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All previously distributed meteorite data sheets, plus a number of new ones for 1979 chondrites are included. A comprehensive sample index listing meteorite name/number, classification, and weathering category is also included. Separate indexes listing all petrologic type 3 and type 4 chondrites, all irons, all achondrites, and all carbonaceous chondrites in the collection is provided.
Carbon-14 measurements were made for meteorites with a Van der Graaf accelerator. Accelerator C-14 dating improved the precision by a factor of ten, allowed the use of smaller sample sizes, and gave speedier results than C-14 dating with counters. A methodology for determining the terrestrial ages of several antarctic meteorites is described and the results are listed.
The individual specimens, arranged by class are described. Within the chondrites, the specimens are grouped according to the Van Schmus-Wood classification, and the descriptions follow the order of increasing petrographic type. The original weight of the specimen is given to the nearest gram (nearest 0.1 gram for specimens weighing less than 100 grams). Material on al characterized meteorites collected together with descriptions of some meteorites is included. Specimens weighing less than 100 grams are listed without descriptions, unless they show distinctive features.
Oktibbeha County, the most Ni-rich iron meteorite, has been analyzed for Ni, Co, Cu, Ga, Ge, As, Sb, Ir, and Au. Cu and Sb are higher than in any other iron, but other trace elements are within the ranges typically found in iron meteorites. Extrapolation of trace element trends in group IAB indicates that Oktibbeha County is a member of this group. This sheds light on the origin of groups IAB and IIICD, which are thought to be derived from impact melts on parent bodies of chondritic composition. Lafayette (iron), another sample reported in the literature to have a similarly high Ni content, is probably a pseudometeorite.
Pristine highlands rocks, i.e., those which have retained the chemical characteristics they acquired from igneous processes, contain metal grains whose Ni and Co contents are distinct from those in most polymict, meteorite-contaminated rocks. The difference is mainly a result of the bulk Ni/Co ratios of pristine rocks being much lower than those of chondritic meteorites. The compositions of metal grains thus provide a rapid and effective criterion for the recognition of pristine highlands samples.
Cosmogenic C-14 is observed in the achondrite ALHA 77256. If ALHA 77256 at fall had the same C-14 activity as Bruderheim, then its terrestrial age is (11.1 + or - 1.0) x 1000 years. The upper limits on the C-14 activities in ALHA 77272, 77214, and 77004 specimens indicate that their terrestrial ages are greater than 34,000, 25,000, and 20,000 years, respectively. The C-14 terrestrial age of ALHA 77003 is (21,000 + 4000 or -3000) years, however, its specific activity is lower than that of contemporary carbon because of its high carbon content. The Ar-39 contents of the six investigated meteorites are all greater than 1000 years. Terrestrial age-location relationships at the meteorite collection site are discussed.
Attempts have been made recently to resolve the problem of depth and size dependences of the production rates of cosmogenic radionuclides within meteorites. The present investigation is concerned with Mn-53 and Al-25 measurements in samples of eight meteorite falls with small recovered masses. The recovered masses of the chondrites lie in the range from 0.35 to 8.4 kg, which corresponds to effective postatmospheric radii in the range from 2.9 to 8.3 cm. The He-3/Ne-21 ratios observed in these stones lie in the range from 6.33 to 8.62, and the Ne-22/Ne-21 ratios lie in the range from 1.132 to 1.248, thus generally indicating lightly shielded samples. The obtained results together with rare gas data are used as a basis for the discussion of the irradiation histories.
The data collection and the interpretation with respect to the mineralogy of meteoritic and terrestrial samples are summarized. The key conclusion is that the Moon underwent a series of melting episodes with complex crystal-liquid differentiation. It was not possible to determine whether the Moon melted completely or only partially. The stage is now set for a systematical geochemical and geophysical survey of the Moon. Emphasis was moved to meteorites in order to sort out their interrelationships from the viewpoint of mineral chemistry. Several parent bodies are needed for the achondrites with different chemical properties. Exploration of Mars is required to test ideas based on the possible assignment of shergottites, nakhlites and chassignite to this planet. Early rocks on the Earth have properties consistent with a heavy bombardment and strong volcanic activity prior to 4 billion years ago.
