摘要
在Crisium月海,Luna24登月点,24088,14及24105,15两个土壤碎屑抛光薄片中共辨认出6种火成岩的岩石类型。在粗粒玄武岩(辉长岩)碎屑中,自富镁橄榄辉长岩、橄榄辉长岩、橄长岩至富铁石英橄长岩形成了自富Mg、Cr至富Fe、Ti的岩石演化系列,上述演化趋势与橄榄石、辉石在相应岩石中的变异趋势相吻合。据分离结晶计算结果及岩石结构表明,橄榄辉长岩中含Mg较高者为演化系列的母岩浆,它的化学成分与Luna 24中玄武岩的平均成分以及绿色火成玻璃相当。富镁橄榄辉长岩为其早期的分离结晶物。富铁石英橄长岩为本次工作中发现的一种粗粒火成岩碎屑,它是演化系列最末端的产物,是由铁质辉长岩经分离64％的辉石、20％的斜长石、85％的铁橄榄石后又遭受了液态不混溶作用形成的含P富Fe的熔体结晶的产物。研究表明,Luna24的玄武岩母岩浆可能存在两种以上。
Six types of igneous rock fragments were distinguished from two polished grain mounts of 250~500 micron soil particles ( 24088, 14 and 24105, 15) . The petrological characteristics are displayed by a progressive variation in rock types from Mg-rich olivine-gabbro to olivine-gabbro, and to ferrogabbro as well as quartz-ferrotroctolite.Basaltic olivines and pyroxenes also exhibit a Fe-rich trend which is consistent with the trend in petrology. According to calculations of fractionation, olivine -gabbro may represent the parent magma from which the ferrogabbro was derived. The chemical composition of olivine-gabbro is the same as the average composition of Luna 24 basalts and green volcanic glasses. The quartz-ferrotroctolite is the first reported occurrence of this coarse -grained mineral assemblage as a distinct rock fragment. It is considered to be a crystal-line product from a Fe-rich melt containing phosphate, and this melt has under-gone fractional crystallization and silicate liquid immiscibility at the late stage.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
1990年第6期617-627,共11页
Earth Science-Journal of China University of Geosciences
关键词
Luna24
月岩
样品
火成岩
岩石学
Crisium Mare, Luna 24, quartz-ferrotroctolite, fractionation and immiscibility.
