Abstracts of 2011 PGFS

Home , Praxiteles (crater)

Co-sponsored by:

Table of Contents

Welcome ………………2

General Information ………………3

Overall Schedule ………………4

Program of Oral Session on Saturday ………………5

Program of Oral Session on Sunday ………………7

Program of Poster Session ………………9

Abstracts of Oral Session ………………O1

Abstracts of Poster Session ………………P1

Welcome

Message from Organizing Committee Chair

Needless to say, this is a special year for us. Disastrous earthquake in March caused uncountable influences on not only our economy, but also research activity. Fortunately none of PERC staffs suffered injuries, however, some laboratory equipment were severely damaged. Consequently we were forced to reschedule the plan of this symposium. Nevertheless, we managed to open this symposium at last by many kind helps from the world. It is our great pleasure to have 78 participants from 10 countries (excluding on-site registration) meeting for this symposium and presenting a variety of topics such as most recent achievements of planetary exploration and fundamental studies of terrestrial geology. We hope that every participant enjoys this symposium as much as we do.

Noriyuki Namiki Chair of Organizing Committee, 2011 PERC Planetary Geology Field Symposium

~“~“~“~“~ “~“~ “~“~ “~“~ “~“~ “~“~ “~“~

Message from Scientific Committee Chair

2011 PERC Planetary Geology Field Symposium is the first attempt in Asia to bring together scientists and engineers involved in various branches of planetary and terrestrial geosciences. Here in this abstract book, you will find papers on surface and internal processes of terrestrial planets, asteroids and icy satellites, papers on terrestrial analogs and biology, and exploration technologies such as rovers and onboard instruments. Effective interactions of planetary and terrestrial geoscientists and engineers have increasingly become important for understanding evolution of surfaces and interiors of planetary bodies. Thus the symposium is intended to foster active discussion among such diverse disciplines, hoping to provide the gained insights to the specific areas.

Goro Komatsu Chair of Scientific Committee, 2011 PERC Planetary Geology Field Symposium

General Information Organizing committee Convener: Takafumi Matsui (PERC/Chiba Institute of Technology) Chairman: Noriyuki Namiki (PERC/Chiba Institute of Technology)

Tomoko Arai (PERC/Chiba Institute of Technology) Kazuhisa Goto (PERC/Chiba Institute of Technology) Ko Ishibashi (PERC/Chiba Institute of Technology) Ryo Ishimaru (PERC/Chiba Institute of Technology) Masanori Kobayashi (PERC/Chiba Institute of Technology) Asako K. Matsumoto (PERC/Chiba Institute of Technology) Sohsuke Ohno (PERC/Chiba Institute of Technology) Hiroki Senshu (PERC/Chiba Institute of Technology) Koji Wada (PERC/Chiba Institute of Technology) Masako Ito (PERC/Chiba Institute of Technology) Yukiyo Kawada (PERC/Chiba Institute of Technology)

Scientific committee Goro Komatsu (IRSPS/Università d'Annunzio) (Chair) Kazuhisa Goto (PERC/Chiba Institute of Technology) Harald Hiesinger (Universität Münster) Kyoko Kataoka (Niigata University) Shoichi Kiyokawa (Kyushu University) Takafumi Matsui (PERC/Chiba Institute of Technology) Alfred McEwen (University of Arizona) Gian Gabriele Ori (IRSPS/Università d'Annunzio) Robert Strom (University of Arizona) Akihiko Yamagishi (Tokyo University of Pharmacy and Life Science)

Sponsor

The Sedimentological Society of Japan (SSJ) Society for Promotion of Space Science West Japan Industry and Trade Convention Association

Overall Schedule November 5, 2011 9:15-9:20 Greeting (Noriyuki Namiki) 9:20-9:25 Welcome Speech (Takafumi Matsui) 9:25-9:30 Objectives of this symposium (Goro Komatsu) 9:30-10:45 Oral session (Mercury and the Moon) 10:45-11:00 Coffee Break 11:00-12:15 Oral session (Mars 1) 12:15-13:45 Lunch time 13:45-14:45 Oral session (Mars 2) 14:45-15:00 Coffee Break 15:00-16:15 Oral session (Comparative Planetology) 16:15-16:30 Coffee Break 16:30-18:00 Poster session 19:00-21:00 Social Dinner at Rihga Royal Hotel Kokura

November 6, 2011 9:15-11:15 Oral session (Asteroids and Icy Satellites) 11:15-11:30 Coffee Break (15 minutes) 11:30-12:45 Oral session (Planetary Exploration) 12:45-14:15 Lunch 14:15-15:15 Oral session (Terrestrial Analogs and Fieldtrip in Central Kyushu) 15:15-15:30 Coffee Break (15 minutes) 15:30-16:45 Oral session (The Relationship between Planetary and Terrestrial Geosciences) 16:45-17:30 Discussion

November 5, 2011: Oral Sessions (International Conference Room)

Mercury and the Moon Chairs: Bob Strom, Tomoko Arai Time No. Presentation Title Presenter 9:30- O1 Geological Results from the MESSENGER Mercury Robert G. Strom (Invited) Orbital Mission 10:15- O2 Lunar and Planetary Geology Explored in Different Tomoko Arai Spatial Scales: Orbital Remote Sensing, On-Site Landing Survey, and Sample Analyses in Laboratory + Kaguya Results

10:45-11:00 Coffee Break (15 minutes)

Mars 1 Chairs: Alfred McEwen, Kazuhisa Goto Time No. Presentation Title Presenter 11:00- O3 Meter-Scale Geomorphology of Mars: Implications for Alfred S. McEwen (Invited) Terrestrial Analogs 11:45- O4 Reconstruction of Martian Atmospheric Circulation Hitoshi Hasegawa System Based on the Eolian Dune Deposits: Comparison with Earth 12:00- O5 Preliminary Experiments of Cyclic Steps on Ice Aiming Miwa Yokokawa to Understanding the Formation of the Spiral Troughs on Mars' North Polar Layered Deposits

12:15-13:45 Lunch (90 minutes)

Mars 2 Chairs: Ken Tanaka, Tomohiro Usui Time No. Presentation Title Presenter 13:45- O6 A New Geologic Map of Mars Kenneth L. Tanaka

14:00- O7 CO2-Related Explosive Alkaline Magmatism in Tomohiro Usui Noachian Gusev Crater on Mars + Mars Exploration Rover Investigations 14:30- O8 The Out-Gassing and Deuteric Alteration as a Source of Gilles Berger Martian Phyllosilicates

14:45-15:00 Coffee Break (15 minutes)

Comparative Planetology Chairs: Takafumi Matsui, Jens Ormö Time No. Presentation Title Presenter 15:00- O9 Japanese Ferropicrites and Martian Rocks: Akira Ishiwatari Geochemical Comparison 15:15- O10 The Role of the Surface Rock as a Chemical Reactant Soichi Omori in the Atmosphere-Ocean System: a Case of the Hadean-Archean Earth and its Implication to Mars 15:30- O11 The Late Veneer: Evidence in Komatiites and Elizabeth Frank Implications for the Moon and Mars 15:45- O12 Strength Contrast between Plagioclase and Oivine and Shintaro Azuma its Significance on Rheological Structure of Earth and Venus 16:00- O13 Effect of Impact Obliquity on the Off-Set of Outer vs. Jens Ormö Nested Crater for Concentric Impact Structures in Layered Targets

16:15-16:30 Coffee Break (15 minutes)

16:30-18:00 Poster Session (90 minutes)

19:00-21:00 Social Dinner at Rihga Royal Hotel Kokura (120 minutes)

November 6, 2011: Oral Sessions (International Conference Room)

Asteroids and Icy Satellites Chairs: Hirdy Miyamoto, Yasuhito Sekine Time No. Presentation Title Presenter 9:15- O14 Geological Processes on the Surface of Asteroid Hirdy Miyamoto (Invited) Itokawa 10:00- O15 Geomorphology and Geology of Vesta Explored by the Horst Uwe Keller (Invited) Dawn Spacecraft 10:45- O16 The Geomorphology of Asteroid 21 Lutetia from In-Situ Philippe Louis Lamy Imaging 11:00- O17 Hydrothermal Systems in Enceladus: Constraints from Yasuhito Sekine Experiments and Observations

11:15-11:30 Coffee Break (15 minutes)

Planetary Exploration Chairs: Noriyuki Namiki, Takashi Kubota Time No. Presentation Title Presenter 11:30- O18 In-Situ Observation of Asteroidal Dust in Future Mission Masanori Kobayashi 11:45- O19 A Proposal for Japanese Geological Exploration of Mars Noriyuki Namiki 12:00- O20 MELOS Plan B: Japan Astrobiology Mars Project Akihiko Yamagishi (JAMP): Search for Microbes on the Mars Surface 12:15- O21 Field Tests on Intelligent Exploration for Planetary Takashi Kubota Rover 12:30- O22 Development of Mobile Robots for Field and Planetary Kazuya Yoshida Exploration

12:45-14:15 Lunch (90 minutes)

Terrestrial Analogs and Fieldtrip in Central Kyushu Chairs: Kyoko Kataoka, Yukio Isozaki Time No. Presentation Title Presenter 14:15- O23 Potential Terrestrial Analog Sites in Asia for Mars Goro Komatsu Research 14:30- O24 Geotectonic Framework of an Ancient Plate Subduction Yukio Isozaki Zone: Generally Convergent but Locally Extensional Aspects in Japan - an example in Kyushu-Ryukyu arc 14:45- O25 Large-Scale Bouldery Volcaniclastic Apron by a Kyoko S. Kataoka Possible Gigantic Outburst Flood, Aso Caldera, Southwest Japan

15:15-15:30 Coffee Break (15 minutes)

The Relationship between Planetary and Terrestrial Geosciences Chair: Goro Komatsu Time No. Presentation Title Presenter 15:30 O26 Terrestrial Analogs and Planetary Geology Victor R. Baker (Invited) 16:15 O27 A New View of Planet Research in the Solar System Shigenori Maruyama

16:45-17:30 Discussion (45 minutes) Chairs: Goro Komatsu, Vic Baker, Shigenori Maruyama

-17:30 Taking Down of Posters

17:30-18:30 Scientific Committee Meeting

Poster Session (Conference Room 21)

Chairs: Hiroki Senshu, Koji Wada Planets and Satellites Number Presentation Title Presenter P1 The Layered Structure of Lunar Maria: Identification of the Shoko Oshigami HF-Radar Reflector in Mare Serenitatis Using Multiband Optical Image P2 Validation of Method for Estimating abundance of FeO Using Arashi Shirai Kaguya (SELENE) Multiband Imager Data P3 Lunar Regolith Soils detected by remote-sensing data Yasunori Miura P4 Monte Carlo Ray-tracing model of the Lunar Soil using LSCC data Un-Hong Wong set P5 Decrease Plans of Carbon Dioxide Gases at Mars and Venus Yasunori Miura P6 Evidence for In-Situ Trough Erosion in Planum Boreum, Mars Alexis Rodriguez P7 How to Learn about the Internal Structure of Mars Hiroki Senshu P8 Numerical Modeling of the Impact-Induced Tsunami on Mars Yasutaka Iijima P9 Classification and Statistics of Landslides in the Valles Marineris, Federica Fiorucci Mars P10 Inverse Analysis of the Debris-Flow Processes on Mars Hajime Naruse P11 Solar Insolation-Induced Destabilization of Subsurface Clathrates: Ryo Ishimaru Implication for the Martian Atmospheric Methane P12 Geological Features on the Surfaces of Saturn's Inner Small Naoyuki Hirata Satellites

Terrestrial Analogs Number Presentation Title Presenter P13 Modern Shallow Ocean Sedimentary Record of Ferric Hydroxide in Takuya Ueshiba Satsuma Iwo-Jima Island, Kagoshima, Japan P14 Structure of Kikai Submarine Caldera Complex, Southern Kyushu Fumihiko Ikegami P15 Estimation of a Possible Impact Crater at Active Volcanic Area like Makoto Okamoto in Japan P16 Sulfidic Deep Ocean Environment Reconstructed from 3.2Ga Ryo Sakamoto Black Shale Sequence in DXCL-DP, Pilbara, Western Australia P17 Depositional Age of the Mesoarchean Strike-slip Basins in the Mami Takehara Cleaverville Area, West Pilbara P18 Detail Stratigraphic, Magnetic, Carbon Isotope Description of Shuhei Teraji Komati Section at the 3.2Ga Mapepe Formation in the Barberton Greenstone Belt, South Africa P19 Buried Carbonate Breccias with Caves as Analogue to the Moon Yasunori Miura and Mars

Terrestrial Analogs (continued) P20 The Radiation Heat Budget of the Antarctic and Mars Polar Vladislav Isaev Regions: Comparative Analysis

Geological Processes Number Presentation Title Presenter P21 Coastal Boulder Deposits as a Possible Terrestrial Analog for Kazuhisa Goto Planetary Geology P22 Spatio-Temporal Changes in Distributional Pattern of Erosional Mayuko Yumi Marks on Solutional Substrate P23 Trial to Make Ramparts: Granular Flow Model of Fluidized Ejecta Koji Wada on Mars P24 Role of Yield Stress Fluid in Planetary Geology Aika Kurokawa

Biology and Astrobiology Number Presentation Title Presenter P25 Filamentous Microbial Fossils from Metabasalt in Low-Grade Masayuki Sakakibara Metamorphosed Jurassic Northern Chichibu Belt, an Accretionary Complex in Central Shikoku, Japan P26 Microbial Trace Fossils Discovered from Altered Basaltic Glass: Hisanari Sugawara Implications of Earth-Analog Study for Astrobiology on Mars P27 Formation of Active Carbohydrate Oligomers in High Temperature Yasunori Miura Environments

Methodology and Technology Number Presentation Title Presenter P28 Mars Environment Simulation Chamber Development at Planetary Sohsuke Ohno Exploration Research Center, Chiba Institute Of Technology P29 Prediction of Elemental Composition of Olivine with Laser-Induced Ko Ishibashi Breakdown Spectroscopy (LIBS) P30 Development of a Laser Ablation Isochron K-Ar Dating Method for Yuichiro Cho Landing Planetary Missions

2011 PERC Planetary Geology Field Symposium

Geological Results from the MESSENGER Mercury Orbital Mission R. G. Strom1, Z. Xiao1,2 and the MESSENGER Science Team 1 Lunar and Planetary Lab., University of Arizona, Tucson, AZ 85721, USA, 2 Faculty of Earth Sciences, China University of Geosciences (Wuhan), Wuhan, Hubei, China 430074; [email protected]

The MESSENGER ( substance. The pits (Fig. 1) are probably volcanic vents that are irregular to arcuate or spacecraft is the first orbital mission circular in shape. They primarily occur within to Mercury. It has imaged the entire surface at impact craters of all sizes and states of 250 m/pix and obtained high resolution images degradation. They range in equivalent diameters of targeted features at resolutions as high as 12 from 2 to 37 km and have bright reddish halos m/pix. MESSENGER has also obtained that are probably pyroclastic deposits. These measurements of the surface composition, the observations indicate that volatiles have played a magnetic field, the exosphere, the gravity field, important part in Mercury’s geologic history. and high resolution topography. These data have revealed a planet that is very different from the Moon and other terrestrial planets. MESSENGER continues to gather new measurements that will greatly improve our knowledge of the planet, including implications for the formation and early evolution of the terrestrial planets. Mercury is a heavily cratered planet, but with a crater density that is generally lower than the lunar highlands. It has extensive volcanic plains units consisting of older intercrater and younger smooth plains. Intercrater plains are the Fig.1 Interior of Praxiteles crater, 198 km in most extensive plains unit on the planet and diameter. Enhanced-color image in which red-to-blue were emplaced during the period of Late Heavy variations indicate relative color; the green channel is a measure of overall albedo. Hollows appear bright Bombardment (LHB) between about 3.9-3.8 Ga blue; the large depression is likely a volcanic vent and [1]. This accounts for the generally lower crater the source of the reddish pyroclastic deposit. Inset is density than the lunar highlands. The two largest image EN0211416219M (53 m/pixel), showing areas of the younger smooth plains occur within details of the bright depressions [5]. and surrounding the 1750 km diameter Caloris The tectonic framework of Mercury is unique basin and in the north high latitude regions first in the Solar System. It consists of thrust faults partly imaged by Mariner 10 and named called lobate scarps first seen by Mariner 10. Borealis Planitia. The newly imaged northern MESSENGER has determined that they are plains cover about 6% of Mercury’s surface. distributed on a global scale. These scarps can They appear to have been flooded in a relatively reach lengths of 1500 km and heights of about 2 short period of time and have a maximum km. The global distribution indicates that thickness over 1 km . Both the Caloris and Mercury has decreased in radius, probably due Northern Plains were emplaced near the end of to interior cooling. In addition, to compressive LHB about 3.8 or 3.7 Ga [2]. There are other faulting, there are other local areas of tension smaller regions of volcanic smooth plains, some fractures (grabens). The floor of the Caloris of which were emplaced much later in basin, and to a lesser extent other large basins, Mercury’s history [3]. The compositional show concentric and radial pattern of ridges and measurements suggest that the lavas are grabens. In the northern plains there are systems generally ultamafic; probably komatiites or of polygonal grabens associated with large komatiitic basalts [4]. flooded craters. There are also geologic features which are [1] Strom R.G. et al. (2008) Science, 321, 79- rare or not found on the Moon or other terrestrial 81. [2] Head J.W. et al. (2011) Science, planets. These include bright hollows and large submitted. [3] Prockter L.M. et al. (2010) pit craters [5]. The bright hollows (Fig. 1) are Science, 329, 668-671.[4] Nittler L.R. et al. primarily associated with crater floors, central (2011) Science, submitted. [5] Blewett D.T. et al. peaks or rings, or crater rims. They are irregular (2011) Science, submitted. depressions surrounded or filled by bright material in various stages of preservation. The bright material is probably some type of volatile

O1 2011 PERC Planetary Geology Field Symposium

Lunar and Planetary Geology Explored in Different Spatial Scales: Orbital Remote Sensing, On-Site Landing Survey, and Sample Analyses in Laboratory. Tomoko Arai Planetary Exploration Research Center (PERC), Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan ([email protected]).

Introduction: Explorations of surface and interior of analyzer (EPMA) in a vacuum condition. In order to planets are keys to understanding the origin and evolution quantitatively determine modal abundances of minerals of planets. Surface geology is a manifestation of various and mineral compositions based on the reflectance spectra, differentiation processes which planets have experienced, reference data set should be an integration of (1) spectral such as magmatic, tectonic and impact events. Planetary reflectance data of the surface of a given sample, and (2) geology can be survey with various approaches, including modal abundance and mineral composition data deter- orbital remote sensing, on-site landing survey, and re- mined by SEM and EPMA, of the same sample surface as turned sample analyses in laboratory. Each approach tells used for (1). The above integrated dataset includes both us about the surface geology in different spatial scales reflectance spectra at a given point and two-dimensional from hundreds kilometers in orbital observation to sub- mineral distribution on the given sample surface, which micron in sample analyses. On-site landing surveys fill the can be viewed with ratios of band depths diagnostic of gap in spatial scales between orbital and laboratory stu- each minerals. We are ready to acquire such reference dies. Since targets of studies, aerial scales of obtained dataset to use a newly-developed Spectral Reflectance data, and physical conditions of data acquisition are all Imager (SRIM), distinct among the three approaches above, ways of data which consists reduction, data calibration, and data interpretation need to of three spec- be optimal for the each approach, respectively. trometers cov- Reflectance Spectral Measurement: Reflectance ering visible to spectra has been long used to study the mineral distribu- near-infrared tion and composition on the lunar, planetary and asteroid- wavelength, al surfaces in ground-based telescopic observation and coupled with an orbital remote sensing in lunar and planetary missions. In automated XY the orbital remote sensing, the target of the measurement sample stages. is generally average mineralogy of regional surface regolith in the scale of tens-to-hundreds meter to kilometers. Fig.1 Photograph of Spectral Reflectance Imager (SRIM). Reference data for the data calibration have been obtained by measuring reflectance spectra of bulk-rock samples in SELENE-2 Lunar Landing Mission: SELENE-2 powder form with grain sizes comparable to regolith. In is a Japanese lunar landing mission which is currently such powered rock samples, multiple mineral phases are planned to be launched around the middle of 2010's. intimately mixed. In contrast, on-site landing observation Landing sites have been evaluated since June last year [1]. allows us to investigate outcrops of crustal bedrocks and Higher-rated candidate sites include craters Tycho and lava flows in context of rocks with texture in the scale of Copernicus for the purpose of resolving the two most fun- centimeter or millimeter. Interpretation of such reflec- damental issues of lunar science: genesis of feldspathic tance spectra obtained by landing survey would require a crust and origin of the Th-rich terrane (PKT). For the new set of database covering individual rocks and their both cases, central peaks are targets for the survey, be- degraded clasts. cause they most likely represent crustal bedrocks which Reference Dataset for Landing Missions: were uplifted upon the crater formation. Rock types Greater varieties of modal abundances and compositional present at the central peaks of Tycho and Copernicus have variations of rocks and minerals would be present within been studied with reflectance spectra of Kaguya Multi- the scale observable by landing exploration, compared to band Imager (MI) and Spectral Profiler (SP) [2, 3]. The those from orbital remote sensing. Reference dataset above reference data set plays a critical role to study crus- should cover a variety of rock types (combination of min- tal rocks either at Tycho or Copernicus by on-site reflec- erals), textures, and mineral compositions as wide as ones tance spectral measurement. expected among returned samples, meteorites, terrestrial Acknowledgements: I thank Drs. Masanori Ko- rocks and what can be suggested from orbital measure- bayashi of PERC and Aya Yamamoto of RESTEC for the ment. Two-dimensional mineral distributions of the target development of SRIM. This study is supported by Grant- outcrops are essential to understanding the local geology. in-Aid for Scientific Research (B). Reflectance spectra are rarely used for characterization References: of minerals and determination of mineral compositions in [1] Saiki K. et al. (2010) AGU,abstract #P51C-1462. laboratory. Instead, mineralogical analyses are done with [2] Ohtake M. et al. (2009) Nature, 461, 236-240. properly-prepared (polished and carbon coated) samples, [3] Arai T. et al. (2011) 42nd LPSC, abstract #2139. using electron-beam instruments, such as scanning electron microscope (SEM) and electron probe micro-

O2 2011 PERC Planetary Geology Field Symposium

Meter-Scale Geomorphology of Mars: Implications for Terrestrial Analogs. A. S. McEwen1 and the HiRISE Team 1Lunar and Planetary Lab, University of Arizona (Tucson, AZ, 85721 USA; [email protected]).

Introduction: The High Resolution Imaging Science is well constrained, it has occurred only in association Experiment (HiRISE) on Mars Reconnaissance Orbiter with the late winter/early spring CO2 frost, when tempera- (MRO) has been imaging Mars at scales near 30 cm/pixel tures are far too low for water [16, 17], confirming the since 2006 [1, 2]. Over 20,000 images have been acquired CO2-frost avalanche model [18]. with over 16,000 Gigapixels of data, covering 1.33% of Recently-discovered features called recurring slope the Martian surface (if it was all unique coverage). More lineae (RSL) are relatively low-albedo features that ex- than 2,400 stereo pairs have been acquired, with meter- tend downslope from bedrock outcrops, often associated scale Digital Terrain Models (DTMs) [3] derived for with small channels, and hundreds of them may form in ~150 scenes. There are also sequences of images for de- rare locations [19]. RSL appear and lengthen in the late tecting changes over hundreds of locations. The images, southern spring/summer from 52°S to 32°S latitudes, fa- DTMs, and stereo anaglyphs are available at voring equator-facing slopes--times and places with peak http://hirise.lpl.arizona.edu/. surface temperatures from ~250-300 K. Liquid brines near the surface might explain this activity, but the Mars at the 1-Meter Scale: The geomorphology of mechanism and source of water are not understood. Mars is diverse, including landforms produced by vol- Other Martian slope features may appear similar to canic, tectonic, fluvial, eolian, impact, mass wasting, gla- RSL. The seasonal, latitude, and slope aspect distribu- cial, periglacial, and seasonal processes. Many of these tions of RSL, and their incremental growth distinguishes landforms appear quite similar to comparable landforms them from streaks on dust-mantled slopes. Small slope on Earth, but are generally much better preserved as Mars lineaments are also seen on high-latitude dunes during lacks the ubiquitous fluvial erosion of Earth. In particular, late winter and spring, as the seasonal CO2 cover is sub- periglacial landforms resulting from slow processes are limating; the hypothesis that these are sand flows initiated very well preserved on Mars [e.g., 4]. Flood-lava [5] and by CO2 sublimation has been confirmed by the appear- impact-crater [6] morphologies are also well-preserved on ance of new dune gullies [20]. Grain flows and boulder tracks removing thin dust covers may resemble RSL, but Mars, better than on Earth, so Mars can even help inform lack seasonality and create a color contrast not seen in us about terrestrial processes. Recent discoveries have RSL. shown that dunes and sand sheets are quite active on Mars today [7]. Implications for Terrestrial Analogs: Meter- The south-polar region contains some truly alien land- scale morphologies on Mars show many similarities to scapes including “spiders” and “Swiss cheese terrain”. terrestrial landforms resulting from impact, volcanic, eo- These strange morphologies are produced by gas sublima- lian, mass wasting, and dry periglacial processes. How- tion-driven activity [8, 9]. ever, processes driven by volatiles (CO2 and H2O) behave Small impact craters (1-30 m diameter) form at a very differently in the low-pressure environment of Mars much higher rate on Mars than on Earth, and provide than on Earth, resulting in both strange landforms without probes of the subsurface, including exposures of clean ice terrestrial analogs (such as “spiders” and “Swiss cheese” down to the middle latitudes [10]. HiRISE has imaged terrain), and in familiar-looking landforms like gullies for more than 200 new impact sites, often with crater clusters which terrestrial analogs may prove misleading. from atmospheric breakup [11]. Some of the most spectacular martian landforms are References: [1] McEwen, A. et al. (2007) JGR 112, very old deposits where the bedrock is well-exposed from E05S02. [2] McEwen, A. et al. (2011) Icarus 205, 2-37. eolian erosion. These include layered terrains with a di- [3] Kirk, R.L., et al. (2008) JGR 113, E00A24. [4] Levy, versity of morphologies and mineral compositions [12- J. et al. (2010) Icarus 206, 229-252. [5] Jaeger, W. et al. 14]. Some of these sites are very well imaged as they (2010) Icarus 205, 230-244. [6] Osinski, G. et al. (2011) have been candidate landing sites for the Mars Science EPSL, in press. [7] Bridges, N. et al. (2011) Geology, in Laboratory rover, to be launched in late 2011 [15]. press. [8] Byrne, S. (2009) AREPS 37, 535-560. [9] Tho- mas, N. et al. (2011) Icarus 212, 66-85. [10] Byrne, S. et Does Water Ever Flow on Mars Today?: Land- al. (2008) Science 325, 1674. [11] Daubar, I. et al. (2011) forms on Mars that might have been produced by water ESPC-DPS, #1649. [12] Wiseman, S. et al. (2010) JGR are of particular interest in the search for extraterrestrial 115, E00D18. [13] Roach, L. et al. (2010) Icarus 206, life, but the geomorphic interpretations are often contro- 253-268. [14] Weitz, C. et al. (2010) Icarus 205, 73-102. versial. Mars has some processes with no counterpart on [15] Grant, J. et al. (2011) PSS 59, 1114-1127. [16] Dun- Earth, driven by the seasonal deposition of CO2 frost das, C. et al. (2010) GRL 37, L07202. [17] Diniega, S. et and/or snow. Gullies and ravines on steep slopes, general. (2010) Geology 38, 1047-1050. [18] Ishii, T., and S. ally believed to be due to very recent flow of water, have Sasaki (2004) LPSC 15, #1556. [19] McEwen, A. et al. been observed (in before-and-after images) to form in (2011) Science 333, 740-743. [20] Hansen, C. et al. recent years. When the seasonal timing of gully formation (2011) Science 331, 283-295.

