The chemical and isotopic studies on the genethis and evolution of the lunar highland materials.

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(1) On the lunar surface, a possibility of the existence of water has been supposed. Therefore, we examined the water-rock interaction, based on the viewpoints of affection by alkaline and aikaline-earth elements on the dissolution process of silicate materials. We showed that the alkaline-earth cations, cspecially Ca^<2+> and Sr^<2+>, promoted the dissolution of silicate and stabilized the dissolved species of silicates. Alkaline-earth elements have been known to be enriched in the lunar surfacc materials and that observation is considered to be important to examine the interaction betwoen water and lunar surface materials.(2) A Iunar meteorite. Asnka-881757 is a new type of mcteorites distinct from Apollo samples. This meteorite gabbroic feature with the age of 3.8 billion years and has been coneidered to reflect old lunar evolution. Thc REE abundances shows a typical cumulate type, as it were "solid type", pattcrn. This implies that lunar gabbro, Asuka-881757, represents the carlier-stage cumulate for the primary lunar magma.(3) The quantitativo analyses of cosmogenic nuclides, such as <-26>^Al or <41>^Ca, make it possible to develop the studies on the history of surface planetary materials. We have developed the new analytical system which consists of ECR (electron cyc.lotron rosonance) ion source and heavy ion linear accelerator. Using this system, we succesefully analysed many trace elemente in several kinds of samples with the detoction limits around 10^<-12>without any sample preparations. Using the technique of full atripping by the high energy acceleration up to 6 MeV/u, <26>^Al-<26>^Mg separation has been achieved to detect <26>^Al with high sensitivity.