The trapping of meteoritic noble gases by solids is simulated through the synthesis of 18 Fe3O4 samples at 350-720 K in a noble gas atmosphere, by means of the reactions: (1) 3Fe + 4H2O yields Fe3O4 + 4H2, using Ne, Ar, Kr and Xe; and (2) 3Fe + 4CO yields Fe3O4 + 4C + carbides, using Xe. Etching experiments suggest an analogy with 'Phase Q' in meteorites. Adsorbed atmospheric gases are present in all samples, and dominate whenever the noble gas partial pressure in the atmosphere is greater than that in the synthesis. While many of the results of Lancet and Anders (1973) appear to have been dominated by such an atmospheric component, others are suspect. When the doubtful samples of Lancet and Anders are corrected or eliminated, the fractionation pattern no longer peaks at Ar, but rather, as in the present sample, rises monotonically from Ne to Xe. No evidence is found for the earlier study's claim of a strong temperature dependence.
Oxygen isotope ratios, siderophile abundances, and siderophile ratios for the Brachina meteorite (a chassignite) are compared with data reported for various chassignites, shergottites, nakhlites, pallasites, iron meteorites, chondrites, lunar low-Ti basalts, and terrestrial basalts. The results show that Brachina is different in origin from other shergottites, nakhlites, and chassignites. It is suggested that all the chassignites, shergottites, and nakhlites could have formed on Mars in an impact event about 180 million yr ago and that Brachina may have been ejected from Mars as a large tektitelike impact-melt blob consisting of Chassigny-like target material and a small amount of Eagle Station trio-like pallasite material.
The fluid inclusions presently described for five stony meteorites brings to seven the number of such meteorites confirmed. Homogenization temperatures are reproducible in each inclusion, and range from 25 C to over 225 C, with some vapor plus liquid inclusions remaining at 225 C, the highest temperature in these microthermometric experiments. Upon cooling, the fluid in some inclusions appears to freeze, as indicated by deformation and immobilization of the vapor bubble at low temperatures. Melting temperatures are by contrast difficult to observe and are not reproducible. Microthermometric data for the fluid in diogenite ALPHA 77256 and inclusions in four chondrites suggest that the fluid is aqueous, with a high solute content.
It is shown that the explanation of terrestrial contamination of the Murchison meteorite is consistent with the analysis of extracts from the meteorite reported by Engel and Nagy (EN) (1982) and is much more probable than their suggestion that the excess of L-enantiomers for several protein amino acids is due to asymmetric synthesis or decomposition. The low abundance of serine and threonine reported by EN may be due to their decomposition during the derivatization procedure, and the absence of methionine, tyrosine, and phenylalanine can be attributed to various causes. The amount of contamination in EN's extracts are estimated from a mass balance of the amino acid enantiomers, and it is found that the amino acids in the HCl could be due entirely to contamination while in the water extract the amount of contamination ranges from about 40 to 97 percent, depending on the amino acid. The argument that contaminants were preferentially extracted by EN's procedure cannot account for the failure to detect methionine, tyrosine, and phenylalanine.
A new technique for high-precision isotopic analyses of Ni is applied to terrestrial samples, Allende inclusions, and materials from other meteorites. It is noted that most of the Allende inclusions analyzed here were previously reported to contain isotopically anomalous Ti. In contrast, the Ni isotopic abundances are found to be indistinguishable from normal within presently obtainable precision, with only one possible exception. The latter inclusion has been shown by others to contain a significantly fractionated magnesium isotopic pattern of 9 parts per thousand/amu. A normal Ni isotopic pattern has also been observed for the chromite/carbon fraction of an Allende acid residue, which is known to have heavy noble gases of highly anomalous isotopic composition. All other meteoritic samples analyzed reveal normal isotopic compositions of Ni; no evidence for effects from now extinct Fe-60 could be detected. Despite ubiquitous isotopic anomalies in Ti from normal Allende inclusions there is no signature of isotopic variations in Ni from the same samples.