O3 2011 PERC Planetary Geology Field Symposium

Reconstruction of Martian atmospheric circulation system based on the eolian dune deposits: comparison with Earth

H. Hasegawa1 1Department of Natural History Science, Hokkaido University ([email protected])

Eolian dunes are particularly suited to comprehensive tively longer time periods (thousand to 10’s of thousand planetary studies because they generally present on the year time-scale) [4]. terrestrial planet, such as Earth, Mars, Venus, and Sat- In addition, based on the reported outcrops of the eo- urn’s moon Titan. Although the distribution and orienta- lian dune strata in the Meridiani Planum [5], the past at- tion of eolian dunes are thought to provide information of mospheric circulation system and changes of the surface the surface wind pattern and atmospheric circulation sys- wind pattern on Mars are examined. Several studies at- tem on the planets and moons, validity of its deposits tempted to reconstruct the past atmospheric circulation on remain uncertain. Earth based on the direction of large-scale cross-bedding Sand dunes are the most widespread eolian features of the eolian dune deposits [6]. Paleowind directions rec- present on Mars. The present study compiled the research orded in the eolian dune deposits in Meridiani Planum results of the present-day Martian atmospheric circulation reveal that the presence of reversing northward and system based on the general circulation model (GCM) southward paleowind flows on Mars in the past [5]. It is experiments and satellite measurements of the cloud considered that the reversed Hadley circulation prevailed movement and temperature profile. The present study in different periods of the precession and eccentricity on also compiled the research results of the reconstructions Mars can explain this reversing paleowind flows. of the surface wind patterns on Mars based on the distri- The present study also focused on the several re- bution and orientation of the eolian dunes. Then, in order search results of the reconstruction of wind circulation to clarify the validity of the distribution and orientation of pattern on Saturn’s moon Titan based on the eolian dune eolian dune deposits, the present-day atmospheric circula- deposits [7,8]. Numerous linear dunes with eastward tion system is compared with the reconstructed surface streamline pattern on Titan have mostly been interpreted wind pattern and the distribution of dune fields on Mars. as evidence of predominantly westerly (eastward) equato- GCM experiments revealed that the Martian atmos- rial surface winds [6]. However, results of GCM experi- pheric circulation is characterized by an asymmetric, ments claimed the presence of such consistent westerly large cross-equatorial Hadley circulation [1]. A symmet- winds, and suggested that the eastward streamline pattern ric, but very weak equatorially symmetric, Hadley circu- of Titan’s dunes may be a result of occasional fast west- lation does occur on Mars, but only near the equinoxes. erlies that elongate the dunes eastward [8]. Because of Mars’ high orbital eccentricity and resulting Therefore, several examples of eolian dune records large seasonal differences in heating, its Hadley circula- on Earth, Mars, and Titan indicate important implications. tion is stronger and wider during northern winter than Although eolian dune deposits are important for recon- southern winter [1]. structing atmospheric circulation on the planets and Reconstructed surface wind patterns indicated by the moons, direct measurements of wind flows or tempera- dune centroid azimuth (DCA) and dune slipface orienta- ture profiles by satellite image and GCM experiments are tion (SF) are mostly consistent with the predominant sur- also necessary. Nevertheless, because eolian dune depos- face wind pattern of the northern hemisphere winter time its are formed in relatively longer time periods (decade to [2]. Namely, both DCA and SF suggests prevailing 10’s of thousand year time-scale), eolian dune deposits southward wind flow in low latitude, and westward flow could provide key information of the mid- to long-term in southern high-latitude (S65°-70°), consistent with GCM atmospheric circulation system on the planets and moons. results. The distributions of dune fields are concentrated on References: the high latitude (S55°-80° and N70°-85°) [2], which are [1] Forget, F., et al. (1999) J. Geophys. Res., 104, 24155– generally lie adjacent to the areas with strongest winds 24176. under the descending branch of the Hadley circulation. [2] Hayward, R.K., et al. (2009) J. Geophys. Res., 114, 1–11. Therefore, it is suggested that the both distribution of [3] Fenton, L.K., and Hayward, R.K., (2010) Geomorphology, dune fields and patterns of dune orientations are reflected 121, 98-121. in the atmospheric circulation patterns on Mars. [4] Parteli E.J.R., et al. (2009) Computer Physics Communica- However, DCA and SF directions in some region tions, 180, 609-611. show different wind flows. Recent report of the inactive [5] Hayes, A. G., et al. (2011) J. Geophys. Res., 116, E00F21. sand dunes in some regions may give clues for this dis- [6] Hasegawa, H., et al. (2011) Climate of the Past Discus- crepancy [3]. It is suggested that periods of the active sions, 7, 119-151. sand dune migrations and depositions are not continuous [7] Lorenz, R.D., Radebaugh, J., (2009) Geophys. Res. Lett. 36, and intermittent on Mars. The numerical experiments L03202. suggested that eolian dune deposits on Mars are deposited [8] Tokano, T., (2010) Aeolian Research 2, 113–127. only during strong wind periods and are formed in rela-

O4 2011 PERC Planetary Geology Field Symposium

Preliminary experiments of cyclic steps on ice aiming to understanding the formation of the spiral troughs on Mars’ North Polar Layered Deposits M. Yokokawa1, N. Izumi2, H. Shimizu1, K. Naito2, T. Yamada2, R. Greve3, and T. Shiraiwa3 1Faculty of Information Science and Technology, Osaka Institute of Technology, 1-79-1 Kitayama, Hirakata Osaka 573- 0196, Japan, [email protected], 2Division of Field Engineering for the Environment, Faculty of Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628, Japan, [email protected], 3Institute of Low Tempera- ture Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo 060-0819, Japan, [email protected]

Introduction: Owing to the advancement of remote we used are (a) Room: -7.6 to -7.0 , Liquid: -6.4 to sensing technology, it has been found that a variety of 6.1 , (b) Room: -8.3 to -8.2 , Liquid: -6.6 . We characteristic landforms on the surfaces of planets other learnt in prior trials that liquid with 17% of ethylene gly- than the earth. Multi-beam sensors, in particular, have col begin to freeze at -6.6 . Therefore, in (a), we aimed clarified even the accumulation structures of the land- to reproduce only a process of ice desolving into the solu- forms beneath the surface. Geology of the other planets is tion (erosional process), and in (b), we intended to repro- now a subject to study for geologists as well as astrono- duce not only the erosional process, also a process of wa- mers. Among such landforms on the other planets, spiral ter in the solution freezing to become ice on the bed (de- troughs observed on the North Polar Layered Deposits of 1 positional process). Mars (NPLD) is intriguing. Though they are suspected to Results: (i) Cyclic steps were formed under erosion- have some relation with katabatic wind blowing on the al conditions (temperature setting (a), Fig.1). Flume ice cap, it has not been known how the spiral troughs are slopes are set to be 10, 19.5, and 30 degrees. The water formed in detail. Considering that the troughs are formed discharges per unit width range from 26.6 to 33.1 cm2/s. perpendicular to the direction of katabatic wind, they are The step length is observed to be different in each case. assumed to be boundary waves rather than streak-like configurations such as rills and gullies. From features that the step length is much larger than the step height, and that internal structures show traces of upstream migra- tion1, the spiral troughs may possibly be cyclic steps2 formed by a density current created by cooling of the atmosphere due to ice. Smith et al (2011)3 have demonstrated that numerical simulation with a cyclic step model can show reasonable consistency with an observed migration rate. In this study, we have performed a series of Fig.1 The resultant topography on the ice surface (RunID: CSIM110716B). Erosional condition. Flume slope is 10 de- physical experiments analogous to the formation of cyclic 2 steps on ice by a density current. gree. Water discharge per unit width is 27.6 cm /s. Started with flat bed and this image was taken after 13 hours. Experimental settings: In the case of Mars, water included in the atmosphere blowing on ice is sublimated (ii) No obvious steps or holes were formed under “ag- to become ice and deposited on the bed covered with ice. gradational” conditions (temperature setting (b)). Though In order to model this process, we used a liquid which needlelike ice covered the whole surface of the ice, no includes water but does not freeze even below the ice spatial difference of growth of the needlelike ice was ob- point. We selected 17 %-83 % ethylene glycol-water so- served. This may suggest no steps are formed in this set- lution, which does not freeze down to -6.5 . We ex- ting. We could not continue this condition sufficiently pected that, if the liquid flows on ice, and is cooled below long because the liquid in the valve was frozen. -6.6 , water included in the liquid freezes to become ice Concluding remarks: In these experiments, we demonstrated that cyclic steps can be formed on rigid ice and deposits on the bed. We used a 1.4 m long, 2 cm (or 4 cm) wide, and 25 by the fluid flowing on the ice surface. Further experi- cm deep flume made by plexiglass. The flume has 8 cm ments will be needed to examine the conditions for ag- high weirs at the downstream end and 1.2 m upstream gradational cyclic steps, which should lead us to understand the migration of the spiral troughs on NPLD. from the downstream end, so that there is an 8 cm deep reservoir. We put water in the reservoir and froze it so Acknowledgements: This study was supported that the flume has an 8 cm ice layer on its bottom. partly by the Grant for Joint Research Program (proposal The flume with ice bed is tilted by 5 up to 30 degrees. No.11-57) of the Institute of Low Temperature Science, The liquid is supplied from a head tank to the upstream Hokkaido University. Discussions with Isaac Smith, Jack, end of the flume, flows on ice in the flume, and was W. Holt, and Wonsuck Kim in University of Texas, Gary dropped from the downstream end into a downstream Parker in University of Illinois were also helpful. reservoir. The liquid in the downstream reservoir is References: [1] Smith, I. B. and Holt, J. W. (2010) pumped up to the head tank. The discharge from the head Nature, 465, 450-453. [2] Kostic, S. et al. (2010) Journal tank to the flume can be adjusted by a valve, and exces- of Hydro-environment Research 3, 167–172. [3] Smith, I. sive water is returned to the downstream reservoir. B. et al. (2011) Abstract of the Fifth Mars Polar Science In point of temperature, we can control only room Conference, Fairbanks, Abstract#6050. temperature in these experiments. Everything in the room is chilled by the air of the room. The temperature settings

O5 2011 PERC Planetary Geology Field Symposium

A New Geologic Map of Mars. K. L. Tanaka1 1U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001, USA, [email protected].

Introduction: A five-year effort to map the global units of specific morphologies and relative ages. This geology of Mars at 1:20,000,000 scale using mainly Mars scheme reduces the number of units to ~40, as local and Global Surveyor (MGS) and Mars Odyssey (ODY) image regional map-unit designations are avoided. Furthermore, and altimetry datasets is nearing completion. This will be units are identified by primary morphologies and compo- the third global geologic map of Mars to be published by sition only (e.g., lobate, knobby, dune, and ice). Addi- the U.S. Geologic Survey. tional landforms or surface textures that are closely asso- Previous maps: The first by Scott and Carr [1] fit ciated with particular units are included in the unit de- on one map sheet at 1:25,000,000 scale and was based on scriptions. Mapped feature lines include morphologic Mariner 9 images (mostly at 1 to 2 km/pixel resolution) designations only (ridge, scarp, trough, etc.), whereas and virtually no topographic data. It consisted of an equa- interpretive designations (e.g., graben, lava-flow margin, torial Mercator and north and south Polar Stereographic fluvial valley) are included as attributes in the map data- projections. This map established the major time- base. No point features are mapped since a purely mor- stratigraphic units on Mars--the Noachian, Hesperian, and phological mapping approach would be unwieldy. Amazonian Periods--based on surfaces of varying relative Efforts are being made to produce precise, representa- ages. tive crater counts of as many map units as possible. Some Less than 10 years later, a three-sheet (1 polar and 2 units are not amenable to crater counting due to their rug- equatorial) 1:15,000,000-scale map series [2-4] was pub- ged relief or complex resurfacing histories. For example, lished based on Viking images (mostly 100-300 m/pixel) some lava-flow sequences display nearly spatially ran- as well as Viking stereophotogrammetry-based topo- dom mixtures of flows of diverse ages. Some units range graphic-contour mapping (1000-m intervals and >1000-m in morphologic character, including crater density, and so vertical error). The projection scheme was the same as the multiple outcrops are being crater counted for such units previous map. The Viking-based map included many re- to establish type crater counts. Craters in many cases gional and local formations, resulting in 90 map units. It smaller than 1 km are included in the counts using Mars also served to delineate the three chronologic periods into Express High Resolution Stereo Camera (mostly > 12 eight epochs (also based on reference surfaces), whose m/pixel) and ODY Context Camera (5-6 m/pixel) images. boundaries were defined at 1, 2, 5, and 16 km cumulative Crater counts are acquired with the CRATERSTATS crater densities [5]. Recently, the crater density for the program [8], which also calculates model absolute ages Hesperian/Amazonian was redefined, and model ages based on the crater production function of [9]. Once map- were calculated for the boundaries based on two widely ping is completed, crater-densities can be readily deter- used crater-production schemes [6]. To facilitate use, the mined for virtually all outcrops for craters >1 km in di- map was digitized twenty years later in Geographic In- ameter using the global crater GIS database of Robbins formation Systems (GIS) format, with linework registered and Hynek [10]. to the more accurate MGS Mars Orbiter Laser Altimeter Acknowledgements: The author acknowledges the (MOLA) standard geodetic control base [7]. mapping efforts of colleagues James Dohm (U. Arizona), The new map: Mapping relies on MOLA digital el- Corey Fortezzo (USGS), Ross Irwin (PSI), Eric Kolb evation models at 460 m/pixel horizontal resolution and 1 (Google, Inc.), and Jim Skinner (USGS). Unit type area m vertical accuracy and Thermal Emission Spectrometer crater counts are being performed and validated for ran- day and nighttime infrared mosaics at 100 m/pixel. These domness by Thomas Platz and Greg Michael (both Freie data sets once again provide a quantum-leap advancement U. Berlin), and Stuart Robbins (SWRI) and Brian Hynek in data quality, permitting more accurate and innovative (U. Colorado) are providing their global crater database. mapping approaches. Mapping line work is digitized in References: [1] Scott D. H. and Carr M. H. (1978) GIS with a 5-km vertex spacing. To publish a single, USGS Map I-1083. [2] Scott D. H. and Tanaka K. L. complete global product, the map will be published using (1986) USGS Map I-1807-A. [3] Greeley R. and Guest J. a psuedocylindrical projection such as Mollweide. One E. (1987) USGS Map I-1807-B. [4] Tanaka K. L. and benefit of this projection is the accurate representation of Scott D. H. (1987) USGS Map I-1807-C. [5] Tanaka K. L. area (versus shape), wherein the relative proportion of (1986) JGR, suppl., E139-158. [6] Werner S. C. and global geologic units can be visually conveyed. The map Tanaka K. L. (2011) Icarus, 215, 603-607. [7] Skinner J. will also include digital supplements as GIS layers as well A. Jr. (2006) LPSC, 37, Abs. 2331. [8] Michael G. G. and as cartographic representations delivered as Google Neukum G. (2010) EPSL, 294, 223-229. [9] Hartmann Earth-compatible Keyhole Markup Language (KML) files. W.K., and Neukum G. (2001) Space Sci. Rev., 96, 165- The latter will allow the broadest possible use of the 194. [10] Robbins S. J. and Hynek B. M. (2010) LPSC, global map product. . 41, Abs. 2257. The map employs a unit grouping system based on broad terrain and morphologic types (highland, lowland, transitional, polar, widespread, and volcanic) that include

O6 2011 PERC Planetary Geology Field Symposium

CO2-Related Explosive Alkaline Magmatism in Noachian Gusev Crater on Mars T. Usui1, 2 1Jonson Space Center, NASA. Mail Code KR, 2101 Nasa Parkway, Houston, TX 77058. 2Lunar and Planetary Science Institute. 3600 Bay Area Blvd. Houston, TX 77058.

Introduction: It has been proposed that Mars was been proposed, because no large carbonate deposits (car- once warm enough to maintain persistent liquid water on bon sinks) or significant atmospheric loss (deduced by 13 its surface [e.g. 1]. Such a warm and wet environment im- į C) that accounts for the early CO2-rich atmosphere plies an effective greenhouse gas (CO2 and/or other vola- have been observed. Moreover, a recent thermodynamic tiles) that was dominantly supplied by early Martian mag- calculation suggests that, under the redox state of the matism [2]. Volatiles profoundly affect the thermodynamic Martian meteorite source mantle (IW to IW+1), transport properties of magma and thus play an important role in of CO2 to the Martian atmosphere has been quite limited generating a variety of igneous rock types. The Mars Ex- and may not be sufficient to account for the greenhouse ploration Rover Spirit has encountered volcanic and vol- conditions. caniclastic rocks having diverse alkaline compositions in Our study suggests that, at least beneath Gusev the Noachian-age Gusev crater [3]. Among them are crater, carbon should have resided in the Martian mantle. Wishstone-class tephrites which have pyroclastic textures Moreover, the Martian mantle should have been enough and unusually high-P2O5 bulk-rock compositions. Investi- oxidized (~QFM) that the carbon could have existed as gating the petrogenesis of the Wishstone-class rocks may carbonatitic melt instead of graphite or diamond. This is yield insights into the effects of CO2 on Noachian magma- consistent with the redox state of Gusev basalts (~QFM) tism as well as its contribution to the greenhouse gas. estimated by the Mossbauer spectrometer as well as the recent findings of carbonate-rich outcrops in Gusev crater Results and Discussions: Two samples (Wishstone [6]. We conclude that the Martian mantle would have and Champagne) of the >95 Wishstone-class rocks were been already oxidized in the Noachian era within a billion investigated by the full set of Athena instruments [4]. years after the core formation. Wishstone and Champagne contain many angular grains or clasts of varying sizes, suggesting a pyroclastic origin. They are unusually enriched in incompatible elements

(e.g. >5 wt% P2O5) with low SiO2 (~43 wt%) and high alkali

(~6 wt% of [Na2O + K2O]) contents. The high- phosphorous tephrite signature is not attributable to secondary aqueous alteration but represents an igneous rock composition [5].

These high-P2O5 whole-rock compositions cannot readily be explained by fractionation of other magmas in

Gusev. We show that the high-P2O5 whole-rock compositions plot above solubility curves of merrillite and apatite

(Ca-phosphate) in a diagram of P2O5 versus aluminum saturation index (ASI) (Fig. 1). Moreover, assessment of the compositional trends produced by the measurements of Figure. 1: Experimentally determined solubility of apatite (Ɣ) brushed and abraded rock surfaces suggests that merrillite and merrillite (U) in silicate melts as a function of melt ASI [7, is the phosphate mineral in Wishstone class rocks. These 8]. Compositional ranges of Wishstone (W) and Champagne (C) observations suggest that that mechanical admixture of plot above both apatite and merrillite solubility limits (approxi- merrillite is required [5]. mated by the dashed curve). RA and Ex indicate RAT-abraded A source supplying merrillite cannot be a common sili- and -extrapolated compositions, respectively; details of the ex- cate magma; instead, it could be a carbonatitic. Consider- ploration analysis are described in [5]. Ranges of ASI values of ing pyroclastic textures of Wishstone Class and their geo- carbonatites, terrestrial basalts, and anorthosites are also logic context, we propose that the Wishstone Class repre- shown. Magmatic fractionation commonly increases the ASI sents an alkaline-rich igneous rock suite that has mechan- value of basaltic magma. ically mixed xenocrystic merrillites, probably during explosive volcanic eruption; the merrillites cry stallized from References: [1] Malin, M.C. and Edgett, K.S. (2003) carbonatitic melt produced by melting of a carbon-bearing Science, 302, 1931-1934. [2] Jakosky, B.M. and Phillips, Martian mantle. R.J. (2001) Nature, 412, 237-244. [3] McSween, H.Y., et al. It has been debated whether CO2 was the effective (2006) JGR, 111, E09S91, doi:10.1029/2006JE002698. [4] greenhouse gas in the early Mars. To maintain persistent Arvidson, R.E., et al. (2006) JGR, 111, E02S01, liquid water on the Martian surface, several bars pressure doi:10.1029/2005JE002499. [5] Usui, T., et al. (2008) JGR, of CO2 is required, which is approximately three orders of 113, E12S44. [6] Morris, R.V., et al. (2010) Science, DOI: magnitude higher than that on present-day Mars [2]. In 10.1126/science.1189667. [7] Sha, L.-K. (2000) GCA, 64, contrast, other greenhouse gases (e.g. methane) have 3217-3236. [8] Watson, E.B. (1980) EPSL, 51, 322-335.

O7 2011 PERC Planetary Geology Field Symposium

The out-gassing and deuteric alteration as a source of martian phyllosilicate. G. Berger1, Beaufort2 and A. Meunier2 1IRAP, Observatoire Midi-Pyrénées, 14 av. E. Belin, 31400 Toulouse, France, [email protected], 2HYDRASA, University of Poitiers, 40 av. Recteur Pineau 86022 Poitiers, France.

Introduction: Geomorphological observations of Mars surface and mineral detection, in particular Conclusion: Even in absence of a stable hydro- hydrated sulphates, militate for the idea that liquid sphere, deuteritic aleration and degassing pathways can water have existed on Mars surface, even if physical generate variable amount of phyllosilicates: large and conditions forbid its presence today. Beside the sul- local argilisation comparable to hydrothermal systems phate formation which requires particular chemical for deuteritic alteration, or discrete deposits but affect- conditions, clay minerals are of particular interest being large areas (several tens of square kilometres) as it cause they are the first by-product of aqueous altera- is the case in Mars sites described by [2]. tion of silicate rocks. Martian clays have been directly References: observed as iddingsite in SNC Martian meteorites [1], [1]Leshin L.A., Vicenzi E. (2006) Elements, 2, and Fe-Mg clays were spectroscopi-cally detected on 157-162. [2] Poulet F. and the OMEGA team (2005) the surface of Mars by OMEGA [2]. Nature, 438, 623-627. [3] Gonçalves N.M.M. et al. Basically, clays are produced on the Earth by two (1990) 9th Int. Clay Conf., pp. 153-162. contrasted mechanisms: bio-mediated alteration of silicate bedrocks by pedogenetic processes or hydrothermal abiotic thermoactivated alteration. The former being speculative in the Mars context, we focused on hydrothermal processes that could happen on Mars and affect volumes of rocks sufficiently important to be detected by remote sensing techniques. Observations and modelling: We tested the assumption of Fe-Mg clays formation during magma degassing by analysing two terrestrial analogues: 1) The Parana flood basalt province (Brazil): The petrographical and mineralogical charac- teristics of clay deposits in the prismatic joints of a lava flow [3] are interpreted here using quantitative chemical and thermodynamical models simulating the basalt interaction with Cl2 rich volatiles. We reproduced an early acidic and oxidizing alteration of the lava flow by out-degassing of H2O-Cl2 fluids with disproportionation reactions, followed by a later more conventional alteration by neutral or alkaline evolved hydrothermal solutions. The above alteration model is supported by the mineralogical observations that clearly evidence two different reaction sequences, within the basalt columns or within the inter- columnar joints. 2) The Piton des Neiges, La Réunion (France): Detailed observations of alteration sequences associated wih a syenitic intrusion within a basaltic edifice (cone-sheet) strongly suggests the contribution of deuteritic water ex- plused during the final crystallization stages of the molten rock. Petrographic observations will be shown and discussed. We suggest that such alterations may be generalized to any explosive volcanism.

O8 2011 PERC Planetary Geology Field Symposium

Japanese ferropicrites and Martian rocks: geochemical comparison Akira ISHIWATARI Center for Northeast Asian Studies, Tohoku University (Kawauchi 41, Aoba-ku, Sendai 980-8576, Ja- pan. [email protected])

Introduction: Ultramafic volcanic rock called “fer- Acknowledgements: I thank Dr. Yuji Ichiyama of ropicrite” occurs in some terrestrial large igneous prov- JAMSTEC for his help in studies of Japanese ferropicritic inces (LIPs) of various ages such as Pechenga (Kola Pe- rocks. I thank Dr. Kazuhisa Goto for encouraging my ninsula, Early Proterozoic), Siberia (Permo-Triassic), participation in this symposium. Parana-Etendeka (Early Cretaceous), and East Greenland References: [1] Ichiyama, Y., Ishiwatari, A., Hira- (Early Cenozoic) [1]. Recently, we found ferropicrites hara, Y. and Shuto, K. (2006) Lithos, 89, 47-65. [2] and related ferrobasalts [1] (rarely with olivine spinifex Ichiyama, Y., Ishiwatari, A., Koizumi, K., Ishida, Y. and texture [2]) from Permian greenstones occurring as basal Machi, S. (2007) Island Arc, 16, 493-503. [3] Filiberto, J. part of a nappe in the Jurassic accretionary complex in (2008) Icarus, 197, 52-59. [4] Barrat, J.A., Gillet, Ph., Obama City, Fukui Prefecture, Japan. Citing our paper, Sautter, V., Jambon, A., Javoy, M. et al. (2002) Meteorit- Filiberto [3] pointed out a close chemical resemblance ics & Planet. Sci., 37, 487-499. [5] Gellert, R., Rieder, R., between these terrestrial ferropicrites and Martian mete- Bruckner, J., Clark, B.C., Dreibus, G. et al. (2006) J. orites (especially shergottites), which include ferrobasal- Geophys. Res., 111, E02S05, doi:10.1029/2005JE002555. tic to ferropicritic volcanic rocks and ultramafic cumu- [6] Fleischer, I., Brückner, J., Schröder, C., Farrand, W., late rocks. Tréguier, E. et al. (2010) J. Geophys. Res., 115, E00F05, Geochemical similarity and difference: In gen- doi: 10.1029/2010JE003621. [7] Zipfel, J., Schröder, C., eral, terrestrial basaltic rocks and Martian shergottites Jolliff, B.L., Gellert, R., Herkenhoff, K.E. et al. (2011) plot in separate fields in the Mg/Si-Al/Si, Ca/Si-Mg/Si, Meteoritics & Planetary Science, 46, 1-20. and Fe-Si diagrams, but terrestrial ferropicrites plot in the same field as the Martian rocks [3]. The ferropicrites containing 20 wt.% or more FeO cannot be produced by partial melting of ordinary terrestrial mantle rock (peridotite), but can be produced by high-pressure partial melting of Fe-rich eclogite that may be a recycled material of the subducted ancient oceanic crust [1]. The origin in the analogous “heavily processed mantle” may be applicable to the Martian shergottites [3]. However, the Martian shergottites [4] and Martian soils/rocks [5-7] are dis- tinctly richer in Mn and Cr than the terrestrial ferropicrites, and this property is also shared by the Martian soils analyzed by “Spirit” in Gusev Crater [4] and by “Opportunity” in Meridiani Planum [6,7]. The two elements behave contrastingly through partial melting and magmatic differentiation processes (incompatible and compatible, respectively), and the fact that the Martian rocks are rich in both elements suggests chemical uni- queness of the Martian mantle. The Martian rocks are also rich in Co but poor in Ni. This does not favor the magmatic origin in the Martian mantle doped with metallic iron or iron sulfide. Implication for pyroxenitic mantle of Mars: The Cr-rich and Ni-poor feature of the Martian mantle suggests that it mainly consists of pyroxene rather than olivine. The chemical resemblance between Martian soils and shergottites suggests widespread occurrence of ferro- pictiric rocks on Mars, contrasting to their scarcity on the Earth. It is possible that Mars’ mantle is more pyroxenitic or eclogitic than the Earth’s peridotitic mantle, and Mars produced much more ferropicritic magmas. Melting temperature of iron-rich eclogite is lower than peritotite, and this may have merited the ancient, long-term, voluminous magma production that was unlikely in the rapidly cooling, small planet.

O9 2011 PERC Planetary Geology Field Symposium

The role of the surface rock as a chemical reactant in the atmosphere-ocean system: a case of the Hadean-Archean Earth and its implication to Mars S. Omori Department Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro-ku, Tokyo, Japan. e-mail: [email protected]

Introduction: Chemical reaction between the solid the oceanic crust to the wedge mantle [3]. During the Earth surface (crust) and the ocean or atmosphere has an subduction-zone metamorphism along the Archean sub- important role in the chemical evolution and stabilization duction-zone geotherm, the carbonated oceanic crust re- of the surface environment. It is suggested that the reac- leases H2O-CO2 fluids with various XCO2 to the wedge tions between the rock and volatiles could affect the mantle, and the fluid reacts with hanging-wall peridotite ocean-atmosphere chemical system. Weathering and to form carbonates again. Although the oceanic crust chemical alteration of the surface rocks occur at the con- could not keep CO2 as carbonate in the Archean high-T tact with the atmosphere or ocean in various temperature subduction, the carbonate was still stable in the peridotite. conditions. Nature of such processes are hydration, redox, The peridotite could contain about 6 wt% of CO2 as car- carbonation, and sulfuration reactions between the rock bonate. On the assumption that the hanging-wall perido- and volatiles. The volatile components can be fixed in the tite was dragged down to deep mantle with the subducting rock by the reactions. It is suggested that the reaction plate, the subduction flux of CO2 into the deep mantle is between the surface and volatiles is a significant function estimated to be on the order of 1012 kg/y [3]. in the ocean-atmosphere system of Earth, if we consider 1 Combination of the hydrothermal carbonation and the to 103 million years for the duration of interest. subduction modeling suggest that the interaction between Change of the system in the Earth’s history: In the oceanic crust and the ocean could significantly modi- the Earth’s history, the resurfacing force, active depth, fy the PCO2 in the atmosphere. This process continued and amount of the sequestrated volatile in the rock have during the Archean and had important role to keep the changed. In the earliest stage of the crust before for- ocean thermally stable. mation of the ocean, dense vapor of the atmosphere react- Mars: The interaction among ocean, atmosphere, and ed directly with the crust which possibly suffered resur- surface rock on the early Mars can be an analog of that on facing by late impact and formation of ejecta [1]. After the Earth. Argued plate tectonics on the earliest Mars formation of the ocean, the komatiitic early crust reacted could also have had important roles on the change in the with seawater to form serpentinite and possibly hydrogen surface environment. which was a possible source of nutrient for the early life Acknowledgements: Dr. K. Kitajima is appreciated [2]. Initiation of plate tectonics was followed by for- for providing the geological data of the North Pole green- mation of basaltic crust. Carbonation of the basaltic oce- stone. anic crust was distinct in Archean and subducted slabs References: [1] Zhanle K. and Sleep N. (2002) Carbon acted as a carrier of CO2 into the mantle [3]. dioxide cycling through the mantle and implications for Mineralogical modeling of the Archean hydro- the climate of ancient Earth, Geological Society, London, thermal alteration: Geological studies of the Archean Special Publications, 99, 231-257. [2] Takai, K. and 4 greenstone belts have shown that plate tectonics had al- colleagues (2005) Ultramafics- Hydrothermalism- ready started at 3.8Ga, and that ocean floor hydrothermal Hydrogenesis-HyperSLiME (UltraH3) Linkage is a key alteration had produced significant amounts of carbonate for Occurrence of Last Universal Common Ancestral within the oceanic crust before subduction [4]. Therefore, (LUCA) Community: Where is it, Lost City or Kairei the subduction of CO2 into the mantle, and volcanic de- (Rainbow)? Eos Trans. AGU, 86(52), Fall Meet. Suppl., gassing from mid-ocean ridges must have been the domi- Abstract. [3] Omori S. & Kitajima K. (2004) Subtraction nant fluxes in the Archean carbon cycle. of the surface CO2 by subduction of the carbonated oce- Geological studies in the Archean greenstone belt have anic crust in the Archean Earth and presumably in the shown that plate tectonics had already started at 3.8Ga, ancient Mars. Joint Meeting for Earth and Planetary Sci- and hydrothermal alteration at mid-oceanic ridge (MOR) ence, Makuhari. [4] Kitajima, K. and 3 colleagues 2001. had caused extensive carbonation in the oceanic crust. We Seafloor hydrothermal alteration at an Archaean mid- examined a nature of the hydrothermal carbonation at the ocean ridge. J. Metamorph. Geol. 19, 581-597. Archean MOR by thermodynamic mineralogical modeling to show a secular change of the degree of carbonation. Reference parameters for bulk rock-composition and physicochemical conditions of the hydrothermal process are taken from those of greenstones in the 3.5Ga North Pole area, Pilbara Craton, Australia [4]. The carbon cycle system in the Archean: The carbonated oceanic crust should have subducted into the mantle and metamorphic devolatilization should have occurred. Stability of carbonate minerals in the oceanic crust and hanging wall peridotite in the subduction zone was estimated including transfer of H2O-CO2 fluid from

O10 2011 PERC Planetary Geology Field Symposium

The Late Veneer: Evidence in Komatiites and Implications for the Moon and Mars E. A. Frank1, W.D. Maier2, and S. J. Mojzsis1 1Dept. of Geological Sciences, University of Colorado, 2200 Colorado Ave, Boulder, CO 80309, USA 2Dept. of Geology, University of Oulu, Linnanmaa, 90014 Oulu, Finland Contact: [email protected]

Introduction: During differentiation, highly sidero- enhancement is also observed on the Moon and Mars phile elements (HSEs) partition strongly into planetary [5,6], suggesting that the LV occurred across the inner cores, resulting in an HSE mantle depletion relative to CI. solar system. An LV impactor may have even be the ori- However, contemporary peridotites show higher than gin of Borealis Basin [2]. Mercury and Venus could have expected HSE concentrations. One explanation is that this experienced LVs as well, though if Mercury is the angrite HSE enhancement was caused by a late accretion event - parent body, there is no evidence of an HSE enhance- a “Late Veneer” - that delivered ~1% of Earth’s current ment. However, the data interpretations are far from con- mass following chemical closure of the core [1]. We can clusive [9]. Venus has clear evidence of plume-driven trace the evolution of the signature in Earth’s mantle us- volcanism that could dredge up material from the lowering komatiites, which are ultramafic extrusive rocks that mid mantle, but even without rock samples we may be sampled the lower-mid mantle in the Archean and early able to find evidence of a LV in its atmosphere [10]. The Proterozoic. There is also evidence for Late Veneers on possibility of the Late Veneer being such a large-scale the Moon and Mars. event makes that period of time among the most mysteri- Delivery: Dynamical predictions indicate that there ous of Earth’s history. was enough material present at this time in the inner solar Acknowledgements: We thank the University of system to provide the required Late Veneer (LV) mass [2]. Colorado, NASA Lunar Science Institute, and NASA Notably, the HSE enhancements in Earth as well as lunar Exobiology program for support. Special thanks to Bill and martian meteorites appears to be in chondritic Bottke, Robin Canup, David Rubie, Norm Sleep, and proportions [3-5]. There are two endmember scenarios for Kevin Zahnle for valuable discussions as well as to delivery: (1) one large, differentiated impactor or (2) Sarah-Jane Barns and Dany Savard for HSE analyses. many small, undifferentiated impactors. If there was one References: [1] Chou C.-L. (1978) Proc. LPSC IX, large impactor, the core must have either been suspended 219-230. [2] Bottke W.F. et al. (2010) Science 330, 1527- in the mantle or broken up to avoid reaching Earth’s core. 1530. [3] Maier W.D. et al. (2009) Nature 460, 620-623. Suspension is unlikely, so the impactor could have been [4] Day M.D. et al. (2007) Science 315, 217-219. [5] destroyed and “rained” back down to Earth surface such Jones J.H. et al. (2003) Chem. Geol. 196, 21-41. [6] Ca- as in the Giant Impact, e.g. [6]. Having small, nup R.M. and Asphaug E. (2001) Science 412, 708-712. undifferentiated impactors negates the core problem but [7] Harrison T.M. (2009) Ann. Rev. Earth Plan. Sci. 37, requires many bodies to be left over from accretion at this 479-505. [8] Frank E.A. et al. (2011) Proc. Goldschmidt time. Where along this spectrum the Late Veneer occurred XXI, 862. [9] Righter K. (2008) LPSC XXXIX, #1936. is unclear. [10] Dauphas N. and Marty B. (2002) JGR, 107 (E12), Timing: In order for the HSEs to have avoided 5129. migrating to Earth’s core, the LV must have occurred between the Giant Impact and the solidification of the first continental crust. The Giant Impact occurred 30-100 Myr after solar system formation and would have reset the core [6], while a delivery of 1% of Earth’s mass would have presumably destroyed the crust. Zircon analyses from the Narryer Gneiss Complex in western Austrailia indicate that the first continental crust solidified ~90-160 Myr later [7]. Rock Record: Komatiites have been used to track the evolution of mantle HSE abundances. Pt data suggest a progressive mixing-in of HSE-containing material over time, followed by a leveling off to roughly present-day peridotite abundances [3]. Our new data of komatiites >3.6 Gyr old - the oldest ever analyzed for HSEs - reveal a surprisingly low Pt abundance (Figure 1, [8]). Figure 1. Pt data from various locales plotted by sample age. Discussion: The new data suggest that the original MgO contents were normalized to 25%. The solid line indicates HSE concentration was low prior to delivery, and the LV the present-day peridotite Pt concentration, and the dashed line material gradually mixed in the mantle until relative ho- shows the mean Pt abundance in the new data >3.6 Ga (data mogeneity to present levels was reached. Although more <3.6 Ga replotted from [3]; data >3.6 Ga from [8]). Analyses analyses is required to fill in the gaps and confirm the were performed using nickel-sulfur fire assay at the Université trend, the consistency between the geochemical and dy- de Québec à Chicoutimi. namical evidence provides a compelling story. An HSE

O11 2011 PERC Planetary Geology Field Symposium

Strength contrast between plagioclase and olivine and its significance on rheological structure of Earth and Venus S. Azuma1 and I. Katayama2 1 Department of Earth and Planetary Systems Science, Hiroshima University (Higashi- Hiroshima, Hiroshima 739-8526, Japan; [email protected]), 2Hiroshima University (Higashi- Hiroshima, Hiroshima 739-8526, Japan; [email protected]).

