2nd Geochemical Investigation of the Aegean Volcanic Arc

该研究项目是在为期两年的“爱琴海火山弧地球化学调查”（1993-1994）项目之后进行的。这些项目的目的是通过火山挥发物的地球化学方法和火山地貌学方法来研究爱琴海火山弧的岩浆活动。由于爱琴海弧具有大陆（非洲）板块俯冲的特征，与大多数与大洋板块俯冲有关的火山弧不同，爱琴海弧对弧火山作用的比较研究具有重要意义。1995年8月18日和9月13日，五名日本调查人员访问了希腊。他们与一名希腊调查员一起对希腊的火山和地热地区进行了实地监测。被调查的地区是位于马其顿（希腊北部）和沿着火山锋的Nisyros和Santrini火山的地热区。在马其顿，对温泉附近的地热进行了监测，并收集了温泉气体和水，以便进行更多的元素和同位素分析。由于该地区远离火山锋，因此研究其是否含有源自爱琴海弧岩浆的岩浆挥发物具有重要意义。在先前对1993年样本的研究之后，来自Nisyros火山的火山气体显示出轻微的氖同位素异常。如果这一发现得到证实，这将是第一次或第二次在电弧样品中发现氖同位素异常。为了确认氖同位素异常，采集了尼西罗斯火山不同火山口的气体样本。对于气体样品，测定了稀有气体和CO_2中碳的化学组成和同位素比值。同时测定了水样的化学成分和氢、氧同位素组成。根据气体样品的（n2 /Ar）和（He/Ar）分系统，爱琴海弧与世界上其他弧形成了不同的关系。这可能与不同的俯冲板块有关；爱琴海弧线属于大陆，其他弧线属于海洋。在1995年方案中，一名希腊调查员于9月19日至10月3日访问日本进行合作。少

This research program follows the 2 years' program "Geochemical Investigation of the Aegean Volcanic Arc" (1993-1994). The purpose of these programs is to investigate magmatic activities in the Aegean volcanic arc by means of both geochemical approach of volcanic volatiles and volcano-geomorpholog-cal approach. Because the Aegean arc is characterized by the continental (African) plate subduction, in contrast to most of volcanic arcs related to oceanic plate subduction, this arc plays an important role for comparative study of arc volcanism.Five Japanese investigators visited Greece during 18 August and 13 September 1995. They carried out field surveillance of volcanic and geothermal areas in Greece with a Greek investigator. The investivated areas are geothermal areas in Makedonia (Northern Greece) and Nisyros and Santrini volcanoes along the volcanic front. In Makedonia, geothermal surveillance around hot spring sites was carried out and hot spring gases and waters were collected for … More elemental and isotope analyzes. As this region is far from the volcanic front, it is important to study whether or not they contain magmatic volatiles derived from Aegean arc magma. After previous studies of 1993 samples, volcanic gas from Nisyros volcano showed a little neon isotope anomaly. If this is confirmed, this is the first or 2nd discovery of neon isotope anomaly in arc samples. In order to confirm neon isotope anomaly, several gas samples from different craters of Nisyros volcano were collected.For gas samples, chemical composition and isotope ratios of rare gases and carbon in CO_2 were determined. While, chemical composition and H and O isotope compositions were determined for water samples. According to (N_2/Ar) vs. (He/Ar) systematics of gas samples, the Aegean arc forms different relationship from other arcs in the world. This may be related to the different subducting slabs ; continental in the Aegean arc and oceanic in many other arcs.In 1995 program, a Greek investigator visited Japan from 19 September to 3 October for collaboration. Less