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Meteorite studies: Terrestrial and extraterrestrial applications, 1994 MICHAEL E. LIPSCHUTZ, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 I n the past year, tantalizing glimpses have been received of a number of bodies in the inner Solar System. Two S-class minor planets (asteroids), 951 Gaspra and 243 Ida, were imaged by the Galileo spacecraft—the latter body was the first minor planet discovered to possess a moon—and a third, 1620 Geographos (another S-class, Apollo asteroid), will be imaged later in 1994 by the Clementine spacecraft. These data, however, constitute mere glances: our detailed knowl- edge of asteroids comes only from studies of their fragments that fall to Earth as meteorites. These planetary materials are studied intensively in ter- restrial laboratories, not only to establish their genetic and evolutionary histories and links to particular asteroid classes but also to determine processes that occurred before the Solar System existed and that led to its formation. Although mete- orites fall sporadically all over the Earth and, in some cases, are recovered for study (cf. Lipschutz et al. 1993, for one inter- esting case), Antarctica provides the only sustained and assured source for meteorite recoveries on a regular basis. It is becoming increasingly evident that the numerous meteorites (more than 15,000 fragments to date representing 3,800± 1,800 separate impact events) provide a different view of their extraterrestrial sources than that provided by the approxi- mately 2,900 meteorites recovered elsewhere on Earth. Cur- rent studies of these materials are supported mainly by the National Aeronautics and Space Administration, with addi- tional help from the National Science Foundation. The research conducted by my group this year involves three techniques: radiochemical neutron activation analysis (RNAA); accelerator mass spectrometry (AMS); and thermo- dynamic modeling of igneous processes. In our RNAA studies, we determine 12-15 trace and ultra- trace elements (microgram-to-gram to nanogram-to-gram levels) in each sample studied, 10 of which (silver, bismuth, cadmium, caesium, indium, rubidium, selenium, tellurium, thallium, and zinc) are thermally labile and give unique infor- mation on the thermal histories of planetary materials. For example, Hiroi et al. (1993, 1994) demonstrated from RNAA and spectral-reflectance data that surfaces of numerous C-, G-, B-, and F-classes of asteroids contain large (and variable) proportions of thermally metamorphosed material excavated from the planets' interiors by impacts. Clear sampling selec- tivity is obvious: the numerous asteroids are represented by only three metamorphosed carbonaceous chondrites—all from Antarctica. All other carbonaceous chondrites (over 70) are unmetamorphosed. Sampling selectivity also is evident for H4-6 chondrites. The Earth's sampling of sources has changed with time—on the short term (from 1855 to 1895) and on the long term, more than 50,000 years (Dodd, Wolf, and Lipschutz 1993; Michlovich et al. in press; Michlovich et al. 1994; Vogt et al. 1994; Wolf and Lipschutz in press a,b). The unique capability of our laboratory to quantify the highly informative, thermally labile trace elements results in our involvement in consortium studies of important meteorites. In the past year, we reported RNAA results for an antarctic Martian meteorite (Treiman et al. 1994) and chondrite hosts and igneous inclusions of three meteorites—all from Antarcti- ca (Wang et al. 1994; Sack et al. 1994)—as well as separated chondrules from nonantarctic meteorites and peculiar, whole-rock samples of them (Lipschutz et al. 1993; Olsen et al. 1994; Petaev et al. 1994; Sears et al. in press). Development has continued on our AMS facility, one of three national AMS facilities in earth science supported by the National Science Foundation. The other facilities (at Wood's Hole Oceanographic Institution and the University of Ari- zona) are carbon-14 (14C) machines; ours (PRIME Lab) is the only one capable of quantifying the full spectrum of cosmo- genic radionuclides: Beryllium- b ('°Be) (half-life, 1.6 million years); • Aluminum-26 ( 26A1) (half-life, 0.74 million years); • Chlorine-36 ( 36 C1) (half-life, 0.30 milion years); • Calcium-41 ( 41 Ca) (half-life, 0.10 million years); and • Iodine-129 (1291) (half-life, 16 million years). In the past year, we chemically prepared almost 350 samples, mainly of '°Be, 26A1, and 36 C1, (Vogt, Wang, and Lipschutz 1994) and have run almost 1,500 samples (Elmore et al. 1994) of terrestrial rocks (Dep et al. 1994) and rain (Knies et al. 1994) and meteorites (Lipschutz et al. 1993; Wang et al. 1994; Mich- lovich et al. in press; Michlovich et al. 1994). The planned upgrade of our AMS has just been completed, and as a result, we anticipate improved resolution and sensitivity as well as higher throughput. In the coming year, we expect 41 Ca and 1291 measurements to become as routine as those of '°Be, 26A1, and 36Cl (Elmore et al. 1994; Vogt et al. 1994). Because of our developments in the applications of mul- tivariate statistics and nuclear chemistry to terrestrial and extraterrestrial materials, invitations to prepare chapters for monographs in these areas have been accepted. These have been completed (Wolf and Lipschutz in press c; Lipschutz in press). Finally, we have demonstrated the application of a newly developed computer analysis program, MELTS, to calculate the crystallization sequence of igneous melts. We used this program to demonstrate that a large igneous inclusion in the antarctic chondrite, Yamato 794046 (Sack et al. 1994), was shock-produced, and we now plan to apply this technique to Martian meteorites, many of which were recovered from Antarctica. This research was supported in part by National Science Foundation grants EAR 89-16667, 92-14636, and 93-05859; ANTARCTIC JOURNAL - REVIEW 1994 49

