70") from the highlands is lower than expected for a predominantly diffuse scattering regime. This behavior may be due to geometric effects in multiple scattering from surface rocks, but fur- ther modeling is required. Areas of lower radar backscatter above an upper critical elevation are found to be generally consistent across the equatorial highlands, with the shift in micro- wave properties occurring over as little as 5ÜÜ m of elevation.
    [Show full text]
  • The Geologic Evolution of Mars: Episodicity Of
    Lunar and Planetary Science XXXVIII (2007) 2271.pdf THE GEOLOGIC EVOLUTION OF MARS: EPISODICITY OF RESURFACING EVENTS AND AGES FROM CRATERING ANALYSIS OF IMAGE DATA AND CORRELATION WITH RADIOMETRIC AGES OF MARTIAN METEORITES. G. Neukum1, A. T. Basilevsky2, M. G. Chapman3, S. C. Werner1, S. van Gasselt1, R. Jaumann4, E. Hauber4, H. Hoffmann4, U. Wolf4, J. W. Head5, R. Greeley6, T. B. McCord7, and the HRSC Co-Investigator Team 1Free University of Berlin, Inst. of Geosciences, 12249 Berlin, Germany ([email protected]), 2Vernadsky Inst. of Geochemistry and Analytical Chemistry, RAS, 119991 Moscow, Russia, 3U.S. Geological Survey, Flagstaff, AZ 86001, USA, 4DLR, Inst. for Planet. Expl., Rutherfordstrasse 2, 12489 Berlin, Germany, 5Brown University, Dept. of Geological Sciences, Providence, R.I. 02912, USA, 6Arizona State Univ., Dept. of Geological Sciences, Box 871404, Tempe, AZ 85287-1404, USA, 7Space Science Institute, Winthrop, WA 98862, USA. Introduction: In early attempts of understanding bution due to resurfacing effects. This method was in the time-stratigraphic relationships on the martian sur- a rudimentary form already applied by [5], refined by face by crater counting techniques and principles of [19], and again refined in the course of our work [29]. stratigraphic superposition, most of the geological units In Fig. 1, examples of measurements showing such cha- and constructs came out as being rather old, in the range racteristic resurfacing effects and the way of extracting of billions of years [1-10]. On the other hand, most of resurfacing ages is shown. As here, most martian crater the ages of the martian meteorites cluster at relatively size-frequency distributions do not follow the relative- young values of around 175 m.y., 300-600 m.y.
    [Show full text]
  • GROWTH and DESTRUCTION CYCLES and ERUPTION STYLES at THARSIS THOLUS, MARS. T. Platz1, PC Mcguire1,2, S. Münn3, B. Cailleau1
    40th Lunar and Planetary Science Conference (2009) 1522.pdf GROWTH AND DESTRUCTION CYCLES AND ERUPTION STYLES AT THARSIS THOLUS, MARS. T. Platz1, P. C. McGuire1,2, S. Münn3, B. Cailleau1, A. Dumke1, G. Neukum1, J. N. Procter4, 1Freie Universität Ber- lin, Institute of Geosciences, Planetary Sciences and Remote Sensing, Malteserstr. 74-100, 12249 Berlin, Germany, [email protected], 2Washington University in St. Louis, McDonnell Center for the Space Sciences, Cam- pus Box 1169, One Brookings Drive, St. Louis, MO 63130-4899, 3 Leibniz Institute of Marine Sciences, IFM- GEOMAR, Wischhofstr. 1-3, 24148 Kiel, Germany, 4Massey University, Volcanic Risk Solutions, Institute of Natural Resources, Private Bag 11222, Palmerston North, New Zealand. Introduction: Tharsis Tholus is located in the mately 31.1×10³ km³, however, if a basal horizontal Tharsis region, approx. 800 km to the ENE of As- plane at 500 m is assumed, an edifice volume of craeus Mons. The edifice of Tharsis Tholus is unique >50×10³ km³ results. among Martian volcanoes as it is structurally divided Volcano-tectonic features: The edifice of Tharsis into sectors suggesting a complex volcano-tectonic Tholus shows the structures of at least four large de- evolution [1-3]. The objective of this study was 1) to formation events. The central and most prominent identify cycles of edifice growth and destruction and structure of the volcano is its central caldera. It is bor- causes of instability, 2) to estimate the mineralogical dered by a well-preserved system of concentric normal composition of rocks and loose deposits, 3) to provide faults. Peripheral ring faults generated individual a time frame of volcanic activity, and 4) to characterize blocks that moved downslope to varying degrees into eruptive styles at Tharsis Tholus.
    [Show full text]