Masaaki Takahashi:

Senior Researcher of Crustal Fluid Team

Geological Survey of Japan, AIST

I am a geochemist focusing on the geochemistry of brine. In Japan, we can recognize four end members from isotopic compositions of hydrothermal water, i.e., meteoric, magmatic (volcanic), Arima and seawater (oil field brine). Three end members except meteoric are brine, essentially. Thus, I am so interested in clarifying significant differences among the geochemical characteristics of them.

I have researched in:

• (1) izu Seven Islands, Flores (Indonesia) and Tongoa (Vanuatu) to know coastal geothermal system
• (2) several GPPs in northeast Japan to know the difference between high salinity geothermal system and low salinity geothermal system
• (3) Iwo-sawa (central Japan) to know geochemical features of fumarolic area in granitic province
• (4) Matsunoyama (central Japan) to know the origin and the formation mechanism of geopressued water, (5) Gassan (northeast Japan) to know the origin of hypersaline brine (Cl>30,000ppm)
• (6) Simikawa (northeast Japan) to know the chemical change of hot spring water during the hydrothermal eruption.