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  • Meteorite studies: Terrestrial and extraterrestrialapplications, 1994

    MICHAEL E. LIPSCHUTZ, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907

    In the past year, tantalizing glimpses have been received of anumber of bodies in the inner Solar System. Two S-class

    minor planets (asteroids), 951 Gaspra and 243 Ida, wereimaged by the Galileo spacecraft—the latter body was the firstminor planet discovered to possess a moon—and a third,1620 Geographos (another S-class, Apollo asteroid), will beimaged later in 1994 by the Clementine spacecraft. Thesedata, however, constitute mere glances: our detailed knowl-edge of asteroids comes only from studies of their fragmentsthat fall to Earth as meteorites.

    These planetary materials are studied intensively in ter-restrial laboratories, not only to establish their genetic andevolutionary histories and links to particular asteroid classesbut also to determine processes that occurred before the SolarSystem existed and that led to its formation. Although mete-orites fall sporadically all over the Earth and, in some cases,are recovered for study (cf. Lipschutz et al. 1993, for one inter-esting case), Antarctica provides the only sustained andassured source for meteorite recoveries on a regular basis. It isbecoming increasingly evident that the numerous meteorites(more than 15,000 fragments to date representing 3,800± 1,800separate impact events) provide a different view of theirextraterrestrial sources than that provided by the approxi-mately 2,900 meteorites recovered elsewhere on Earth. Cur-rent studies of these materials are supported mainly by theNational Aeronautics and Space Administration, with addi-tional help from the National Science Foundation.

    The research conducted by my group this year involvesthree techniques: radiochemical neutron activation analysis(RNAA); accelerator mass spectrometry (AMS); and thermo-dynamic modeling of igneous processes.

    In our RNAA studies, we determine 12-15 trace and ultra-trace elements (microgram-to-gram to nanogram-to-gramlevels) in each sample studied, 10 of which (silver, bismuth,cadmium, caesium, indium, rubidium, selenium, tellurium,thallium, and zinc) are thermally labile and give unique infor-mation on the thermal histories of planetary materials. Forexample, Hiroi et al. (1993, 1994) demonstrated from RNAAand spectral-reflectance data that surfaces of numerous C-,G-, B-, and F-classes of asteroids contain large (and variable)proportions of thermally metamorphosed material excavatedfrom the planets' interiors by impacts. Clear sampling selec-tivity is obvious: the numerous asteroids are represented byonly three metamorphosed carbonaceous chondrites—allfrom Antarctica. All other carbonaceous chondrites (over 70)are unmetamorphosed. Sampling selectivity also is evidentfor H4-6 chondrites. The Earth's sampling of sources haschanged with time—on the short term (from 1855 to 1895)and on the long term, more than 50,000 years (Dodd, Wolf,and Lipschutz 1993; Michlovich et al. in press; Michlovich et

    al. 1994; Vogt et al. 1994; Wolf and Lipschutz in press a,b). Theunique capability of our laboratory to quantify the highlyinformative, thermally labile trace elements results in ourinvolvement in consortium studies of important meteorites.In the past year, we reported RNAA results for an antarcticMartian meteorite (Treiman et al. 1994) and chondrite hostsand igneous inclusions of three meteorites—all from Antarcti-ca (Wang et al. 1994; Sack et al. 1994)—as well as separatedchondrules from nonantarctic meteorites and peculiar,whole-rock samples of them (Lipschutz et al. 1993; Olsen et al.1994; Petaev et al. 1994; Sears et al. in press).

