隕石とマントル層の化学成分についての一考察

抄録

In the past, petrological data have provided the principal contributions towards our knowledge of the constitution of the meteorite. It is now possible to look into the differentiation of the meteorites in which a wide variety of properties are reasonably well specified by the similar way as in petrological studies. If it is possible to establish within reasonable limits the chemical composition of the meteorites, an enormous simplification will be achieved.
The systems of (Na₂O+K₂O) -Fe-OMgO and CaO-FeO-MgO have been studied for meteorites and rocks by means of the three component variation diagrams. The main fractionation trend is continuously shown from chondritic achondrites, H- iron group chondrites, L- iron group chondrites, carbonaceous chondrites, to basaltic achondrites and also from basaltic achondrites to rock variations. From the variation curve of main chemical components against the factor (MgO+FeO +Na₂O +K₂O), we may see that it is in the main fractionation sequence and is transitional between the meteorite group and the rock group.
From this observation, we can assume that the primitive chemical composition of meteorites is rather the chondritic achondrite composition than the carbonaceous chondritic composition and the differentiation system of the appearance of the mineral phase as outlined by geologists on the rock series is consistent with the phase relationships found in the meteorite series. The chemical composition of the mantle could be inferred by these hypotheses.