related to both ice-ablation rates and meteorite-weatheringrates in the antarctic environment.

A search for new meteorite concentration sites was con-ducted at ice patches associated with Reckling Peak, GriffinNunatak, Brimstone Peak, Tent Rock, and Sheppard Rocks.One specimen was found at Outpost Nunatak, an outlier ofGriffin Nunatak, but none were found at the other sites. Itmay be significant that at all of these sites the downstreamiceflow direction was open to David Glacier and the upstreamsides of these barriers appeared to be areas of snow accumu-lation rather than ice-ablation zones.

This work was supported by National Science Foundation

grant DPP 78-21104. Other members of the field party wereJoanne Danielson, Harry Y. McSween, Jr., Louis A. Rancitelli,Ludolf Schultz, and John Schutt. We particularly thank PeterDahl for allowing Danielson to associate with his party inorder to conduct the Taylor Valley meteorite survey.

References

Annexstad, J . 0., and Nishio, F. 1980. Glaciological studies in AllanHills, 1979-80. Antarctic Journal of the U.S., 15(5), 65-66.

Fireman, E. L. 1980. Radioactive dating and the compositions of thegas in antarctic ice. Antarctic Journal of the U.S., 15(5), 67-68.

Characterization of antarcticmeteorites

BRIAN MASON

Department of Mineral SciencesSmithsonian InstitutionWashington, D.C. 20560

During the past year I have continued to characterize ant-arctic meteorites collected in Victoria Land (Allan Hills, Rec-kling Peak, Elephant Moraine, Darwin Glacier) by W. A. Cas-sidy (principal investigator) and his colleagues during the1978-79 and 1979-80 field seasons. This work has requiredthe preparation of several hundred polished thin sections ofthe meteorites, their examination with a petrographic micro-scope, and analysis of the minerals with an electron-beammicroprobe. Individual meteorites are classified by mineralcomposition and textural relationship.

Meteorites are classified into four groups: (1) chondrites-stony meteorites containing chondrules, which are rounded

aggregates of silicate minerals, usually 0.2-2 millimeters indiameter; (2) achondrites— stony meteorites without chon-drules; (3) stony-irons—meteorites consisting of subequalamounts of silicate minerals and nickel-iron; and (4) irons—meteorites consisting essentially of a nickel-iron alloy, thenickel content usually in the 5-20 percent range. Chondrites,which make up by far the most common meteorite group, aresubdivided into classes according to increasing iron contentof the pyroxene: enstatite (E) chondrites; olivine-bronzite (H)chondrites; olivine-hypersthene (L and LL) chondrites; andcarbonaceous (C) chondrites, a separate small group charac-terized by a matrix containing carbonaceous material.

Of the 268 meteorites characterized from the Victoria Landcollections, 132 are H chondrites, 82 are L chondrites, 8 are LLchondrites, 4 are C chondrites, and 1 is a unique chondrite notreadily classified; no E chondrites have been identified; thereare 20 achondrites, I stony-iron, and 20 irons.

Ursula B. Marvin and I have collaborated in editing Catalogof Antarctic Meteorites, 1977-1978, published in 1980 as num-ber 23 in Smithsonian Contributions to the Earth Sciences. Wehave in press Catalog of Meteorites from Victoria Land, Antarc-tica, 1978-1980, which will be published as number 24 inSmithsonian Contributions to the Earth Sciences. Copies of theseare available on request.

Antarctic meteorites: Their curationand study

D. D. BOGARD and J . 0. ANNEXSTAD

Lyndon B. Johnson Space CenterNational Aeronautics and Space Administration

Houston, Texas 77058

A total of 792 meteorite specimens have been recovered fromthe vicinity of McMurdo during the last five field seasons(Cassidy 1980, personal communication; Cassidy et al. 1980;Cassidy, Olsen, and Yanai 1977; Shiraishi 1979; Yanai 1978,1979; Yanai et al. 1978). Several thousand meteorite specimenshave been recovered near the Yamato Mountains by the Jap-anese since 1969 (Matsumoto 1978; Shiraishi et al. 1976; Yanai1976, 1978; Yanai et al. 1981; Yoshida et al. 1971). The high rate

of recovery of meteorites from Antarctica contrasts sharplywith that for the rest of the Earth, where only 5-10 meteoritesare recovered annually to augment the 2,100 known nonant-arctic meteorites. These nonterrestrial materials have provideda significant new resource for understanding the origin andevolution of our solar system.