Introduction: It is thought that plate tectonics is a cated by extrapolation from power-law relations. How- product of the localized brittle failure in the lithosphere ever, our experimental results indicate that olivine can be and viscous flow in the asthenosphere, and strength pro- weaker than plagioclase [5]. In materials with a relatively file is a key to understand tectonics of terrestrial planet strong chemical bonding such as silicates, Peierls mecha- [1] . Physical properties, such as temperature and pressure nism becomes dominant at low temperatures [6]. Based and stress, and the chemical compositional layering be- on deformation mechanism map, deformation of olivine tween crust and mantle result in a strong rheological lay- could be controlled by this type of flow mechanism under ering in the planet interior. It has been estimated by pre- our low temperature experiments. Thereby, the strength vious experiments that the brittle-ductile transition occurs contrast between plagioclase and olivine are reversed at in the planet interior and deformation mechanisms can be low temperatures. Some natural observations, such as changed with increasing depth. In the present study, we boudin structure of plagioclase in olivine matrix from the evaluate rheological variation in the crust-mantle transi- Oman ophiolite, suggest that the strength contrast tion based on new series of deformation experiments, and between plagioclase and olivine might be reversed under discuss why plate tectonics doesn't exist in the other ter- different geological conditions. This observation agrees restrial planets except the Earth. with our results. Consequently, our result of this experi- In case of the earth, two different models on the strength ments supported "creme brullee" model, in which the profile in the continental lithosphere have been proposed. upper mantle below the Moho is expected to be compa- The first is the "jelly sandwich" model that had been em- rable or less viscous than crustal materials e.g.,[3], as braced for the past two decades. This model is that a continental strength profile and showed us that flow law weak middle and lower crust are sandwiched between can not be applied for low temperature conditions. strong upper crust and strong mantle lithosphere just like We conducted experiments under dry condition to evalu- a jelly sandwich e.g., [2]. The second one is the "creme ate strength profile of terrestrial planets like dry Venus. brullee" model, in which the upper mantle is significantly Venus has been thought as a similar planet to the Earth weak, and consequently region for viscous deformation because of closet to the Earth in mass, density, size and in continues into the mantle depth [3] . These two models of distance from Sun [7] . However, Venus has extraordi- strength profile are given by extrapolating frictional nary crustal features and plate tectonics doesn’t seem to strength and viscous flow law of each material to tem- work in this planet. This can be a result of different perature and pressure corresponding to the Earth’s inte- rheological property on the Venus. In previous study, rior. behavior of Venusian lithosphere have been inferred by Deformation Experiment: In this study, we per- deformation experiments of dry diabase e.g. [8]. Our ex- formed experiment to directly determine the relative periments show that olivine is always stronger than pla- strength between plagioclase and olivine without any gioclase under dry condition. It is considered from these extrapolating of flow law; the crustal materials consist results that the decoupling occurs between lower crust predominantly of plagioclase that largely control defor- and upper mantle on Venus. There is possibility that this mation of the crust, whereas deformation of the upper decoupling and this strength contrast between crust and mantle is largely controlled by olivine. These samples are mantle results in stopping plate tectonics. We are going to together sandwiched between alumina pistons in a simple report our result under dry conditions of deformation ex- shear geometry and we used the hot-pressed samples and periments, and difference in rheological structure between performed deformation experiments using solid-medium Earth and Venus. deformation apparatus. The experimental conditions were Acknowledgements: We thank Institute for Study of ranging 1GPa and 400-1000 °C, corresponding conditions the Earth’s interior, Okayama University for experimental approximately to Moho of the terrestrial planets under assistance of making starting material. water-rich and dry conditions. References:[1] Burgmann, R. and Dresen, G. Experimental Results: The experimental results (2008) Annu. Rev. Earth Planet. Sci., 36, 531–567. [2] under wet conditions show that plagioclase is expected to Chen, W-P.and Molnar, P. (1983) JGR, 88, 4183- 4214. be a little bit weaker than olivine or show almost no dif- [3] Jackson, J. (2002) GSA Today, 12, 4–9. [4] Brace, ference in strength at temperatures of the continental Mo- W.F. and Kohlstedt, D. (1980) JGR, 85, 6248- 6252. [5] ho of the Earth, ca. 500- 600 °C. Moreover, we found the Azuma, S. et al. (2010) JMPS, 105, 286-290 [6] Tsenn, change of relative strength contrast between plagioclase M.C. and Carter, N.L. (1987) Tectonophysics, 136, 1- 26. and olivine at low temperature; plagioclase becomes [7] Taylor, S. R. and McLennan, S. (2008) Planetary stronger than olivine at 400 °C. Plagioclase is generally Crusts. pp.181, Cambridge University Press, New York. believed to be weaker than olivine [4],which is also indi- [8] Mackwell, S.J. et al. (1998) JGR, 103, 975-984.

O12 2011 PERC Planetary Geology Field Symposium

Effect of impact obliquity on the off-set of outer vs. nested crater for concentric impact structures in layered targets. J. Ormö1 and A. P. Rossi2 1Centro de Astrobiología, Instituto Nacional de Tecnica Aeroespacial, 28850 Torrejon de Ardoz, Spain ([email protected] csic.es), 2Jacobs University Bremen, Campus Ring I, 28759, Bremen, Germany ([email protected])

Introduction and aim of study: Most natural im- periments at the Facility for Experimental Impact Crater- pacts occur with an oblique trajectory of 45°. Still, due to ing at Centro de Astrobiología, Spain. the high kinetic energy most impacts produce circular Preliminary results and discussion: Here, we craters with rather centro-symmetric ejecta layer. How- present a martian crater that shows both offset concentric- ever, a lowering of the impact angle with respect to the ity and pristine, irregular (“butterfly”) ejecta distribution horizon affects the expression of the resulting impact cra- (Fig. 2). The crater is about 700m wide and located in ter in several ways (e.g. elongated shape, non-uniform layered deposits (likely ground ice as indicated by poly- cross-section, non-uniform ejecta distribution). gons) in Arcadia Planitia (194.847 E 46.582 N). The effect of impact angle on the ejecta distribution has Fig. 1. Numerical (3D) long been used as a tool to establish the projectile trajec- simulation of the Lockne tory for craters: At angles below 45° the ejecta distribu- impact. Image adapted from tion gets more downrange preference. With continued [6]. The outer circle repre- decrease of impact angle there is a drastic decrease of sents the rim of water cav- ejecta uprange from the crater and a so-called “forbidden ity, and the inner circle the zone” develops. At very low angles a “forbidden zone” rim of the basement crater also develops downrange of the crater, leading to a “but- surrounded by ejecta (wider terfly” pattern [1]. downrange than uprange). One of the few craters on the Earth that maintains an ejecta layer that still displays the direction of the impact is the Lockne crater in central Sweden [2]. The impact Fig. 2. Concentric occurred 456Ma in an epicontinental sea. Lockne´s mor- impact crater on phology is also strongly affected by the weak upper target Mars with outline layer (seawater and sediments) that covered the rigid and ejecta distribu- crystalline basement. The crater displays a 3.5km wide tion highlighted. brim surrounding an 8km wide, nested, basement crater. Inferred direction The brim is a surface partially stripped from both water of impact from the and sediments before the deposition of the basement cra- right. HiRISE im- ter ejecta. The resulting concentric shape is in analogy age with lunar craters in regolith-covered rock [cf. 3]. In ex- ESP_018522_2270. perimental craters formed in water over sand it is noticed how the outer crater in the water cavity may be much In comparison with the geologically well-constrained 3D wider than the nested crater and how a shallow excava- simulation of the Lockne crater in Fig.1 the similarities tion flow develops along the interface with the more re- are striking. Thanks to the ejecta distribution it is possible sistant substrate [4]. The same effect is noticed in the to see how the brim of the martian crater is wider in the numerical simulations of the Lockne crater [5; 6]. Fur- downrange direction. Further indication of direction of thermore, 3D simulation shows how the brim gets wider impact is also provided by the asymmetric ejecta distribu- on the downrange side of the nested crater [6]. Conse- tion around the nested crater that fits well to the Lockne quently, there is an apparent off-set between the nested analogue. crater and the surrounding outer crater in the weaker, up- Conclusions: The offset in concentricity of craters per part of the target (Fig.1). formed in layered targets may prove to be a viable alter- Our aim is to develop off-set crater concentricity into a native to the ejecta distribution in determining the impact method to determine impact direction and obliquity for direction and angle. layered-target craters, especially if the ejecta layer is Acknowledgements: The work by J. Ormö is sup- poorly preserved. ported by the grant AYA2008-03467 ⁄ESP from the Span- Method: Layered targets are frequent on both the ish Ministry of Science and Innovation. Moon and Mars, but possibly also elsewhere in the Solar References: [1] Gault D. E. and Wedekind J. A. (1978) th System. To evaluate the influence of the obliquity on the Proceedings 9 Lun. Plan. Sci. Conf., 3843–3875]. [2] Lind- amount of off-set at a concentric crater it is a prerequisite ström M. et al (2005) Planet. Space Sci., 53(8), 803–815. [3] that the crater also shows a well preserved ejecta layer. Quaide W. L. and Oberbeck V. R. (1968) J. Geophys. Res., 73, In a first step we are comparing a few selected craters on 5247–5270. [4] Gualt D. E. and Sonett C. P. (1982) Geol. Soc. Mars with the terrestrial analogue Lockne. The next step Am. Spec. Pap.., 190, 69–102. [5] Ormö J. et al. (2002) J. Geo- will be quantitative studies and mapping of concentric phys. Res., 107(12), 31–39. [6] Shuvalov V. et al. (2005) Impact craters on Mars and the Moon, and oblique impact ex- Tectonics (eds. Koeberl C., Henkel H.,), Impact Studies, Springer, 405–422.

O13 2011 PERC Planetary Geology Field Symposium

Geological processes on the surface of asteroid Itokawa H. Miyamoto1 and F. Nimmo2 1University Museum, University of Tokyo, Tokyo 113-0033, Japan 2 Dept. Earth and Planetary Sciences, University of California Santa Cruz, CA 95064, USA

The Hayabusa spacecraft’s observation in 2005 reveal asteroid where sorting processes have acted to redistribute that apparently loose material are covering the surface of materials according to grain size [3]. Despite surface Itokawa, which has important implications for evolutions gravity verging on about 0.01milligee, Itokawa not only of small asteroids [1]. Hayabusa spacecraft performed retains particulate material, but shows evidence of gravi- touchdown rehearsals, imaging navigation tests, and two tational sorting based on grain size and possible touchdowns on an approximately 300m-scale asteroid, downslope regolith migration. This fact has signi¿cant Itokawa, which is by far the smallest asteroid ever studied implications for future mining of small asteroids. First, a at high resolution. Samples obtained at that period were very careful approach may be required to move rubble- safely returned to Japan in 2010. The analyses of returned pile asteroids in their entirety to other orbits, due to their samples, more than 1,500 smaller than 100 microns parti- low strength. Second, if Itokawa is typical, it should be cles, confirm that Itokawa is LL5 chondritic body from possible to ¿nd large boulders on such bodies and the overall petrology and elemental abundances of miner- transport them in their entirety into low Earth orbit for als [2]. use in space manufacturing. During the above operations near Itokawa, Hayausa Some boulders on the surfaces of gravels in high- also obtained close-up images (Figure) of the asteroid resolution images hold bright circular dots, which can be with resolutions up to 6mm/pixel, which revealed that interpreted as microcraters. Interestingly, the ages derived Itokawa is covered by ¿ne- and coarsegrained materials, from the microcraters matches pretty well with those es- from granules to boulders up to tens of meters. These timated from dust collected from the asteroid surface (be- ¿ndings are completely different from previous expecta- lieved to have been exposed there for about eight million tions of small asteroids, which were believed to have no years [2]). regolith (loose material overlying the surface). Analyses of returned samples indicate that Itokawa References: [1]Fujiwara, A. et al., Science 312, was probably made up from interior fragments of a larger 1330, 2006; [2] Nakamura, T. et al., Science 333, 6046, asteroid that broke apart [2], which is consistent with its 2011; [3] Miyamoto, H. et al., Science 316, 1011, 2006 appearance; Itokawa appears to be a so-called rubble-pile

Figure: High-resolution images of Itokawa and their locations

O14 2011 PERC Planetary Geology Field Symposium

Geomorphology and Geology of Vesta Explored by the Dawn Spacecraft. H. U. Keller1, C. T. Russel2, A. Nathues3, M. C. De Sanctis4, R. Jaumann5, H. Y. McSween6, and C. A. Raymond7, and the Dawn Science Team 1Institut für Geophysik und extraterrestrische Physik (IGEP) Universität Braunschweig, Mendelssohnstr. 3, 38106 Braun- schweig, Germany, [email protected], 2Institute of Geophysics and Planetary Physics University of California Los Angeles USA, 3Kometen und Planeten Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany, 4INAF IASF Roma Italy, 5Institut für Planetenforschung DLR Berlin Germany, 6Department of Earth and Planetary Sci- ences University Tenn – Knoxville Knoxville USA, 7Jet Propulsion Laboratory California Institute of Technology Pasa- dena USA

The Dawn spacecraft (Russell et al., 2007) has been in orbit around asteroid 4 Vesta for more than 100 days revealing an unprecedented, diverse, low gravity, planet-like differentiated body. The payload of Dawn comprises a framing camera (FC), a visible to infrared imaging spectrometer (VIR), and a gam- ma-ray and neutron detector (GRaND). Vesta is observed from 3 orbit stages with image scales of 227, 63, and 17 m/px, respectively. The CCD detector of FC covers the wavelength range 400 to 1000 nm applying 7 band-pass filters optimized for Vesta’s spectrum. VIR covers the spectrum from 400 nm to 5 m. At the time of PERC the systematic coverage from the intermediate high altitude mapping orbit (HAMO), about 700 km above the surface, will have finished and the spacecraft will be in transition to the low altitude mapping orbit (LAMO) where priority will Image of Vesta captured by Dawn on July 17, 2011 be given to the GRaND instrument. Impact cratering Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA dominates the geomorphology of Vesta that reveals a diversity of crater forms and states including ejecta blankets, tectonic structures caused by big impacts, and overall coverage by regolith. Craters with dark rays, bright rays, and dark and bright rim streaks suggest buried stratigraphy. Large equatorial troughs may be related to the formation process of the south polar structure, a depression with a diameter of ca. 460 km already observed by Hubble Telescope images. The off-central position of a prominent mound surrounded by complex ridge and groove patterns underlines the asymmetry of this structure. Even though crater walls are not obvious an origin due to a large impactor possibly triggering endogenic upwelling is the most probable explanation. Combin- ing the lunar crater size frequency and chronology with impact frequencies adjusted for Vesta leads to a surface age of only ca. 3.8 Gy, considerably smaller than the formation age of the HED meterorites origi- nating from Vesta.

Albedo and color maps based on filter ratios (FC) and spectral slopes (VIR) reveal large and small scale physical and compositional diversities of Ves- ta's surface. A major aim is to correlate surface areas and lithologies with the composition of the HED meteorites.

O15 2011 PERC Planetary Geology Field Symposium

The geomorphology of asteroid 21 Lutetia from in-situ imaging. P. L. Lamy1 , L. Jorda1, and N. Thomas2 1Laboratoire d'Astrophysique de Marseille, 38 rue Frédéric Joliot ́ Curie, 13388 Marseille, France (e-mail: Phi- [email protected]), 2Physikalisches Institut, Sidlerstr. 5, University of Bern, CH́3012 Bern, Switzerland.

We present an overview of the surface geomorphology of asteroid 21 Lutetia observed using the high resolution images from OSIRIS, the imaging system onboard the European Space Agency’s Rosetta spacecraft. The surface of 21 Lutetia is highly complex with significant interactions between ancient and more recent structures [1], see Fig.1. A wide range of surface morphologies are seen including heavily cratered terrain, extensive sets of lineaments, young impact craters, and a ridge the height of which is more than 1/5th of the mean radius of the body. Very young and very old terrains are seen in close prox- imity. The longest continuous lineament is over 80 km long. The lineaments show regionaĺdependent organi- zation and structure. Several categories of lineament can be described. Lineaments radial to impact craters as seen on other asteroidal bodies are mostly absent. Although the lineaments may be of seismic origin (and possibly the result of several impact́induced events), impacts producing recent large craters place serious constraints on seismic phenomena. In particular, stronger attenuation of shocks than seen on other asteroidal bodies seems to be required. Inhomogeneous energy transport, possibly matching observed inhomogeneous ejecta deposition may offer explanations for some of the observed phenomena. Some impact craters show unusual forms which are probably the result of impact into a surface with relief comparable to the resultant crater diameter and/or oblique impact. .

Acknowledgements: OSIRIS was built by a consortium of the Max-Planck- Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany, CISAS - University of Padova, Italy, the La- boratoire d'Astrophysique de Marseille, France, the Insti- tuto de Astrofísica de Andalucia, CSIC, Granada, Spain, the Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Técnica Aeroespacial, Madrid, Fig. 1. Surface features. (A) Closest approach image, with Spain, the Universidad Politéchnica de Madrid, Spain, the insets showing details under different illumination cond Department of Physics and Astronomy of Uppsala Uni- tions. (B) The central 21 km diameter crater cluster in versity, Sweden, and the Institut für Datentechnik und Baetica. Arrows a, b, and c point to landslides. Landslides Kommunikationsnetze der Technischen Universität a and b appear to have buried the boulders that are perva- sive within the crater (average density of 0.4 boulders km- Braunschweig, Germany. 2). Landslide b may have exposed a rocky outcrop. A sim- The support of the national funding agencies of Ger- ilar possible outcrop is seen opposite (e). Note the mottled many (DLR), France (CNES), Italy (ASI), Spain (MEC), appearance of the material at point d. (C) The boundary Sweden (SNSB), and the ESA Technical Directorate is between Baetica (young terrain associated with the central gratefully acknowledged. crater cluster) and Noricum (old terrain) is extremely well-defined in some places as indicated by the arrows a. References: Arrows b and c highlight curvilinear features. (D) Arrows [1] Sierks, H., Lamy, P. L., et al. (2011) Science, in c, d, and e point to further curvilinear features on the sur- press face of Lutetia. In the Narbonensis region, most curvilinear features show this orientation. Note how the curvilinear features cut the crater and its rim.

O16 2011 PERC Planetary Geology Field Symposium

Hydrothermal systems in Enceladus: constraints from experiments and observations. Y. Sekine1, T. Shibuya2, T. Kuwatani1, K. Suzuki2 1Dept. Complexity Sci. & Engr., Univ. of Tokyo ([email protected]), 2Precam. Ecosystem Lab., Japan Agency for Marine-Earth Sci. & Tech.

Introduction: One of the most remarkable find- Results & discussion: We found that forma- ings by the Cassini spacecraft is water-rich plumes erupt- tion of N2 from NH3 is kinetically inhibited under the ing from warm fractures near the south pole of Enceladus proposed hydrothermal conditions by the previous mod- [1]. Given such geological activity and the detection of els [4, 5] (i.e., temperature of ~300–400 degrees C, pH of sodium salts in the plume, the interior of Enceladus is ~8–11). This is because NH3 decomposition proceeds likely to contain an interior ocean above its rock core [2]. inefficiently due to efficient H2 production by serpentini-

Direct samplings of Enceladus’ plume by the Ion and zation of olivine. The typical H2 concentration in the so- Neutral Mass Spectrometer (INMS) and Cosmic Dust lutions reaches ~3–30 mmol/kg. Based on these experi-

Analyser (CDA) onboard the Cassini spacecraft have ments, we conclude that N2 formation is not determined revealed that the plume is composed mainly of H2O with by equilibrium of ammonia dissociation but is mainly

CO2, CH4, NH3, and other hydrocarbons [2, 3]. The ab- controlled by the concentration of H2 formed by interac- undances of some of volatiles, e.g., CO2, CH4, and NH3, tions with the rock materials. resemble those in comets, suggesting that these abun- Our experimental results suggest that even at high dances are typical of primordial outer solar system ma- temperatures and high CO2 content, NH3 dissociation terial [3]. However, the plume also contains proportions would not have proceeded in Enceladus, if interactions of of volatiles that are elevated or depleted compared to the ocean with the rock core had occurred at the same comets, suggesting formation or loss of these molecules time. Previous studies interpret the lack of N2 in the via chemical reactions inside Enceladus [3]. plumes as evidence for a cold ocean [5]. Alternatively,

Previous studies suggest that N2 is a promising in- we suggest that it is possible that Enceladus possessed a dicator for reconstructing temperature of hydrothermal hot and H2-rich ocean, at least at some time in its history. systems in Enceladus [4], because it is required to be In fact, more recent Cassini INMS observations suggest formed by thermal dissociation of primordial ammonia in H2 concentration in the ocean currently may be as high as the interior. Matson et al. [4] suggest that, if a significant 5 to 50 mmol/kg [6], which is consistent with our expe- amount of N2 is observed in the plumes, it may indicate rimental results. Furthermore, the Cassini CDA recently high temperatures in the interior, such as 250 degrees C found nano silica particles (SiO2) in the plumes [7]. In or above. This is based on the thermodynamic equili- our experiments, we also found the formation of sub- brium calculation of ammonia dissociation. Recently, the micrometer-size silica particles after the experiments. We

Cassini observations have revealed a lack of N2 in the consider that these particles were probably formed by plumes [5]. According to the equilibrium composition, precipitation of dissolved SiO2 in response to a tempera- these observations suggest that Enceladus’ ocean remains ture decline at the end of the experiments, suggesting that cold and inactive throughout its history. However, nano silica particles in Enceladus’ plumes also could whether equilibrium is achieved or not strongly depends have been formed by precipitation of dissolved silica in on the kinetics of hydrothermal reactions. thermal gradient in hydrothermal systems. These new Experimental: Here, we report the first results of observations would be consistent with our hypothesis of laboratory experiments simulating hydrothermal systems hot and H2-rich hydrothermal systems in Enceladus, on Enceladus. The experiments were conducted by using which potentially support methanogenic microbial com- a steel-alloy autoclave, which pressurized a flexible gold munities. tube reaction cell to 400 bars. As starting materials, we used an aqueous solution of 2% ammonia and sodium References: [1] Porco et al., Science 311, 1393 (2006). hydrogen carbonate as the source of CO2. Powdered oli- [2] Postberg et al., Nature 474, 620 (2011). [3] Waite et vine was also introduced into the reaction cell as an ana- al., Nature 460, 487 (2009). [4] Matson et al., Icarus 187, log of the rock materials in Enceladus. During the expe- 569 (2007). [5] Hansen et al., Geophys. Res. Lett. 38, riments, we analyzed the variations of the dissolved gas L11202 (2011). [6] Waite et al. LPSC abstract 42, 2818 species in the solution with a GC and GCMS. We col- (2011). [7] Postberg et al., AOGS abstract 8, PS06-A013 lected mineral residue after the experiments and analyzed (2011). it with SEM-EPMA and X-ray diffraction.

O17 2011 PERC Planetary Geology Field Symposium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³GHEULV´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

O18 2011 PERC Planetary Geology Field Symposium

A Proposal of Japanese Rover Mission for Geological Exploration of Mars. N. Namiki1,G.Komatsu2,T.Usui3, S. Sugita4,H.Miyamoto4, T. Kubota5,G.Ishigami5,H.Demura6,T.Okada5,Y.N. Miura4,Y.Cho4,K.Goto1,H.Senshu1,K.Wada1,K.Ishibashi1,T.Arai1,M.Kobayashi1, S. Ohno1, and Mars rover study group 1Planetary Exploration Research Center, Chiba Institute of Technology (2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan, [email protected]), 2International Research School of Planetary Sciences (Universita’ d’Annunzio, Viale Pindaro 42, 65127 Pescara, Italy), 3Johnson Space Center, NASA (Mail code KR, 2101 Nasa Pkwy, Houston, TX 77058-3696, USA), 4The University of Tokyo (7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0032, Japan), 5Institute of Space and Astronautical Science, JAXA (3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan), 6The Univer- sity of Aizu (Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580, Japan).

Introduction: We propose a rover geological explo- In order to reveal the history of the environmental ration for a future Mars mission of Japan. Previous Mars change, many orbital and rover missions were carried out missions have revealed a diversity of Mars environment by NASA, ESA, and the former Soviet Union. They cla- and have indicated a complex of various physical and rified formation of clays, sulfates, and anhydrous ferric chemical processes at the surface. By investigating a oxides and suggested transition of chemical condition series of surface materials, a rover exploration allows us with age. However, still many problems are left unre- to understand an evolutionary trend of the landing site solved. For example, an existence or absence of ancient and to resolve the complicated nature. Unfortunately, ocean has not been settled [1-3]. A new discovery of however, our proposal of geologic exploration was not carbonate rocks from CRISM images [4] possibly explain selected as a main scientific objective of Japanese next loss of CO2 from the ancient atmosphere, while lithology Mars mission. We continue working on conceptual de- of the carbonate has not been examined. Thus in-situ signs of the mission and developing rover and instru- investigation of sedimentary rocks may leads further un- ments for future geological exploration on Mars. derstanding of the chemical processes during the period MELOS mission: MELOS is a Japanese mission to of the rapid environmental change. Mars to be launched between 2020 and 2024. Currently On the other, a new hypothesis regarding the cause of the mission is in Phase A, that is, the working group is the environmental change is proposed by [5]. It is sug- creating a preliminary design and project plan. This gested that massive volcanic degassing into the atmos- name stands for “Mars Exploration with Lander-Orbiter phere resulted in a change from reduced to oxidized state Synergy” indicating a joint mission by planetary scientist at the surface. While volcanic rocks have drawn less community including atmospheric, plasma and magne- attention than sedimentary rocks in the previous missions, tospheric, and solid planetary scientists, and engineers. its importance is worth revisiting with new instruments. MELOS consists of one or two orbiters and a lander Rover Development: A rover for lunar and plane- for Entry, Descent, and Landing (EDL) experiment. A tary exploration is being developed by a group of engi- scientific objective of the orbiters is to investigate either neers at JAXA, Tohoku, Chuo, and Meiji universities (i) climate system of frozen solid planet, or (ii) escape (Fig. 1). This rover weighs about 70 kg, and is 1.2 m mechanism of H2OandCO2 from exosphere. Because long, 2 m wide and 1 m high. It is capable of autonom- each objective requires specific orbits, they cannot be ous navigation, moving at 0.02-0.05 m/sec on the average, achieved in a single mission. The working group is cur- riding over a bump less than 0.2 m and climbing a slope rently discussing which objective to be prioritized. of 15 to 30°. With new instruments under development, JAXA engineers are designing the EDL lander at our technological level is almost ready for the exploration. present. The lander has extra options such as rover, air- References: [1] Head J. W. III et al. (1999) Science, plane, powered paraglider, and dust sampler that grazes 286, 2134-2137. [2] Di Achille, G. and Hynek, B. M. the top of atmosphere then returns to the Earth. Scientific (2010), Nature Geosci., 3, 459 - 463. [3] Taylor, G. J. et objectives of the EDL lander include (iii) seismic obser- al. (2006) JGR, 111, doi:10.1029/2005JE002645. vation of planetary interiors and (iv) search of life on [4] Michalski, J. R. and Niles, P. B. (2010) Nature Geos- Mars, but will be focused on either one by the end of ci., 3, 751–755. [5] Bibring, J.-P. et al. (2006) Science, 2011. Geological exploration using a rover is currently 312, 400-404. categorized as an extra option of the EDL lander. There- fore our primary target of the full-scale geological exploration is not MELOS, but subsequent missions. Scientific Objectives of Geologic Exploration: There remain important and unresolved issues in Mars science, such as formation of dichotomy, commencement and cessation of core dynamo, volcanism derived from mantle convection, rapid environmental change of the atmosphere, loss of H2OandCO2, and possible occurrence of life. Among them, the environmental change is Fig. 1. A picture of Japanese rover, Micro-6. generally regarded as a key of those closely related issues.

O19 2011 PERC Planetary Geology Field Symposium

MELOS Plan B: Japan Astrobiology Mars Project (JAMP): Search for Microbes on the Mars Surface. A. Yamagishi1 and MELOS Life Search Sub-working Group 1Department of Molecular Biology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachiouji-shi, Tokyo 192-0392 JAPAN, [email protected].

Introduction: The liquid water is considered to be a critical factor for life. Gibbs free energy is another factor that should be counted to sustain life for long duration. The Gibbs free energy is obtained by reaction between reductant and oxidant, or from any other non-equilibrium state of matter. As an example, aerobic organisms use carbohydrate and oxygen for getting Gibbs free energy. Many types of chemoautotrophic mechanisms are known for the process as well. On Mars surface, methane and oxidative compound such as ferric oxide or sulfate are found, and they can be a source of Gibbs free energy. Iron-dependent methane oxidizing bacteria was found in marine environment on Earth [1]. This finding suggests possible presence of methane-oxidizing bacteria on Mars surface [2], if local thermal environment and other resources permit proliferation and metabolism of the same type of bacteria during limited portion of time period.. Aim of MELOS Plan B: Our project aims to search for bacterial cells, especially the methane-oxidizing microbes on Mars surface. Martian soil will be sampled from a depth of about 5 or 10 cm below the surface, where organisms are supposed to be protected from harsh UV light on Mars surface. Small particles will be transferred to analysis section. The particles are stained by cocktail of fluorescence dyes, and examined by a fluorescence microscope. Principle of Identification of Life on Mars: Combination of fluorescence dyes is selected to identify life forms from the soil sample [2]. Intercalating fluorescence dye such as SYBR Green is used to detect genetic compounds such as DNA. Combination of dyes is used to detect membrane surrounding the “cell”. Substrate dye that emits fluorescence upon cleavage by the catalytic reaction is used to detect the catalytic activity of the “cell”. A combination of staining reagents is chosen based on the definition of life. Membrane separating cell from ambient leads to identification of “individual”. Catalytic reaction of enzymes drives “metabolism”. The combination is useful also for detecting pre-biotic organic material as well as remnant of ancient life. Target of Life Search Plan in MELOS 2: Hy- drolysis of the polymers in the “cell” followed by HPLC or soft ionization MS for amino acid analysis is effective in examining whether Martian life is identical or different from terrestrial life [2]. The number and type of the amino acids as well as chirality will be analyzed to distin- guish if the polymers are contamination made by Earth- related life form. References: [1] E. J. Beal, et al., Science 325, 184-187 (2009) [2] A. Yamagishi, et al., Biol. Scie. Space 24, 67-82 (2010).

