Research on the source volcanoes for micro-tephra gains in Antarctic ice sheet.

本研究的目的是探讨利用南极冰盖的微温颗粒进行温年代学测年的可能性。以南极洲的H15冰芯为样本。我们从形貌和化学性质上识别出~ 10μm大小的微tephra颗粒的存在。通过对H15冰芯中微颗粒数量与SO_4^<2->气溶胶浓度的比较，可以确定其类型（灰型或气体型），即(1)世界范围内的一些火山喷发同时释放颗粒和SO_2气体，(2)一些火山喷发主要释放SO_2气体，(3)一些火山喷发主要释放颗粒。对粒径为100μm的tephra颗粒进行了LA/ICP-MS分析。但对于10μm大小的微颗粒则不完全。用仪器中子活化法分析了世界各地几种火山喷发岩中微量元素的含量。

Purpose of this research is to check a possibility of tephrochronological dating use of micro tephra particles in Antarctic ice sheet. The H15 ice core in Antarctica was used as sample.1. We recognized the existence of 〜10μm size of micro tephra particles from the shape and the chemistry.2. Comparison between the numbers of micro tephra partices and the concentration of SO_4^<2-> aerosol in H15 ice core indicates the types (ash type or gas type) that is (1) some of world wide eruptions release both tephra particles and SO_2 gas, (2) some of them release mainly SO_2 gas, and (3) some of them release mainly tephra particles.3. We succeeded LA/ICP-MS analysis for single tephra particle of 100μm size. But for 10μm size of micro tephra particles did not complete.4. Trace elements contents in some world wide eruption tephras were analyzed by instrumental neutron activation analysis.