Abstract:

n recent years,among the unusual meteorites recovered in Antarctic and non-Antarctic region,eight groups of primitive achondrites are recognized:acapulcoites,brachinites,lodranites,ureilites,winonaites,silicates in Ⅰ ABⅠⅠⅠ CD irons,aubrites and angrites.Acapulcoites and lodranites are rocks from a common parent body based on their similar mineralogies,mineral compositions,thermal histories,oxygen isotopic compositions and cosmic ray exposure ages.The isotopic,chemical and mineralogical similarities suggest that Ⅰ ABⅠⅠⅠ CD silicates and winonaites are from a common parent body.We review petrologic evidence that Ⅰ ABⅠⅠⅠ CD silicates and winonaites,brachinites,acapulcoiteslodranites and ulreilites formed by nebular processes and had undergone high grade metamorphism and different degree of partial melting.We classified these meteorites as nonmagmatic primitive achondrites.The aubrites and angrites are igneous rocks,but they have not been extensively differentiated into different lithologies.We classified these meteorites as magmatic primitive achondrites.Thus,up to date,there are six parent bodies of primitive achondrites.