O20 2011 PERC Planetary Geology Field Symposium

Field Tests on Intelligent Exploration for Planetary Rover T.Kubota1, M.Otsuki1, T.Shimada1, G.Ishigami1, M.Sakuta2, O.Ann2, T.Shimizu2, K.Otsu2, 1Institute of Space and Astronautical Science, JAXA (3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210, JAPAN, ku- [email protected]), 2The University of Tokyo ((3-1-1, Yoshinodai, Chuo-ku, Sagamihara, 252-5210, JAPAN).

Introduction: Several missions to explore the moon commands while the operator’s planning the path, and as or Mars by unmanned mobile robots are being planned a consequence, that is time consuming. Moreover, to for scientific observation. In recent years, many research- avoid collision between the waypoint path and obstacles, ers have studied and developed planetary rovers for un- a rover requests the operator to regenerate its waypoint manned surface exploration of planets. Such rovers have path, which causes further delay until new path data are performed traverses on rough terrain, reliable navigation received. Therefore, an advanced navigation scheme is and science instrument control. The rovers carried some necessary for efficient and safe exploration by the rover science instruments and obtained a lot of scientific results for planetary explorations. on Mars. NASA is planning to send a new bigger robotic For lunar exploration, basically it may be possible to laboratory in MSL mission in 2011. operate surface explores from ground station. Because of In Japan, new lunar or planetary exploration missions time delay and limited telemetry data, however, advanced including landers and rovers are earnestly under studying. navigation scheme is also required even for safe and effi- Those missions follow up SELENE (SELenoligical Engi- cient exploration on the moon. A rover itself causes posi- neering Explorer), a lunar global remote sensing mission. tion estimation errors and dead reckoning errors, because One of main missions for lunar robotics exploration in of slips of wheels etc. For corresponding to an unknown post SELENE missions is to demonstrate the technologies obstacle, a conventional autonomous path planning algo- for lunar or planetary surface exploration and human ac- rithm is a solution, and it can be applied for short range tivities on the moon in the near future. The following top path planning between each waypoint. On the other hand, science will also be conducted in the robotics mission. a rover is continuously updating the environment data set. The working group was also established in 2008 in Japan The original path may result the rover to follow a trajec- to study Japanese Mars exploration. In the preliminary tory that might cause a collision to obstacles. Therefore, it study, orbiters and landers cooperatively explore Mars. is required to compensate waypoints by using the latest Some explorers, such as surface exploration rover, wide measurement data. area exploration by airplane, subsurface exploration by Field Tests: Some field test are conducted to inves- mole type robots are under study. tigate the effectiveness of the proposed navigation This paper firstly presents robotic exploration plans scheme by the developed rover. The results of field test for future lunar or planetary in Japan. Then this paper are presented and discussed in detail. describes the design and implementation of test-bed rov- References: ers for the future planetary missions requiring long trav- [1] T.Kubota, M.Otsuki, Y.Kunii, Y.Kuroda, Auton- erses and rover-based observation. This paper also dis- omy and Intelligence for Lunar or Planetary Surface Ex- cusses an intelligent navigation and guidance scheme for plorer, Proc. of 27th Int. Symposium on Space Technol- long distance traverse. Finally this paper presets the field ogy and Science, 2009-k-20, 2009. [2] T.Kubota, et al., test by developed experimental rover. Preliminary Study on Lander System and Scientific In- Test-bed Rover: As a new test-bed, Micro6 has vestigation for Next Mars Exploration, Proc. of 27th Int. been developed with capability to carry out a variety of Symposium on Space Technology and Science, 2009-k- the novel mission sequences. Micro6 is not designed for 21, 2009. [3] G.Ishigami, T.Kubota, M.Otsuki, the mission specific, but for pushing the technology ad- T.Shimada, S.Takanishi, O.Ann, Experimental Study on vance. Figure 1 shows the first design of Micro6. The Mobility and Navigation for Exploration Rover in Natu- Micro6 has the novel suspension system called HEXUS ral Rough Terrain, 27th Int. Symposium on Space Tech- which has failure tolerant feature. Wheel design must be nology and Science, 2011-d-87p, 2011. done for mission oriented, because its performance is seriously affected by surface condition. The Micro6 in- stalled a smart manipulator system for detailed surface exploration. The key technology of Micro6 project is to develop intelligent software architecture. Rover Navigation: In the case of a remote environment like the moon or planets, time-delay occurs between the ground station on the earth and the explorers due to their distance and the limited capacity of commu- nication bandwidth. It is thus difficult to compose a closed loop control structure between the ground station and the explorer system. Conventional tele-operation methods cause the behavior called “Move & Wait” to a movement of an explorer. An explorer has to wait for Figure Developed Rover Micro6

O21 2011 PERC Planetary Geology Field Symposium

Development of Mobile Robots for Field and Planetary Exploration Kazuya Yoshida1 and Keiji Nagatani2 1Dept. of Aerospace Engineering, Tohoku University, Aoba 6-6-01, 980-8579 Japan, [email protected] 2Dept. of Aerospace Engineering, Tohoku University, Aoba 6-6-01, 980-8579 Japan, [email protected]

Introduction: The Space Robotics Laboratory in rough terrain with a large amount of slippage, an inte- Department of Aerospace Engineering, Tohoku Univer- grated system has been developed using inertial sensors, sity has been developing technologies for mobile robotics visual odomatry and GPS when it is available. Also de- and conducting various filed experiments using a number veloped a 3D mapping system of the environment using of robot hardware (rover) test beds, looking at future ap- laser ranging sensors. These systems are useful for plication to field and planetary exploration missions. This autonomous or semi-autonomous navigation of the rovers. paper summarizes previous and recent activities about Manipulation: A manipulator arm is useful when field and planetary robotics from the aspects of hardware handling rock/soil samples in the geological survey. Our test beds and core technologies. recent models of El Verde and Quince have on-board Rover test beds: Since 1995, the Space Robotics manipulator arm. For example, in 2010, we conducted Lab has been devoted to the study on space robotics and such an experiment of remote operation that the Quince the activities on planetary rovers has started in 1997. One robot, that was dispatched into a field location in Mt. of early test bed to study the rough terrain mobility was Asama was remotely operated through a satellite commu- Nexus 6 (Fig. 1), which is a six-wheel robot using nication link to travel and find a rock sample, then pick- Rocker-Bogie type of passive link suspension system. up by the onboard manipulator arm and retrieve in a sam- Dune (Fig. 2) is a four-wheel test bed, developed after ple container (Fig. 5). Nexus 6, for the study of traction mechanics in loose soil environment such as dry sand or regolith on the Moon. In 2005, Dr. Keiji Nagatani joined the lab and then the study on mobile robotics research was accelerated. El Dorado- I/II (Fig. 3) and El Verde (Fig. 4) are currently opera- tional test beds, all of which have four wheels and a passive suspension system called “rocker.” Each wheel is mounted on the both ends of a rocker link. Two rocker links are connected to each other on the vehicle chassis through a differential gear. Relative to the chassis, when Fig. 1: Test bed “Nexus 6” Fig. 2: Test bed “Dune” one rocker goes up, the other goes down. The chassis maintains the average angle of both rockers. In this way, all four wheels keep contact on uneven terrain with distributed load of the chassis, while having a moderate motion of the chassis against bumpy motion of the wheels. Another family of test beds have infinity track system for locomotion. Kenaf and Quince (Fig. 5) are successful models of track-based mobile robots designed by Prof. Koyanagi in Chiba Institute of Technology. These models Fig. 3: Test bed “El Dorado-II” Fig. 4: “El Verde” use articulated sub-crawlers to increase the rough terrain mobility. The track vehicle is now superior mobility in loose and rough terrain to wheeled vehicles, but it is also known that the maintenance of the tracks is also the issue. Therefore, track-based rovers have been accepted in terrestrial applications, but wheel-based rovers accepted in planetary applications where the maintenance tasks are not expected. Traction mechanics: One of the major research issue of the authors’ group is traction mechanics of robot rovers in loose soil environment. A semi-empirical model based on continuum distribution of normal and shear stress in the wheel/track and soil contact area has been Fig. 5: “Quince” in remote operation at Mt. Asama studied to understand the maximum performance of the rovers. References: The following article describe a re- Sensing, mapping, localization and naviga- search summary with a large number of reference articles: tion: Integrated sensor technology to estimate the rover [1] Kazuya Yoshida "Achievements in Space Robotics", position in a local and global coordinate is another impor- IEEE Robotics & Automation Magazine, Volume: 16, tant issue. For a robust odometry system that works in Issue: 4, pp.20-28, 2009.

O22 2011 PERC Planetary Geology Field Symposium

Potential Terrestrial Analog Sites in Asia for Mars Research. G. Komatsu1, 1International Research School of Planetary Sciences, Università "G. d'Annunzio", Viale Pindaro 42, 65127 Pescara, Italy ([email protected])

Introduction: Terrestrial analog study has a long lakes emerge in some occasions. Mars is known to have history since the dawn of planetary exploration. In order experienced mass movements as recorded along many to understand geological environments and processes op- steep slopes. erated on planets and satellites, scientists have utilized the Coastal processes. The coastline of the western Pacif- knowledge of similar conditions found on Earth. Mars ic collectively is the longest in the world, extending along research, in particular, has been active in this approach. tropical to arctic conditions. The coastlines are affected Due to generally cold and dry environmental conditions by various modifications such as storms and tsunamis. prevalent on Mars, its suitable terrestrial analogs sites are The examples of coastal processes in Asia are available often searched in cold polar regions and dry continental for comparative studies to understand putative coastlines deserts. Asia, despite its extremely large geographical on Mars. extent (Fig. 1), has been relatively neglected in the terre- Continent: strial analog investigations. This may have been because Glaciation and peri-glacial processes. High eleva- of absence or near-absence of local planetary geology tions of the Asian Continent such as Himalayas, Tian communities, or often difficult access to potentially inter- Shan, Altai, and Sayan have been rich in activities of glac- esting analog sites in the region. Here in the paper, I will iation, both present and in the past. Rock glaciers also present some examples of terrestrial analog sites in Asia, occur in various parts of the mountain ranges. The areas which deserve attention and consideration from the plane- around the glaciers have been in the realm of peri-glacial tary geology community. processes. Hydrology is influenced by the glaciation, producing ice-dammed lakes for example. Some of the ancient ice-dammed lakes are known to have failed and released catastrophic floods. Ancient subglacial volcanism is also documented, and its associated jökulhlaup events have been hypothesized. A cold and wet climate during the glaciations promoted formation of lakes in desert regions that are hot and dry today, such as in Gobi Desert. The Martian environments, with its almost certain presence of peri-glacial activities under the present or past climate and speculated glaciations, is comparable to many of the high elevations of the Asian Continent. The catastrophic flooding and subglacial volcanism may find occurrences of similar events also on ancient Mars. Aeolian processes. The large areas of the interiors of the Asian Continent are occupied with desert or semi- deserts today. Examples include Gobi and Taklamakan Deserts. Both depositional and erosional features such as Figure 1. Island arcs and the continental part of Asia. ergs and yardaings are common, making an ideal compari- Google Earth image. son to the desert-rich planet Mars. Island arcs: Impact craters. Impact craters are known in parts of Volcanism. Island arcs in the western Pacific are geo- the Asian Continent although many more are likely wait- logically one of the most active regions on Earth. For ing for future identifications. Among all, Lonar Crater examples, volcanic eruptions are observed very frequently formed in the Deccan Plateau basalt would be a good in the region and their style ranges from lava extrusion, comparison to may impact craters occurring in, presuma- pyroclastic flow to lahar, producing features such as bly, basaltic materials of Martian surfaces. Lonar Crater shield and composite volcanoes, cinder cones, and rhyolit- also hosts a lake, which should be compared to a number ic domes. Gigantic calderas of pre-historic formation are of speculated paleo-crater lakes on Mars. also widely distributed. In addition, a great number of Conclusions: The potential values of terrestrial ana- active hydrothermal systems are present. Many of the log sites in Asia for Mars research are great although very volcanic features observed in the island arcs of Asia have few of them have been utilized in comparative investiga- been interpreted to exist also on Mars, and identifications tions to date. In order to increase their effective utiliza- of minerals linked with hydrothermal processes on Mars tion in planetary geology research, it is fundamental to enhance the importance of similar processes in Asia. raise awareness of these rich resources through research Mass wasting. A combination of active tectonics and projects and conferences. Geologists who study such sites high precipitation in Asian island arcs results in frequent should also be involved in planetary research through col- mass movements such as landslides. Landslide-dammed laborative efforts with planetary geologists.

O23 2011 PERC Planetary Geology Field Symposium

Geotectonic framework of an ancient plate subduction zone: generally convergent but locally extensional aspects in Japan Y. Isozaki1 1Dept. Earth Science and Astronomy, The University of Tokyo (3-8-1 Komaba, Meguro, Tokyo 53-8902, Japan; [email protected])

The geology of Japan provides several key criteria to de- repetition of ocean-ward continental growth and conti- tect plate tectonics–driven tectonic features on terrestrial nent-ward contraction of an active arc-trench system. planets; overall subduction-related structures, and also some rift-related ones in relatively local context. Isolation from continents: The Japanese Islands became isolated to be in an island-arc form as today in Geotectonic history of Japan: The ca. 700 million 20-15 Ma when regional rifting took place in the eastern year-long geotectonic history of the Japanese Islands margin of Asia. The attenuation of the pre-existing con- comprises three distinct intervals; i.e., (1) passive conti- tinental crust eventually formed a 1000 km-wide back-arc nental margin stage off the South China continental mar- basin. The rifting accompanied normal fault-related local gin (ca. 700–520 Ma), (2) active margin stage character- basins and bimodal volcanism. The unique Miocene ized by an arc-trench system (ca. 520–20 Ma), and (3) pyroclastic (so-called green tuff) deposits thickly accu- island arc stage off East Asia (20 Ma to the pre- mulated along the southern margin of the back-arc basin. sent). These three intervals are chronologically separated by two major boundaries with significant tectonic epi- On-going rifting in back-arc: Another rift basin is sodes; i.e., the ca. 520 Ma tectonic inversion from a pas- now under construction in the back-arc of Ryukyu Islands sive to an active margin by the initiation of subduction to split the shallow East China Sea. The main scar of this from the Pacific side, and the ca. 20 Ma rifting of the nascent rift system is recognized as the Okinawa trough Asian margin. The latter corresponds to the back-arc on the west of the Okinawa main island. Active hydro- basin (Japan Sea) opening that made the complete isola- thermal vents were recognized along this deep trough in tion of the modern island arc system of Japan. the back-arc domain. This rift is currently propagating northward and its northern frontier is penetrating into Growth of a continental crust: The main orogenic middle of Kyushu. By cross-cutting the arc elongation growth, i.e. the production of juvenile crust, occurred obliquely, the Beppu-Shimabara graben in mid-Kyushu during the 2nd and 3rd stages by the long-term oceanic forms a new rift system with NE-SW trending normal subduction from the Pacific side. The formation of juve- faults and associated Quaternary volcanism including the nile crust occurred magmatically beneath the volcanic arc world-famous Mt. Aso and Mt. Kuju. In particular, Mt. of the subduction zone, whereas the spatial growth took Aso (with ring structure of caldera) forms one of the 3 place tectono-sedimentarily along the trench. This largest volcanos on the Earth. Such a unique set of geo- growth pattern along an active (subduction-related) conti- morphologies is a key feature for local extension tecton- nental margin (the Pacific-type orogeny) is the sole prac- ics within an overall convergent plate boundary. tical process for increasing continental crust through time. During the last 500 million years, the overall Japan seg- Continental collision suture in Japan: The east- ment of the S. China craton likely has grown for ca. 400 ern extension of the continent-continent collisional suture km oceanward. between North and South China blocks was debated for years, as there is no clear feature like ultrahigh-pressure Growth and shrinkage: Nonetheless the latest lines metamorphic belt in Korea and Japan; however, it was of information, mostly from detrital zircon chronology of lately identified in Japan as a chain of fragmentary rem- orogenic sandstones, require a significant re-writing of nants of the Triassic medium-pressure metamorphic belt. the evolutionary history of the Japanese Islands. Particu- On the basis of the suture trajectory, the South China- larly noteworthy is the effect of tectonic erosion even related origin of the main part of Japan is confirmed, during the active subduction regime. Age spectra of whereas the smaller domains along the Japan Sea (Hida detrital zircon from sandstone recorded the provenance and Oki belts) are identified as detached fragments of history with various Paleozoic-Mesozoic granite ba- North China. thokiths. In modern Japan, however, the Early Paleozoic to Middle Mesozoic granites occur highly limitedly, ex- References: [1] Isozaki, Y., Aoki, K., Nakama, T., cept for small scattered remnant bodies less than several Yanai, S. (2010) Gondwana Research, 18, 82–105. km in diameter. The ancient sandstone data confirmed [2] Isozaki, Y. (1996) Island Arc, 5, 289-320. that provenance with huge granitic batholith belts developed and disappeared in Japan in multiple times. This Keywords: Japan, South China, arc, trench, accretion, remarkable disagreement between the limited distribution batholith, detrital zircon, tectonic erosion, collision suture of older granites and the predominance of their clastic grains in sandstones suggests the effectiveness of past tectonic erosion processes in the fore-arc domains. Dur- ing the ca. 500 m.y. –long subductin-related history, the orogenic growth of Japan is explained as the intermittent

O24 2011 PERC Planetary Geology Field Symposium

Large-scale bouldery volcaniclastic apron by a possible gigantic outburst flood, Aso caldera, southwest Japan Kyoko S. Kataoka1 and Yasuo Miyabuchi2 1Research Institute for Natural Hazards and Disaster Recovery, Niigata University, Ikarashi 2 8050, Nishi-ku, Niigata 950-2181, Japan ([email protected]) 2Faculty of Education, Kumamoto University, Kurokami 2-40-1, Kumamoto 860-8555, Japan.

Introduction: Syn- and post-eruptive volcaniclastic outburst flood event with large volume and magnitude resedimentation by water process (i.e. lahar as Indonesian caused by a breach of the caldera rim rather than from term) can be induced by heavy rain, snow and ice melt normal floods by meteorological triggers. resulting from heat of pyroclasts, lava, or geothermal, direct draining of crater- or caldera-lake water by an erup- Paleoflood hydrology: Our tentative estimation tion [1-4], and dam failure of crater- or intracaldera-lakes for the feasible paleoflood is > 1.5 km3 for the Takuma and volcanically dammed impoundments [5-7]. Among gravel bed and ~1-6 km3 of released water when the flow them, catastrophic outburst floods by a breach of volcanic condition was hyperconcentrated one. Regression rela- dam or caldera rim can cause large-magnitude ones with tionship amongst other volcanogenic floods leads to large volume of impounded water with sediments [8-10]. 32,000-113,000 cumecs of peak discharge of the flood. The extreme floods can travel long distance from the Such gigantic flood events have been revealed recently source volcano that ultimately affect the landform and and become more and more common around caldera vol- hydrology further downstream areas. canoes on Earth. Therefore, such kind of volcanogenic outburst floods must provide some hints to understand Aso caldera, Shira River and Takuma (boul- similar events on Mars and other planets where numerous dery) gravel bed: This study focuses on geomorphic and gigantic caldera morphology are found. and sedimentary features in the Shira River catchment implying a volcanogenic catastrophic flood from Aso References: [1] Major, J.J., Newhall, C.G. (1989) caldera southwest Japan, after the 90 ka Aso-4 ignimbrite Bulletin of Volcanology, 52, 1-27. [2] Pierson, T.C., eruption. Previous studies (e.g., [11-12]) showed the Janda, R.J., Thouret, J.-C., Borrero, C.A. (1990) Journal presence of three discrete horizons of lacustrine deposits of Volcanology and Geothermal Research 41, 17-66. [3] in the intracaldera area after the 90 ka eruption and dis- Cronin, S.J., Neall, V.E., Lecointre, J.A., Palmer, A.S., cussed the possibility of draining of caldera lake water (1997) Journal of Volcanology and Geothermal Research from the outlet in relation with active faults nearby the 76, 47-61. [4] Thouret, J.C., Abdurachman, K.E., Bour- caldera rim. dier, J.L., Bronto, S. (1998) Bulletin of Volcanology, 59, An apron-shaped (or fan-shaped) morphology spread- 460-480. [5] Macías, J.L., Capra, L., Scott, K.M., Espín- ing to the west of the caldera rim of Aso volcano, namely dola, J.M., García-Palomo, A., Costa, J.E. (2004) Takuma gravel bed, is composed of 5-6 m thick in out- Geological Society of America Bulletin 116, 233-246. [6] crop order, filling underlying topography with more than Kataoka, K.S., Urabe, A., Manville, V., Kajiyama, A. 11 m. The gravel bed overlies Aso-4 ignimbrite with (2008) Geological Society of America Bulletin, 120, sharp erosional contact locally. At the distal end of the 1233-1247. [7] Manville, V. and Cronin, S.J. (2007),EOS, apron, the gravel beds abut to the underlying dissected Transactions (AGU) 88(43), 441-442. [8] Waythomas, lahar deposits derived from the Aso-4 ignimbrite. The C.F., Walder, J.S., McGimsey, R.G., Neal, C.A. (1996) stratigraphic relationship shows that lahar deposits, de- Geological Society of America Bulletin, 108, 861-871. veloped inside the Aso-4 ignimbrite plateau, was deeply [9] Manville, V., White, J.D.L., Houghton, B.F., Wilson, dissected by persisted pluvial activities and finally the C.J.N. (1999) Geological Society of America Bulletin valley was filled by Takuma gravel bed. 111, 1435-1447. [10] Kataoka, K.S. (2011) Geomorphol- The Takuma gravel bed contains no silt and clay, but ogy, 125, 11–26. [11] Watanabe, K. (1998) Shin- is composed of pebble and cobble with sandy matrix. The Kumamoto-Shishi (Studies in the History of Kumamoto sediments are lithic-rich with subordinate amount of pum- City), 103-108. [12] Watanabe, K. (2001) Ichinomiya- ice from Aso-4 ignimbrite. Diffuse horizontal stratifica- Choshi (Studies in the History of Ichinomiya Town), tions or low-angle cross-stratifications in the sediments 241p. with meter-sized boulders as outsized clasts suggest deposition from hyperconcentrated flow rather than debris flow. The deposits are totally aggradational with no channels and scours, indicating at least one single gigantic flood event had occurred. The bouldery sedimentary facies of the Takuma gravel bed does not match with the capability deduced by the present Shira River and its limited catchment size. Therefore, the Takuma gravel bed constituting the volcaniclastic apron is most probably derived from a gigantic

O25 2011 PERC Planetary Geology Field Symposium

Terrestrial Analogs and Planetary Geology V.R. Baker 1 1Department of Planetary Sciences, The University of Arizona. Tucson, AZ 84721; [email protected]

Introduction: In doing field geology on Earth the inves- controlled experiments on its subject matter, e.g., volca- tigator has the benefit of an interplay between (1) detailed noes, ice sheets, and subduction zones. Instead, there examination of samples and rock outcrops, and (2) com- must be alternative means to test or corroborate the vari- pilations of regional syntheses, most effectively through ous hypotheses. This testing or corroboration is accom- geological mapping. In contrast, planetary geology must plished by adopting the hypotheses (they become “work- contend with the directionality of space exploration, in ing hypotheses”[6]), and then exploring their conse- which extraterrestrial bodies are first encountered glob- quences for consistency, coherence and consilience. ally by remote sensing at low-resolution. Subsequent, Consistency entails a lack of contradiction, such that a high-resolution imagery then allows focusing on details, causative hypothesis for a geological phenomenon is not but sample and outcrop studies can only come later, and contradicted by an indicated historical sequence of devel- then only at one or a few discrete locations. opment. Coherence requires an explanation that is suffi- The Problem of Convergence (Equifinality): ciently comprehensive to align with other known explana- The directionality of planetary exploration leads to a tions of closely related phenomena. Finally, a tentative problem that has been characterized as convergence or hypothesis achieves consilience, literally, a ‘jumping to- “equifinality”, in which it is thought that similar effects gether’ of knowledge [7], if it leads to a kind of ‘explana- (landforms, structural patterns, etc.) are generated by dif- tory surprise’ in which a completely different set of phe- ferent combinations of causative processes [1]. An ex- nomena from that being tentatively explained is discov- ample is the debate over the origin of the Moon’s crater- ered or recognized, such that (1) the newly recognized like landforms first seen in telescopic views. Were they phenomena are clearly related to the phenomena under were caused by explosive volcanism or by meteor im- investigation, and (2) that they are adequately explained pacts? Planetary geology works at resolving such con- by the tentative hypothesis that was originally proposed vergence issues though a combination of increased reso- in a more limited context. Though consilience does not lution [2] and the study of terrestrial features that serve as confer truth via formal logic, its operation is associated analogs to the extraterrestrial features [3]. Instead of an with the most fruitful scientific investigations. equifinality of “craters” being formed by two different The geological investigator tentatively presumes a kinds of processes, terrestrial analogs eventually indicated well-reasoned analogy to be true, and then infers what that there are actually different kinds of craters, each would be expected, consistent with that presumption. In corresponding to their respective causal processes. practice, the classification of phenomena, the recognition Analogies in Science: All science relies upon the of potential analogs, and the corroboration of working use of analogy [4], where “analogy” implies similarity hypotheses via consistency, coherence, and consilience among like features of two otherwise different things. all occur during the course of regional planetary mapping. Models and computer simulations are actually extremely The mapping process itself allows the geologist to con- strong analogies, in which attributes presumed to be fun- tinually assess hypotheses for a feature’s cause and age damental to the two things being compared (attributes by checking these against the mapped relationships. such a basic physics or mathematical structure) are incor- Planetary Processes: The immense diversity of porated into a simplified system that can then be com- planetary processes represented on Earth includes tecton- pared (via testing) to the “real world.” Geologists com- ics, volcanism, and impact, as well as erosion, transport, monly use a weaker form of analogy, but one that takes and deposition by mass movement, wind, water, and ice. advantage of natural regularities that allow direct com- These processes all relate to similar phenomena on other parisons between “real world” entities, such that a newly planetary surfaces [8], with Mars being particularly inter- discovered feature can be compared to features already esting in having features that correspond to nearly every known. In this way insights gained from the comparison terrestrial analog. contribute to further investigation into the cause of the By focusing of study on Earth processes that are effec- unknown feature. Geological analogies serve not so tive on other planetary bodies an interesting side-effect much to provide definitive explanations as they do to arises: “…it has caused terrestrial geologists to look on provide a source for hypotheses that move geological earth for features and relationships better displayed on research into productive lines of inquiry [5]. other planetary surfaces”[9]. The recently increased rec- Role of Terrestrial Analogs in Planetary Ge- ognition of the role of lunar-like impact cratering in Earth ology: Unlike the newly discovered geological phenom- history provides an example of this feedback effect. ena on other planets, geological phenomena on Earth are References: [1] Schumm, S.A. (1991) To Interpret much more likely to have both their key features and their the Earth. [2] Zimbelman, J.R. (2001) Geomorphology causes known. Thus, the sharing of key features between 37, 179-199. [3] Mutch, T.A. (1979) Rev. Geophys. Space terrestrial analogs and extraterrestrial phenomena can Phys. 17, 1694-1722. [4] Hess (1966) Models and Analo- suggest possible causes for the latter through the under- gies in Science. [5] Gilbert, G.K. (1896) Science 3, 1-12. standing of the terrestrial causes. These possible causes [6] Chamberlin, T.C. (1890) Science 15, 92-96. [7] then become hypotheses that require further testing. Whewell, W. (1840)The Philosophy of the Inductive Sci- For experienced geologists this generation of hy- ences. [8] Baker, V.R. (2008) Earth-Surf. Proc. Land. 33, potheses from analogs is not a trivial “look alike” exer- 1341-1354. [9] Sharp, R. P. (1980) Ann. Rev. Earth cise. Unlike classical physics, geology cannot perform Planet. Sci. 8, 231-261.

O26 2011 PERC Planetary Geology Field Symposium

A new view of planet research in the solar system. S. Maruyama1 1Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo, Japan. ([email protected])

Abstract: Recent discovery of exo-solar planets over 1000 has demonstrated that the so-called standard model established in our solar system cannot explain the distribution of rocky and gaseous planets around the central stars. Our solar planetary system may not be a standard among the G-star planets in our Galaxy. One of the diffi- culties to interpret the distribution of planets around the central stars is the final droplet in the central stars. For the planet research in our solar system, I propose the research of the past distance from the central star Sun, back to 4.6Ga, and self-rotation speed, using the rhyth- mical sedimentary rocks on the planetary surfaces including the Earth as an example. The past glaciation history of the planets can be used as a function of snow line. In the case of the Earth, the first glaciation was 2.9Ga, and re- peatedly occurred at 2.3Ga, 0.8-0.6Ga, 0.3Ga, and since 0.02Ga, suggesting the nearly constant position of the Earth 150 millions of km from the Sun since its birth at 4.6Ga. Similar tests for the rest of solar planets are necessary. Cratering rate on the Moon and Mars seems to have a pulse peak at 4.0Ga after the cessation of heavy bombardment to form the Earth at 4.6Ga. If this event is re- stricted to be only in the inner rocky planets including asteroid belts, the event could be interpreted by the late- stage bombardment of icy planetesimals from the Kuiper belt by the resonant interaction between Jupiter and Sa- turn [1]. Compared with heavy late-stage bombardment within our solar system, much heavier scale events could have been occurred, triggered by the starburst in our Galaxy. For example, Paleproterozoic and Neoproterozoic snow- ball Earth could be due to the starbursts at 2.3Ga and 0.8- 0.6Ga. Moreover, collision of our solar system against Dark Clouds must have also occurred during the 4.6Ga long history of our solar system. To reconstruct the Space paleogeography of our solar system and to differentiate the history outside from our solar system, the material researches fallen on the planetary surface through time such as deep-sea sediments on the Earth could be possible in future on the other planets. References: [1] K. Tsiganis, R. Gomes, A. Morbi- delli, and H. F. Levison (2005) Nature, 435, 459–461.

O27 2011 PERC Planetary Geology Field Symposium

The Layered Structure of Lunar Maria: Identification of the HF-radar Reflector in Mare Serenitatis Using Multiband Optical Image. S. Oshigami1, S. Okuno1, Y. Yamaguchi1, M. Ohtake2, J. Haruyama2, T. Kobayashi3, A. Kumamoto4, and T. Ono4 1Nagoya University, 2 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3Korean Insti- tute of Geoscience and Mineral Resources, 4Tohoku University.

