Studies of thermal histories of rocks and meteorites on the basis of the analysis of compositional variation of the constituent minerals

A number of studies have been made by means of the electron probe X-ray microanalyser JEOL JXA733equipped in 1984。In what follows the results are summarized briefly.1.Compositional variation of phenocrysts indicates that the coexisting low-alkali tholeiitic and calc-alkalic rocks in a few Quaternary volcanoes of Northeast Japan may have been originated independently through the respective magmatic evolutionary processes.2。The feldspar geothermometer indicates that the crystallization temperature of potassium feldspar in association with plagioclase increases downwards regularly in the Okueyama granite complex，Kyushu.3。Ankaramitic relict glass shards in a greenstone of the Kanto mountains Chichibu terrane，has a peculiar chemical composition very rich in Fe and Na，which favour the crystallization of riebeckite under the low-grade metamorphism.4。The metamorphic grade varies from the greenschist to the granulite facies in the southernmost part of the Hidaka belt，Hokkaido。A gabbroic reaction rim has been produced around an amphibolite xenolith captured in lherzolitic peridotite.5。The aggregates of opaque minerals in unequilibrated enstatite chondrites would habe been originated from nickel-iron metal phase through various reactions occurred under the various temperatures.6。The closure temperature of a few chondrites has been estimated as 900°C，740°C and 540°C according to three different mineral thermometers.This may be due to the different diffusivity in the minerals.

A number of studies have been made by means of the electron probe X-ray microanalyser JEOL JXA 733 equipped in 1984. In what follows the results are summarized briefly.1. Compositional variation of phenocrysts indicates that the coexisting low-alkali tholeiitic and calc-alkalic rocks in a few Quaternary volcanoes of Northeast Japan may have been originated independently through the respective magmatic evolutionary processes.2. The feldspar geothermometer indicates that the crystallization temperature of potassium feldspar in association with plagioclase increases downwards regularly in the Okueyama granite complex,Kyushu.3. Ankaramitic relict glass shards in a greenstone of the Kanto mountains Chichibu terrane,has a peculiar chemical composition very rich in Fe and Na,which favour the crystallization of riebeckite under the low-grade metamorphism.4. The metamorphic grade varies from the greenschist to the granulite facies in the southernmost part of the Hidaka belt,Hokkaido. A gabbroic reaction rim has been produced around an amphibolite xenolith captured in lherzolitic peridotite.5. The aggregates of opaque minerals in unequilibrated enstatite chondrites would habe been originated from nickel-iron metal phase through various reactions occurred under the various temperatures.6. The closure temperature of a few chondrites has been estimated as 900゜C,740゜C and 540゜C according to three different mineral thermometers. This may be due to the different diffusivity in the minerals.