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Meteoritics & Planetary Science 44, Nr 3, 1–33 (2009) Abstract available online at http://meteoritics.org The Meteoritical Bulletin, o. 95 Michael K. WEISBERG1, 2*, Caroline SMITH3, 4, Gretchen BENEDIX3, Luigi FOLCO5, Kevin RIGHTER6, Jutta ZIPFEL7, Akira YAMAGUCHI8, and Hasnaa CHENNAOUI AOUDJEHANE9 1Department of Physical Science, Kingsborough Community College and the Graduate School of the City University of New York, 2001 Oriental Blvd., Brooklyn, New York 11235, USA 2Department of Earth and Planetary Science, American Museum of Natural History, Central Park West New York, New York 10024, USA 3Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK 4School of Geographical and Earth Science, University of Glasgow, Scotland, G12 8QQ, UK 5Museo Nazionale dell’Antartide, Università di Siena, Via Laterina 8, I-53100 Siena, Italy 6Mailcode KT, NASA Johnson Space Center, 2101 NASA Parkway, Houston, Texas 77058, USA 7Sektion Meteoritenforschung, Forschungsinstitut und Naturmuseum Senckenberg, Senckenberganlage 25, D-60325, Frankfurt am Main, Germany 8Antarctic Meteorite Research Center, National Institute of Polar Research, 1-9-10 Kaga, Itabashi, Tokyo 173-8515, Japan 9Université Hassan II Casablanca, Faculté des sciences, Département de Géologie, BP 5366, Mâarif, Casablanca, Morocco *Corresponding author. E-mail: [email protected] (Received 25 February 2009) Abstract–The Meteoritical Bulletin No. 95 reports 1093 (282 non-Antarctic and 801 Antarctic) newly approved meteorite names and their recovery histories, macroscopic descriptions, petrography, mineral compositions and geochemistry. Meteorites reported include lunar meteorites, eucrites, mesosiderites, angrites, ureilites, an acapulcoite, and H, L, LL, R, CO, CM, CK and CV chondrites. Three new falls, the Bunburra Rockhole (Australia) eucrite and the recent (Nov., 2008) Buzzard Coulee (Canada) H4 chondrite, and Tamdakht (Morocco) H5 chondrite are reported. ITRODUCTIO meteorites are reported in table format only and fewer in full written descriptions. Additional full written descriptions for This issue of The Meteoritical Bulletin reports 1093 newly some entries may be found in the online database, http:// approved meteorites including 3 from specific locations in tin.er.usgs.gov/meteor/metbull.php. Africa (Table 1), 128 from Northwest Africa (Table 2), 6 from North America (Table 3), 12 from South America (Table 4), AFRICA 801 from the Grove Mountains, Antarctica, collected by the China Antarctic Research Expedition (Table 5), 3 from Algeria, Morocco, and Other Locations in Africa Australia (Table 6), 139 from Oman (Table 7) and 1 from Thailand (Table 8). Included are three falls: the 2007 Bunburra El-Oued 31°32′, 8°53′E Rockhole (Australia) eucrite, the (Nov. 2008) Buzzard Coulee Algeria (Canada) H4 chondrite and the (Dec. 2008) Tamdakht Found 1952 (Morocco) H5 chondrite. The meteorites reported in this Ordinary chondrite (H4) bulletin span a wide range of achondrite and chondrite groups. History: The meteorite was recognized by Smail Mostefaoui Featured in full written descriptions are the three new in his hometown El-Oued at the regional Museum “Le petit falls, as well as finds from Algeria and South Africa, a new Musée du Monde.” The present director of the Museum, CO3 from Chile, a CM-like meteorite with an anomalous Mr. Ahmed Chaouki Bouclifa, explained that the meteorite oxygen isotope composition, 3 ungrouped achondrites, 5 was discovered in 1952 by the French army during their patrol lunar meteorites, a shergottite, and an unusual ureilite from in Zemoul el Merkr dunes Southeast of the El-Oued city. Oman. In the tables are new ureilites, an angrite, an Physical characteristics: The total mass = 2.305 kg in two acapulcoite, eucrites, a howardite, mesosiderites, a pallasite, pieces (1.485 and 0.820 kg). The fusion crust in both CV3, CO3, and CK4 chondrites, and an R3.7 chondrite. This fragments is incomplete and has little rust and brownish color. bulletin also marks a slight change in format in which more The interior is darker. 