WORKSHOP ON EXTRATERRESTRIAL MATERIALS FROM COLD AND HOT DESERTS • • # ...• "· • • i • + •• + • • . + + • .. + • �. • ++ + •• • • • + + + .... + + + • + + ., + • ...... "!'...+ • July 6-8,1999 Kwa-Mtane, Pianesberg, South Africa LPI Contribution No. 97 WORKSHOPON EXTRATERRESTRIALMATERIALS FROM COLD AND HOT DESERTS July 6-8, 1999 Kwa-Maritane, Pilanesberg, South Africa Edited by Ludolf Schultz, Ian A. Franchi, Arch M. Reid, and Michael E. Zolensky Sponsored by Lunar and Planetary Institute Max-Planck-Institutflir Chemie University of the Witwatersrand Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 LPI Contribution No. 997 Compiled in 2000 by LUNAR AND PLANET ARY INSTITUTE The Institute is operated by the Universities Space Research Association under ContractNo. NASW-4574 with the National Aeronautics and Space Administration. Material in this volume may be copied without restraint forlibrary, abstractservice, education, or personal research purposes; however, republication of any paper or portion thereof requires the written permission of the authors as well as the appropriate acknowledgment of this publication. This volume may be cited as Schultz L.; Franchi I., Reid A., and Zolensky M., eds. (2000) Workshop on Extraterrestrial Materials from Cold and Hot Deserts. LPI Contribution No. 997, Lunar and Planetary Institute, Houston. 99 pp. This volume is distributed by ORDER DEPARTMENT Lunar and Planetary Institute 3600Bay Area Boulevard Houston TX 77058-1113 Phone: 281-486-2172 Fax: 281-486-2186 E-mail: [email protected] Mail order requestors will be invoiced for the cost of shipping and handling. LP[ Contribution No. 997 iii INTRODUCTION Since 1969 expeditions fromJapan, the United States, and European countries have recovered more than 20,000 meteorite specimens fromremote ice fieldsof Antarctica. They represent approximately 400�000 distinct falls,more than all non-Antarctic meteorite falls and finds combined. Recently many meteorite specimens of a new "population" have become available: meteorites fromhot deserts. It turnedout that suitable surfaces in hot deserts, like the Sahara in Africa, the Nullarbor Plain in Westernand South Australia, or desert high plains of the U.S. (e.g., Roosevelt County, New Mexico), contain relatively high meteorite concentrations. For example, the 1985 Catalogue of Meteorites of the British Museum lists 20 meteorites from Algeria and Libya. Today, 1246 meteorites findsfrom these two countries have been published in MetBase 4.0. Four workshops in 1982, 1985, 1988, and 1989 have discussed the connections between Antarctic glaciology and Antarctic meteorites, and the differencesbetween Antarctic meteorites and modemfalls. In 1995, a workshop addressed differencesbetween meteorites from Antarctica, hot deserts,and modem falls, and the implications of possible different parent populations, infall rates, and weathering processes. Since 1995 many more meteorites have been recovered fromnew areas of Antarctica and hot deserts around the world. Among these finds are several unusual and interesting specimens like lunar meteorites or SNCs of probable martian origin. The Annual Meeting of the Meteoritical Society took place in 1999 in Johannesburg, South Africa.As most of the recent desert finds originate fromthe Sahara, a special workshop was planned prior to this meeting in Africa.Topics discussed included micrometeorites, which have beencollected in polar regions as well as directly in the upper atmosphere. The title "Workshop on ExtraterrestrialMaterials from Cold and Hot Deserts" was chosen and the following points were emphasized: (1) weathering processes, (2) terrestrialages, (3) investigations of "unusual" meteorites, and (4) collection and curation. Fig. 1. Meteorite findsin the Sahara. Cluster in Algeria belongs to Fig. 2. Meteorite findsof the USA show a cluster in dry areas the Acfer and Tanesrouffinds, those in Libya to Hammadahal of Texasand New Mexico. Hamra andDar al Gani. Fig. 3. Numerous meteorite finds show up at the Nullarbordesert in Fig. 4. The many Antarctic meteorites arefound on Blue Australia. Icefieldslocated along the TransantarcticMountains andat the Yamato Mountains. LP/ Contribution No. 997 v CONNS Program................................................... ..............................................................................................ix Summary of Previous Workshop ......................................................................................................... 1 Workshop Summary ............................................................................................................................. 3 Collections, Collecting Areas, and Pairing Problems ................................................................. 