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Nineteen nonporphyritic pyroxene and pyroxene/olivine chondrules, chondrule fragments, and irregular objects were studied from two equilibrated chondrites, the ordinary (L/LL5) Knyahinya chondrite and the Rumuruti type (R4) Ouzina chondrite. Major element contents for almost all objects in the chondrites are disturbed from their chondritic ratios, most probably during metamorphic re-equilibration. However, the volatile elements (Na2O+K2O) in Ouzina scatter around the CI line, probably the result of being generated and/or processed in different environments as compared with those for Knyahinya. All studied objects from Knyahinya and Ouzina possess systematically fractionated trace element abundances. Depletion of LREE with respect to HREE and ultra-refractory HFSE documents variable degrees of LREE transport into an external mineral sink and restricted mobility of most of the HREE and HFSE. Moderately volatile elements preserve volatility-controlled abundances. Strongly fractionated Rb/Cs ratios (up to 10× CI) in all studied objects suggest restricted mobility of the large Cs ion. All studied objects sampled and preserved Y and Ho in solar proportions, a feature that they share with the nonporphyritic chondrules of unequilibrated ordinary chondrites. Fil: Varela, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; Argentina Fil: Sylvester, Paul. Memorial University Of Newfoundland; Canadá Fil: Engler, Almut. University of Graz; Austria Fil: Kurat, Gero. Universidad de Viena; Austria

Although considerable progress has been made in unraveling the origin(s) of fayalitic olivines in dark inclusions (DIs), many questions remain still unresolved and/or controversial. We combine a chemical and petrographic study of the Allende dark inclusion 4884-2B (AMNH, New York) and ATEM studies of a fragment of the dark inclusion Allende AF (NHM, Vienna) and discuss an alternative way in which fayalitic olivines could have formed. Allende dark inclusion 4884-2B contains a few aggregates with variable proportions of transparent and feathery olivine. Two such objects (aggregates A and B) are the focus of this study as they preserve glasses that can help in deciphering the nature of the processes involved during olivine growth and subsequent olivine transformation. The petrographic and chemical characteristics of aggregates A and B indicate that the forsteritic stack olivines may be pseudomorphs of clear olivine crystals. The ATEM studies in All-AF suggest that fayalitic olivines may be the result of secondary processes (e.g., metasomatic exchange reactions) operating in the solar nebula. Transformation may have occurred through the mediation of a dry gas phase involving nonvolatile major elements, such as Mg and Fe (e.g., Dohmen et al. 1998). This mechanism could reveal olivine growth patterns (e.g., stacked platelets due to a rapid growth regime) and may have contributed to the development of their fibrous aspect while preserving the shape (i.e., volume) of the crystals. This highly selective process did completely or partially transform ferromagnesian minerals, but affected the fine-grained mesostasis only slightly. Fil: Varela, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; Argentina Fil: Zinner, Ernst. University of Washington; Estados Unidos Fil: Kurat, Gero. Universidad de Viena; Austria Fil: Chu, Hao Tsu. Central Geological Survey; República de China Fil: Hoppe, Peter. Max Planck Institute for Chemistry; Alemania

Asuka-31 (Asuka-881757) is a new type of gabbroic mare basalt which is similar to VLT mare basalts from Apollo 17 and Luna 24. The small lunar meteorite Yamato-793169 was described to have petrologic characteristics that are similar to those of A-881757; this similarity is confirmed here for trace element compositions. We studied bulk (powder) samples and mineral and rock fragments of A-881757. The mineralogy and mineral chemistry of the separates from A-881757,111 is that of a coarse-grained gabbroic rock of VLT composition; the texture of the mesostases suggests some metamorphic recrystallization with highly unequilibrated mineral compositions. As for mineral phases, we found plagioclase, pyroxene, fayalite, Fe-Ni metal, silica, apatite, and some trace minerals. In addition, we found ulvospinels associated with Na-rich plagioclase, fayalite, apatite, ilmenite, SiO_2,Fe-sulfide, and a rare metal (0.3wt% Ni, 2.0wt% Co) which has a composition unknown so far from any lunar rocks. The trace element contents found in the mineral separates and fragments correspond closely to the mineralogical findings. The chondrite normalized REE patterns for the bulk samples of A-881757 and Y-793169 are relatively flat, with some light REE depletion that is typical of mare basalts. The plagioclasedominated subsamples A31-CL, A31-CL2,and A31-YC show a distinct positive Eu anomaly. The bulk trace element composition of Y-793169 is almost identical to that of A-881757. Solar-wind dervved noble gas and exposure age studies of A-881757 and Y-793169 have indicated marked differences between the two meteorites, indicating that they might have been ejected in different events. These two new gabbroic, VLT-like, mare basalts are therefore valuable new additions to the lunar meteorite collection.

