Unequilibrated chondrites

Bouvier, A., Vervoort, J. D. and Patchett, P. J. (2008) The Lu-Hf and Sm-Nd isotopic composition of CHUR constraints from unequilibrated chondrites and implications for the bulk compositions of the terrestrial planets. Earth and Planetary Science Letters, 273, 48-57. 

Busemann, H., Baur, H., Wider, R. (1997) Noble gas component Q in HF/HCl-resistant residues of unequilibrated chondrites. Lunar Planet. Sci., XXVIII, 183 1. 

Brearley A. J. (1996) Nature of matrix in unequilibrated chondrites and its possible relationship to chondrules. In Chondrules and the Protoplanetary Disk (eds. R. H. Hewins, R. H. Jones, and E. R. D. Scott). Cambridge University Press, Cambridge, pp. 137-151. 

Jones R. H. and Lofgren G. E. (1993) A comparison of FeO-rich, porphyritic olivine chondrules in unequilibrated chondrites and experimental analogues. Meteoritics 28, 213-221. 

FeAl204 primary phase in many CAI varieties Fe-rich ( secondary ) in altered zones and in Wark-Lovering rims. unequilibrated chondrite types (except Cl)... 

Perovskite CaTiOa A primary phase in some CAI varieties common also in Wark-Lovering rims Common in CAIs in all unequilibrated chondrite t)fpes (except Cl)... 

Anorthite CaAlzSijOg A primary phase only in type B CAIs a secondary phase in many melilite-bearing CAI varieties Common in CAIs in most unequilibrated chondrite types (except Cl), as a rim phase type B CAIs are restricted to CV3 chondrites... 

Primitive achondrites. They are achondrites that exhibit equilibrated, metamorphic textures, possibly modified by impact. Rare members have relict chondritic textures, but examples with classic, unequilibrated chondritic (i.e., type 3) textures are absent. They have compositions of lithophile, siderophile, chalcophile, and atmophile elements that are at most only moderately fractionated from the range of nebular materials. Some members may be quite fractionated, but the group as a whole is dominated by primitive materials. 

Gooding JL, Mayeda TK, Clayton RN, Fukuoka T (1983) Oxygen isotopic heterogeneities, their petrological correlations, and implications for melt origins of chondrules in unequilibrated ordinary chondrites. Earth Planet Sci Lett 65 209-224... 

Huss GR, MacPherson GJ, Wasserburg GJ, Russell SS, Srinivasan G (2001) Aluminum-26 in calcium-aluminum-rich inclusions and chondrales from unequilibrated ordinary chondrites. Meteorit Planet Sci... 

Virag A, Zinner E, Lewis RS, Tang M (1989) Isotopic compositions of H, C, and N in C8 diamonds from the Allende and Murray carbonaceous chondrites. Lunar Planet Sci XX 1158-1159 Volkening J, Papanastassiou DA (1989) Iron isotope anomalies. Astrophys J 347 L43-L46 Volkening J, Papanastassiou DA (1990) Zinc isotope anomalies. Astrophys J 358 L29-L32 Wadhwa M, Zinner EK, Crozaz G (1997) Manganese-chromium systematics in sulfides of unequilibrated enstatite chondrites. Meteorit Planet Sci 32 281-292... 

Guan, Y., Huss, G. R. and Leshin, L. A. (2007) 60Fe-60Ni and 53Mn-53Cr isotope systems in sulfides from unequilibrated ordinary chondrites. Geochimica et Cosmochimica Acta, 71, 4082-4091. 

Wadhwa, M., Zinner, E. and Crozaz, G. (1997) Mn-Cr systematics in sulfides of unequilibrated enstatite chondrites. Meteoritics and Planetary Science, 32, 281-292. 

Ion probe (SIMS) measurements of (26Al/27Al)0 for chondrules from several meteorite groups. The right axis shows the formation time relative to CAIs, the oldest solids formed in the solar system. These data indicate that chondrule formation started at least 1 Myr after CAIs formed and continued for 1-2 Myr. For CR chondrites, in addition to the plotted data, a similar number of chondrules show no resolvable evidence for 26Al. Data for unequilibrated ordinary chondrites (UDC) from Kita ef al. 

Gopel, C., Manhes, G. and Allegre, C.-J. (1994) U-Pb systematics of phosphates from unequilibrated ordinary chondrites. Earth and Planetary Science Letters, 121, 153-171. 

Huss, G. R., Tachibana, S. and Nagashima, K. (2007) 26A1 and 60Fe in chondrules from unequilibrated ordinary chondrites. Meteoritics and Planetary Science, 42, A57. 

McKeegan, K. D., Greenwood, J. P., Leshin, L. A. and Cosarinsky, M. (2000) Abundance of 26 A1 in ferromagnesian chondrules of unequilibrated ordinary chondrites (abstr.). Lunar and Planetary Science XXXI, CD 2009. 

Rudraswami, N. G. and Goswami, J. N. (2007) 26A1 in chondrules from unequilibrated L chondrites onset and duration of chondrule formation in the early solar system. Earth and Planetary Science Letters, 257, 231—244. 

The diamonds first recognized by Lewis et al. (1987) have now been traced to every class of chrondritic meteorite (Alexander et al. 1990 Huss 1990 Russell et al. 1991) and are known to occur as a component within the matrix. The amounts available for extraction reach a maximum of 900 ppm but decline to nothing in higher petrologic grades. The cut-off point in unequilibrated ordinary chondrites is about type 3.6 but for enstatite chondrites the type 4s still contain diamond. Progressive... 

Schelhaas, N., Ott, U. Begemann F. 1990 Trapped noble gases in unequilibrated ordinary chondrites. Geochim. Cosmochim. Acta 54, 2869-2882. 

Forsterite Possibly the most common coarse-grained phase present in all carbonaceous and unequilibrated ordinary chondrites, as well as a minor phase in enstatite chondrites and achondrites, is olivine ((Mg,Fe)2Si04). Most olivine contains significant Fe and does not show CL however a small fraction of the olivine is Mg-rich (forsterite) and shows brilliant CL. This same phase is present in... 

Figure 5. Range of the Cr CL peak position for extraterrestrial forsterites. The separation of forsterites of C3 carbonaceous chondrites and unequilibrated ordinary chondrites from the other types suggests that single grains can be assigned to one of the two groups.

Alexander C. M. O., Hutchison R., and Barber D. J. (1989) Origin of chondrule rims and interchondrule matrices in unequilibrated ordinary chondrites. Earth Planet. Sci. 95, 187-207. 

Aluminum-magnesium isotope measurements of aluminum-rich chondrules in ordinary and carbonaceous chondrites were summarized by Huss et al. (2001). About 10-15% of all aluminum-rich chondrules smdied show Mg. The inferred ( Al/ Al)o ratio of these chondrules is (0.5-2) X 10 , which is consistent with the values found in ferromagnesian chondrules from type 3.0-3.1 unequilibrated ordinary chondrites (Kita et al, 2000 McKeegan et al, 2000b Mostefaoui et al, 2000 2002). 

Brearley A. J. (1993) Matrix and fine-grained rims in the unequilibrated C03 chondrite, ALHA77307 origins and evidence for diverse, primitive nebular dust components. Geochim. Cosmochim. Acta 51, 1521-1550. 

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