Paleomagnetic investigations (1979-1982) of the nature of the magnetization process and the magnetizing fields which produced magnetization in lunar and meteoritic materials are surveyed. Natural remanence magnetization (NRM), as well as thermoremanence magnetization (TRM), have been measured in carbonaceous chondrites and and L-chondrites to characterize the formation processes occurring when the magnetization was induced. Chemical remanence magnetism, together with the NRM, has been examined in noncarbonaceous chondrites, and NRM intensity and locations have been probed in achondrites. The magnetism has been concluded to arise either from solar magnetic fields, solar nebula magnetic fields, dynamo magnetic fields in the meteorite parent bodies, or locally generated fields caused by processes such as impacts. Lunar samples with NRM have been dated to origins less than 3.6 b.y., and could have been caused by shocks, such as from impacts less than 3 m.y. ago. Discussions of TRM, dynamo, and possible transient magnetic fields from hypervelocity meteoroid impacts as origins of magnetism on the surface and in a lunar magnetic core are presented.
The partitioning of Ir, Ge, Ga, W, Cr, Au, P, and Ni between solid metal and metallic liquid is investigated as a function of temperature and the S-concentration of the metallic liquid. The partition coefficients for siderophile elements, such as Ir, W, Ga, and Ge, are found to increase by factors of 10-100 as the S-concentration of the metallic liquid increases from 0-30 wt percent. Partition coefficients for other siderophile elements, such as Ni, Au, and P, increase by factors of only 2-3. In contrast, a decrease is seen in the partition coefficients for the more chalcophile element Cr. These experimentally determined coefficients are used in conjunction with a fractional crystallization model to reproduce the geochemical behavior of Ni, P, Au, and Ir during the magmatic evolution of groups IIAB, IIIAB, IVA and IVB iron meteorites. The mean S-concentration for each group increases in the order IVB, IVA, IIIAB, IIAB, which is in accordance with cosmochemical prediction. However, the geochemical behavior of Ge, Ga, W, and Cr cannot be reproduced in an internally consistent way. It is concluded that the magmatic histories of these iron meteorite groups are more complex than has been generally assumed.
The meteorite thought to be best described as a lunar highland regolith breccia from a non-KREEPy region. The controversy that remains as to the most likely source region is discussed. It is noted that several large lunar nearside craters have been proposed (Ostertag and Ryder, 1983). After finding a very-low-titanium (VLT) mare basalt clast in a thin section of ALHA 81005, Treiman and Drake (1983) have suggested that this constrains the source to being near a region with VLT basalt. It is pointed out, however, that the unexplored far side of the moon cannot be ruled out. Most of the lithic clasts that are abundant in the meteorite are members of the anorthosite-norite-troctolite highland suite. It is noted that plagioclase compositions in lithic clasts and single grains are calcic (An94-98).
The isotopic abundances of the noble gases (He, Ne, Ar, Kr, Xe) are reported for Antarctic ALHA 81005. It contains solar wind-implanted gases whose absolute and relative concentrations are quite similar to lunar regolith samples but not to other meteorites. ALHA 81005 also contains a large excess Ar-40 component which is identical to the component in lunar fines implanted from the lunar atmosphere. Large concentrations of cosmogenic Ne-21, Kr-82, and Xe-126 in ALHA 81005 indicate a total cosmic ray exposure age of at least 200 million years. The noble gas data alone are strong evidence for a lunar origin of this meteorite.
The content of trace elements (siderophile Co, Au, As, Sb, Ga; chalcophile/mobile Se, Te, Bi, In, Ag, Zn, Tl, Cd; lithophile Rb, Cs, U) is investigated to ascertain whether the meteorite is of lunar origin. Five elements reflect lunar crustal processes, whereas the remaining 11 siderophile and mobile elements suggest 1.4 + or - 0.5 percent micrometeorite admixture or enrichment by thermal redistribution on the moon. It is found that the impact launching of ALH A81005 to the earth was not attended by substantial shock loading. A Martian origin for severely shocked SNC meteorites is therefore considered plausible.