Using the X-ray flare observations of low-mass protostars, we developed numerical simulations of thermal processing and irradiation of protoCAIs in the magnetic reconnection ring within the X-wind formulation. Observed X-ray flare luminosities have been used to model various simulation flare characteristics. Several approximations have been made regarding the thermal evolution that involve condensation, evaporation, and coagulation of protoCAIs. Ensembles of refractory cores with ferromagnesian mantles were evolved for irradiation production of the short lived nuclides 7Be, 10Be, 41Ca, 36Cl, 26Al, and 53Mn. Three distinct grain-size distributions of protoCAIs with refractory cores in the ranges of 32 micrometer-20 mm, 125 micrometer-16 mm, and 500 micrometer-13 mm were thermally evolved for irradiation. The latter two size distributions were found to result in the accumulation of protoCAIs in the reconnection ring during an X-wind cycle, and hence can account for the total inventory of 26Al in the early solar system. The canonical value of ~5 x 10^(-5) for 26Al/27Al can be inferred from the impulsive flare simulations by a suitable choice of simulation parameters. However, in most of the remaining simulations, the irradiation of protoCAIs by superflare(s) with Lx > 10^32 ergs s^(-1) subsequent to their thermal processing in the reconnection ring would be required to explain the experimental abundances of the short-lived nuclides. These superflares have never been reliably observed in young stellar objects. If they are real, they would be extremely rare. The paucity of these superflares could impose stringent constraints on the validity of the X-wind irradiation scenario as the source of the short-lived nuclides.

Detailed analysis of cumulate and melt inclusion assemblages in the chassignites provide important constraints on the nature of the melt trapped as inclusions in cumulus olivine (and, by extension, parental magma compositions), the pressures of crystallization, and magmatic volatile contents. These mineral assemblages show strong similarities to the experimental fractionation assemblages that produce the sodic silica-saturated alkalic lavas on Earth (e.g., Ascension Island, Azores, the Nandewar volcano of Australia). The experimental assemblages were produced from silica-saturated hawaiite at pressures above 4.3 kbar with dissolved water contents above 0.5 wt%. Such pressures are consistent with Ti:Al ratios of the melt-inclusion pyroxenes in the Chassigny meteorite. Pyroxene compositions suggest early high crystallization temperatures and thus relatively low initial water and F contents. Feldspars indicate that melt evolution proceeded to rhyolite compositions both within the interstices of the cumulate olivine and within the melt inclusions, even though rhyolitic glass is only found within olivine-hosted polyphase melt inclusions. The observed rhyolite glass is compositionally similar to the alkali-rich rhyolite of Ascension Island which is produced experimentally by crystallization of hawaiite. It is proposed that the melt trapped in cumulus olivine of the Chassigny dunite was similar to a terrestrial silica-saturated hawaiite, while that trapped in olivine of the Northwest Africa (NWA) 2727 dunite was less evolved, perhaps mildly alkalic basalt. Melts similar to terrestrial intra-plate tholeiite could be parental to the cumulus minerals and evolve upon crystallization at pressures above 4.3 kbar and water contents above ~0.4 wt% to mildly alkalic basalt, silica-saturated hawaiite, and alkali-rich rhyolite. The melt inclusion assemblages are inconsistent with either crystallization of a low-Al, high-Fe basalt, or low pressure crystallization of a terrestrial-like tholeiite.

Buck Mountain Wash (BMW) is a new genomict breccia (H35) found in the Franconia (H5) strewn field in Arizona that shows complex brecciation and shock effects. It contains three distinct chondritic lithologies in sharp contact: a) a main lithology that consists primarily of petrographic type 5 material but which has finely intermixed type 3 and 4 material, b) a shockblackened (shock stage S5) type 3 lithology (lithology A), and degrees C) a shock-blackened type 3/4 lithology(lithology B). Buck Mountain Wash was lithified after impact-mixing and impact-melting of weakly and strongly metamorphosed materials, possibly at depth in the regolith of the parent body. Shock effects included brecciation on a fine scale, localized impact-melting of silicates, partial melting, and mobilization of metal-sulfide, and chemical fractionations that produced non-H-group composition kamacite by two disequilibrium mechanisms. Shock heating did not cause significant thermal metamorphism in the shock-blackened lithologies of BMW, except possibly in areas adjacent to whole-rock shock melt. During lithification, cooling must have been rapid at high temperatures to preserve glass and inhomogeneous silicate compositions, but not so fast at lower temperatures as to produce dendritic metal-sulfide globules or martensite.

We obtained two-dimensional concentration maps for the minor elements Fe and V in 21 spinel crystals in the Allende type B1 inclusion TS-34 with a 4-5 micrometer resolution. Locally high concentrations of Fe occur along at least one edge of the spinels and decrease toward the center of the grains. Enrichment in V can also occur along edges or at corners. In general, there is no overall correlation of the Fe and V distributions, but in local regions of two grains, the V and Fe distributions are correlated, strongly suggesting a local source for both elements. In these two grains, opaque assemblages are present that appear to locally control the V distributions. This, coupled with previous work, suggests that prior to alteration, TS-34 contained V-rich metal. Oxidation of this metal during alteration can account for the edge/corner V enrichments, but provide only minor FeO contributions, explaining the overall lack of correlation between Fe and V. Most of the FeO appears to have been externally introduced along spinel boundaries during alteration. These alteration phases served as sources for diffusion of FeO into spinel. FeO distributions in spinel lead to a mean attenuation length of ~8 micrometer and, using literature diffusion coefficients in isothermal and exponential cooling approximations for peak temperatures in the range 600-700 degrees C, this leads to a time scale for calciumaluminum- rich inclusion (CAI) alteration in the range of decades to centuries.

Shock recovery experiments to determine whether magnetite could be produced by the decomposition of iron-carbonate were initiated. Naturally occurring siderite was first characterized by a variety of techniques to be sure that the starting material did not contain detectable magnetite. Samples were shocked in tungsten-alloy holders (W = 90%, Ni = 6%, Cu = 4%) to further ensure that any iron phases in the shock products were contributed by the siderite rather than the sample holder. Each sample was shocked to a specific pressure between 30 to 49 GPa. Transformation of siderite to magnetite as characterized by TEM was found in the 49 GPa shock experiment. Compositions of most magnetites are >50% Fe^+2 in the octahedral site of the inverse spinel structure. Magnetites produced in shock experiments display the same range of sizes (~50-100 nm), compositions (100% magnetite to 80% magnetite-20% magnesioferrite), and morphologies (equant, elongated, euhedral to subhedral) as magnetites synthesized by Golden et al. (2001) and as the magnetites in Martian meteorite Allan Hills (ALH) 84001. Fritz et al. (2005) previously concluded that ALH 84001 experienced ~32 GPa pressure and a resultant thermal pulse of ~100-110 degrees C. However, ALH 84001 contains evidence of local temperature excursions high enough to melt feldspar, pyroxene, and a silica-rich phase. This 49 GPa experiment demonstrates that magnetite can be produced by the shock decomposition of siderite as a result of local heating to >470 degrees C. Therefore, magnetite in the rims of carbonates in Martian meteorite ALH 84001 could be a product of shock devolatilization of siderite as well.