The excitement meteorite investigators experience over theantarctic finds arises from both the large number of well-pre-served new specimens and from the existence of a few rareand unique specimens (table). For example, the recoveredantarctic eucrites and diogenites (achondrites formed byigneous processes on asteroidal parent bodies) have essentiallydoubled the total number of such known meteorites. Many ofthe antarctic eucrites show intriguing petrological and chem-ical differences from other eucrites; these differences are notyet understood. Two new specimens of Shergottitelike achon-drites (peculiar, igneous meteorites with geologically youngages which some investigators speculate may have originatedon Mars) have doubled the number of Shergottite specimensknown. The antarctic Shergottites show a greater diversity in

62 ANTARCTIC JOURNAL

A summary of 269 classified antarctic meteorites in the U.S.collection

Meteorite type

Number of specimens

Carbonaceous chond rites 4Type H chond rites

H-3

4H-4

28H-5

71H-6

33Type L chond rites

L-3

18L-4L-5

4L-6

58Type LL chond rites (L-3, L-5, and

L-6

8Achondrites

Eucrites and howardites 12Ureilites 3Diogenites 2AubritesShergottitelike 2

MesosideritesIrons 19

Note. An additional 288 meteorite specimens weighing less than 150grams each are currently undergoing classification and detailedstudy by five investigator groups in the United States, England, andAustralia. The 103specimens recovered during the 1980 fieldseasonare not yet classified. It is known that a number of antarctic meteoritespecimens represent common meteorite falls, and additional pairedspecimens undoubtedly will be found; however, the diversity andnumber of separate meteorites in the collection is still large.

their petrology and composition than those found previouslyin other parts of the world (Reid in press). Two carbonaceouschondrites from Antarctica were found to contain complex,nonbiotic, organic molecules; these data confirm analogousresults previously found in an Australian meteorite (Cronin,Pizzarello, and Moore 1979; Holzer and Oro 1979; Kotra et al.1979). The second iron meteorite known to contain diamondswas found recently in Antarctica, but in this specimen thediamonds apparently were formed by preterrestrial processesrather than by impact with the Earth (Clarke, Appleman, andRoss 1981). It has now. been determined that several antarcticmeteorites are as much as 700,000 years old. This informationwill aid further study of old solar emissions (which have inter-acted with these meteorites) and long-term movement of ant-arctic ice, through an understanding of the mechanisms ofmeteorite concentration (Evans, Rancitelli, and Reeves 1979;Fireman, Rancitelli, and Kirsten 1979; Nishiizumi et al. 1981).

Meteorite studies are major contributors to such diversespace science topics as element nucleosynthesis, our early solarsystem, igneous and surficial processes on asteroidal parentbodies, the history of solar emissions, and complex primordialorganic molecules. Investigations of antarctic meteorites areequally diverse and include, among others, the petrology,chemistry, ages, physical properties, and energetic particleinteractions.

To facilitate the recovery and scientific study of antarcticmeteorites, the National Science Foundation (NSF), theNational Aeronautics and Space Administration (NASA), andthe Smithsonian Institution have supported cooperative pro-grams to (1) develop specific collection and preliminary exam-

ination protocols (Annexstad and Cassidy 1980), (2) providedocumented samples for scientific investigations in responseto specific requests, and (3) aid and coordinate research byscientific consortia. As a consequence of such programs, theU.S. antarctic meteorites make up one of the most valuable,best documented, and most accessible collections available toresearchers. Since inception of the cooperative program in1978, investigators at the meteorite curatorial facilities at NASA,the Johnson Space Center (for stony meteorites), and theSmithsonian Institution (for iron meteorites) have made phys-ical descriptions and classifications of some 269 antarcticmeteorites and have allocated some 1,200 separate samples to90 investigator groups in 13 countries (Duke, Bogard, andAnnexstad 1981). Preliminary information about the speci-mens is reported to some 500 scientists and institutions viaperiodic publication of the Antarctic Meteorite Newsletter,which was specifically created at the Johnson Space Center forthis purpose. A more permanent record of the program andthe meteorite collection is published in catalogs as SmithsonianContributions to the Earth Sciences (Marvin and Mason 1980).

References

Annexstad, J . 0., and Cassidy, W. A. 1980. Collecting and processingVictoria Land meteorites. Memoirs of National Institute of PolarResearch (Tokyo), Special Issue 17, 14-20.

