Experimental Study on the Chemical Processes Associated with Formation of Volcanic Gas

众所周知，火山挥发分控制着岩浆的形成条件，与火山喷发活动密切相关。人们对火山挥发物的化学成分进行了大量的观测研究，并从理论上对火山脱气现象进行了研究。然而，迄今为止，还没有通过实验方法来了解火山挥发物的起源和演化。在本研究项目中，我们试图根据以下三个步骤确定火山气体形成过程中的化学过程。1：使用高压装置在化学控制环境下形成微小气泡。2.建立显微光谱学方法，测定合成或天然矿物流体包裹体的化学成分。3：改进火山气体的现场化学分析。对于1，我们在各种化学条件下重复进行了气泡形成实验。对于2，我们开发了具有极高灵敏度的显微荧光光谱系统。在使用该系统的许多结果中，必须提到的是，流体包裹体的化石压力可以根据C0_2的拉曼位移的压力依赖性来估计。3.研制了微型气相色谱仪现场测定火山气体的系统。对漫发射火山气体的化学信息也取得了较好的结果。

It is well-known that volcanic volatiles control the condition of magma and are related to eruptive activities. A lot of observational studies on the chemical composition of volcanic volatiles have been already conducted, and degassing phenomena has been studied in view of theoretical point. However, experimental approach to understand the origin and evolution of volcanic volatiles has not been carried out yet. In this research project, we tried to make sure the chemical processes during the formation of volcanic gas according the following 3 steps. 1: Formation of minute bubbles under chemically-controlled environment using a high pressure apparatus. 2 : Establishment of micro-spectroscopy to, determine chemical cpmposition of fluid inclusions of synthesized or natural minerals. 3 : Improvement of in-situ chemical analyzes of volcanic gas. As to 1, we repeated bubble formation experiments under various chemical conditions As to 2, we developed a system of micro-raman spectroscopy with extremely high sensitivity. Among the many results using this system, it must be mentioned that fossil pressure of fluid inclusions, could be estimated based on pressure-dependence of raman shift of C0_2. As to 3 we developed a in-situ system of determination of volcanic gas using a micro gas chromatograph. We also obtained good results on chemical information of volcanic gas of diffuse emission.