Introduction: Determining the vertical structure of There are some craters in Mare Serenitatis, where dis- the lunar mare deposits is essential for understanding the tinct layered structures of mare basalts are observed on volcanic history of the Moon. The Lunar Radar Sounder their inner walls in the MI data. Specifically, the Bessel (LRS) onboard Kaguya detected widespread horizontal crater (21.8°N and 17.9°E) and the Bessel-H crater reflectors under some nearside maria [1, 2, 3]. The lay- (25.7°N and 20.0°E) are examined. The diameters of the ered structures of mare basalts are also discernible on Bessel and Bessel-H crater are about 15.0 and 4.0 km, some fresh crater walls in the Multiband Imager (MI) respectively. At least three layers are observed on the data. Comparison between the layered structures ob- crater wall of these two craters in the FeO content maps. served in the MI data and the subsurface reflectors de- Parts of the crater walls with clear layering in the FeO tected in the LRS data is essential for identifying the sub- content maps have relatively higher Is/FeO values, indi- surface reflectors and revealing the structural features in cating that these parts of the crater walls are pristine as a greater detail. In order to discuss the mare volcanism by result of denudation by landslides. The mean thicknesses estimating underground structure using the LRS data, of each layer observed on the crater wall in the FeO con- firstly we have to examine the features of detected sub- tent map are estimated from the DTMs derived from the surface reflectors and to identify their nature. In this pa- Kaguya Terrain Camera (TC) data. The estimated relative per, the LRS data and MI data are examined simultane- error of the TC DTMs is about 10 m [11]. ously, aiming to identify the nature of the reflectors, fo- Discussion: The relation between the subsurface cused on the Bessel and Bessel-H craters in Mare Sereni- reflectors and layered structures of mare basalts observed tatis. on the crater walls in the MI data is discussed in order to LRS observations: The LRS detects, using FM- identify the subsurface reflectors. The LRS images pass- CW radar (4–6 MHz), echoes from subsurface disconti- ing the Bessel crater show a single subsurface reflector in nuities where the dielectric constants change abruptly [4]. most of the area, while those passing close to the Bessel- Continuous subsurface reflectors are clearly detected in H crater indicates a single reflector under the southern the LRS B-scan images for limited areas of the maria [2, area of the crater and double reflectors in the northern 3]. Based on the appropriate range of relative permittivi- region. ties for solid lunar rocks [5], the actual depths of the sub- We estimate the rim and underground structures under surface reflectors can be determined to range from a few the assumption that overturn and structural uplift of sur- to several hundred meters. face rock units occurred at the crater formation [12] for The depth of the subsurface reflectors within each both the Bessel and Bessel-H craters. Estimated under- mare is much shallower than previous estimates of the ground structures around the Bessel and Bessel-H craters mare basalt thickness [e.g., 6] for most cases. As dis- indicate that the subsurface reflector lies on the basalt cussed by [2], the presumed depths of the reflecting inter- layer boundary with different composition. As a conclu- faces, as well as the parallelism between the local lunar sion, these subsurface reflectors are regolith layers surface and the reflectors, indicate that the reflectors are formed during the long hiatus of volcanic activities as not the basements of the mare but an interface between suggested by [1]. different basaltic rock facies. In addition, model calcula- References: [1] Ono T. et al. (2009) Science, 323, tions using the simplified radar equation [7] indicate that 909–912. [2] Oshigami S. et al. (2009) Geophys. Res. the detected subsurface reflectors are not interfaces be- Lett., 36, L18202. [3] Pommerol A. et al. (2010) Geophys. tween basalt units with different chemical compositions Res. Lett., 37, L03201. [4] Ono T. and Oya H. (2000) but those between a basalt layer and a high-porosity layer. Earth Planets Space, 52, 629–637. [5] Champbell, B.A. MI observations: The MI took images in nine (2002) Radar Remote Sensing of Planetary Surface, spectral bands. The visible bands (VIS) have wavelengths Cambridge Univ. Press, Cambridge. [6] De Hon R.A. and of 415, 750, 900, 950, and 1000 nm, while the near- Waskom J.D. (1976) Lunar Planet. Sci. Conf. 7th., 2729- infrared bands (NIR) have wavelengths of 1000, 1050, 2746. [7] Phillips R.J. et al. (1973) Apollo 17 Preliminary 1250, and 1550 nm [8]. The spatial resolution of the VIS Science Report (NASA SP-330), pp. (22-)1-26, NASA, range is 20 m/pixel at a nominal altitude of 100 km, while Washington, D. C. [8] Ohtake M. et al. (2008) Earth the spatial resolution of the NIR range is 62 m/pixel at the Planets Space, 60, 257–264. [9] Lucey P.G. et al. (2000) same nominal altitude [8]. The maps of the FeO and TiO2 J. Geophys. Res., 105(E8), 20,297-20,305. [10] contents in the studied area are derived from the MI data Shkuratov Y.G. et al. (2005) Sol. Syst. Res, 39(4), 255– based on the method presented by [9]. The maps of the 266. [11] Haruyama J. et al. (2009) Geophys. Res. Lett, clinopyroxene content and maturity degree (Is/FeO) are 36, L21206. [12] Melosh H.J. (1989) Impact cratering: A derived from the MI data based on the method presented geologic process, Oxford University Press, New York. in [10].

P1 2011 PERC Planetary Geology Field Symposium

Validation of Method for Estimating abundance of FeO Using Kaguya (SELENE) Multiband Imager Data 1 1 1 2 3 3 A.Shirai ѽ , S.Oshigami , Y. Yamaguchi ,N.Namiki,M.Ohtake, Y. Karouji 1Nagoya University, 2Chiba Institute of Technology, 3Japan Aerospace Exploration Agency

Introduction: The degree of the space weathering is 㻝㻚㻜㻡㻿㻱㻝㻝㻿㻱㻞㻿㻱㻠㻔㻝㻕 called "maturity". Several methods to eliminate influence 㻿㻱㻠㻔㻞㻕 of space weathering and estimate abundance of FeO and 㻜㻚㻥㻡㻣㻡㻜

㻛㻾㻜㻚㻥㻥㻡㻜

TiO2 were developed from detailed studies of using a 㻾 meteorite or the sample of the moon [e.g., 1, 2]. These 㻜㻚㻤㻡 method are based on the following experiments with re- 㻜㻚㻤

㻜㻚㻣㻡 spect to FeO content : The ratio of reflectance at 950 nm 㻜㻚㻜㻤㻜㻚㻜㻥㻜㻚㻝㻜㻚㻝㻝㻜㻚㻝㻞㻜㻚㻝㻟㻜㻚㻝㻠㻜㻚㻝㻡㻜㻚㻝㻢㻾 (R ) to that at 750 nm (R ), that is R /R , decrease 㻣㻡㻜 950 750 950 750 Figure 1: Some example of R /R versus R trends as iron abundance in a mineral increases, while R /R 950 750 750 950 750 derived from craters in Mare Serenitatis. increases and R750 decreases as maturity increases. How- ever, various problems are pointed out. One of the prob- Results: We confirmed the observation by staid and lems is the possibility that effect of the space weathering Piters [3] that trends of constant iron but varying maturity is not completely isolated from FeO content in this me- are parallel in two maria using Kaguya MI data. On the thod. Lucey et al. [1] assume that a plot of R /R vs 950 750 other hand, the slope of maturity trend does not match R concentrated into the optimized origin as space wea- 750 with that indicated by Wilcox et al. [4]. Average slope of thering advances for most minerals, but it is suggested the maturity trend is 1.35 radians, while that derived from that trends of constant iron but varying maturity are paral- Clementine data is 1.39 radians [4]. Then we calculated lel than radial in the mare [e.g., 3]. Wilcox et al. [4] pro- coefficients of Wilcox algorithm (equation (1)) consistent vided a plot of R /R versus R through the study of 950 750 750 to our results derived from the MI data by calculating the about 10,000 craters in six mare regions using spectros- parameter Ȩ’ for Apollo sampling sites with FeO content copic data of the Clementine. Their algorithm, derived from trends on the plot, better compensates for maturity grater than 10 wt%. Linear approximation to the plot of and provides less uncertainties due to maturity variations FeO content versus Ȩ’ for the sampling sites gives the than previous studies. [e.g., 4] equation (2). In this study, We first examine the maturity variation Wt %FeO (116.12Ȩ') 54.23 (1) trend in the mare using Kaguya Multiband Imager (MI) R0.95 data. Then these results are compared to the assumptions Ȩ' R0.75sinȟ cosȟ (2) in the Lucey method [1] and the Wilcox method [5]. And R0.75 finally, we develop an algorithm to estimate FeO content Discussion: We compared the FeO content map of and maturity degree for Kaguya MI data. Lucey method [2] (a) to that of Wilcox method [4] using coefficients estimated in this study (b). Mean error of the Method: We investigated the effects of varying maturity Lucey method in Apollo sampling sites is 1.42 wt% and in areas of constant FeO content in Mare Humorum and that of Wilcox method is 1.36 wt%. The ejecta of small Mare Serenitatis, we selected craters according to the craters in the map derived from Lucey method appear to following conditions as suggested by Wilcox et al. [4]. have higher iron abundance than inside of these craters, whereas those in the map derived from this study do not 1. Craters with a diameter of less than 3 km. as the effect of maturity have been completely removed. In order to avoid craters that have excavated different lithofacies material from below the surface unit, we set (a) (b) 2 km 2 km an upperbound on crater diameter. 11 wt% 17.5 wt% 11 wt% 17.5 wt% 2. Fresh craters. To identify fresh craters, we used Optical Maturity (OMAT) index [5]. We selected regions centered on fresh craters with at least a portion of the crater with OMAT > 0.3. Figure 2: FeO map in Mare Serenitatis We summed up the data with respect to craters on each surface unit defined by Kodama et al. [6]. References: [1] Lucey P. G. et al. (1995) Science, 268, 1150-1153. [2] Lucey P. G. et al. (2000a) JGR, 105, 20,297-20,305. [3] Staid M. I. and Piters C. M. (2000) Icarus, 145, 122-139. [4] Wilcox B. B. et al. (2005) JGR, 110, E11001. [5] Lucey P. G. et al. (2000b) JGR, 105, 20,377-20,386. [6] Kodama S. et al. (2000) JRSSJ, 20, 12-23.

P2 2011 PERC Planetary Geology Field Symposium

Lunar Regolith Soils Detected by Remote-Sensing Data Y. Miura Yamaguchi University

Introduction: Remote-sensing data of the IR spec- 1) Crystalline matrix in regolith soils: Lunar highland tral show crystalline minerals of rocks, breccias regolith rocks shows crystalline matrix even in regolith soils (for soils on any planetary bodies by the space exploration. example, the Apollo sample 68501, as shown in Fig.1 However, airless Moon, Venus and asteroids shows [2]). Remote IR spectral data cannot be separated from mainly regolith soils covered on the surfaces. The main basement rocks or broken regolith soils when the samples purpose of this paper is to elucidate various states of re- are crystalline grains. This is because remote IR data are golith soils explained as rocks on the Moon, asteroids and obtained only mineral crystalline parts (not the rocks). Venus without atmosphere [1-3]. 2) Glassy matrix in regolith soils: Lunar basalt breccias Glassy states of lunar interior and surface: show glassy matrix even in regolith soils (for example, There are three sites to be reserved glassy solid states the Apollo sample 15299[2]). Remote IR spectral data from gas or liquid states on the Moon as follows (cf. Ta- cannot be separated from original glassy samples or bro- ble 1) [3]: ken breccias and regolith soils. This is because remote IR 1) Lunar interior: This type of glassy blocks are consi- data are not obtained from glassy parts (except micro- dered to be formed by planetary giant impact (i.e. pri- crystalline parts). mordial Earth and Mars-sized planet), which are caused 3) Intermediate crystalline matrix in regolith soils: In- by state change of interiors called as moonquakes. termediate matrix of crystalline and glassy mixture are Shallow glassy blocks formed from gas and fluids are obtained some remote IR spectral data, but original considered to form lunar cave of depression structure. sources are not sure to be analyzed by remote IR data due 2) Impact crater surface: This type of glassy blocks are to detection of main mineral data (without rock informa- formed at melt-sheet, monomict and polymict breccias in tion). impact craters, together with eject blocks outside the craters, which are observed at Earth and other planetary sur- Table 2. Three kinds of texture of lunar regolith soils. faces at normal impact process. Although impact crater is 1) Crystalline matrix in regolith soils: not overlapped at air- and water-planets of Earth, but Highland rock (68501). Strong peak of the IR da- airless Moon shows overlapped impact craters for a long ta. history. 2) Glassy matrix in regolith soils: 3) Regolith soils formed by continuous collisions: Airless Basalt breccias (15299). Few peaks of the IR data. Moon (and Venus and asteroids) show continuous colli- 3) Intermediate crystalline matrix in regolith: sions by the solar winds, cosmic dusts, smaller meteoro- Mixture of crystalline and glassy parts (not rock) ids, comets and cosmic ray etc. for long periods. Main data of remote-sensing measurements are detected by this type of glassy grains. Significant data of the regolith soils are mainly composed of main basement rocks at the highland and mare basalt. In this sense, it is very difficult to be distinguished whether the remote-sensing data are based on basement rocks or regolith soils, which are very sensitive affairs for selecting next landing site to collect and analyze the samples. Fig.1. Optical micrographs of crystalline regolith soils of the Apollo 68501 highland soils. Plane (left) and cross Table 1. Three kinds of glassy states in the Moon. (right) polarized lights. Image width 4mm. The remote IR 1) Lunar deeper and shallow interior: spectral data cannot be separated from basement rock or Formed by giant impact. Moved by moonquakes, broken regolith soils due to mineral data from the IR data. shallow caves and depressed basin. 2) Impact crater surface: Summary: The results are summarized as follows: Formed at melt-sheet, breccias and eject blocks. 1) There are three lunar glassy states as the interior, sur- Overlapped impacts at airless Moon. face impact crater and broken continuous collisions. 3) Regolith soils by continuous collisions: 2) There are three lunar textures of crystalline, interme- Formed by the solar winds, smaller meteoroids diate and glassy matrices. 3) Remote IR data cannot be and comets etc. Remote-sensing data of regolith separated from basement rocks or broken regolith soils. soils mainly from main basement rocks. References: [1] Meyer C. (2003): NASA Lunar Pe- trographic Thin Section Set.67 pp. [2] Graf J.G. (1993): Lunar Soils Grain Size Catalog. NASA Refer. Publicati Lunar regolith soils: Lunar regolith soils show on 1265. [3] Miura Y. (1987): Applied Physics (Tokyo), three kinds of mixtures from crystalline and glassy grains Spec. Issue 1-6; J. Yamaguchi Geo. Sci., 1-5. as follows (in Table 2 [1-3]):

P3 2011 PERC Planetary Geology Field Symposium

Monte Carlo Ray-tracing model of the Lunar Soil using LSCC data set Un-Hong Wong1 and Yunzhao Wu2 1Institute of Space Science, Macau University of Science and Technology, Macao, China ([email protected]) 2Nanjing University, Nanjing China ([email protected])

Introduction: Exploration of the refrac- Our approach provides the reflectance of the lunar tion/reflection of the Lunar soil and rocks is one of the surface based on Hapke radiative transfer model the tested important topic in exploration of Geology and Chemical reflectance index of the lunar mineral sample of the Apol- element of the Lunar surface, from astronomical observa- lo projects. Once the mineral of the lunar surface are de- tion using telescope [1] to Lunar exploration using space- termined/defined, the reflectance can be provided for any craft (Apollo Projects, Chandrayaan-1, Kaguya and CE-1). direction of the incident light (based on the light source) Using the spectrum to determine the chemical compo- and reflected light (based on the viewing position). sition of the mineral is one of the most important objectives in Remote-sensing. Geometrical optics models and Image Light radiative transfer models are commonly used for this pur- Plane Source pose. While geometrical optics models investigated the Lens ray's reflection/refraction between the particles, radiative Reflection transfer models focus on the refraction intensity of different composition of the mineral. Hapke model is a radia- Volume of the tive transfer model which well describes the relationship lunar soil of the optical constant and the reflectance index of the Figure 1 : Our Monte Carlo Ray-tracing model mineral. Optical constant of a mineral is still hard to be determined accurately. Simulation result: reflectance index of the sample Computer simulation had become a powerful tool in by Apollo 16 project is used, the topography of the lunar analyzing and modeling phenomena in a wide range of soil volume is based on the result laser altimeter of CE-1 applications, especially for the research topic where it is of the landing site of Apollo 16 spacecraft (from 9.9375 difficult or high cost to measure data, such as Astrophys- to 19.9375 E. longitude, 5.0625 to 15.0625 S. latitude). ics and Space Science, Monte Carlo method and Ray- The resolution of the of the height map is 256x256 and tracing algorithm is widely used in simulating analysis the resolution of the ray tracing simulation is 512x512. optically contrast structure of particles with complex shapes [2]~[5]. Excellent works done by Lucey [6]~[8] not only found out the relationship between the optical constant and the composition of proportion of Fe and Mg of the olivine, pyroxene, etc, but also a provided a well approximation to found out the optical constant from a known reflectance index using the inverse Hapke model is proposed. Carle Pieters and Hiroi [9] made great contribution, Figure 2: Simulation result,(Left) Grayscale (Right) most of the lunar mineral samples taken back in the Apol- Color-mapped result, red color represents the higher re- lo projects had been tested, the reflectance index of those flectance region while blue color represents the lower tested sample is provided - the LSCC data set. reflectance region. reflectance index of visible spectrum provided by Acknowledgements: This study is supported by the RELAB and Lucey's method were used to find out the Macau Science and Technology Development Fund (Grant: (approximated) optical constants of the lunar mineral, 018/2010/A). than the reflectance index of any phase angle could be References: calculated using the Hapke model. [1] K. Saiki, K. Saito, H. Okuno, A. Suzuki, Y. Ya- In this paper, a Monte Carlo Ray-tracing model of the manoi, N. Hirata, and R. Nakamura. (2008) Earth Planets Lunar Soil is provided, for the purpose of simulating the Space,60, 417-424.[2] W.M. Grundy, S.Doute, and B. features of the reflection/reflection of visible spectrum of Schmitt. (2000) JGR, Vol. 105, No. E12 p29,291-29,314. the lunar soil. The model is actually a simulation of a [3] D. Stankevich, Yu. Shkuratov. (2004) JQSRT 87, spectrometer of a Lunar Exploration spacecraft, measur- p289̢296. [4] M. Mikrenska, P. Koulev, J.-B. Renard, E. ing the lunar soil data while the spacecraft orbiting the Hadamcik, J.-C. Worms. (2006) JQSRT 100, p256̢267. Lunar. In our model, a volume representing the topogra- [5] Yevgen Grynko, and Yuriy Shkuratov. (2007) JQSRT phy and the type of the mineral of the lunar soil is con- 106, p56–62. [6] P.G. Lucey. (1998) JGR 103(E1), 1703– structed. the Ray trace form the spectrometer to the vol- 1713. [7] P.G. Lucey. (2004) GRL 31(L08701). [8] P.G. ume and then trace back to the light source. Shadows will Lucey. (2006). JGR 111(E08003). [9] C.M. Pieters, AND be provided if the ray is blocked. The intensity of the re- T. HIROI. (2004). Lunar and Planet Sci. XXXV, Abstract flected ray is calculated using the Hapke model. #1720.

P4 2011 PERC Planetary Geology Field Symposium

Decrease Plans of Carbon Dioxide Gases at Mars and Venus Y. Miura Yamaguchi University

Introduction: Carbon-dioxide (CO2)-rich atmos- 2) Condensed carbon-bearing hot atmosphere on pheres of Mars and Venus formed at the Earth-type water-less Venus should be considered to be changed planetary histories should be decreased by some ideas to global cold air by state changes of CO2 amount to and techniques to produce CO2-poor planets, which is fluid and solid states by using any shock wave energy very significant to decrease hot CO2 affairs in present at the next exploration projects (Table 2) [1, 2]. Earth from to stop climate warming affairs. The main purpose of this paper is to elucidate CO2-rich and - Table 2. Volcano and CO2 change on Venus [1, 2]. poor atmospheres in Venus and Mars, by comparing 1) Young volcanoes on previous volcanic Mt. with climate history of recent Earth [1, 2, 3, 4]. Volcano with young lava & old Mt. structure. Comparative CO2 changes on Earth: Global 2) State changes of hot-air to fluid and solid: changes from “cold to hot climates” on air- and water- Strong carbon-rich cycles from gas to fluid and solid planet Earth are four events with mass extinctions. by using any shock wave energy (as next projects). Increased CO2 amount for hot atmosphere is caused by volcanic explosion and impact from carbon-bearing Carbon-rich cold atmosphere on Mars: From rocks to produce hot CO2 in air, as listed Table 1 [1, 2]. comparing with water-planet Earth, present water poor On the other hand, global changes “from hot to cold Mars shows characteristic features as follows (cf. Ta- cold climates” on dynamic Earth which are main clues ble 3). in Venus in future plan, are summarized as follows: 1) Progressive and active formations of volcanic moun- 1) Changes from hot to cold climates for recent 600Ma tains cannot be observed on present Mars, but interior history on recent Earth are four events with six biolog- fluids (CO2) are observed locally by recent explorations. ical mass extinctions. 2) Carbon-bearing cold atmosphere on water-poor Mars 2) Decreases of CO2 amounts at the four changing sites should be considered to be changed to global hot air by are obtained after global climate changes. Decreased state changes of CO2 amount to fluid and solid states by CO2 amount changes are caused by stopped volcanic using any shock wave energy by next Mars projects. explosions and impacts on carbon-bearing rocks.

3) Multiple and irregular changes of CO2 amounts Table 3. Fluids and CO2changes on Mars [2, 3]. which only volcanic effects to decrease CO2 amount 1) Interior fluids on Mars: cannot be explained, are obtained before global change Interior fluids (with CO2 ) are observed locally. of climates “from hot to cold airs” on the four major 2) State changes of cold CO2 air to fluid and solid: changing sites. Therefore, strong controls of sea-water Strong carbon-rich cycles from gas to fluid and solid and carbon-rich rocks in water-planet Earth are inevit- by using any shock wave energy (as next projects). able for CO2 amount changes, as listed Table 1 [1, 2].

Summary: Carbon dioxides (CO2) on hot Venus and Table 1. Global CO2 change of water-Earth. cold Mars are considered to be changed from gas to states 1) Global changes from cold to hot climates: of fluids and solids by using some shock wave energy at Increased CO2 amount by volcanic activity the next exploration projects. and/or impact on carbon-bearing rocks. References: 2) Global changes from hot to cold climate: [1] Miura Y. (2011): International Venus Workshop th Decreased CO2 amount by stopping of (9 VEXAG Sci. conf., NASA; Washington D.C.) volcanoes & impacts on carbon-rich rocks pp.2.http://venus.wisc.edu/workshop/vexag/ 2011/ 9thVEXAG_Abstract_Booklet.pdf. Carbon-rich hot atmosphere on Venus: [2] Miura Y. (2011):First International Planetary Cave From comparing with water-planet Earth, present wa- Research Workshop (Carlsbad, USA). pp.2. #8005, terless Venus shows characteristic features as follows: #8006.http://www.lpi.usra.edu/meetings/caves2011/ 1) Progressive formations of volcanic mountains [3] Miura Y., and Fukuyama S. et al. (1999): Jour. cannot be observed on present Venus, but young Materials Processing Tech., 85, 192-193. volcanic lava from the interiors should be observed [4] Miura Y. (1994): Astro. Soc. Pacific Conf. Ser., by using old volcanic Mt. structures (in Table 2). 63, 259-264.

P5 2011 PERC Planetary Geology Field Symposium

EVIDENCE FOR IN-SITU TROUGH EROSION IN PLANUM BOREUM, MARS. J.A.P. Rodriguez1-3, K. L. Tanaka4, and Hideaki Miyamoto3 1Planetary Science Institute, Tucson, AZ 85719- 2395, USA ([email protected]); 2 State key laboratory of information engineering on surveying, mapping and remote sensing, Wuhan University, China; 3 The University Museum, University of Tokyo, 113-0033, Japan; 4U.S. Geological Survey, Flagstaff, AZ 86001, USA Stratigraphy within troughs: Observations and interpretations: The floors of north polar troughs commonly exhibit systems of parallel/sub- parallel elliptical depressions and promontories. For example, Fig. 1 shows part of the layered floor of a trough, which includes two adjacent depressions and a promontory within it (blue arrows). These features reveal concentric parallel layers exposed throughout the entire relief of the trough’s section in which they occur (see inset elevation profile). In zones of topographic overlap, these features share some layers (Fig. 2). The existence of clusters of depressions and promontories that exhibit concentric parallel layers Fig. 1 View of a trough system in Planum Boreum. throughout the entire relief of individual troughs de- Arrows show two depressions and a promontory monstrates that trough formation involved the erosion aligned with the main trough. Part of a CTX mosaic, and truncation of gently dipping polar strata following centered at 84°41' N., 112°6' W., 6 m/pixel. their emplacement. The trough floors consist of clus- Varying rates of ablation and erosion related to ters of elliptical depressions lacking evidence for eo- wind-induced changes in the distribution, thickness, lian erosion, such as for example that resulting from and direction/degree of mobility of the dark sedimenta- katabatic winds transporting sand-sized particles, ry deposits may have contributed to the observed dis- which are known to produced systems of linear paral- versity in the dimensions of the depressions. lel ridges and grooves (i.e., yardangs). Yardangs are Fig. 2 Close-up view on a depression and adjacent presently developed in places on present-day Planum Boreum surfaces; where they are associated with deeper sculpturing, such as at the head of Chasma Boreale, they form broad, shallow, open troughs aligned with the predominant, katabatic wind direction. In contrast, development of enclosed spiral troughs appears to have involved the nucleation and subsequent amalgamation of widespread systems of depressions of various dimensions. The long axes of individual elliptical depressions are generally aligned with that of the troughs in which they occur (Fig. 1). In turn, individual troughs trend perpendicular to the regional slope, promontory shown in lower left part of Fig. 1. Arrows demonstrating that erosion was more effective perpen- trace a single layer. dicular to the mean/peak direction of solar illumination. This geologic scenario implies that trough forma- We propose that ablation by solar insolation and sub- tion did not produce large amounts of erosional detri- limation of the polar ice was the primary mechanism tus. Instead, the ablation of the polar ice must have leading to the formation of non-migratory depressions. transferred sublimated water vapor through the atmos- Local variations in surface albedo, such as caused by phere to precipitate on surfaces and in near-surface the accumulation of low-albedo lithic fines, could ac- pore space in zones of stability at lower latitudes. count for heterogeneous rates of surface ablation. In Conclusions: We conclude that the amalgamation addition, the maximum depth of ablation within a de- of clusters of depressions produced by in-situ ablation pression would have been limited by its width (which of pre-existing ice-rich polar deposits led to the forma- in turn controls the duration of solar illumination on tion of north polar troughs in this particular case study. the dark sediments on their floors, as a function of depth).

P6 2011 PERC Planetary Geology Field Symposium

How to learn about the internal structure of Mars. H. Senshu1 1Planetary Exploration Research Center, Chiba Institute of Technology. 275-0016, 2-17-1, Tsudanuma, Narashino city Chiba, JAPAN. ([email protected]).

Introduction: Internal structure of Mars is one of reason, a long-wavelength convection pattern achieved. the most important information to understand thermal However they do not discuss why such a viscosity jump evolution of Mars. However, after successes of over 10 could take place in the martian mantle. orbiters and 8 landers, we do not know even the size of its Lately, the existence of pyroxene is proposed as a core. This may be simply because previous missions aim possible candidate to occur such a viscosity jump [10] to unveil the surface morphology and surface process. since pyroxene-majorite phase transition take place under Then, what is to be observed next to unveil the internal the pressure-temperature condition corresponding to the structure and thermal history of Mars in the future mis- middle of the martian mantle. Thus if martian mantle con- sions? tains not only olivine but also enough pyroxene, the vis- In this presentation I’d review what we have learned cosity jump occurs as a natural result. about martian internal structure from exploration and then, Some studies also try to explain the concentrated and discuss what we should observe next to learn about the long-lasting volcanic activity. Harder and Christensen internal structure and thermal history of Mars. succeed to form a superplume in their mantle convection What we have learned from exploration: model by taking into account the upper-lower mantle Density and moment of Inertia. The size and mass (or, boundary [11]. However as is pointed out by later studies, gravity) are fundamental parameters to describe a planet. it takes over one hundred billion years to merge ascending The density calculated from these parameters makes a hint plumes into one superplume. On the other hand, recently, on the composition: Mars is a mixture of metals and rocks. Zhong [6] shows that by taking into account the effect of However density is not conclusive until we know the pre- pyroxene-series phase boundary a huge volcanic province cise composition of metal and rock parts. And moreover occurs self-consistently. density does not tell us the internal structure. What is to be observed next?: As is described Moment of inertia is a diagnostic parameter of internal above, we do not know much about the internal structure structure. The estimated value for Mars, 0.3662±0.0017 of Mars since previous exploration missions aim to unveil [1], tells us that Mars has a dens core at the center of it. the surface environment. We need exploration mission Given the moment of inertia the density of metallic core aiming to internal structure to understand the internal can be determined as a function of core radius, while the structure and thermal evolution of Mars: i.e. seismic, nu- density of silicate mantle is only weakly depends on the tation, and/or precession observations. Especially if the core radius [2]. power of phase boundary between pyroxene and majorite k2 love number and Q value. These parameters would have been observed, we could know deductively represent the energy dissipation of sound waves within a the composition of martian mantle and the mechanism of planet. The dissipation efficiency highly depends on the degree-one convection. phase of interior. The love number is estimated from the Understanding of martian thermal history is, of course, orbit evolution of martian satellite, Phobos. The large a key to understand the formation mechanism of martian value of k2 love number (0.153±0.017 [3]) indicate that geology. Thus explanation to unveil Mars is required now. the martian core remains molten, which contains light References: [1] Folkner W. M. et al. (1997) Science, elements such as sulfur and probably hydrogen [4]. 278, 1749–1751. [2] Sohl F. et al. (2005) JGR, 110, Dichotomy. Mars is known to show dichotomy. The E12008. [3] Yoder C. F. et al. (2003) Science, 300, 299– northern hemisphere is low and smooth, while the other 303. [4] Lognonné P. (2005) Annu. Rev. Earth Planet. hemisphere is high and heavily cratered. At the same time Sci., 33, 571–604. [5] Nimmo F. et al. (2008) Nature, 453, Mars also represent east-west dichotomy. The solarsys- 1220–1223. [6] Zhong S. (2009) Nat. Geosci., 2, 19–23. tem-largest volcanic province occurred on the west he- [7] Roberts J. H. and Zhong S. (2006) JGR, 111, E06013. misphere of Mars while there is only one visible volcano [8] Zuber M. T. et al. (2000) Science, 287, 1788–1793. on the other hemisphere. Such a global and outstanding [9] Zhong S. and Zuber M. T. (2001) EPSL, 189,75–84. morphology would constrain the internal structure and [10] Keller T. and Tackley P. J. (2009) Icarus, 202, 429– thermal history of Mars. 443. [11] Harder H. and Christensen U. R. (1996) Nature, Numerical model predictions: Models are pro- 380, 508–509. posed so far to form the North-South dichotomy. Some of them proposed exogenic reason [e.g., 5] while others proposed endogenic mechanism [e.g., 6], or hybrid of them [e.g., 7]. However, Zuber et al. [8] shows the crustal thickness declines smoothly from north to south, indicating the N-S dichotomy being endogenic. Zhong and Zuber [9] demonstrated that if a viscosity jump of factor 25 occurs at the middle of mantle by some

P7 2011 PERC Planetary Geology Field Symposium

Numerical modeling of the impact-induced tsunami on Mars. Y. Iijima1, K. Goto2, K. Minoura1, G. Komatsu2, 3, F. Imamura4, 1Dept. of Earth Science, Tohoku Univ. (6-3, Aramaki Aza Aoba, Sendai, Miyagi 980-8578, Japan; [email protected], [email protected] ), 2 Planetary Explora- tion Research Center, Chiba Institute of Technology (2-17-1 Tsudanuma, Narashino, 275-0016 Chiba, Japan; kgo- [email protected]), 3IRSPS, Univ. G. d’Annunzio (Viale Pindaro, 42 65127 Pescara, Italy; [email protected]), 4Disaster Control Research Center, Graduate School of Engineering, Tohoku Univ. (Aoba 06, Sendai, Miyagi 980-8579, Japan; [email protected] )

Introduction: Northern lowlands of Martian surface maximum wave heights at locations 2, 3, and 4 are 20–50 are considered to have been once occupied by large bo- m, while those at 1, 5, and 6 are 1–10 m. From these re- dies of water, and candidates of paleo-shorelines have sults and terrestrial analogues, geological and sedimento- been hypothesized based on geomorphological features logical features of tsunami on Mars is likely to be re- [1]. These paleo-shorelines, however, are highly contro- mained near the shoreline, which should be observable in versial, and some landforms which were once interpreted high-resolution satellite images. as “shoreline” have been disputed because these contacts Reference: [1] Parker T. J. et al. (1989) Icarus, 82, seem to lack features of definitive shorelines when ob- 111–145. [2] Ghatan G. J. and Zimbelman J. R. (2006) served by high-resolution images [2]. To discuss geolog- Icarus, 185, 171–196. [3] Dohm J. M. et al. (2009) Plane- ical and sedimentological aspects of the purported paleo- tary and Space Science, 57, 664–684. [4] Matsui T. et al. shorelines on Mars, we must pay attention to the condi- (2001) LPSC XXXII, Abstract #1716. [5] Ormö J. et al. tions of Mars that are different from those of Earth, low- (2004) Meteoritics & Planetary Science, 39, 333–346. er gravity, lower density of atmosphere, and lack or near- absence of tectonic and tidal activities [3]. As a common phenomenon on Mars and Earth, we focus on the tsunami caused by meteorite impacts into oceans [3, 4]. The tsunami could have caused cataclysmic effects on paleo- shorelines and may have left a variety of geological and sedimentological features, which might be observable in high-resolution imageries. Meteorite impact into paleo-ocean: The duration of the ocean on Mars is estimated to be from 0.1 to 800 Myr [5]. Even if we assume the minimum estimates, a few meteorite impacts into the ocean are expected to occur [5]. Considering that only one large impact into ocean is strong enough to leave traces of its tsunami to the entire shorelines [3], it is plausible that geological and Figure 1. A map collectively showing maximum veloci- geomorphological features of tsunamis may have re- ties of tsunamis at each grid caused by 21 impact events, mained in and around the paleo-ocean. during 24 hours after the impact. Impact craters are Numerical simulation: In this study, we conducted shown as black dots and land areas are shown as black 2D (depth averaged) numerical simulation of impact- area. induced tsunami on Mars, and assessed time series variations of velocity and water level at the candidate paleo- shoreline. We used the present topography data (MOLA) in part of the northern plain shown in Fig. 1, and assumed that the mean elevation of the ocean surface is - 1500 m (corresponding to the Meridiani shoreline [5]). The numerical simulations were conducted based on the long-wave theory with non-linearity. We set 21 craters with 50 km in diameter (Fig. 1), and observed water level, maximum water level, and maximum velocity for each cases. Results: The maximum velocities at each grid of all of simulations are shown in Fig. 1. Velocity is high near the shorelines (>12 m/s), whereas the velocity is relatively low at the shoreline of Arabia Terra (~3 m/s) because tsunami inundation is hampered by the rim of the crater which is located in front of the shoreline. The time series variation of water level caused by one Figure 2. Time series variations of water level at the loca- crater (star mark in Fig. 1) are shown in Fig. 2. Receding tions shown in Fig. 1. The position of the crater is indi- and rushing waves are observable at each locations. The cated in Fig. 1 as white star.