3 Weathering Effects ......................................................................................................................4 Terrestrial Age Determinations ................................................................................................... 5 InterplanetaryDust Particles....................................................................................................... 5 Noble Gases and Cosmic-Ray Effects........................................................................................ 6 Repositories of Desert Meteorites ........................................................................................................ 7 Acknowledgments .................................................................................................................................. 9 Abstracts .............................................................................................................................................. 11 The Natural ThermoluminescenceSurvey of Antarctic Meteorites: Ordinary Chondrites at the Grosvenor Mountains, MacAlpine Hills, Pecora Escarpmentand Queen Alexandra Range, and New Data for Elephant Moraine Ice Fields P. H. Benoit and D. W. G. Sears ................................................................................... 11 Meteorites fromthe Nullarbor, Australia: An Update A. W.R. Bevan, P.A. Bland, and A. J. T. Jull ............................................................... 15 Ice Flow as the Principal Sink for Antarctic Meteorites P. A. Bland, A. J. T. lull, A. W.R. Bevan, T. B. Smith, F. J. Berry, and C. T. Fillinger ......................................................................................................... 17 Pairing among EET87503 Group Howardites and Polymict Eucrites P. C. Buchanan, D. J. Lindstrom, and D. W. Mittlefehldt ............................................. 21 Chemical Alteration of Hot Desert Meteorites: The Case of Shergottite Dar al Gani476 G. Crozaz and M. Wadhwa ........................................................................................... 25 vi Deserts IIWorkshop Chemical Compositions of Large Interplanetary Dust Particles fromthe Stratosphere and Small Antarctic Micrometeorites: Evidence forElement Loss and Addition in the Antarctic Micrometeorites G. J. Flynn, S. R. Sutton, and W. Klock ......................................................................... 28 The Influence of Terrestrial Weathering on Implanted Solar Gases in Lunar Meteorites I. Franchi,A. B. Verchovsky, and C. T. Pillinger ......................................................... 33 Meteorites fromCold and Hot Deserts: How Many, How Big, and What Sort M. M. Grady .................................................................................................................. 36 Using 14C and 14C-1°Be forTerrestrial Ages of DesertMeteorites J. T. Juli, P. A. Bland, S. E. Klandrud, L. R. McHargue, A. W. R. Bevan, D. A. Kring, and F. Wlotzka.......................................................................................... 41 The Gold Basin Strewn Field, Mojave Desert, and its Survival from the Late Pleistocene to the Present D. A. Kring, A. J. T. lull, and P.A. Bland .................................................................... 44 ThermallyMobile Trace Elements in Carbonaceous Chondritesfrom Cold and Hot Deserts M. E. Lipschutz .............................................................................................................. 46 HistoricalNotes on Three Exceptional Meteorites of SouthernAfrica: The Cape of Good Hope, Gibeon, and Hoba U. B. Marvin .................................................................................................................. 48 SaharanMeteorites with Short or Complex Exposure Ages S. Merchel, M.Altmaier, T. Faestermann, U. Herpers, K. Knie, G. Korschinek, P. W. Kubik, S. Neumann, R. Michel, and M. Suter ...................................................... 53 Cosmogenic and Trapped Gas Components in the MartianMeteorite Dar al Gani476 fromHot Desert S. V. S. Murty and R. K. Mahapatra .............................................................................. 57 Thermal Effectson Mineralogy, Noble Gas Composition, and Carbonaceous Material in CM Chondrites T. Nakamura, T. Kitajima, and N. Takaoka.... ............................................................... 61 TerrestrialAges of Antarctic Meteorites - Up Date 1999 K. Nishiizumi, M. W. Caffee, and K. C. Welten ............................................................. 64 Type I Cosmic Spheres: Key to a Major but Poorly Sampled Asteroid Population? L. E. Nyquist .................................................................................................................. 65 LI Contribution