Cassidy, W. A. 1980. Antarctic search for meteorites 1979-80. Antarc-tic Journal of the U.S., 15(5), 49-50.

Cassidy, W. A. Personal communication, 1981.Cassidy, W. A., Annexstad, J . 0., Rancitelli, L. A., and Benda, L.

1980. Results of the 1979-80 U.S. antarctic meteorite expedition. Paperpresented at the 11th Lunar and Planetary Science Conference, John-son Space Center, Houston, 17-21 March 1980.

Cassidy, W. A., Olsen, E., and Yanai, K. 1977. Antarctica: Deep-freezestorehouse for meteorites. Science, 198, 727-731.

Clarke, R. S., Appleman, D. E., and Ross, D. R. 1981. Allan HillsA77283: An antarctic iron meteorite containing pre-terrestrial impact-produced diamond and lonsdaleite. Paper presented at the Sixth Sym-posium on Antarctic Meteorites, 19-20 February 1981, Tokyo.

Cronin, J. R., Pizzarello, S., and Moore, C. B. 1979. Amino acids inan antarctic carbonaceous chondrite. Science, 206, 335-337.

Duke, M. B., Bogard, D. D., and Annexstad, J. 0. 1981. Curatorialaspects of the antarctic meteorite program in the United States.Paper presented at the Sixth Symposium on Antarctic Meteorites,19-20 February 1981, Tokyo.

Evans, J . S., Rancitelli, L. A., and Reeves, J. H. 1979. 26jtj content ofantarctic meteorites: Implications for terrestrial ages and bombard-ment history. Proceedings of the 10th Lunar and Planetary ScienceConference, 1, 1061-1072.

Fireman, E. L., Rancitelli, L. A., and Kirsten, T. 1979. Terrestrial agesof four Allan Hills meteorites: Consequences for antarctic ice. Sci-ence, 203, 453-455.

Holzer, C., and Oro, J. 1979. The organic composition of the AllanHills carbonaceous chondrite (77306) as determined by pyrolosis-gas chromatography mass spectrometry and other methods. Journalof Molecular Evolution, 13, 265-270.

Kotra, R. K., and Shimoyama, A., Ponnamperuma, C., and Hare,P. E. 1979. Amino acids in a carbonaceous chondrite from Antarc-tica. Journal of Molecular Evolution, 13, 179-184.

Marvin, U. B., and Mason, B. (Eds.). 1980. Catalog of antarctic meteo-rites, 1977-1978. Smithsonian Contributions to the Earth Sciences, 23.Washington, D.C.: Smithsonian Institution.

Matsumoto, Y. 1978. Collection of Yamato meteorites, East Antarcticain November and December 1975, and January 1976. Memoirs of theNational Institute of Polar Research (Tokyo), Special Issue 8, 38-50.

Nishiizumi, K., Imamura, M., Arnold, J . R., and Honda, M. 1981.Cosmogenic 53Mn in Yamato and Allan Hills meteorites. Paper pre-

1981 REvIEw 63

sented at the Sixth Symposium on Antarctic Meteorites, Tokyo,19-20 February 1981.

Reid, A. In press. Antarctic achondrite. In U. B. Marvin and B. Mason(Eds.), Smithsonian Contributions to Earth Sciences.

Shiraishi, K. 1979. Antarctic search for meteorite by U.S.-Japan jointparty, 1978-1979. Memoirs of National Institute of Polar Research(Tokyo), Special Issue 15, 1-12.

Shiraishi, K., Naruse, R., and Kusunoki, K. 1976. Collection of Yamatometeorites, Antarctica, in December 1973. Antarctic Record, 55,49-60.

Yanai, K. 1976. Search and collection of Yamato meteorites, Antarctica,in November and December 1974. Antarctic Record, 56, 70-81.

Yanai, K. 1978. First meteorites found in Victoria Land, Antarctica,

December 1976 and January 1977. Memoirs of National Institute ofPolar Research (Tokyo), Special Issue 8.

Yanai, K. 1979; Meteorite search in Victoria Land, Antarctica, in1977-1978 austral summer. Memoirs of National Institute of PolarResearch (Tokyo), Special Issue 12, 1-8.

Yanai, K., Cassidy, W. A., Funaki, M., and Glass, B. P. 1978. Pro-ceedings of the 9th Lunar and Planetary Science Conference, 1, 977-988.

