Petrological studies on the HED meteorites and their parent bodies

陨石标本1152为无角化全晶无球粒陨石，具有独特的结构。该陨石的岩性与已知的无球粒陨石有很大的不同，但其化学成分和矿物组合可归为霍华德陨石群之一。样品的矿物组合与大多数howardites相同，主要由辉石（En47.4-82.5 Fs17.4-34.8 Wo0.9-35.2）和斜长石（Ab5.8-10.4 An89.2-94.2 Or0.0-0.3）和部分橄榄石（Fo58.6-63.0 Fa37.0-41.4）组成。它的整体化学性质也几乎与华长岩相同，如典型的华长岩Yamato-791157多晶角砾岩。样品的独特结构可能表明该样品受到了霍华德石成分的冲击。然而，作者认为该陨石标本是在可能的小行星4灶神星HED（howardite - eucrite - diogite）母体上首次发现的岩浆作用形成的具有无角砾-全晶结构的howardite陨石。1152陨石的总体化学成分为：49.50SiO_2,0.09TiO_2,7.34Al203,6.28Fe_2O_3,9.73FeO,0.37MnO,19.02Mg0,5.58CaO,0.19Na_2O,<0.02K20,0.1H_2O(+),0.10H_2O(-),0.21P_2O_5,0.52Cr_2O_3,1.42FeS,<0.1Fe，总重量百分比（%）为100.57。

The meteorite specimen 1152 is an unbrecciated-holocrystalline achondrite showing quite unique texture. The lithology of this specimen is quite differ from all known achondrite meteorites, however it might be classified to one of howardite group for its chemical compositions and mineral assemblages. The specimen is as same as mineral assemblage of the most howardites, and it consists mainly of pyroxene(En47.4-82.5 Fs17.4-34.8 Wo0.9-35.2) and plagioclase(Ab5.8-10.4 An89.2-94.2 Or0.0-0.3) with some olivine(Fo58.6-63.0 Fa37.0-41.4). It is also almost same bulk chemistry of howardite, such as typical howardite Yamato-791157 polymict breccia.The quite unique texture of the specimen might be indicated that this specimen is impactite with howardite compositions. However author expected that the meteorite specimen is the first howardite with unbrecciated-holocrystalline texture originated by the magma process on the HED(Howardite-Eucrite-Diogite) parent body possible asteroid 4 Vesta. The bulk chemical compositions of the specimen 1152 meteorite is 49.50SiO_2,0.09TiO_2,7.34Al203,6.28Fe_2O_3,9.73FeO,0.37MnO,19.02Mg0,5.58CaO,0.19Na_2O,<0.02K20,0.1H_2O(+),0.10H_2O(-),0.21P_2O_5,0.52Cr_2O_3,1.42FeS,<0.1Fe, and tatal 100.57 in weight percent(%).