Development of an internally heated gas apparatus useful for crustal geological problems

各种地质现象(如火山活动、变质作用、地震等)发生在日本(典型的岛弧)之下的地壳环境中。为了研究这些地质现象，我们开发了一台SMC-5000内热式气体装置，它能够产生高达5000巴的压力和1600摄氏度的温度。由于高压气体调整法的控制非常严格，我们被迫将最高压力从8000降至5000，并不得不放弃自动调压阀。此外，SMC-5000还具有优良的调压系统、快速淬火装置、精确的温度控制能力和长时间(长达一周)的高压实验耐久性。利用SMC-5000装置，我们对北海道Hidaka变质带和秋田县Ichiomegata陨石坑中的一些下地壳角闪岩进行了熔融实验。用电子探针测定了熔体的分数以及熔体和残留物的组成，并与钙碱性火山岩的岩石学数据进行了对比。在此基础上，我们提出了日本火山深层根带的模型。

Various geological phenomena (e.g., volcanic activity, metamorphism, earthquakes, etc) take place under crustal environment beneath Japan (a typical island arc). In order to study these geologic phenomena, we developed an internally heated gass apparatus SMC-5000 which are capable to generate pressure for up to 5000 bars and temperature to 1600 degree centigrade. Due to the very severe control under the High-pressure Gas Regulation Law, we oblighed to lower the maximum pressure from 8000 to 5000 and had to abandone the automatic pressure regulating valve. Otherwise the SMC-5000 was built with excellent pressure regulating system, rapid quenching device, precise temperature controlling capability and long durability for holding very long (up to a week long) high pressure experiments.Using the SMC-5000 apparatus, we conducted melting experiments on some lower crustal amphibolites taken from the Hidaka metamorphic belt in Hokkaido and the Ichiomegata crater in Akita prefecture. The melt frctions as well as the composition of melt and residues were determine with EPMA.The results were then compared with petrologic datra on calc-alkaline volcanic rocks. Based on the comparison, we proposed a model for the deep root zone of Japanese volcanoes.