    Development has continued on our AMS facility, one ofthree national AMS facilities in earth science supported by theNational Science Foundation. The other facilities (at Wood'sHole Oceanographic Institution and the University of Ari-zona) are carbon-14 (14C) machines; ours (PRIME Lab) is theonly one capable of quantifying the full spectrum of cosmo-genic radionuclides:• Beryllium- b ('°Be) (half-life, 1.6 million years);• Aluminum-26 (26A1) (half-life, 0.74 million years);• Chlorine-36 (36C1) (half-life, 0.30 milion years);• Calcium-41 (41 Ca) (half-life, 0.10 million years); and• Iodine-129 (1291) (half-life, 16 million years).In the past year, we chemically prepared almost 350 samples,mainly of '°Be, 26A1, and 36C1, (Vogt, Wang, and Lipschutz1994) and have run almost 1,500 samples (Elmore et al. 1994)of terrestrial rocks (Dep et al. 1994) and rain (Knies et al. 1994)and meteorites (Lipschutz et al. 1993; Wang et al. 1994; Mich-lovich et al. in press; Michlovich et al. 1994). The plannedupgrade of our AMS has just been completed, and as a result,we anticipate improved resolution and sensitivity as well ashigher throughput. In the coming year, we expect 41 Ca and 1291measurements to become as routine as those of '°Be, 26A1, and36Cl (Elmore et al. 1994; Vogt et al. 1994).

    Because of our developments in the applications of mul-tivariate statistics and nuclear chemistry to terrestrial andextraterrestrial materials, invitations to prepare chapters formonographs in these areas have been accepted. These havebeen completed (Wolf and Lipschutz in press c; Lipschutz inpress).

    Finally, we have demonstrated the application of a newlydeveloped computer analysis program, MELTS, to calculatethe crystallization sequence of igneous melts. We used thisprogram to demonstrate that a large igneous inclusion in theantarctic chondrite, Yamato 794046 (Sack et al. 1994), wasshock-produced, and we now plan to apply this technique toMartian meteorites, many of which were recovered fromAntarctica.

    This research was supported in part by National ScienceFoundation grants EAR 89-16667, 92-14636, and 93-05859;

    ANTARCTIC JOURNAL - REVIEW 1994

    49

  • National Aeronautics and Space Administration grants NAG9-48 and 9-580 and NAGW-3396 and 3640; Department ofEnergy grant DE-FG07-80ER1 072SJ; and the W.M. KeckFoundation.

    ReferencesDep, L., D. Elmore, M.E. Lipschutz, S. Vogt, F.M. Phillips, and M.

    Zreda. 1994. Depth dependence of cosmogenic neutron-captureproduced 36G1 in a terrestrial rock. Nuclear Instruments andMethods in Physics Research, B92(1-4), 301-307.

    Dodd, R.T., S.F. Wolf, and M.E. Lipschutz. 1993. An H chondritestream: Identification and confirmation. Journal of GeophysicalResearch-Planets, 98(8), 15105-15118.

    Elmore, D., L. Dep, R. Flack, M.J. Hawksworth, D.L. Knies, E.S.Michiovich, T.E. Miller, K.A. Mueller, F.A. Rickey, P. Sharma, P.C.Simms, H.-J. Woo, M.E. Lipschutz, S. Vogt, M.-S. Wang, and M.C.Monaghan. 1994. The Purdue Rare Isotope Measurement Labo-ratory. Nuclear Instruments and Methods in Physics Research,B92(1-4), 65-68.

    Hiroi, T., G.M. Pieters, M.E. Zolensky, and M.E. Lipschutz. 1993. Evi-dence of thermal metamorphism on C, G, B, and F asteroids. Sci-ence, 261(5124), 1016-1018.

    Hiroi, T., G.M. Pieters, M.E. Zolensky, and M.E. Lipschutz. 1994.Possible thermal metamorphism on the C, G, B, F asteroidsdetected from their reflectance spectra in comparison with car-bonaceous chondrites. Proceedings of the NIPR Symposium onAntarctic Meteorites, 7, 230-243.

    Knies, D.L., D. Elmore, P. Sharma, S. Vogt, R. Li, M.E. Lipschutz, G.Petty, J. Farrel, M.G. Monaghan, S. Fritz, and E. Agee. 1994. 7Be,10Be, and 36G1 in precipitation. Nuclear Instruments and Methodsin Physics Research, B92(1-4), 340-344.

    Lipschutz, M.E. In press. Neutron activation analysis and accelera-tor mass spectrometer studies of extraterrestrial materials. Pro-ceedings of the Symposium on Applications of Nuclear Chemistry.

    Lipschutz, M.E., S.F. Wolf, S. Vogt, E. Michlovich, M.M. Lindstrom, M.E.Zolensky, D.W. Mittlefehldt, C. Satterwhite, L. Schultz, T. Loeken, P.Scherer, R.T. Dodd, D.W.G. Sears, P.H. Benoit, J.F. Wacker, R.G.Burns, and D.S. Fisher. 1993. Consortium study of the unusual Hchondrite regolith breccia, Noblesville. Meteoritics, 28(4), 528-537.