P8 2011 PERC Planetary Geology Field Symposium

Classification and statistics of landslides in the Valles Marineris, Mars. F. Fiorucci1,2, M. T. Brunetti1, M. Santangelo1,2, M. Cardinali1, P. Mancinelli2,G. Komatsu3,4, K. Goto4, H. Saito5, F. Guzzetti1 1CNR IRPI, via Madonna Alta 126, 06128 Perugia, Italy, 2Università degli Studi di Perugia, P.zza dell’Università, 06123 Perugia, Italy, 3International Research School of Planetary Sciences, Università "G. d'Annunzio", Viale Pindaro 42, 65127 Pescara, Italy, 4Planetary Exploration Research Center Chiba Institute of Technology, 2-17-1 Tsudanuma, Nara- shino, Chiba, 275-0016, Japan, 5Center for Spatial Information Science, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8568, Japan.

Introduction: We use high and ultra-high-resolution logue (Mount Saint Helens, USA) (right) [2]. (c) Mar- images and data by (i) the High-Resolution Stereo Camera tian debris flow / avalanche (left), and its terrestrial ana- (HRSC) on-board the ESA Mars Express satellite, (ii) the logue (Mount Cook, New Zealand [3]) (right). Mars Orbiter Laser Altimeter (MOLA) on-board the NASA Mars Global Surveyor, and (iii) the Context Cam- We classify the 184 mapped landslides in the Valles era (CTX) on-board the NASA Mars Reconnaissance Marineris in three classes, including 63 debris flows, 58 Orbiter, to map and classify landslides in the Valles Mari- slides, and 63 rock glaciers. Our new inventory shows a neris, Mars. The study area, in the western sector of the significantly larger number of failures than previously Valles Marineris, covers 1×105 km2, about the size of recognized in the same general area [4]. An example of Iceland, with ground elevations in the range from -4500 m the mapped landslides is shown in Figure 2. to 6200 m. To map the landslides, we use satellite images For the new data set of Martian slope failures, we ob- and elevation data available through Google Earth (© tain a set of morphometric measures, including landslide 2011 Google). First, we use the ultra-high-resolution im- and volume of the failed deposit. We find that landslide ages captured by CTX camera to define key interpretation area is in the range from 1.3×105 m2 to 2.6×109 m2. For a criteria for the geomorphological detection and classifica- subset of 46 landslides of the slide type, we estimate the tion of landslides in selected areas where landslide fea- volume of the deposit, which spans the range 107 m3 to tures were distinct. Next, we apply the defined criteria to 1013 m3. For 69 landslides of the debris flow and slide the entire study area exploiting the high-resolution images types we determine the H/L ratio, a proxy for the apparent obtained by the HRSC camera to detect and map 184 coefficient of friction [5], which we find in the range 0.18 landslides. We classify the landslides on morphological - 0.49. criteria [1] based on the similarity with terrestrial mass movements (Figure 1).

(a)

Figure 2. Portion of the landslide inventory map prepared for the Valles Marineris. Red lines show boundaries of landslide deposits and depletion areas.

References: (b) [1] Cruden, D.M., Varnes, D.J. (1996) in: Turner, A.K. and Schuster, R.L. (eds.) Landslides, Investigation and Mitigation, Transp. Res. Board Spec. Rep. 247, Washington D.C., 36-75. [2] Rockglacier.blogspot.com/2010/05/mount-st- sthelens-30-years-of.html. [3] Landslide of the world. Ed. By Kyoji Sassa (1999). (c) [4] Quantin, C., Allemand, P., Delacourt, C. (2004) Figure 1. (a) Martian landslide of the slide type (left), Planet. Space Sci., 52(11), 1011-1022, and its terrestrial analogue (Mount Toc, Italy) (right). doi:10.1016/j.pss.2004.07.016. (b) Martian rock glacier (left), and its terrestrial ana- [5] Legros, F. (2002) Eng. Geol., 63, 301-331.

P9 2011 PERC Planetary Geology Field Symposium

!! " #$ % &'! ()&& * + , - . , ,/

0$$/ $ /$ 1$$,2 , 9:; 98/$ /$$$$ 134, 5, 9:&;:!;9 /$$$ / /$ / 5, 5/ 6 2 :9 !; 5/, E$$$$$ $ # 5 / 1 , 2 5 /$$ / 5 / 1 1,7 58/5 $/$9 E 5 5 9 / :5; , 3)4, 2 5 /:/;/ 3&4,# 95- 5 5<5=/,+ 8//// & 5$,21 $ :A; 5/8

/9/51 5 / $95% $/$ / ,?/ 1 / ,#$$5 / $5/$ 5 F$ ,G/ /3!4,258/ F$/5/ $ //5 $, 59 $1 5/, 2 /$$ /5// 5 // 6 5,?/ / 5 $ 5 $ 5@#5 , $ ,2$ $ @# 5$ 9 9/ 53A4- 5$/<5= 5 $5,25 & 9// / B :; ! /1,

& ( & & ! ) ! 3411,, $H, ,:&BBB; &!!B &!!),3&4#:IIJ; & &A) &I', 3!4 @ , 7, :&BBJ; !"AJKA&, 3A4# #, *, :&BB; # $ " :&; JJKJ&I, 3)4 E *, ,*,?,7%*,E, G,#,1$, , ,, % &'( !'(K!JJ & & ! :!;

5 / C5D /D

$ D D $ 5 8D 5/ , %/$

P10 2011 PERC Planetary Geology Field Symposium

Solar Insolation-Induced Destabilization of Subsurface Clathrates: Implication for the Martian Atmospheric Methane R. Ishimaru1, G. Komatsu2,1, and T. Matsui1, 1Planeary Exploration Research Center (PERC), Chiba Institute of Technology (Chitech) 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan ([email protected], [email protected]), 2International Research School of Planetary Sciences, Università d’Annunzio, Viale Pindaro 42, 65127 Pescara, Italy.

Introduction: Four groups of spacecraft and ground- tion is estimated using the physical properties of subsur- based observations have reported independently the de- face materials and time scale of the variation [7]. Since a tection of methane in the Martian atmosphere [1-5]. The 5 times an annual skin depth is a measure of depth to fact that different observational instruments obtain similar which temperature variations of the surface propagate [8], results (seasonal variation and global mean amount of we use the depth as the propagation depth of temperature CH4) implies that methane actually exists on Mars alt- variation. If a seasonal temperature variation can propa- hough each observation has a specific problem of their gate to a clathrate-forming depth, then destabilization of own. Thus, in this study, we propose a release mechanism clathrates is assumed to occur. of CH4 based on a hypothesis that it indeed exists on Mars. Results and Discussion: In the case of low- The observed distribution of CH4 is localized ones [1, latitude regions, the clathrate-forming depth tend to be 3-5], which suggests existence of localized sources of deeper because the mean surface temperature of low- CH4 because the time required for global mixing in the latitude regions is relatively high (a 210 K). However, we martian atmosphere is very short. CH4 release from sub- found that 5 times the annual skin depth can reach clath- surface clathrates has been proposed as a plausible source rate forming depth for binary clathrates mainly composed of CH4 [6]. Since the region where clathrates are stable of CO2. In this case, the temperature of the binary clath- exists in the subsurface martian environment [6], CH4 are rates oscillates seasonally. This induces a cycle of destabi- expected to be stored as methane clathrates when CH4 is lization and stabilization of clathrates, suggestive of CH4 delivered or produced in the subsurface. This is likely to release. Since CO2-rich clathrates are deficient in CH4, occur because the origin of CH4 on Mars could be subsur- CH4 release from them may be consistent with the small face biological or geochemical activities such as serpen- quantity of CH4 observed in the atmosphere [1-5]. tinization of basalt [e.g., 4, 6]. Then, dissociation of such Here, the effects of local slopes also need to be con- clathrates may release CH4 into the atmosphere. sidered. Specifically, poleward facing slopes experience a Destabilization of clathrates is required for dissocia- geometrically-reduced incident solar radiation, resulting tion of clathrates. Here, we show the possibility that solar in lower surface temperature [8]. This would allow for- insolation induces the destabilization of subsurface clath- mation of clathrates at shallower depths capable of gain- rates. Clathrates are destabilized via temperature increase. ing large amplitude of temperature oscillations, which If solar heating can increase the temperature in the area of raise the probability of CH4 release. subsurface clathrates, a resultant CH4 release may con- Next, in the case of polar cap, we found that clathrate- tribute to the presence of CH4 in the martian atmosphere. forming regions is very shallow (< 2.5 m) because of low Two regions have been suggested as a source of mar- temperatures of the polar cap (155 K). Then, an annual tian CH4; low-latitude region [4, 5] or northern polar cap skin depth is larger than clathrate-forming depth regard- [3]. Since destabilization of subsurface clathrates is con- less of the clathrate composition. Thus, an anticipated trolled by surface temperature and subsurface environ- large temperature increase may lead to the CH4 release via ment, we consider these two regions in this study. dissociation of clathrates. Model: In this study, we examine insolation-induced It is to be noted that it could take time for CH4 to be destabilization of clathrates considering stability condi- released into the atmosphere through the destabilization tions of clathrates and thermal conduction in subsurface. of clathrates: the reaction time for dissociation of clath- First, a clathrate-forming region (depth) is determined rates and the required time for the CH4 to seep upward from stability conditions of clathrates. Multiple gas spe- into the atmosphere are not well known. Further observa- cies can occupy clathrate cavities to form multicomponent tions of CH4 release is expected to impose constraints on clathrates [6]. Since the major constituent in the martian our model, providing a clue to understanding the origin atmosphere is CO2, CO2 is likely to be trapped as binary and release mechanism of CH4 on Mars. clathrates together with CH4 on Mars. Binary clathrates References: [1] Formisano V. et al. (2004) Science, containing both CO2 and CH4 form at lower pressures 306, 1758-1761. [2] Krasnopolsky V. et al. (2004) Icarus, than pure CH4 clathrates; binary clathrate can form at 172, 537-547. [3] Geminale A. et al. (2011) Planet. Space shallower depths than CH4 clathrates. This makes it easier Sci., 59, 137-158. [4] Mumma M. J. et al. (2009) Science, for insolation to heat the subsurface clathrates. We use the 323, 1041-1045. [5] Fonti S. and Marzo G. A. (2010) Chastain and Chevrier (2007)’s values [6] as stability P-T A&A, 512, A51. [6] Chastain B. K. and Chevrier V. conditions of each clathrate ranging from pure CH4 clath- (2007) Planet. Space Sci., 55, 1246-1256. [7] Turcotte D. rate to CO2-rich binary clathrates. Second, an depth (an- L. and Schubert G. (2002) Geodynamics. 2nd edition, nual skin depth) to which a seasonal temperature variation Cambridge Univ. Press. [8] Mellon M. T. and Phillips R. (due to insolation) of the surface propagates via conduc- J. (2001) J. Geophys. Res., 106, 23165-23179.

P11 2011 PERC Planetary Geology Field Symposium

Geological features on the surfaces of Saturn’s inner small satellites Naoyuki Hirata1 and Hideaki Miyamoto1 1University Museum, University of Tokyo, Tokyo 113-0033, Japan ( [email protected]).

High resolution images of Saturn’s inner small other satellites and a ring system. As a result, satellites obtained by Cassini spacecraft (Fig. the surface features and prosperities can be 1) reveal that they have variety of geological largely different from those of asteroids. In this features on their surfaces. Similar to small talk, we well briefly review recent asteroids, these small satellites typically have a observations of the geological features on the microgravity environment without thermal surfaces of these satellites and discuss possible metamorphism. However, different from roles of electro-static levitations of dust asteroids, these satellites have likely particles on these satellites. experienced complicated interactions with

Fig. 1: High-resolution images of Saturn’s inner small satellites obtained by Cassini probe. (a) Pan (PIA08405), (b) Daphnis (N00156643), (c) Atlas (PIA08405), (d) Prometheus (N00150211), (e) Pandora (N00039262), (f) Janus (N00152953), (g) Epimetheus (N00098337), (h) Pallene (N00164310), (i) Telesto (N00041296), (j) Calypso (N00151485), (k) Polydeuces (PIA08209), and (l) Helene (PIA12723).

P12 2011 PERC Planetary Geology Field Symposium

Modern shallow ocean sedimentary record of ferric hydroxide in Satsuma Iwo-Jima island, Kagoshima, Japan. T. Ueshiba1, S. Kiyokawa1, S. Goto2, K. Oguri3, T. Ito4, M. Ikehara5, K.E. Yamaguchi6, T. Nagata1, T. Ninomiya1 and F. Ikegami1 1.Department of Earth and Planetary Sciences, Kyushu University, Hakozaki, Fukuoka, Japan [email protected](T. Ueshiba), [email protected](S. Kiyokawa), 2.National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan [email protected] 3.Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan [email protected] 4.Faculty of Education, Ibaraki University, Mito, Ibaraki, Japan [email protected] 5.Center for Advanced Marine Core Research, Kochi University, Nankoku, Kochi, Japan [email protected] 6.Department of Chemistry, Toho University, Funabashi, Chiba, Japan [email protected]

Satsuma Iwo-Jima is an active volcanic island located We found two sedimentological events that play im- about 40 km south of Kyushu Island, Japan. It has many portant roles in forming sediments in Nagahama Bay; hot springs, and is surrounded by patches of reddish heavy rainfall and strong typhoon. The thick tuff beds (T1, brown and white colored seawater. Nagahama Bay, a T2 and T3) formed by reworking sediments induced by small port located in the southern part of the island, re- heavy rainfall (in 2000, 2001 and 2002). The sand bed tains reddish brown seawater and precipitates ferric hy- formed by hydrodynamic mixings due to strong typhoon droxide[2]. We conducted a multidisciplinary study to in- events in 2004. Therefore, nine orange-colored lamina- vestigate mechanisms and histories of precipitation of the tions between T2 and T3 were made in a year, implying sediments. From 2009 to 2011, we obtained 1m-long core that formation of such ferric-rich layer possibly occur, on samples from the bay that record sedimentation of mainly average, about once per month. ferric hydroxide during the last 11~13 years since dredg- References: [1] Japan Meteorological Agency ( ac- ing in 1998. We compared their stratigraphy with (a) 11 cessed 1st February 2011) years’ meteorological data and (b) volcanic activity rec- http://www.jma.go.jp/jma/menu/obsmenu.html ord in that period. [2]T.Ninomiya and S.Kiyokawa, (2009), Memoirs of Thirteen short cores were collected from Nagahama the Faculty of Sciences Kyushu University, Series D, Bay. They were mainly reddish-brown mud. The lower Earth and Planetary Sciences,32,2,1-14. unit contained three layers of white and pink tuff beds (T1, [3]H.Shinohara, K.Kazahaya, G.Saito, N.Matushima, T2 and T3) with thickness of 1~9 cm. The upper unit and Y.Kawanabe, (2002), Earth Planets Space,54,175- mainly contained sand bed and reddish-brown mud. The 185. reddish-brown mud had mainly ferric-rich materials, but included minor rock fragments and volcanic glass. The tuff beds were mainly composed of volcanic glass. Sand bed was essentially a mixture of rock fragments, volcanic glass, and ferric-rich fine materials. The reddish-brown mud had very fine orange-colored laminations (1~2 mm thick/each), that are evident in especially nine laminations between T2 and T3. This orange-colored laminations had mostly ferric-rich materials. 11-years-long meteorological data of the Satsuma Iwo-Jima island recorded heavy rainfalls (precipitation over 100 mm/day) in June 2000 (189 mm/day), June 2001 (124.5 mm/day), and June 2002 (122 mm/day), and three events of strong typhoon in 2004 (maximum wind speed: 40.3 m/s, 54.3 m/s and 44.6 m/s), 2005 (43.3 m/s), and 2007 (50.2 m/s). These meteorological events were reflected in the sediment record. Volcanic activity was intensified from September 1997[3] to October 2004[1]. During that time, ash was spewed out from and deposited near the volcano. Tuffa- ceous beds in the sediments of Nagahama Bay recorded such volcanic activity; however reworking of sediments by meteorological events were found to obscure such records.

P13 2011 PERC Planetary Geology Field Symposium

Structure of Kikai submarine caldera complex, southern Kyushu. F. Ikegami1 , S. Kiyokawa1, T. Ueshiba1, H. Oiwane2, K. Nakamura3 and K. Kameo4 1Kyushu Univ., 2National Inst. Polar Research, 3JAMSTEC, 4Atmosphere Ocean Res. Inst. Univ. Tokyo.

Introduction: Kikai Caldera[1] is a mostly sub- y Two overlapped circular normal fault system has been merged caldera located in 50km southern off Kyushu Is- found. Outer one has 18 km while inner one has 15km land, Japan. Only two inhabited islands, Takeshima and of their diameters. Inner fault is appeared in bathymetry Satsuma Iwojima are located on northern rim of the pro- as deep, ring-shaped trench-like structure. posed caldera while numerous submarine volcanoes are y Massive dykes are intruded along the both fault system. likely to be existed as rocks and banks seen in bathymetry They might be the possible source of ignimbrites. maps[2], [3]. The caldera was the possible source of y The ringed trench-like structure is not filled by deposits Akahoya co-ignimbrite tephra[4] in 7300 cal. BP[5] which in most part. It indicates the formation of the structure is considered as the latest VEI-7 class eruption in Japan. is the newest major deformation event in Kikai complex. The caldera may be also the eruptive center of another y W-E oriented steep basin is located between southern two[6], likely at least three ignimbrites[7] in Pleistocene part of the two fault systems. It is buried by nearly 1km- epoch. The biggest historical activity was the eruption of thick stratified deposits. 1934-35 which formed new Showa Iwojima Island[8]. The y The survey lines at the southeastern end of the complex mass of the eruption is roughly estimated as 0.37 cubic shows plunge of the volcanic basement rocks. The area kilometers[9] and that is the biggest eruption in Japan past was reported as major negative gravity anomaly in the 100 years. Excluding the 1934 eruption, all observed recent observation[7] that indicates presence of a buried events are at Satsuma Iwojima including small ash-ejecting caldera structure. eruptions and continuous intense hydrothermal activity. Bathymetry of shallow areas: y Showa Iwojima, the newly formed island by 1934-35 Bathymetry map of Kikai Caldera Complex[3] eruption has the volume of 0.16 cubic km. y Major southwestward lava robe can be seen in Showa Iwojima. It covers more than 0.3 square km. y Showa Iwojima and other three top-flattened seamounts are found inside of the circular depression. They are lo- Showa Iwojima cated only in western part of it. Showa Iwojima might Ў Takeshima be the smallest in the four possible submarine volcanoes. Conclusion: Kikai is a complex of multiple calderas, Satsuma Iwojima possibly three or more. The time lapse of the eruptive cen- ters shows northwestward movement. Lack of sediments in the circular trench-formed structure indicates climatic caldera collapse was occurred after ignimbrites ejection in Akahoya eruption. After Akahoya, most volcanic activity is likely located only in western part of the Kikai, with Showa Iwojima and multiple slightly huge(<1 cubic km) submarine volcanoes. References: [1] Matsumoto (1943) Jpn.Geol. Geog., 19, Special number. [2] Maritime Safety Agency Jpn. (1982) Basic map of the sea in coastal waters, 6351. [3] Onodera et al. (2009) Tech. B. Hydrography Oceanogra- phy, 27, 92-97. [4] Machida and Arai (1978) Quaternary Res., 17(3), 143-163. [5] Fukuzawa (1995) Quaternary Survey methods: Two seismic reflectional observa- Res., 34, 135-149. [6] Ono et al. (1982) Geol. Surv. Jpn., tions had been conducted in 2010 and 2011, as KT-10-18 1-80. [7] Moriwaki (2000) JGU2000 Abstract, Qa-004. and KT-11-11 with a research ship Tanseimaru from [8] Tanakadate (1935a) J. Mineral Petrol Sci., 13, 184- JAMSTEC. Totally 24 survey lines had been recorded 190. [9] Tanakadate (1936) J. Mineral Petrol Sci., 16, 67- with 48 channel streamer cable and G-I gun of 150 cubic 74. [7] Onodera et al., (2010) Tech. B. Hydrography inches. We also held a multi-beam bathymetry survey for Oceanography, 46, 103-107. shallow areas which remained unobserved in past observations. The survey is conducted as a co-operative research with Mishimamura municipal government and Kyushu University. Seismic observed structure: y Eastern part of Kikai complex is covered by thick, stratified facies which have rather strong reflection surfaces while western part is mostly consisted by scattered facies and rocks.

P14 2011 PERC Planetary Geology Field Symposium

Estimation of a possible impact crater at active volcanic area like in Japan. M. Okamoto Kyushu International University (Division of Earth Sciences, Faculty of Economical Sciences), 1-6-1Hirano, Yahata-higashi ku, Kitakyushu, 805-8512 Japan. E-mail address: [email protected]

Introduction: I have a lot of traditional localities Discussion: The locality in this study is still now and heritages of natural zeolites given as a geological most discussed geological area and I have investigated importance in Japan. Recently we have found a new more than ten years to elucidate their generation or locality that small grains generate into the vein let after formation process in Japan. But that is not concluded the the hydrothermal alteration of sedimentary minerals at initial generation for the first time on the basis of Takamatsu crater district. The purpose of this study is to orogenic system in mid Japan. I have considered the indicate an geological significance making as a special occurrence of this locality as follows that : at first I have locality and define the standard value for regarding of a lot of active volcanic formation and then much of small this occurrences. I suggest an example for a special mountains are conformed around there, in next that is locality as a previous and remarkable presence in Japan. caved by an extra-terrestrial matter which likes an iron meteorite, after that the surface of those mountain were Geological Settings: The locality in this study weathered and eroded the wind or rain shock-induced the is still now not determined that the generation process by catastrophy by an active volcanic eruption or earthquake shock induced after it makes them or volcanic intrusion, all over the world. which we called ‘kardera’ is generated around huge acidic volcanic eruption. That is Takamatsu crater, which is named by Prof.Kono(1994) as for geophysical References: abnormal data and most discussed its geological area. I have much investigated more than twenty years to [1]Minato, H. and no.111 Committee of Japan Academic elucidate their generation or formation process in Japan. Association (1994), Utilization and Properties of Natural But there is many distributed volcanic rocks at Neozoic Zeolites. Univ. Tokyo Press, pp.318. era around Takamatsu crater inside Takamatsu city in Japan. Besides I have first found some zeolite minerals [2] Kawano, Y. et al.(1994) Geophysical survey of Takamatsu inside the crater, which is some changed their content of Crater in Kagawa Prefecture, Japan. Lunar and Planetary Symposium, 27, 67-70. another one. Okamoto and Miura(1998) have studied more. [3]Okamoto M. and Miura Y. (1998) Zeolite minerals found at the Takamatsu crater. Study on Liberal Arts at KIU, 5 (2), 17 – Basic experiment for mineralogical 28. properties: The sample searched for fundamental mineralogical properties were measured by X-ray powder [4] Okamoto M. and Sakamoto E. (2000) Application of Natural th diffraction (XRD) and X-ray fluorescence (XRF). Zeolite to purify polluted water. Proc. 6 International Identification of mineral composition was determined Conference of Applied Mineralogy, Goettingen, Germany. from XRD and XRF. Micrographs of the Zeolites and Vol.1, 197 - 200. Bamboo coal have been performed by the Scanning [5] Passagllia E. (1975) The crystal chemistry of mordenites. Electron Microscopy (SEM) (Fig. 1). The surface areas of Contrib. Mineral. Petrol., 50, 65 - 77. a samples were obtained by the B.E.T. method. The cation exchange capacity (C.E.C.) of these samples with [6] Passagllia E., Artioli G., Gualtieri A. and Carnevali R. + variable amounts of NH4 was investigated by the batch (1995) Diagenetic mordenite from Ponza, Italy. Eur. Jour. isothermal exchange method (25 㷄㪃㩷㪈㩷㪿㫆㫌㫉㪀㪅 Mineral., 7, 429 - 438.

Results: I have obtained a new occurrence inside the Takamatsu crater in this study and then I have elucidated a new found that some small grains occur into the vein let in the whitish rocks on the surface of wall rock at Takamatsu Crater in this survey area. I have shown some pictures of the outline on outcrops in bellows that:: the first one is the whole view of outcrops in this study and those are changed whitish. The next one is the altered rocks containg small grains of natural zeolites by SEM. According to the analytical results using by XRD and SEM, we have obtained a zeolite minerals. Besides I have obtained some altered zeolites including a little different chemical contents of K- feldspar and so on.

P15 2011 PERC Planetary Geology Field Symposium

Sulfidic Deep Ocean Environment Reconstructed from 3.2Ga Black Shale Sequence in DXCL-DP, Pilbara, Western Australia. R. Sakamoto1*, S. Kiyokawa1, H. Naraoka1, M. Ikehara2, T. Ito3, Y. Suganuma4 and K. E. Yamaguchi5 1Department of Earth and Planetary Sciences, Kyushu University; 6-10-1, Hakozaki, Fukuoka, 812-8581, Japan. ([email protected]*, [email protected], [email protected] ) 2Center for Advanced Marine Core Research, Kochi University; 200, Monobe-otsu, Nankoku, Kochi, 783-8502, Japan. ([email protected]) 3Faculty of Education, Ibaraki University; 2-1-1, Bunkyo, Mito, Ibaraki, 310-8512, Japan. ([email protected]) 4National Institute of Polar Research; 10-3, Midori-cho, Tachikawa, Tokyo, 190-0014, Japan. ([email protected]) 5Department of Chemistry, Toho University; 2-2-1, Miyama, Funabashi, Chiba, 274-8510, Japan. ([email protected])

The 3.2 Ga Dixon Island - Cleaverville formations in with intermittent circulation of sea water. We also suggest the coastal Pilbara terrane, Western Australia, are among that highly 34S-enriched seawater sulfate had already ex- the best-preserved examples of Mesoarchean sedimentary isted in the Mesoarchean ocean (e.g., [4] and [5]). sequences [1]. The DXCL-DP (Dixon Island - Cleaver- We thank Dr. Arthur Hickman and Mr. Mike Doepel ville Drilling Project; [2]) was conducted in 2007 where for their help in conducting the DXCL-DP. We modern-weathering-free cores including black shale were acknowledge fininancial support from JSPS successfully recovered (DX, CL2 and CL1 in ascending (No.18253006, No.1434053). order and about 200 m in total length). Here we report the References: results of microscopic observation and geochemical anal- [1] Kiyokawa S. et al. (2006) GSA Bulletin, 118, 3-22. ysis for sulfur to reconstruct the deep ocean environment [2] Yamaguchi K.E. et al. (2009) Scientific Drilling, 7, in the Mesoarchean era. 34-37. These core samples include pyrite as laminae and tiny [3] Berner R.A. (1984) Geochemica et Cosmochemica crystal. Tiny pyrite crystals are divided into three mor- Acta, 48, 605-615. phological types; spherical, hollow, and filled types. [4] Kakegawa, T. and Ohmoto, H. (1999) Precam. Res. Based on microscopic observation, pyrite laminae are 96, 209-224. found to be composed of an aggregate of these pyrite [5] Yamaguchi K.E. (2002) Ph.D. dissertation, Pennsyl- crystals, where spherical-type pyrite crystals were over- vania State University. grown by pore-space filling pyrite (filled type). The sulfur content of black shale increases from 0.9 wt.% (DX) 1.8 wt.% (CL1) on average. The Corg/S ratios (by wt.%) range from 0.5 (CL1) to 1.7 (DX). Despite a few stratigraphic levels that have >2.0 Corg/S (organic carbon to sulfur) ratios, most of the samples in these three cores have Corg/S ratios < 1.0. Although S content of DX core is generally lower than that of the other cores, DX core has many thin pyrite laminae. On the other hand, CL1 and CL2 cores have few pyrite laminae but many disseminated fine-grained pyrite. Sulfur isotope compositions were measured for pyrite laminae and bulk black shale that include fine-grained pyrite. They range from –10.1 to +26.8 ‰ (relative to CDT) and randomly vary with stratigraphic height. High- ly 34S-enriched values are outstanding in the Archean S isotope record published to date. Based on these observations, we suggest the following scenario of sedimentary pyrite formation. Spherical-type pyrite crystallized syngenetically or during early diagene- sis. Those pyrite crystals likely formed in euxinic environments like Black Sea (e.g., [3]), as suggested by the relationship between their Corg and S contents. Such the environment is further supported by the S isotope evidence; The 34S-enriched pyrite is interpreted to have formed as a result of active sulfate reduction by bacteria in euxinic condition where utilization of sulfate was near complete and intense Rayleigh fractionation occurred

P16 2011 PERC Planetary Geology Field Symposium

Depositional age of the Mesoarchean strike-slip basins in the Cleaverville area, West Pilbara. Mami Takehara1, Shoichi Kiyokawa1, Kenji Horie2, Takashi Ito3, Minoru Ikehara4, Kosei E. Yamaguchi5, Ryo Sakamo- to1, Tomoaki Nagata1, Yuhei Aihara1 1Kyushu University (6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan), 2National Institute of Polar Research (10- 3, Midoricho, Tachikawa, Tokyo 190-8518, Japan), 3Ibaraki University (2-1-1, Bunkyo, Mito, 310-8512, Japan), 4Kochi University (200 Monobe Otsu, Nankoku, Kochi, 783-8502, Japan), 5Toho University (2-2-1 Miyama ,Funabashi-shi, Chiba, 274-8510, Japan).