1 © The Meteoritical Society, 2009. Printed in USA. 2 M. K. Weisberg et al. Petrography (M. Bourot-Denise, MHP): The chondritic composition Fe0.85–0.87S and pentlandite (Fe,Ni)1.02–1.10S. The texture is clearly visible. The metal is almost completely bulk chemistry of the large clast is chondritic, although U, Th, altered. The silicates show cracks filled with Fe-hydroxide. La and Ce are enriched and Na, K are depleted compared to Some melt pockets are present; one thin section is crossed the average compositions for ordinary chondrites. Absolute with a cm-sized vein of polycrystalline sulfide. Some olivine PGE (Ir = 234 ppb; Ru = 351 ppb; Rh = 81 ppb; Pt = 478 ppb; grains contain sulfide-filled cracks. Pd = 361 ppb), Ni (5850 ppm) and Co (326 ppm) Mineral compositions and geochemistry: Olivine: mean concentrations are ~30–40% lower than in average LL Fa = 20.1 ± 0.8; low-Ca pyroxene: mean Fs = 17.3 ± 0.6. The chondrites. Despite the absence of metal, the bulk Fe content magnetic susceptibility value (log χ = 4.61) measured by of the clast is chondritic. Bulk S isotope analyses yielded δ34S J. Gattacceca (CEREGE) is consistent with a high weathering values of −0.1‰ and −0.4‰, and individual sulphide degree. minerals analysed by in situ laser combustion revealed a Classification: Ordinary chondrite H4; W3/W4; S3. range of values from −0.9‰ to +0.1‰. 53Cr/52Cr ratio in the Type specimens: A total of 30 g (2 pieces and two thin large clast is 0.38 ± 0.05ε. sections) is on deposit at MH. The Museum in El-Oued Classification: LL6 chondrite, shock stage S5, weathering holds the main mass. grade W0. Specimens: A total of ~20 g is on deposit at the Transvaal Morokweng 26°22′20.89′′S, 23°31′26.24′′E Museum, Pretoria, South Africa. Dr W. D. Maier holds the Northwest Province, South Africa, near the small town of main mass. Dr. M. Andreoli holds 4 small pieces (between 2 Morokweng and 22 g). Find June 2004 LL6 ordinary chondrite Tamdakht 31°09.8′, 7°00.9′W History: The meteorite was found by Dr. Marco Andreoli in Tamdakht, (Ouarzazate) Morocco June 2004 while conducting a detailed petrographic description Fall: 20 December 2008, 22:37 hrs (local time; UT+00) of the M3 borehole. The M3 borehole had been drilled in Ordinary chondrite (H5) 2000 to investigate the mineral potential of the ~30 km History (H. Chennaoui-Aoudjehane): On December 20, meltsheet of the ~144 Ma Morokweng impact crater. The 2008, witnesses from a number of locations in Morocco meteorite was intersected at a depth of ~766 m within the (Agadir, Marrakesh, Ouarzazate) observed a meteor with a W 870 m thick meltsheet. Petrographic and compositional to E trajectory. According to the local newspaper, Al Massae evidence indicates the presence of many other, smaller (of December 27th), people from the high Atlas Mountains fragments in various stages of recrystallization (Hart et al. (between Marrakesh and Ouazazate) heard a sound and felt an 2002). aftershock. Due to the high relief in this mountain region, Physical characteristics: The main mass is ~750 g. The covered with snow at this time of the year, searching for the meteorite is mostly unaltered, apart from a thin (~1 mm) meteorite was a difficult task. The first reports on finding brown corona containing unidentified Fe silicates and K-rich pieces of a meteorite came a couple of weeks later. The largest sheet silicates interpreted to be the result of alteration by the impact pit is located near Oued Aachir (1.10 m diameter and meltsheet. 