Two small samples of the new lunar meteorite Yamato-793274 have been studied for mineralogical, petrological, and geochemical composition. The meteorite has a coarse grained texture and consists of a dense breccia that contains relatively large and abundant mineral fragments (clinopyroxene, plagioclase, olivine, ilmenite), rare fine-grained granulitic (poikilitic) breccias, and some mostly brownish devitrified glass. The matrix is abundant, dense, and consists of mineral fragments and interstitial mostly recrystallized glass. One large recrystallized melt breccia of anorthositic-noritic-troctolitic (ANT) composition was found. All plagioclase fragments are highly anorthitic, and olivine compositions range from Fo_. The occurrence of these breccias and plagioclases, as well as the chemistry of some matrix glass, is consistent with an origin from the lunar highlands. However, some glasses have a considerably more mafic composition and show admixture of a low mg-component. Pyroxenes are unusually abundant when compared with other lunar meteorites. They usually show exsolution lamellae, are heavily shocked, and their compositions show a bimodal distribution, with low-mg pyroxenes most probably of mare origin. Among opaque phases, kamacite, and a Co-rich taenite were found, and, for the first time in lunar rocks, the rare higher phosphide barringerite, (Fe, Ni)_2 P. The bulk major and trace element composition is unlike the anorthositic lunar highland meteorites (e. g., ALHA81005,Y-791197,Y-86032,MAC88104/5), but somewhat similar to the newly identified mare meteorite EET87521. The mineral compositions as well as the major and trace element compositions of the bulk show a close similarity to certain VLT mare basalts, e. g., the Luna 24 ferrobasalts. This is obvious, for example, in a plot of molar Mg/(Mg+Fe) vs. TiO_2 content. The lithophile trace element abundances in Y-793274 are similar to EET87521 and Apollo 17 and Lunar 24 VLT's. The REE patterns show higher abundances (about 20-10×Cl) than the anorthositic meteorites and a small negative Eu anomaly. They are similar to EET87521 and some Apollo 14 green volcanic glasses. From the mineralogical and chemical data, pairing with any other lunar meteorite is very unlikely. Y-793274 is a shock lithified fragmental breccia containing a minor regolith component and numerous mafic mineral fragments and glasses. It is a mixture of about two thirds mare material and one third highland component, and therefore different from all previously known lunar meteorites.

Yamato-86032 is a shock-lithified anorthositic fragmental breccia. It consists mainly of highly feldspathic meta-breccias and meta-meltrocks and possibly contains a small contribution from mare lithologies, but there is no indication of a KREEP component. In many respects Y-86032 is similar to the previously described lunar meteorites Y-82192/3,but there are some notable differences. We have analyzed about 40 major and trace elements in bulk matrix, impact melt, and clast samples from two chips of Y-86032. The abundances of most lithophile and incompatible elements are lower in Y-86032 than in Y-82192 (which contains very low abundances compared to normal lunar highland rocks). The REE abundances are comparable to those of Y-82192. The elements Sc, Cr, Mn, Fe and Co have significantly lower abundances than in Y-82192,and the siderophile element pattern is also different. Since cosmic ray exposure data indicate pairing of Y-86032 with Y-82192/3,the source region for these meteorites on the moon must have been fairly heterogeneous.