The Mesoarchean Pilbara Coastal Greenstone belt is detrital zircon age, therefore, indicates that the D2 fault- located the northwestern part of the Pilbara Craton, ing occurred after about 3020 Ma. Western Australia. The Karratha Granitoid is overlain by oceanic island arc complex, which is composed of the References: mafic volcanic rocks, felsic volcanic-clastic rocks and [1] S. Kiyokawa et al., 2002, Tectonics, 21, 8-1-8-24. chert – black shale – BIF sedimentary sequence (the Re- [2] J. Smith et al., 1998, Precambrian Res., 88, 143-171. gal, Dixon Island and Cleaverville Formation). They [3] D. R. Nelson, 1998, Geol. Surv. of West. Aust., Perth. formed by the collision between continent and oceanic [4] S. Kiyokawa and A. Taira, 1998, Precambrian Res., island arc (D1) and deformed by strike-slip faulting (D2) 88, 109-142. (Kiyokawa et al., 2002). Ages of this area were reported as follows: the Kar- ratha Granitoid: 3261 ± 4 Ma and granite porphyry intrusive rocks: ca. 3020 Ma (Smith et al., 1998; Nelson, 1998; Kiyokawa et al., 2002). These intrusive rocks both truncated D1 structures and are deformed by D2 faulting. On the other hand, in the Cleaverville coast area, it well preserves lower metamorphosed rocks than around this area. The Cleaverville Formation is comformably overlain by the Lizard Hills Formation, which is composed of the 66 Hill and 44 Hill Member (Kiyokawa and Taira, 1998). The 66 Hill Member is accumulated along the Cleaverville Syncline, which is formed by D1 folding. In this area, the depositional age is reported ca. 3020 Ma (Nelson, 1998), which they expected to be the age of the uppermost part of the Cleaverville Formation. However, if the depositional age of the Cleaverville Formation was about 3020 Ma, the time span between the D1 and D2 would be so short that it is difficult to interpret the history of tectonic, erosion and stratigraphic evolution in this area. Here, in this study, we estimated depositional age of the strike-slip basins (red-colored sandstone of the 44 Hill Member) through the detrital zircon dating. Zircon grains of this sample were relatively angular and grain size was 50 – 150 m. In order to decide the analytical spots, we selected the sections that were less affected by alteration with the compositional images of the zircon grains. Using SHRIMPat National Institute of Polar Research, the diameter of primary beam was focused up to 10 m based on the available sections for analysis. As a result, about 20 grains of the total 61 grains were barely affected by Pb-loss and U-Pb system was preserved. U-Pb ages indicated that the 44 Hill Member includes two groups: (1) 3010 – 3030 Ma and (2) 3200 – 3280 Ma. The zircon grain’s shape showed that these prove- nances were relatively close to the basins. The ages of these two groups, group1 indicates the age of the Kar- ratha Granitoid and group2 the age of granite porphyry intrusion, respectively. Accordingly, 44 Hill Member’s zircons have a probability of being derived from these rocks. The D2 faulting occurred after the granite porphyry intrusive rocks became to expose on land surface. The

P17 2011 PERC Planetary Geology Field Symposium

Detail stratigraphic, magnetic, carbon isotope description of Komati section at the 3.2Ga Mapepe Formation in the Barberton Greenstone Belt, South Africa Shuhei Teraji1, Shoichi Kiyokawa1, Minoru Ikehara2 1Univ. Kyushu, 2Univ. Kochi

The Mapepe Formation is the lowermost part of the Fig Tree C-group: High k value (1.0~5.010-3 SI~70~42010-3 SI): Group in the Barberton Greenstone belt, and its sedimentary age boudinage red chert. Boudinage part has high k value. D-group: of single zircon U-Pb datings is 3260 to 3230 Ma (Kroner et al. Very high k value (15~3010-3 SI~70~42010-3 SI): red chert 1991). Our study area (Komati section) is located along the Ko- with iron bed. mati River near the border to Swaziland. This section preserved Summery: The Komati section of the Mappepe Formation pre- more than 300m-long continuous outcrop and consists of well- served well stratified record of the deep sea environments. 1) stratified sedimentary sequence with bedded chert and shale. We Well preserved bedded iron and shale sequence formed by black performed 1/100 scale geologic mapping to identify stratigraphic shale – iron rich shale and chert bed to the top. 2) Fine grain continuity. The Komati section is divided into 6 blocks (B1-, B2-, detrital matter with in shale increase to the top. 3) Iron matter C-, D1-, D2- and E-block) bounded by the deformed zones. gradually increase to the upper domain. Magnetic susceptibility Thickness of each blocks is 6.8m, 45m, 22.8m, 19m, 5.7m and also show similar pattern. 4) Carbon isotope well preserved de- 23m, respectively. Total thickness of the studied reaches 128m. cline carb from 25 to 30 par mil in middle part of 3 domains. The studied section may be divided into the following four rock These decline data is not related by lithologic changes. It might types. 1) massive white chert; 2-3 cm thick and partly boudinage. be show organic matter intensive activity during constant sedi- 2) red chert: laminated, red-colored bedded chert and white-red mentations. After decrease organic isotope data, iron matter chert. Most of them formed lamination bearing boudinage nodule. gradually increases to the top. Well laminated bed preserved 3) massive black shale (massive); partly greenish color shales. 4) following sedimentation signal. First organic matter (might be red-brown (Fe-rich) shale; highly weathered iron rich zone and cyanobacteria) grows at the surface of ocean. Organic matter partly preserved magnetite bed. In each block, the red-brown precipitated at the bottom of ocean floor. Cyanobacteria might be shale amounts to 60%, white chert 20%, and red chert and black produced oxygen to the surface. Oxidation occur of ferruginous shale 10%. Red chert is increasing and red-brown shale is de- matter and they precipitated above organic shale. Chert material creasing to the top at each block. The average thickness of B1 partly covered by silica matter at the surface of ocean. Origin of block’s black- and red-brawn- shale is 11mm and E block’s is silica may be supersaturated silica from hydrothermal water. This 17mm. cyclic laminated bed may be shown the record the iron sedimen- The total organic carbon of black shale is ranging from 0.01 to tation. Iron bed formed gradually and cyclically occurred during 16.12wt%, with an average of 2.68wt% (n=154). Carbon iso- cyanobacteria activity and oxidation iron matter at the ocean 13 toped delta C values of the black shale ranging between - surface. Shallowing upward and increasing black shale beds were 38.84per mil and -20.52per mil, with an average of 26.63per mil affected by producing from continental origin sediments and (n=154). nutrient matter to the top. Magnetic susceptibility (k) is measure of the degree of minerali- zation for a material in response to applied magnetic field. In this study, we measured magnetic susceptibility at two ways. 1) Ver- tical sections: total 128m thick whole stratigraphic at 3cm intervals. 2) Horizontal sections: totally 83 beds at 4m along in each bed. Vertical signal shows that the Magnetic susceptibility is increasing to the top in each block. Based on the horizontal variations of magnetic susceptibility, we divide into 4 groups; A- group: Low k value (0.110-3 SI~1.010-3 SI). It consists of black shale, red-brown shale and white chert. B-group: Medium k value (1.0~5.010-3~7010-3 SI): red chert and white-red chert.

P18 2011 PERC Planetary Geology Field Symposium

Buried Carbonate Breccias with Caves as Analogue to the Moon and Mars. Y. Miura Yamaguchi University and EUR-AIC University

Introduction: Time- and location-analyses of terres- proposed Takamatsu impact event about 15 million years trial analog of limestone blocks with buried and broken ago in present center of the Sea of Japan. Strong shock caves are inevitable for next planetary exploration on the wave energy to form Japanese islands (mainly western Moon, Mars and Venus. The main purpose of this paper part) makes transportation of buried Akiyoshi limestone is to elucidate terrestrial analog of buried and broken old blocks with deeper Cretaceous granite up to the surface to Karst limestone blocks with caves to apply the Moon and form caves followed by weathering. The Akiyoshi limes- Earth-type planets. [1-4]. tone rocks are remnants of stopped carbon cycle at the Akiyoshi limestones as terrestrial analog: The Permian end, and started again carbon cycle by followed Akiyoshido (cave) and Akiyoshidai (plateau) are located water process. at Mine-City, Yamaguchi Prefecture, western Honshu Planetary application of the Akiyoshi event: (main) Island in Japan (Fig.1a) as isolated large blocks. For next planetary exploration, the Akiyoshi limestone Age of Akiyoshi limestone is ca. 350Ma to 250Ma in breccias are significant as follows: 1) Original coral reef Paleozoic period as old blocks in young volcanic islands limestones are stopped and buried by impacts on sea- in Japan. The size is about 130 km2 (13,000ha) on plateau water to transport and lifted to the surface by impact to be of 200m to 400m in height. Among 450 limestone caves, weathered. These type breccias will be found with caves main Akiyoshido Cave is huge as 420,000 m3, long as on fluid-bearing planetary bodies of fluid-bearing interior. 10km length, and took 300,000 years to form recently on 2) Wide limestone blocks in U.S.A. (Carlsbad and Mam- present surface lifted from shallow interiors for ca. moth) formed regularly under sea-water, have few irregu- 335Ma to 235Ma absence at active Earth (Fig.1b). Karst lar feature which is found mainly on water Earth. tableland of the Akiyoshi district is a landscape topogra- Geological Map of Western part of Japan Oume phy formed by the dissolving of carbonate limestone or (b) Akiyoshi limestone blocks (crater) (a) Akiyoshi geological site marble by water, when surface or ground water becomes Permian limestone breccias weakly acidic and reacts chemically with atmospheric or Taishakukyo Atetsudai soil carbon dioxide. The Akiyoshi Karst liemstones are Akiyoshidai,-do (Yamaguchi) Granite found as caves, sinkholes (dolines), vertical shafts, disap- Plate movements

Hiraodai pearing streams, and springs, to complex underground MTL water system at present surface (same as Hiraodai). (Map: Geol. Survey of Japan, 1997) Reservoir of carbon-bearing cyclic system: (c) Akiyoshi limestone breccias (Karren) (d) Akiyoshi original site (before moving) Calcium carbonates (calcite or limestone) are considered to be main reservoirs of carbon in the water planet Earth. Original site of Akiyoshi limestone Total carbon content in global circulation system is blocks on shallow coral reefs 9 (350miilion years ago) 50,000GtC (Gt=10 t). Almost all carbon (i.e. 94% of car- (350 million years ago) bon) can be found in sea water, which suggests main cir- (cf. Univ. Chicago) culation system of CO2 including formation of limestone. Carbon content of atmosphere and land life is ca.750GtC and 2,200GtC, respectively. Rapid (short range) cyclic carbon through life organic compounds is only 61GtC. Fig.1. (a) Geological site of the Akiyoshi blocks. (b) The Carbon content of the Akiyoshi district showing “Karren Akiyoshi limestone block remained as crater-like feature. (a flock of sheep by impact breccias)” (Fig.1c) is esti- (c) Wide Akiyoshi breccias Karren. (d) Original site of mated from limestone as 42GtC. the Akiyoshi coral reefs near the Equator. New results of the Akiyoshi Plateau: The Akiyoshi limestones which have many fossils of Carboni- Summary: The results are summarized as follows: ferous to Permian Periods, were created in southern 1) Old limestones are stopped and buried by impacts to Equator about 350 million years ago (Fig.1d). As stop- transport and lifted to the surface by impact to form caves, ping sedimentation of the Paleozoic limestone in shallow which will be found with caves on other planetary bodies sea water, original Akiyoshi limestones were strongly if fluid phases are existed. 2) Wide and regular limestone broken to survive under crust ground (with old China blocks formed regularly under sea-water, are found blocks) by strong catastrophic event at the Permian end mainly on water-rich planet Earth. (ca. 250 million years ago) , where almost all sea living References: [1] Kaiho Y. et al. Geology, 29, 815- species (97%) were disappeared as large mass extinction. 818. [2] Miura Y. et al. (2004): LPI Contrib., 1197, After transporting to northern part of Asia with two Chi- #2150. [3] Miura Y. (2003): J.Yamaguchi Earth Sci., 50, na continents blocks (more than 5,000km), western part 13-18. [4] Miura Y. (2006): Akiyoshi Cave Plateau Field of the Honshu island of Japan was separated from big Guide (English), 1-16 (ICEM2006). [7] Miura Y. (2010): China continent where the Akiyoshi (and Hiraodai) li- LPI Contribution (AbSciCon, USA), CD#5398. mestone blocks are isolated to form the Sea of Japan by

P19 2011 PERC Planetary Geology Field Symposium

THE RADIATION HEAT BUDGET OF THE ANTARCTIC AND MARS POLAR REGIONS: COMPARATIVE ANALYSIS O.N. Abramenko1, I.A. Komarov1, V.S. Isaev1 Moscow State University, Faculty of Geology, Geocryological Department, 119991 Moscow, Leninskie Gory, bldg. 1. [email protected], [email protected], [email protected]

Introduction: The time and space radiation heat pat- by the heat transfer coefficient. The latter was assumed to terns have been investigated at five polar Antarctic sites be 2–5 W/(m2*K) proceeding from empirical data (Novolazarevskaya, Molodezhnaya, Bellinshausen, Mir- obtained in laboratory at pressures and temperatures ny, and Vostok). Similar variability appears in data from typical of the Mars high latitudes [5]. The heat spent for Mars polar ice caps. The reported comparative analysis sublimation (ablimation) of CO2 or H2O ice was evaluated allows evaluating the contributions from different ther- from mean annual values of the process intensity obtained mophysical components of the radiation heat budget in the using GMCD. The CO2 and H2O ice sublimation heat was Antarctic and Mars high-latitude regions. estimated with regard to its temperature dependence [6]. Discussion: The study has focused on comparing The heat flux from the surface to the ice was calculated as quantitative and qualitative parameters that represent the a solution to the thermal conductivity differential equation radiation heat budget in Antarctica and in polar Mars. at the respective boundary conditions. The models Mars is a planet with a thin atmosphere, a thick cryos- included a two-layer section for the northern ice cap and a phere, and permanent ice caps at both poles. On the Earth, three-layer section for the southern cap [7]. it is the Antarctic that is similar to the Mars high-latitude Conclusions: The components of the radiation heat regions. The inventory consisted of the following data: budget in the Earth’s Antarctic and Mars’s high latitudes (1) long-term average solar flux during selected observa- demonstrate qualitatively similar patterns, but there is tion periods (at clear sky, with cloud amounts less than 2, some difference in their magnitudes. Namely, backscat- and at up to 10); (2) statistically processed data on tered and absorbed radiation is slightly lower on Mars monthly and yearly totals of the radiation budget compo- than at the Antractic Novolazarevskaya site. Unlike the nents;(3) statistically processed data on monthly and year- Earth, the Mars surface temperature is due mostly to beam ly totals of direct beam solar radiation at normal incidence solar heat rather than atmospheric heat transport. As a result, the temperature may be locally 272 K while the and atmospheric clearness index . rd mean of the north ice cap periphery in the early summer is As part of the 53 Russian Antarctic Expedition, 235 K (Ls = 90°, where Ls is solar latitude). Generally, one of us [1] set up a test station at the Novolazarevskaya the mean diurnal air temperature at 5 m above the Mars site, in the Schirmacher oasis located 80 km far from the surface varies through a year from 143.1 to 249.9 K on northern Antarctic coast in the central Queen Maud Land. the southern ice cap and from 147.8 to 230.4 K on the The objective was to test the method for measuring the northern cap. According to our estimates of the perma- surface heat budget, to monitor the temperature, the ther- frost thickness and the Mars cryosphere as a whole, the mal conductivity, and the thaw depth. The annual temper- permafrost is from 1000 m thick at the equator to 3600– ature cycles were monitored with loggers which were 3750 m at the polar caps [7]. The mean thickness of courtesy of the Fairbanks University (Alaska, USA). The frozen ground is 2300 m, which is greater than the test station was operated within the limits of the CALM terrestrial mean. The total ice volume in a 2300 km thick program (Circumpolar Active Layer Monitoring) [2]. spherical layer (the Mars outer radius being 3394 km) is The time and space patterns of the surface radia- (0.4–2.0)*108 km3, as estimated by different authors, tion heat budget components in the Mars polar regions which is about two orders of magnitude more than the were investigated using the Global Mars Climate Data- total volume of the polar ice caps. base produced jointly by Laboratoire de Météorologie Dynamique du CNRS (LMD, Paris) and Atmospheric, References: [1] Abramenko O.N., 2009. Methods for Oceanic and Planetary Physics, Department of Physic investigating the surface radiation heat budget compo- (AOPP, Oxford University, Oxford, England UK) [3]. nents and thaw depths in Schirmacher oasis (Antarctica). The ranges of annual reflected radiation generally Vestn. MGU, Ser. 4, Geol., No. 4, 67–69. [2] Brown J., for the Mars high latitudes are 414–750 W/m2 for the Hinkel K.M., Nelson E.F., 2000. The Circumpolar Active northern ice cap and 532–840 W/m2 for the southern ice Layer Monitoring (CALM) program: research designs and cap. The absorbed radiation ranges, respectively, as 658 initial results. Polar Geogr., 24 (3), 165–258. [3] The to 2016 W/m2 and from 702 to 1539 W/m2. The radiation global Mars Climate Database. (http://www- data for the northern and southern polar regions were mars.lmd.jussieu.fr/). [4] Budyko M.I., 1956. Heat Budg- processed on a space grid for the coordinates 90°, 86.2°, et of the Earth’s Surface [in Russian]. Gidrometeoizdat, 82.5°, 78.8°, 75° N and S; 135°, 90°, 45°, 0° W and 45°, Leningrad, 256 pp. [5] Lebedev D.P., Perel'man T.L., 90°, 135°, 180° E to analyze annual cycles of the surface 1973. Heat and Mass Transfer in Vacuum Sublimation [in and atmospheric infrared radiation, absorbed and reflect- Russian]. Energiya, Moscow, 336 pp. [6] Komarov I.A., ed radiation, and mean monthly surface temperatures. The 2003. Termodynamics and Heat-and-Mass Transfer in radiation heat budget components were calculated with an Permafrost [in Russian]. Nauchnyi Mir, Moscow, 603 pp. equation used to process the Earth’s ground surface data [7] Komarov I.A., Isaev V.S., 2010. The Crylogy of Mars [4]. Turbulent heat transfer was found as the surface-air and other Planets of the Solar System [in Russian]. temperature difference (according to GMCD) multiplied Nauchnyi Mir, Moscow, 232 pp.

P20 2011 PERC Planetary Geology Field Symposium

Coastal boulder deposits as a possible terrestrial analog for planetary geology K. Goto1, G. Komatsu2,1, Y. Iijima3, K. Minoura3, 1 Planetary Exploration Research Center, Chiba Institute of Technol- ogy (2-17-1 Tsudanuma, Narashino, 275-0016 Chiba, Japan; [email protected]), 2IRSPS, Univ. G.d’Annunzio (Viale Pindaro, 42 65127 Pescara, Italy; [email protected]), 3Dept. of Earth Science, Tohoku Univ. (6-3, Aramaki Aza Aoba, Sendai, Miyagi 980-8578, Japan; [email protected], [email protected] )

Introduction: A large volume of data is now avail- ciently high to displace meter-scale boulders according to able for sedimentary research on Mars. The spatial reso- the terrestrial examples [12]. lution of the images obtained from the High Resolution HiRISE imageries revealed that the surface of the Imaging Science Experiment (HiRISE) reaches up to ap- northern lowlands, which is called as the Vastitas Bore- proximately 25 cm/pixel [1]. This resolution is sufficient alis Formation (VBF), are filled with ~2 m size boulder to recognize boulders-size clasts (>25.6 cm) on the Mar- deposits [1]. The boulders are concentrated around circu- tian surface, which might have been deposited through lar structures of probable impact origin, but they are pre- various processes such as meteorite impacts, slope fail- sent over most of the VBF with uniform densities [1]. ures, and hydrological activities [e.g., 1, 2]. Thus, boulder Although the origin of the VBF is still controversial, we deposits on the Martian surface can be an important fu- infer that presence of boulders does not necessarily con- ture sedimentological research target. tradict the paleo-ocean hypothesis, since they could have Boulders deposited by hydrological activities such as been reworked by the impact-generated tsunamis. flood [3, 4] and wave activities [5] are well studied on Earth, and are considered as important flow indicators. In fact, several inversion methods allow us to estimate the flow condition (e.g., flow direction and hydrodynamic force) from boulder deposits. In this study, we review sedimentary features of coastal boulders deposited by storm waves and tsunamis, which have not been recognized as a terrestrial analog for planetary geology.

Coastal boulders on Earth: Storm waves and tsunamis can cast ashore huge boulders of more than hun- Figure 1. Imbricated storm wave boulder deposit at the dred tons in weight on Earth (Fig. 1) [5]. Because of the Amami-Oshima Island, Japan. The scale bar is 4 m long. difference of wave periods of the storm wave and tsunami, the difference in transport distance of boulders are useful criteria to discriminate them [5]. Grain size distribution of boulders deposited by the storm waves shows exponen- tially fining landward trends due to the exponential decrease of the wave force. Such boulders sometimes show imbrication features (Fig. 1). On the other hand, tsunami boulders are scattered in wide area without systematic grain size or spatial distributions, because such boulders are displaced and transported by one or a few largest waves which are insufficient to create systematic distribution of boulders. Figure 2. HiRISE image of the Vastitas Borealis Forma- tion (VBF) (Image: NASA/JPL/University of Arizona: Implication for Martian paleo-oceans: Northern TRA_000846_2475). lowlands of Martian surface may have been once occupied by large bodies of water, and candidate paleo- Reference: [1] McEwen A. S. et al. (2007) Science, 317, shorelines have been presented based on geomorphologi- 1706–1709. [2] Howard A. D. et al. (2007) LPSC cal and sedimentological features [e.g., 6], although criti- XXXVIII, Abstract #1168. [3] Baker V. R. (2009) Annu. cisms still remain [7]. If paleo-oceans indeed have existed, Rev. Earth Planet. Sci., 37, 393-411. [4] Kehew A. E. et tsunamis generated by meteorite impacts into the oceans al. (2010) Global Planet. Change, 70, 64-75. [5] Goto K. [8, 9, 10] might have affected the paleo-coastal zones and et al. (2010) Earth Sci. Rev., 102, 77-99. [6] Parker T. J. left geomorphological and sedimentological features such et al. (1989) Icarus, 82, 111–145. [7] Ghatan G. J and as reworked boulder deposits. Zimbelman J. R. (2006) Icarus, 185, 171–196. [8] Matsui Iijima et al. [11] conducted numerical modeling of im- T. et al. (2001) LPSC XXXII, Abstract #1716. [9] Dohm J. pact-generated tsunami on Mars with an assumption of a M. et al. (2009) Planetary and Space Science, 57, 664- 50-km-diameter impact crater formed on the ocean floor. 684. [10] Mahaney W. C. et al. (2010) Planet. Space. Sci., According to their results, the maximum velocities are 58, 1823-1831. [11] Iijima Y. et al. (2011) PERC Planet. high near the shorelines (>12 m/s). This velocity is suffi- Geol. Field. Symp., this volume. [12] Goto K. et al. (2010) Mar. Geol., 268, 97-105.

P21 2011 PERC Planetary Geology Field Symposium

Spatio-temporal changes in distributional pattern of erosional marks on solutional substrate Mayuko YUMI1 and Yoshiro ISHIHARA2 1Fukuoka University ([email protected]) for first author, 2Fukuoka University ([email protected]).

Introduction: Various erosional marks or features, Result and discussion: In the present study, the such as thumb marks and thumb prints on meteorites and dimensions of erosional marks (depth, length, and width) tektites [1], [2], flute and groove marks on the base of changed with a change in the flow velocity and geometry sediment-gravity flow deposits [3], [4], and flute marks of erosional marks, and the distribution pattern of ero- and scallops on the walls in limestone caves [5], are ob- sional features varied with a change in the duration of the served on solutional- or erosional-substrates on the earth’s experiments. When the flow velocity of water flows is surface. Although these erosional marks or features have a high, the dimensions of erosional features are small and wide range of sizes and forms, the general features of the- the features have relatively irregular forms. The change in se marks are parabolic on a plain surface; the cross sec- the length of the marks brought about by a change in the tions of these parabolic forms have two sides that are flow velocity is higher than the changes in the width and steeper than the other side. Because the cross-sectional depth of the marks. The geometries of the erosional fea- asymmetry of these erosional marks indicates the paleo- tures resemble one other when the water flow has a high current direction, these marks are very useful tools in the flow velocity, and the marks are distributed closely when fields of geology and speleology [6], [7], [8], [9]. the duration of the experiments is long. The duration of The study of geometry of these marks and fluid me- this transformation changes with a change in the flow ve- chanics with formative process of them have been carried locity, i.e., a high flow velocity induces a fast transfor- out in experimental, especially on cave scallops and flute mation. These results suggest that the erosional features marks under sediment-gravity flow deposits [10], [11], that are exposed to the flow for a sufficient duration, or to [12]. In these studies, the cross-sectional size of the marks a high flow velocity of the water flow, exhibit a relatively changes with a change in the fluid velocity or water tem- regular form and distribution, whereas the substrates that perature; further, the classification of the plan view of the are exposed to the flow for an insufficient duration, or to a marks formed on the plain surface is discussed [10], [11], low flow velocity, exhibit irregular forms and distribu- [12]. Moreover, the study of the marks in terms of fluid tions. In addition to the dimensions of the erosional marks mechanics suggests that the factors that control the geom- [12], the distribution and geometry of the erosional marks etry of the marks are the flow velocity, dissolution rate, may help to estimate the flow velocity and the duration of molecular diffusivity of the substrate, and rate of dissolu- the flow that form these marks. tion [13]. The distribution pattern of these marks in the Acknowledgements: This research was partially plan view also changes with a change in the flow velocity supported by the Grant-in-Aid for Scientific Research (C) and the size of the concave region of the marks [10]. A (No. 21540476), Japan Society for the Promotion of Sci- previous study [10] suggests that the differentiation of the ence. distribution pattern reflects the states of the flow (laminar References: [1] Baker, G. (1959) Mem. Nat. Muse- or turbulent flows). From these studies, it is suggested that um, 23, 1-313. [2] Williams, D. T. (1959) Smithsonian the distribution of the marks is closely related with the Contr. Astrophys., 3, 47-67. [3] Kuenen, P. H. (1957) J. flow velocity and the flow states. Further, the temporal Geol., 65, 231-258.[4] Dzulynski, S. and Walton, E. K. development of the distribution pattern of the marks is not (1965) Sedimentary Features of Flysch and Graywackes. clear because the experiments in the previous study main- 274 pp. [5] Curl, R. L. (1966) Trans. Cave Res., 7, 121- ly focused on a single erosional mark and not the devel- 160. [6] Bretz, J. H. (1942) J. Geol., 50, 675-811. [7] opment of patterns. Experimental studies also reveal the Coleman, J. C. (1945) Geol. Mag.,82, 138-139. [8] Cole- steady state of erosional marks under ideal conditions; man, J. C. (1947) Proc. Speleol. Soc., 6, 57-67. [9] Ford, however, erosional marks in the field vary in terms of the D. C. and Williams, P. (2007) Karst Hydrogeology and size, geometry, and distribution pattern, especially the Geomorpholog. [10] Allen, J. R. L. (1971) Sediment. marks on the same erosional surfaces. In this study, we Geol., 5, 167-385. [11] Goodchild, M. F. and Ford, D. C. conduct an experimental study of erosional marks by con- (1971) J. Geol., 79, 52-62. [12] Curl, R. L. (1974) Bull. trolling the flow velocity and the duration as well as the Nat. Speleo. Soc. 36, 1-5. [13] Blumberg, P.N. and Curl, spatio-temporal pattern of the erosional marks. R. L. (1974) J. Fluid Mech., 65, 735-751. Method: In this study, we use an experimental flume having a length of 3.0 m, depth of 0.3 m, and width of 0.07 m. The substrate forming the marks is plates made of plaster (plaster was also used in the previous studies [10], [11], [12], [13]). The water flowing in the flume is inter- changed with fresh water at periodic intervals in order to avoid the saturation of gypsum. The temporal develop- ments of the marks are obtained by pictures taken at regular intervals.

P22 2011 PERC Planetary Geology Field Symposium

Trial to Make Ramparts: Granular Flow Model of Fluidized Ejecta on Mars. K. Wada1 and O. S. Barnouin1, 2 1Planetary Exploration Research Center, Chiba Institute of Technology, Japan ([email protected]), 2Affiliation The Johns Hopkins University Applied Physics Laboratory, Laurel, MD.

Introduction: Ejecta deposits of Martian craters rolling due to the grain angularity, expressed by a critical show evidence for extensive surface flow not typically rolling displacement. As an initial condition of our DEM seen at other craters on the Moon and Mercury. The exact calculations, we consider a 5-degree wedge of an ejecta mechanism for why such surface flow occurs remains curtain composed of 2958 grains with a radius of 35 m, unclear, but it must be indicating some unique surface each traveling on ballistic paths prior to deposition. This environmental condition. Typically fluidizing agents such initial condition was obtained by using the ejecta scaling as water or an atmosphere have been proposed to be re- relationship[9, 10], assuming a transient crater with a ra- sponsible for the formation of these deposits [e.g., 1-5]. dius of ~5 km. Simple granular flows can explain a wide range of Results and discussion: By introducing rolling flow features at landslides including their long run-out resistance in our granular flow model, we have succeeded distance and lineaments, without necessarily invoking any in stopping ejecta motion effectively (Fig. 1). However, volatiles [e.g., 6]. They might also explain fluidized depo- we have not yet succeeded in making an obvious rampart. sits, with their long run-out, circumferential lineaments, This may be due to other simplification of our model such thin deposit layers, and ramparts, also without necessarily as the small number of grains considered, and their fairly invoking any volatiles or an atmosphere. In order to in- large size. Secondary cratering of the surface material and vestigate simple granular flow models for such ejecta de- their subsequent flow might also play a role. Further stu- position, we use the three dimensional distinct element dies will explore all these factors. method (DEM)[7]. This method calculates the motion of each individual ejecta grain, taking into account mechanical interactions between grains. Our initial study [8] showed that the surface condition is important: smooth plains with a low coefficient of friction, or readily erodible plains can produce long run-out ejecta flow. Such smooth or readily erodible martian surfaces could be the result of sedimentary processes associated with large amounts of water that existed on Mars. While our initial model showed that ejecta surface flow was fairly easy to achieve, it possessed too many simplifications that did not permit the formation of ramparts at the distal end of the ejecta deposits. One of the obvious simplification was that all the grains in our model were true spheres without any rolling resistance. As a consequence, grains kept rolling on flat surfaces even if the surface had a finite friction [8]. A necessary condition to make a rampart is that the distal ejecta must stop ad- vancing. In the DEM, this implies giving the ejecta grains rolling resistance that reflects their natural angularity. Figure. 1: Side views and top views of deposited ejecta (400 This study, thus, investigates how giving ejecta grains sec after the start of the calculation) for the cases of (a) roll- rolling resistance in the DEM might generate ramparts, ing resistance included (the rolling resistance parameter dcrit = 0.5) and (b) without rolling resistance (d = 0). and impact the overall emplacement and flow of granular crit ejecta. Numerical method and settings: In our DEM References: [1] Carr M. et al. (1977) JGR, 82, model, the mechanical interaction forces and torques be- 4055–4065. [2] Mouginis-Mark P. (1979) JGR, 84, tween spherical grains in contact (and the floor) are ex- 8011–8022. [3] Schultz P. H. and Gault D. E. (1979) JGR, pressed by the Voigt-model, which consists of a spring 84, 7669–7687. [4] Barnouin-Jha O. S. and Schultz P. H. and dash-pot pair, in both normal and tangential direc- (1996) JGR, 101, 21,099–21,115. [5] Baloga S. M. et al. tions. The spring gives elastic forces based on the Hert- (2005) JGR, 110, E10, E10001. [6] Campbell, C. S. et al. zian elastic contact theory. The dash-pot expresses energy (1995) JGR, 100, 8267–8283. [7] Cundall P. A. and dissipation during contact to realize energy dissipation Strack O. D. L. (1979) Geotechnique, 29-1, 47–65. [8] with a given coefficient of restitution. For the tangential Wada K. and Barnouin-Jha O. S. (2006) MAPS, 41, direction, a friction slider is introduced to express Cou- 1551–1569. [9] Housen K. R. et al. (1983) JGR, 88, lomb's friction law with a given coefficient of friction. In 2465–2499. [10] Maxwell D. E. (1977) in Impact and this study, we introduce a rolling resistance between Explosion Cratering, 1003–1008. grains (and also the floor), which models the difficulty of

P23 2011 PERC Planetary Geology Field Symposium

Role of Yield Stress Fluid in Planetary Geology Aika Kurokawa1 and Kei Kurita2 Earthquake Research Institute, University of Tokyo ([email protected], 2 [email protected])

Introduction: Magmatic lava is characterized by C) Viscosity vs. Temperature (Thermogel350) various degrees of mixture of contrasting components such as silicate melt, crystals and bubbles. Due to this nature the flow behavior becomes complicated. Particularly in the increasing fraction of crystals the lava changes from liquid to solid. During this course emergence of yield stress is a key. The yield stress is an important factor to control the morphologies of lava flow, by which planetary remote sensing can estimate the nature of lava (ref. 2). Viscosity of the suspension (concentration of 2.0wt%) at In this presentation we report rheology of Thermogel, shear rate of 0.4 is shown as a function of temperature. mostly focusing on how the yield stress emerges by Viscosity decreases greatly in the range 27 - 31. changing concentration and temperature. Aqueous suspension of Thermogel is an analogue material of lava. D) Size vs. Temperature (Thermogel350) Thermogel in the suspension shrinks its volume above the transition temperature, which drastically changes the volume fraction of solid phase. We investigate the yield stress in relation to the jamming transition.