70 cm depth, 31°09.8′N, 7°00.9′W), with a stone exceeding Petrography W. D. Maier (UQué, Pretoria), M. A. G. 30 kg and many small fragments. A second one is smaller, Andreoli (SAEC, Wits), I. McDonald (Cardiff), M. D. (about 20 cm diameter and 10 cm depth; 31°09.9′N Higgins (UQué), A. J. Boyce (SUERC), A. Shukolyukov 07°02.3′W) located 2 km W from the first one; the main mass (Scripps), G. W. Lugmair (Scripps), L. D. Ashwal (Wits), P. from the second impact was probably about 500 g. Nine new Graeser (Pretoria), E. Ripley (Indiana), and R. Hart impacts coordinates have been reported by S. Buhl and M. (Ithemba): Apart from the thin (1 mm) corona containing Aid, and P. Thomas reported 3 other impacts. A strewn field brown alteration minerals, the meteorite is seemingly of at least 25 km long and 2 km wide has been outlined. unaltered. Petrographic study revealed diagnostic features of Physical characteristics: Total weight is presently estimated a highly equilibrated chondrite breccia, including numerous to be 100 kg. Pieces recovered as of February 15, 2009, are subangular chondrite fragments, and several well-preserved 30 kg, 1.5 kg, 3.8 kg, 3.69 kg, 2.4 kg, 1.5 kg, 1 kg, 800 g, and chondrules of porphyritic pyroxene, barred olivine, and radial 399 g. One major fragment of 1.7 kg and many small pieces pyroxene. The number of preserved chondrules is relatively from the same stone (ranging 500 to below 1 g) were also low. Both minerals commonly show undulatory and mosaic recovered. The largest fragment shows a nearly complete dull extinction. The matrix material has a well-developed granular gray fusion crust, other pieces are 90% crusted to free of texture with 120° triple junctions. crust, often broken along preexisting fractures. Thick fusion Geochemistry: Both olivine (Fo67–70) and orthopyroxene crust, locally more than 1 mm. (En69–73) are homogenous within individual grains and Petrography (Albert Jambon, Omar Boudouma, D. Badia throughout the meteorite. Plagioclase is mostly An33–50, some UPVI and M. Denise, MHP): Abundant chondrules with to An17, chromite has 44–48% Cr2O3. Pyrrhotite has visible but not well-delimited outlines. Chondrule size is The Meteoritical Bulletin, No.
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  • The Origin and History of Ordinary Chondrites: a Study by Iron Isotope Measurements of Metal Grains from Ordinary Chondrites

    The Origin and History of Ordinary Chondrites: a Study by Iron Isotope Measurements of Metal Grains from Ordinary Chondrites

    Available online at www.sciencedirect.com Geochimica et Cosmochimica Acta 72 (2008) 4440–4456 www.elsevier.com/locate/gca The origin and history of ordinary chondrites: A study by iron isotope measurements of metal grains from ordinary chondrites K.J. Theis a,*, R. Burgess a, I.C. Lyon a, D.W. Sears b a School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK b Arkansas Center for Space and Planetary Science and Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA Received 15 August 2007; accepted in revised form 30 May 2008; available online 14 June 2008 Abstract Chondrules and chondrites provide unique insights into early solar system origin and history, and iron plays a critical role in defining the properties of these objects. In order to understand the processes that formed chondrules and chondrites, and introduced isotopic fractionation of iron isotopes, we measured stable iron isotope ratios 56Fe/54Fe and 57Fe/54Fe in metal grains separated from 18 ordinary chondrites, of classes H, L and LL, ranging from petrographic types 3–6 using multi-col- lector inductively coupled plasma mass spectrometry. The d56Fe values range from À0.06 ± 0.01 to +0.30 ± 0.04& and d57Fe values are À0.09 ± 0.02 to +0.55 ± 0.05& (relative to IRMM-014 iron isotope standard). Where comparisons are possible, these data are in good agreement with published data. We found no systematic difference between falls and finds, suggesting that terrestrial weathering effects are not important in controlling the isotopic fractionations in our samples.