Yanai, K., Hedeyasu, K., and Tamio, N. 1981. Japanese antarctic meteo-rite search in 1979-1980 season. Paper presented at the Sixth Sym-posium on Antarctic Meteorites, Tokyo, 19-20 February 1981.

Yoshida, M., Ando, H., Omoto, K., Naruse, R., and Ageta, Y. 1971.Discovery of meteorites near Yamato Mountains, East Antarctica.Antarctic Record, 39, 62-65.

Meteoritic metal from Antarctica

Roy S. CLARKE, JR.

Department of Mineral SciencesSmithsonian InstitutionWashington, D.C. 20560

During the past 2 years, curation, distribution, and prelim-inary characterization of the iron meteorites recovered fromAntarctica by the joint U.S.-Japanese field teams during the1977-78 and 1978-79 field seasons have been managed fromthe National Museum of Natural History, Washington, D.C.Eight individual meteorite specimens from the Allan Hills,nine from Derrick Peak, and one from Purgatory Peak that wascollected by a University of Maine field party, were involved.The specimens weighed from 85 grams to 138 kilograms, pre-senting a series of challenging problems for our sample prep-aration laboratory. Initially, progress was slow, but the instal-lation of additional modern metal-cutting equipment hashelped us overcome this problem.

Distribution of the Allan Hills and Derrick Peak specimenswas made first to the National Institute of Polar Research(NIPR), Tokyo. Half of each specimen from the Allan Hills wassent to the NIPR. The nine Derrick Peak specimens presenteda special problem. They have highly unusual and attractiveexternal surfaces, and the similarities between these specimens suggest that they are all from the same fall. Rather thansplit each specimen, only the two largest specimens (59 and138 kilograms) were halved to provide material for the Nll'R.The seven smaller specimens were divided between the twocollections.

As of late May 1981, research allocations had been approvedfor 10 of the 15 iron meteorite specimens retained in the U.S.antarctic collection. (Approval comes from the MeteoriteWorking Group, an official committee established by theNational Science Foundation and composed of representativesof the Smithsonian Institution, the Johnson Space Center, theNational Science Foundation, and the science community.)More than 50 individual subsamples have been distributed tosix principal investigators in three countries. The results oftheir efforts are beginning to appear in the literature.

My colleagues and I have completed initial characterizationof the Allan Hills and Purgatory Peak irons (Clarke et al. 1980).The results are summarized in the table; the specimens are

grouped according to the individual meteorite falls that arerepresented. The nickel content is an important discriminator;combined with trace-element data, it leads to the more refinedchemical group classification given in the right-hand columnof the table. The structural classification is determined by thenature of the Widmanstätten pattern, a metallographicallyrevealed expression of the meteorite's internal structure. Fiveseparate iron meteorite falls have been recovered in the AllanHills, and because of location and structural considerations,the Purgatory Peak specimen appears to represent a sixth dis-tinct fall. The four Allan Hills specimens grouped together areindividual pieces of a single coarse octahedrite (Og) fall. Acoarse octahedrite is a meteorite with a wide-banded Wid-manstätten pattern. A second distinct coarse octahedrite wasalso present in the Allan Hills, as was a fine octahedrite (Of).The other two Allan Hills specimens are a hexahedrite (H), ameteorite without a Widmanstätten pattern, and an ataxite(D), a meteorite with metallographic structure too fine to beseen except under high magnification.

Characterization of Allan Hills and Purgatory Peak ironmeteorites

Nickel(weight inStructuralChemical

Sample percent)classificationgroup

ALHA77250 6.8 Og IA

A77263 6.8 Og IA

A77289 6.8 Og IA

A77290 6.8 Og IA

ALHA77283 7.3 Og IA

ALHA77255 12.2 DAnom

ALHA78100 H IIA

ALHA78252 9.3 Of IVA

P0PA77006 7.3 Og IA

A particularly interesting individual from among thesemeteorites is ALHA77283. It is the second iron meteorite knownto contain the high-pressure association of carbon minerals,graphite- diamond -lonsdaleite (Clarke, Appleman, and Ross1981). This association of three different crystallographic mod-ifications of the element carbon had previously been knownfrom the Canyon Diablo iron meteorite, the projectile thatexcavated Meteor Crater, Arizona. In the Canyon Diablo case,the graph ite- diamond -lonsd aleite association is thought tohave formed from preexisting graphite as a consequence ofhigh temperature and pressure caused by the intense shock

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