Results: A) Shear Stress vs. Shear Rate (Thermogel400)

The size of Thermogel particle was measured by the light scattering method, which exhibits drastic change between 25 - 30 .

Discussion: From Figure C) and D) the rheology is shown to be sensitive to the volume fraction of the gel. The emergence of yield stress corresponds to the Shear stress decreases with temperature at the same shear transition from low viscosity to high viscosity regime. rate. The suspension behaves as Newtonian fluid at high Since viscosity and yield stress are controlled by the size temperature and as non-Newtonian fluid at low of Thermogel particle, this suggests the change is related temperature. At lower temperatures shear-thinning nature to the jamming transition. The physical process that some becomes evident. materials such as particles, foams aggregate with increasing density is jamming. Then the material behaves B) Yield Stress vs. Concentration (Thermogel400) as solid. In our case, it would happen because Themogel particles become large by absorbing water. Among characteristic morphologies of lava flow levee structure is known to be sensitive to yield stress of flowing material. Since the emergence of yield stress is mostly controlled by volume fraction of solid phase shown in this research, existence/non-existence of levee structure can constrain the crystal concentration of the lava. We evaluated yield stress by fitting the Hershel Bulkley If we specify the boundary between solid and liquid in model to the relation between shear stress vs. shear rate. lava flow and how lava flow is affected by yield stress The figure shows the yield stress as a function of the fluid, we would have a much better understanding of concentration of Thermogel around transition temperature. volcanic landform. Thermogel would be a useful It is clear that yield stress increases with a rise in analogue to magmatic lava in analyzing lava flow. concentration of the gel. References: [1] Peder C. F. Møller, Jan Mewis and Daniel Bonn (2006) Soft Matter, 2006, 274-283. [2] J. Vaucher, D. Baratoux, M.J. Toplis, P. Pinet, N. Mangold, K. Kurita (2009) Icarus, 200, 39-51

P24 2011 PERC Planetary Geology Field Symposium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±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±/DWH 'HYRQLDQ SLOORZ UHVXOWV RI PLQHUDORJLFDO DQG JHRFKHPLFDO DQDO\VHV RI D EDVDOWVDQGLQWHUSLOORZEUHFFLDIURP*HUPDQ\FRQVLVWRI ILODPHQWRXVFU\SWRHQGROLWKLFFRPPXQLW\LQDSUH-XUDVVLF FKDPRVLWHLOOLWHDQG7L2PLQHUDOVWKDWPD\LQLWLDOO\KDYH EDVDOWLFVDPSOHIURPWKHORZJUDGHPHWDPRUSKRVHG-XUDV EHHQ RYHUJURZQ E\ LOOLWH HJ >@ IROORZHG E\ WKH GH VLF 1RUWKHUQ &KLFKLEX %HOW DQ DFFUHWLRQDU\ FRPSOH[ LQ FRPSRVLWLRQ RI RUJDQLF PDWWHU DQG ODWHU LQILOOLQJ RI ILOD FHQWUDO6KLNRNX-DSDQ PHQWRXVPROGVE\ FKDPRVLWH DQG VXUURXQGLQJ LOOLWH 7KH *HRORJLF2XWOLQH7KHDFFUHWLRQDU\FRPSOH[RIWKH @7KHERXQG)HVXEVHTXHQWO\ LVFKDUDFWHUL]HGE\SHOLWLFPpODQJHWKDWFRQWDLQVEORFNVRI VHUYHV DV D QXFOHDWLRQ VLWH IRU WKH SUHFLSLWDWLRQ RI PRUH JUHHQVWRQH FKHUW OLPHVWRQH EDVDOW DQG VDQGVWRQH 7KH FRPSOH[DXWKLJHQLFPLQHUDOVLQFOXGLQJFKDPRVLWH0DQ\ SUHVHQWGD\PLQHUDOL]LQJEDFWHULDDUHFKDUDFWHUL]HGE\WKH SHOLWLF PpODQJH LQ WKLV DUHD KDV EHHQ VXEMHFWHG WR PHWD SURGXFWLRQ RI HDUO\VWDJH )HULFK FU\VWDO JUDLQV >@ 7KH PRUSKLVPRIWKHORZHUSUHKQLWHWRSXPSHOO\LWHIDFLHV>@ @)XUQH+HWDO 3UHFDPEULDQ DQGį2YDOXHVDUHEHWZHHQ±ÅDQG±Å7KH 5HV ± >@7VXML 7 6DNDNLEDUD 0 į&YDOXHVRIFDOFLWHDUHORZHUWKDQWKHYDOXHVREWDLQHG -*HRO6RF-DSDQ>@6DNDNLEDUD0 IRUFDOFLWHWKDWJUHZGXULQJPHWDPRUSKLVPRIWKH1RUWK HWDO -0HWDPRUSKLF*HRO>@7KRUVHWK, HUQ&KLFKLEX%HOW>@ +HWDO (DU 3ODQ6FL/HWW±>@3HFN 'LVFXVVLRQ 7KHPLQHUDORJLFDOSHWURJUDSKLFDODQG JHRFKHPLFDO GDWD LQGLFDWH WKDW WKH ILODPHQWV ZLWKLQ WKH PDQQ-HWDO *HRELRORJ\±>@.RQKDXVHU LQWHUVWLWLDO PDWUL[ RI WKH @)RUWLQ'HWDO $PHU0LQHUDO±

P25 2011 PERC Planetary Geology Field Symposium 0LFURELDOWUDFHIRVVLOVGLVFRYHUHGIURPDOWHUHGEDVDOWLFJODVV,PSOLFDWLRQVRIHDUWK DQDORJVWXG\IRUDVWURELRORJ\RQ0DUV +6XJDZDUD06DNDNLEDUD0,NHKDUD-6/DLUG *UDGXDWHVFKRRORI6FLHQFHDQG(QJLQHHULQJ(KLPH8QLYHUVLW\%XQN\RFKR0DWVX\DPD(KLPH-DSDQ &HQWHUIRU$GYDQFHG0DULQH&RUH5HVHDUFK.RFKL8QLYHUVLW\%0RQREH1DQNRNX.RFKL±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±0LGGOH 3HUPLDQ ,EDUD RSKLROLWH >@ RI WKH 0DL]XUX ORK\DOLFKQXVYXOJDULVLVSUHVSHFWLYHO\EDVHG RQ WKH V\V WHFWRQLFEHOWVRXWKZHVW-DSDQLQFOXGLQJWKHLUPRUSKRORJ\ WHPDWLFLFKQRWD[RQRP\>@ DQG SHWURJUDSK\ DQG WKH UHVXOWV RI DQDO\VHV RI FDUERQ 7KH ǻ &3'% YDOXHV ORZHU WKDQ ±Å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±SXPSHOO\LWH 7KLV UHVXOW VXJJHVWV LQ WXUQ WKDW WKH & ZDV SURGXFHG E\ IDFLHV DQGLQ]RQH,, SUHKQLWH±DFWLQROLWHIDFLHV PLFURELDO DFWLYLW\ DQG UHPDLQHG DW WKH ULP RI WKH WXEH 'HVFULSWLRQ RI PLFURELDO WUDFH IRVVLOV *UDQXODU 3KRVSKDWHPLQHUDOVZLWKLQWKHWXEHPD\DOVR KDYH RULJL PLFURELDO WUDFH IRVVLOV RFFXU DV LUUHJXODU FOXVWHUV ZLWKLQ QDWHGIURPPLFURELDODFWLYLW\=LQFLVNQRZQWREHPREL YHLQVDQGDORQJIUDFWXUHZDOOVZLWKLQDOWHUHGEDVDOWLFJODVV OL]HGE\ELRVRUSWLRQDFFXPXODWLRQRUELRSUHFLSLWDWLRQ>@ 7KH\DUH ȝPLQGLDPHWHUDQGFRQVLVWRIWLWDQLWH7XE DQGWKHUHODWLYHO\KLJKFRQFHQWUDWLRQVRI=QLQWKHWXEXODU XODUPLFURELDOWUDFHIRVVLOVRFFXUDORQJIUDFWXUHZDOOVDQG PLFURELDOWUDFHIRVVLOVPD\LQGLFDWHPLFURELDODFWLYLW\ LQ YHLQV ZLWKLQ DOWHUHG EDVDOWLF JODVV DQG DUH ȝP 2YHUDOOWKHUHVXOWVVXJJHVWWKDWPLFURELDOWUDFHIRVVLOV ZLGH DQG ȝ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± >@.RLGH < PHWDEDVDOW URFN ZHUH DQDO\]HG E\ PDVV VSHFWURPHWHU WR -RXU *HRO 6RF -DSDQ >@ $OW GHWHUPLQHWKHLUǻ &3'%YDOXHV7KHUHVXOWDQWYDOXHVYDU\ -& 0DWD3 (DUWK3ODQHW6FL/HWW± IURP ±Å WR Å DQG RI WKH VDPSOHV \LHOG >@ 7KRUVHWK ,+HW DO D &KHP *HRO ǻ &3'%YDOXHVORZHUWKDQ±Å7KHVHUHVXOWVLQGLFDWH ±>@)XUQHV+HWDO E &KHP*HRO WKDW EDFWHULDO DFWLYLW\ RFFXUUHG SULRU WR WKH IRUPDWLRQ RI ±>@6XJDZDUD+HWDO $EVW-DS*HRVFL WKHYHLQVDQGSRROV>@ 8QL%%*3>@*DGG*0 0LFURELRO (OHPHQWDOPDSSLQJDQDO\VLV(OHPHQWDOPDSSLQJ RI D WXEXODU PLFURELDO WUDFH IRVVLO ZDV SHUIRUPHG E\ 6(0±('6 DQG PLFUR3,;( 7KH 6(0±('6 DQDO\VLV UHYHDOHGORFDOFRQFHQWUDWLRQVRI&ZLWKLQWKHWXEHDQGDW LWVULP7KHFRQFHQWUDWLRQVRI&ZLWKLQWKHWXEHVKRZSRV LWLYHFRUUHODWLRQVZLWK6L$ODQG.ZKHUHDVWKH&FRQ FHQWUDWLRQV DW WKH ULP VKRZ QR VLJQLILFDQW FRUUHODWLRQV

P26 2011 PERC Planetary Geology Field Symposium

Formation of Active Carbohydrate Oligomers in High Temperature Environments. Y. Miura Yamaguchi University and EUR-AIC University

Introduction: Carbohydrate with C,H and O ele- Nitrogen-bearing compounds by shock wave: ments are significant at dynamic cyclic system of water- Miller (1953)[6] synthesized nitrogen-bearing amino- and air-planet with life activity. Polymerization of or- acid from inorganic compounds by shock wave energy of ganic carbohydrates which are called as supramolecules spark energy in localized laboratory. Similar organic ni- of oligomers [1] are inevitable to form high molecules of trogen-bearing compounds can be formed by natural active life. However narrow range of re condition to form shock wave energy of thunder storm, volcanic eruption, monomer to oligomer should be discuss in natural envi- hydrothermal vent in deep sea, asteroids or cosmic ray ronments. bombardments on ocean water. The main purpose of the present paper is to elucidate However it takes long time to form anaerobic bacteria natural environments of polymerization as oligomers. for chemical evolution. First life on primitive Earth and Formation of active carbohydrates struc- Mars (or Venus) is considered to be formed by tiny ture: Miura (1994, 1996, 1997) [1–4] reported that RNA/DNA organisms of nitrogen-bearing compounds in some carbohydrate (CH2O)n show oligomers and that large amounts of active carbohydrate solution with higher lactic acid (C3H6O3) reveals SO3 organic oligomer struc- temperature. The difference in amounts between large ture {(C3H6O3) z} with characteristic biological activity carbohydrates and small nitrogen-bearing organic com- as supramolecule [1] (n and z as integer). The ring crys- pounds results in long history of about 1 Ga to form life- talline structure can duplicate it to polylactic acid [3-5]. precursors of prokaryotic cell on primordial Earth and This indicates that primitive copying process are suitable Mars (or Venus). environments to form polymerization from monomer to Cyclic process of carbon-bearing materials: From oligomers or polymers before establishing duplication recycle system of carbon-bearing materials on the Earth, process such as the RNA or DNA complex of life activi- the constituent organic compounds of life-materials are ty. considered to be one material state of the various com- Active oligomers at high temperature: The SO3 pounds between inorganic and organic compounds ex- molecules can be synthesized at laboratory strictly under pressed by equation (1). In this sense, supramolecules of acid liquid condition and high temperature of 180°C. This lactic acid oligomers SO3 are significant intermediates to suggests that active carbohydrates oligomers can be produce enzyme-like activity on the Earth and Mars (or formed widely on primitive seawaters on the Earth and Venus). As sea-water and atmosphere of planets which Mars (or Venus) with higher temperature induced by are inevitable for recycle system of carbon-bearing mate- strong shock wave energy (such as volcanism, earthquake rials between inorganic and organic compounds cannot and ocean meteoritic impact) [3-5]. exit for long geological history, then chemical evolution Large amounts of synthetic SO3 are formed from L- required for producing life-complex from prokaryotic (in lactic acid monomer with inert gas of nitrogen, rapid stir- anoxic environments) to eukaryotes (in oxygen-rich envi- rer (360 rpm) and with 180°C for 10 h. After cooling the ronments) cells is considered to be main process on pri- molten solution , the fractions of lactic acid oligomers are mordial planetary surface [5]. measured by the proton-NMR (H¬NMR), high perfor- Space exploration of carbon-bearing fossils: mance liquid chromatography (HPLC), and field- Light elements of carbon-hydrogen-oxygen-nitrogen desorption mass spectrometry (FD-MS) to obtain the po- organisms can remain as fossils of carbonates, phos- lymerization indices (z) of the oligomers [3-5]. phates ,oxides or sulfides in anoxic primordial environ- Two types of the oligomer were obtained as a closed ments by secondary reaction. In fact, nano-grains with ring CR (C3H4O2)z, and an open chain OC {(C3H4O2)z- carbon-bearing materials are observed as remnants of H2O]. Computer program CHEM3D indicates that z=5 dynamic reactions by high-resolution electron microsco- oligomers have a zig-zag ring structure CR with a large py [7]. Such materials are obtained at next space explora- cavity , or chain feature OC, and that the z=11 oligomers tion by in-situ observation and /or sample collection me- have a C-shaped curled ring CR with an open chain, or thod. simple curled chain feature OC. The closed ring struc- References: tures are confirmed by adding Na ions or H2O molecule [1] Lehn J.-M. (1995): Supramolecular Chemistry, into the vacant hole of the ring structure CR, which are 271pp. VCH, Weinheim, Germany. [2] Miura Y. (1994): produces at ocean-water with salts and water with high Astro.Soc. Pacific Conf. Series, 63, 259–264. [3] Miura temperature conditions [3-5]. Y. (1996): Proc. 29th ISAS Lunar and Planet.Sympo. Carbon-bearing ocean to form oligomers: (ISAS, Japan), 29, 289–292. [4] Miura Y. (1996) : Grain Among various species of primitive life are considered to Formation Workshop (Hokkaido Univ., JGR KK-B1), be formed in primordial Earth and Mars (and Venus) with XVIII, 5–8. [5] Miura Y. (1997): Workshop on Early liquid systems [13], it takes ca. 1 Ga due to its complex Mars (LPI), #3036. [6] Miller S.L. (1953): Science, 117, chemical evolution. During anaerobic or photosynthetic 528–529. [7] Miura Y. (2010): LPI Contribution (Ab- bacteria, the main organic materials are (CH2O)n compo- SciCon, USA), CD#5398. sition as following equation (1) [5]: nCO2 + nH2O -> (CH2O)n + nO2 (n:integer) (1)

P27 2011 PERC Planetary Geology Field Symposium

Mars Environment Simulation Chamber Development at Planetary Exploration Re- search Center, Chiba Institute Of Technology. S. Ohno1, N. Namiki1, K. Ishibashi1, M. Kobayashi1, T. Arai1, H. Senshu1, K. Wada1,K. Goto1,R. Ishimaru1,A.Yamagi- shi2, H. Miyamoto3, S. Sugita4, G. Komatsu1,5, and T. Matsui1. 1Planetary Exploration Research Center (PERC), Chiba Institute of Technology (Chitech), 2-17-1, Tsudanuma, Narashino, Chiba, 275-0016, Japan, , 2 Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan, 3The University Museum, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan, 4Department of Complexity Science and Engineering, University of Tokyo, Kashiwa, 277-8561, Japan 5International Research School of Planetary Sciences, Universití d' Annuzio, Viale Pindaro, 42, 65127, Pescara, Italy.

Importance of the Laboratory Simulation of The Mars environment simulation chamber has a main the Martian Surface Environment: The surface en- room of 800 mm in the diameter and 1000 mm in the vironment of the Mars is unique in the solar system and length. An extension tube unit of 200 mm in the diameter very hard on the instruments for planetary explorations. and 8 m in the total length is quipped. Most of the expe- The low temperature and pressure conditions of the Mar- rimental studies of the instruments and Martian science tian atmosphere are serious to the instruments, especially are planned to be conducted using the main room. The to the movable components, sensors, and electronics. extensional tube unit is focused on the purpose of devel- Carbon dioxide, the dominant molecular species in Mar- opment of the laser induced breakdown spectroscopy tian atmosphere, can easily condense at the low tempera- (LIBS) system that are investigated in PERC/Chitech [2, tures of the Martian surface and exert bad influences on 3] and planned to contribute to the scientific observations the instruments. Furthermore, instruments must be proof of the future Japanese missions for planetary exploration. against the strong winds and abundant dust on the Martian The main room of the chamber is able to be cooled surface. Thus, an artificial reproduction of the surface down to -120 °C. The main room is equipped with an condition of the Mars is essential to develop, construct, aluminum internal shroud with tubes for liquid nitrogen to test, and calibrate the instruments for future Martian ex- cool the chamber. A sample table is also equipped in the ploration missions. main chamber. The height of the table is adjustable. In addition to the instrumental research and develop- Temperature of the table is also equipped with tubes for ment, the artificial reproduction of the surface condition liquid nitrogen to cool down to -120 °C and to be con- of the Mars plays important roles to investigate the geo- trolled precisely and independently to the shroud. The logic, geomorphologic, meteorological and/or biologic temperature of the shroud and the sample table is con- processes occurring on the surface of the Mars. Recently, trolled by the flow rate of the liquid nitrogen. This me- many complicated and interesting geologic and geomor- thod is easy to cool them down to -120 °C. phologic features of the Martian surface have been ob- The extension tube unit has five short tubes and the to- served in detail. However, the formation mechanisms of tal length of ~8 m. Each short tube is set on rails and the geologic and geomorphologic features are poorly un- movable along the rails. The system of the rails and the derstood. The geologic and/or geomorphologic analogue extension tubes are designed mainly for experiments of experiments in artificial Martian environments and de- laser induced breakdown spectroscopy. We can conduct tailed investigation of the formation mechanisms are re- laser breakdown experiments at the various distances. quired to understand the implications to the evolution of The system of the rails allows us to compare precisely the the Mars. Astrobiologic studies are also ones of the most experiments using a laser equipment set in the main room important and appealing subjects of the Mars. It is impor- and set on an optical table. These experiments strongly tant not only to search and assess the possibility of the promote the investigation of the physics of LIBS and de- existence of life on the present and/or past Mars, but also velopment of planetary LIBS system. to discuss about the migration of the terrestrial life caused by artificial spacecrafts and natural processes such as References: [1] Yamagishi A. et al., (2007) Biolog- hypervelocity impacts [e.g., 1]. Experimental study of the ical Sciences in Space, 21, 3, 67–75. [2] Ishibashi K. et habitability of microorganism on the artificially repro- al. (2009) LPS XXXXI. [3] Ishibashi K. et al. (2009) Pro- duced Martian environments strongly helps us to under- ceedings of the 42th ISAS Lunar and Planetary Sympo- stand the possibility and distribution of the life on the sium. Mars. Development of Mars Environment Simulation Chamber at PERC/Chitech: A new Mars environment simulation chamber is being developed in the Planetary Exploration Research Center (PERC), Chiba Institute of Technology (Chitech) in Japan. The aim of its development is to reproduce the surface conditions of the Mars and to contribute the instrumental development and Mar- tian science.

P28 2011 PERC Planetary Geology Field Symposium

Prediction of Elemental Composition of Olivine with Laser-Induced Breakdown Spec- troscopy (LIBS). K. Ishibashi1, T. Arai1, K. Wada1, S. Ohnno1, H. Senshu1, N. Namiki1, T. Matsui1, S. Kameda2,Y. Cho3, S. Sugita4 1Planetary Exploration Research Center, Chiba Institute of Technology (2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan; [email protected]), 2Col. of Sci., Rikkyo Univ. (Tokyo, Japan), 3Dept. of Earth and Planet. Sci., Univ. of Tokyo (Tokyo, Japan), 4Dept. of Comp. Sci. & Eng., Univ. of Tokyo (Chiba, Japan).

Introduction: Laser-induced breakdown spectroscopy (LIBS) is one of the elemental analysis methods [e.g., 1]. Pulsed laser beams are irradiated on targets to produce plasmas, and the emitted lights from plasmas are measured with a spectrometer. Qualitative and quantitative analysis can be carried out by analyzing the acquired spectra. LIBS has a potential for being a powerful elemental analysis method for satellite and planetary explorations [e.g., 2, 3]. Since LIBS has a high spatial resolution much less than 1 mm, it has a potential for Figure 1. The results of Mg# prediction: (a) The case-(i) measuring minerals that are components of rocks. How- analysis. (b) The case-(ii) analysis. The Mg# predicted with ever, LIBS has an inevitable problem called matrix LIBS are plotted against that measured with EDX for each effects. If the physical state of samples is different, ac- sample. The solid line is a target line on which the predicted quired spectra differs among the samples even with the values are equal to the measured values. same elemental composition. This phenomenon prevents measured with EDX for each sample. All plots are almost accurate measurements. In this study, we investigated the along a target line, showing the prediction accuracy possibility to predict the elemental abundance of olivine, seems to be good. Root mean squared error of prediction which is one of the important minerals. We also investi- ൌ ඥσሺ௡ ݕ െݕො ሻଶΤ݊, where ݕ is the measured ) gated the effect of sample physical states on the ௜ୀଵ ௜ ௜ ௜ -value, ݕො is the predicted value, ݅ is the subscript for sam prediction accuracy of elemental abundance. ௜ ples, ݊ is the number of samples) is about 1.4, which Experiments: We prepared two types of olivine means that the Mg# is predicted within the error of ±1.4. samples. One is a natural olivine (Type-I olivine), and the Although the different types of samples were analyzed, other is an end-member-mixed olivine (Type-II olivine) the prediction accuracy is sufficient for all the samples. Type-II olivines were made by mixing the powder of oli- Figure 1(b) shows the result for case-(ii) analysis. vine’s end members (i.e., fayalite and forsterite) and There seems to be a systematic error; the predicted Mg# pressing them. The six type-I olivines (Mg# = 83.9, 87.8, are smaller than measured Mg# for all the samples. This 90.2, 90.2, 90.9, 91.2) and the eight type-II olivines (Mg# might be due to the matrix effects. In this case the refer- = 75.0, 77.5, 80.0, 82.5, 85.0, 87.5, 90.0, 91.0) were pre- ence samples include only the type-II olivines the pared. Here, Mg# is defined as Τሺ ൅ ሻ ൈ ͳͲͲ. physical state of which is different from that of the un- The elemental composition of the samples was measured known samples (i.e., type-I olivine). This result indicates with energy dispersive x-ray spectroscopy (EDX). that even PLS cannot overcome the matrix effects unless LIBS spectra of the olivine samples were acquired the reference samples are prepared appropriately. with a LIBS system; the laser pulse energy is 10 mJ, the If a PLS regression model is made using only a sam- diameter of laser beam spot is 200 ȝm, the wavelength of ple set with specific physical state, the model is just spectra is 320-790 nm, the spectral resolution is <0.5 nm. specialized for the same physical state samples, leading to These specifications are feasible for LIBS in planetary worse prediction accuracy for other type samples. This explorations. corresponds to the case-(ii) analysis. However, if a PLS Analysis: The acquired spectra were analyzed with model is made using the multi-physical state samples partial least squares regression (PLS) method to predict such as the case-(i) analysis, PLS extracts the information the abundances of the major elements. PLS is one of the that correlates well with elemental abundance from spec- multivariate analysis methods and is expected to over- tra. come the matrix effects problem mentioned above [4]. Conclusions: We tested the prediction of the com- We tested two cases of analysis. (i) One olivine sample is position of olivine with LIBS. The acquired LIBS spectra regarded as an unknown sample, and the others are re- were analyzed with PLS to predict the abundances of the garded as reference samples with which a PLS regression major elements. The results indicate that the prediction model is made. Then, this process is repeated for all the accuracy is sufficient as long as the reference samples are samples. (ii) Type-I olivines are regarded as unknown prepared appropriately. samples, and type-II olivines are regarded as reference References: [1] Cremers, D. A. and Radziemski, L. samples with which a PLS regression model is made. J. (2006) Handbook of Laser-Induced Breakdown Spec- Results and discussion: Here we will show the troscopy. [2] Wiens, R. et al. (2005) LPS XXXVI, Abstract results for Mg# on behalf of the predicted elemental com- #1580. [3] Sharma, S. K. et al. (2009) LPS XL, Abstract position. Figure 1(a) shows the result for case-(i) analysis. #2548. [4] Clegg S. M. et al. (2009) Spectrochim. Acta The Mg# predicted with LIBS are plotted against that Part B 64, 79–88.

P29 2011 PERC Planetary Geology Field Symposium

Development of a laser ablation isochron K-Ar dating method for landing planetary missions. Y. Cho1 , Y. N. Miura2, and S. Sugita3 1Dept. of Earth and Planetary Sci., the University of Tokyo (7-3-1, Hongo, Bunkyo-ku, Tokyo, Japan; [email protected] tokyo.ac.jp), 2Earthquake Research Institute, the University of Tokyo (1-1-1, Yayoi, Bunkyo-ku, Tokyo, Japan) 3Dept. of Complexity Sci. and Eng., the University of Tokyo (5-1-5, Kashiwanoha, Kashiwa, Chiba, Japan).

Introduction: Absolute age determination of plane- rocks are within 11% of uncertainty, although some min- tary surfaces are extremely important for understanding erals, such as olivine, yield larger error. When these re- the evolution of planets. However, no chronological sults are combined, the absolute abundance of K inside a measurements have been made for planetary materials crater can be estimated within 15% of accuracy. with geologic contexts except for the lunar samples. Alt- Third, we irradiated a synthesized glass sample con- hough the absolute ages for Martian surfaces have been taining ~10-1 cc STP/g of 40Ar (prepared by Dr. Mibe at estimated based on the lunar crater chronology and the ERI). We found that 4 10-9 cc of 40Ar and 1 10-11 cc of orbital calculations of asteroids [1, 2], there still remain 36Ar were released per a pulse. Blank levels for the QMS uncertainties as large as 1 billion years [3]. If the absolute system at m/Z = 36 and 40 were 2 10-11 cc and on the ages of Martian rock samples from a geologic unit whose order of 10-11 cc, respectively. Electric noise level of the crater number density is known are determined with 10% QMS (~1 10-13 A) was equivalent to 7 10-12 cc for the accuracy, it will constrain histories of surface environ- current setup. ments and igneous activities of Mars. In this study, we are developing a new in-situ dating Discussion: Feasibility of K-Ar dating of Mar- method based on the Potassium-Argon (K-Ar) dating tian rocks. Our experimental results indicate that K can technique [4] toward future landing planetary missions. be measured accurately for rocks with 1 wt% of K2O. We propose a new method to extract K and Ar simultane- Although rocks with 1 wt% of K2O are found by Mars ously from a sample with a laser irradiation and to Exploration Rovers, 100 ppm of K2O, as found in Sher- measure K with the laser-induced breakdown spectrosco- gotties [6], is expected to be more common on Mars. py (LIBS) and Ar with a quadrupole mass spectrometer Thus, about a factor of 100 of sensitivity improvement (QMS). Although in-situ K-Ar dating methods have been would be required for Martian missions. proposed for previous missions [5], we expect that our Our results of Ar extraction experiments suggest that method can obtain more accurate ages than those. This is for the rocks with 1 wt% of K2O and 1 Gyr in age, in because isochron measurements are possible in our meth- which decay of 40K yields ~10-5 cc/g of 40Ar and it is nec- od. We built the new LIBS-QMS experimental system essary to measure ~10-8 cc/g of 36Ar to estimate the con- (Fig. 1) optimized for K-Ar dating and conducted the tribution of non-radiogenic 40Ar, measurable amount of following experiments to examine possibilities to meas- 40Ar and 36Ar would be released by 10 and 104 laser puls- ure (1) absolute abundance of K within 20% of accuracy es, respectively. Here the evaporation mass of rocks is by LIBS and (2) small amount of 36Ar contained in rocks assumed to be 102 ng/pulse, as we obtained previous ex- in order to evaluate contamination by non-radiogenic 40Ar periments though it is about 2 times larger than that we (36Ar could be less than 40Ar by 2-3 orders of magnitude). have obtained in this experiment. Although further improvements in detection limits Experimental: First, for the purpose of obtaining would enable measurements of more K-depleted or calibration curves of K abundance with LIBS, we irradi- younger rocks on Mars, this study indicates that our in- ated laser pulses on 13 rock samples with 100 ppm to 5 strument can measure K and Ar for such rocks as found wt% of K2O and observed the emission lines of K from by MER. these samples. An Nd:YAG laser was used to deliver pulses with 50 mJ of energy and 4 102 Mm in spot diameter. Plasma emission was observed by an ICCD camera coupled with a spectrograph. We obtained mass spectra to measure Ar isotopes, 36Ar and 40Ar. Because Ar gas was released from the sample by the laser irradiation with other gaseous species including H2O and hydrocarbons, such interfering gas species are removed by Ti,-Zr getter system. The purified gas was introduced to the QMS and the amount of Ar was measured.

Results: We obtained two calibration curves from K emission lines at 766.49 nm and 769.89 nm. Our results Fig.1 Experimental system. show that K concentration can be measured within the relative accuracy of 10% for 2000 ppm to 5 wt% range. References: [1] Neukum et al. (2001) Space Sci. Rev., The detection limit was 1000 ppm for the current system. 96, 55–86. [2] Ivanov (2001) Space Sci. Rev., 96, 87-104 Second, the volumes of laser-ablated craters on rock [3] Doran et al. (2004) Earth Sci. Rev., 67, 313–337. [4] Kelley samples are measured with an optical microscope. The (2002) [5] Talboys et al. (2009) Planet. Space Sci., 57, 1237- observations indicate that the crater volumes of basaltic 1245 [6] Nyquist et al. (2001) Space Sci. Rev., 96, 105-164

P30