Meteorite eucrite

Figure 8. Figure (a) after Clayton et al. (1976, 1977). The scales are as in Figure 1. The O isotopic compositions of the different meteorite classes are represented ordinary chondrites (H, L, LL), enstatite chondrites (EFl, EL), differentiated meteorites (eucrites, lAB irons, SNCs) and some components of the carbonaceous chondrites. As the different areas do not overlap, a classification of the meteorites can be drawn based on O isotopes. Cr (b) and Mo (c) isotope compositions obtained by stepwise dissolution of the Cl carbonaceous chondrite Orgueil (Rotaru et al. 1992 Dauphas et al. 2002), are plotted as deviations relative to the terrestrial composition in 8 units. Isotopes are labeled according to their primary nucleosynthetic sources. ExpSi is for explosive Si burning and n-eq is for neutron-rich nuclear statistical equilibrium. The open squares represent a HNOj 4 N leachate at room temperature. The filled square correspond to the dissolution of the main silicate phase in a HCl-EIF mix. The M pattern for Mo in the silicates is similar to the s-process component found in micron-size SiC presolar grains as shown in Figure 7.

Differentiated (planetary) Achondrites Angrites Aubrites Brachinites HED meteorites Eucrites Howardites Diogenites Ureilites Stony-irons Pallasites... 

Patchett, P. J. and Tatsumoto, M. (1980) Lu-Hf total-rock isochron for eucrite meteorites. Nature, 288, 571-574. 

Kleine, T., Mezger, K., Mtinker, C., Palme, H. andBischoff, A. (2004) Hf- W isotope systematics of chondrites, eucrites, and Martian meteorites chronology of core formation and early mantle differentiation in Vesta and Mars. Geochimica et Cosmochimica Acta, 68, 2935-2946. 

In most respects, asteroid 4 Vesta is geochemically similar to the Moon. As judged from howardite-eucrite-diogenite (HED) meteorites (see Chapter 6), Vesta is an ancient, basalt-covered world (Keil, 2002). Its rocks are highly reduced, and its depletions in volatile and siderophile element abundances resemble those of lunar basalts. And like the Moon, Vesta is hypothesized to have had an early magma ocean. The exploration of Vesta is now in progress, and within a few years we may have enough data to discuss it in a similar way that we have considered the Moon. 

Righter, K. and Drake, M. J. (1997) A magma ocean on Vesta core formation and petro-genesis of eucrites and diogenites. Meteoritics and Planetary Science, 32, 929-944. 

The Apollo 11 rocks contain large amounts of ilmenite, as can be seen from Tables 2 and 3 (high titanium content). We have plotted the chemical composition of rock sample 12018 in Fig. 3a vs. that of the carbonaceous chondrites (the most primitive of all meteorites), in Fig. 3b vs. the basaltic achondrite (eucrite) Juvinas (a class of meteorites which have undergone magmatic differentiation) and in Fig. 4 vs. the average composition of the Earth s... 

HED meteorites howardites, eucrites, diogenites Mesosiderites Pallasites... 

Figure 29 Weight percentages of FeO and MnO in solar-system basalts and martian meteorites. Filled circles are SNC basalts, open circles are other martian meteorites, and filled squares are Mars surface materials. Martian meteorites have essentially the same FeO/MnO ratio as do Mars surface materials and eucrite basalts. Only Chassigny has a comparable FeO/MnO ratio to terrestrial basalts (source Treiman et al., 2000).

Goodrich C. A. and Righter K. (2000) Petrology of unique achondrite Queen Alexandra Range 93148 a piece of the pallasite (howardite-eucrite-diogenite ) parent body Meteorit. Planet. Sci. 35, 521—535. 

Pun A., Keil K., Taylor G. J., and Wider R. (1998) The Kapoeta howardite implications for the regolith evolution of the howardite-eucrite-diogenite parent body. Meteorit. Planet. Sci. 33, 835-851. 

Takeda H. (1997) Mineralogical records of early planetary processes on the howardite, eucrite, diogenite parent body with reference to Vesta. Meteorit. Planet. Sci. 32, 841-853. 

---