    Michiovich, E.S., S. Vogt, J. Masarik, R.C. Reedy, D. Elmore, and M.E.Lipschutz. 1994. 26M, 10Be, and 36C1 depth profiles in the Canyon

    Diablo iron meteorite. Journal of Geophysical Research-Planets,99(11), 23187-23194.

    Michlovich, E.S., S.F. Wolf, M.-S. Wang, S. Vogt, D. Elmore and M.E.Lipschutz. In press. Chemical studies of H chondrites—V. Tem-poral variations of sources. Journal of Geophysical Research-Planets, 100(3).

    Olsen, E., A. Davis, R.S. Clarke, Jr., L. Schultz, H.W. Weber, R. Clay-ton, T. Mayeda, E. Jarosewich, P. Sylvester, L. Grossman, M.-S.Wang, M.E. Lipschutz, I.M. Steele, and I. Schwade. 1994. Watson:A new link in the HE iron chain. Meteoritics, 29(2), 200-213.

    Petaev, M.I., L.D. Barsukova, M.E. Lipschutz, M.-S. Wang, A.A.Ariskin, R.N. Clayton, and T.K. Mayeda. 1994. The Divnoe Mete-orite: Petrology, chemistry, oxygen isotopes and origin. Meteorit-ics, 29(2), 182-199.

    Sack, R.O., M.S. Ghiorso, M.-S. Wang, and M.E. Lipschutz. 1994.Igneous inclusions from ordinary chondrites: High temperatureresidues and shock melts. Journal of Geophysical Research-Plan-ets, 99(12), 26029-26044.

    Sears, D.W.G., A.D. Morse, R. Hutchison, R.K. Guimon, L. Jie, G.M.O.'D. Alexander, P.H. Benoit, I. Wright, C. Pillinger, T. Xie, andM.E. Lipschutz. In press. Metamorphism and aqueous alterationin low petrographic type ordinary chondrites. Meteoritics.

    Treiman, A.H., G.A. McKay, D.D. Bogard, M.-S. Wang, M.E. Lip-schutz, D.W. Mittlefehldt, L. Keller, M.M. Lindstrom and D. Gar-rison. 1994. Comparison of the LEW 88516 and ALH A77005Shergottites. Similar but distinct. Meteoritics, 29(5), 581-592.

    Vogt, S., M.-S. Wang, and M.E. Lipschutz. 1994. Chemistry opera-tions at Purdue's Accelerator Mass Spectrometry Facility.Nuclear Instruments and Methods in Physics Research, B92(1-4),153-157.

    Wang, M.-S., E.S. Michlovich, S. Vogt, and M.E. Lipschutz. 1994.Labile trace elements and cosmogenic radionuclides in chon-dritic hosts of three consortium igneous inclusions. Proceedingsof the NIPR Symposium on Antarctic Meteorites 7, 144-149.

    Wolf, S.F., and M.E. Lipschutz. In press a. Chemical studies of Hchondrites—IV. New data and comparison of antarctic popula-tions. Journal of Geophysical Research-Planets, 100(3).

    Wolf, S.F., and M.E. Lipschutz. In press b. Chemical studies of Hchondrites—VI. Antarctic/non-antarctic compositional differ-ences revisited. Journal of Geophysical Research-Planets, 100(3).

    Wolf, S.F., and M.E. Lipschutz. In press c. Multivariate statisticaltechniques for trace element analysis. In M. Hyman and M.Rowe (Eds.), Advances in analytical geochemistry.

    Compositional studies of new groups of chondritic meteoritesALAN E. RUBIN and GREGORY W. KALLEMEYN, Institute of Geophysics and Planetary Physics, University of California,

    LosAngeles, California 90024-1567

    The abundances of refractory and common nonvolatileelements in chondritic meteorites are similar to those in

    the Sun's photosphere. These meteorites represent unfrac-tionated samples of the solid materials that existed in theearly solar nebula. Different groups of chondrites have dis-tinct bulk compositions and mineralogical and textural char-acteristics; researchers infer that each group was derivedfrom a separate asteroid. The large number of meteorite

    samples discovered in Antarctica in the last 25 years (morethan 15,000) has led to the discovery of new chondritegroups. During the last year, we analyzed members of twonew groups by instrumental neutron activation analysis todetermine the concentrations of 27 elements with differentgeochemical affinities. We combined these data with miner-alogical and petrographic studies to characterize the chon-drite groups.

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