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1. ࡣࡣࡌࡵ 1977 ᖺࡢᾏᗏ⇕ỈᄇฟᏍࡢⓎぢ௨᮶ࠊ⌧ᅾ࡛ࡣᩘⓒࡢ⇕ỈᄇฟᏍࡀⓎぢࡉࢀ࡚࠾ࡾࠊ୰ࡣ㠀 ᖖཎጞⓗ࡞ᚤ⏕≀ࢆᐟࡍ⇕ỈᄇฟᏍࡀᏑᅾࡍࡿࡇࡀ᫂ࡽ࡞ࡗ࡚ࡁࡓࠋࡇࡢࡼ࠺࡞⇕Ỉ⣔ ࡣࠊ࣐ࣥࢺࣝࢇࡽࢇᒾࡢ⺬⣠ᒾస⏝ᨭ࠼ࡽࢀࠊ⇕Ỉࡀ㠀ᖖỈ⣲㸦H2㸧ᐩࢇ࡛࠸ࡿ࠸ ࠺≉ᚩࡀ࠶ࡿࠋࡑࡋ࡚ࠊ⇕Ỉ୰ࡢ H2ࢆ࢚ࢿࣝࢠ࣮௦ㅰ⏝ࡍࡿᚤ⏕≀ࡀ୍ḟ⏕⏘⪅࡞ࡾࠊኴ 㝧ගࡸගྜᡂࡢ⏘≀㸦㓟⣲ࡸ◲㓟࡞ࠊ㓟⣲Ⓨ⏕ᆺගྜᡂ⏕≀ࡀㄌ⏕ࡋ࡚ࡽᾏὒ୰✚ࡉ ࢀࡓ㓟ⓗ≀㉁㸧౫Ꮡࡋ࡞࠸ᚤ⏕≀⏕ែ⣔ࡀᏑᅾࡋ࡚࠸ࡿࠋࡇࡢࡼ࠺࡞ࡇࡽࠊ⌧ᅾ࡛ࡣࠊ ࡇࡢࡼ࠺࡞ H2ᐩࡴ⇕Ỉࢆᄇฟࡉࡏࡿ⇕ỈᄇฟᏍࡀࠊ⏕ㄌ⏕ࡢሙࡋ࡚᭷ຊ࡞ೃ⿵࡞ࡗ࡚࠸ ࡿࠋ୍᪉ࠊኴྂ௦ࡢᆅ㉁グ㘓ṧࡉࢀ࡚࠸ࡿᾏὒᆅẆࡣࠊཌࡉࡀ⌧ᅾ㸦⣙ 6 km㸧ࡢ㸱ಸ⛬࠶ࡗ ࡓ᥎ᐃࡉࢀ࡚࠾ࡾࠊࡇࡢࡼ࠺࡞ሙྜࡣࠊ࣐ࣥࢺࣝࢇࡽࢇᒾࡀᾏᗏ㏆ࡃࡲ࡛ୖ᪼ࡋ࡚ࡃࡿࡇ ࡣ㠀ᖖ⛥࡛࠶ࡿࠋࡋࡓࡀࡗ࡚ࠊᙜࡣ࣐ࣥࢺࣝࢇࡽࢇᒾࢆẕᒾࡍࡿᾏᗏ⇕Ỉάືࡣࢇ Ꮡᅾࡋ࡞ࡗࡓ⪃࠼ࡽࢀࡿࠋࡋࡋࠊኴྂ௦࡛ࡣࠊ࣐ࣥࢺࣝࢇࡽࢇᒾࡢ௦ࢃࡾ⺬⣠ᒾ స⏝ࢆ㉳ࡇࡍᒾ▼ࡋ࡚ࠕࢥ࣐ࢳࢺࠖ࠸࠺ⅆᒣᒾࡀᏑᅾࡋࡓࡇࡀ▱ࡽࢀ࡚࠸ࡿࠋࢥ࣐ࢳ ࢺࡣࠊ࣐ࣥࢺࣝࡢ ᗘࡀ㧗ࡗࡓึᮇᆅ⌫࠾࠸࡚ࡢࡳ㢖⦾ᄇฟࡋࡓ㉸㧗 ࡢ࣐ࢢ࣐ࡀ෭ ࠼ᅛࡲࡗࡓᒾ▼࡛ࠊࡑࡢᏛ⤌ᡂࡣ࣐ࣥࢺࣝࢇࡽࢇᒾࡼࡃఝ࡚࠸ࡿࠋᆅ㉁グ㘓ࡽࡳ࡚ࡶࠊ ኴྂ௦ࡢࢥ࣐ࢳࢺ࣐ࢢ࣐ࡣࠊཌ࠸ᾏὒᆅẆࢆ✺ࡁᢤࡅ࡚ᾏᗏࡢ⮳ࡿᡤ࡛ᄇฟࡋ࡚࠸ࡓࡇࡀ ணࡉࢀ࡚࠸ࡿࠋࡇࡢࡼ࠺࡞⌮⏤ࡽࠊኴྂ௦ࡼࡾࡶ࣐ࣥࢺࣝࡢ ᗘࡀ㧗ࡗࡓ࡛࠶ࢁ࠺ෞ⋤௦ ࡛ࡣࢥ࣐ࢳࢺᾏᗏⅆᒣάືࡀάⓎ࡛࠶ࡗࡓࡇࡀᐜ᫆᥎ ࡛ࡁࠊෞ⋤௦ࡢࢥ࣐ࢳࢺࢆ ẕᒾࡍࡿᾏᗏ⇕Ỉ⣔࡛ࡣࠊ⺬⣠ᒾస⏝ࡼࡾ㔞ࡢ H2ࡀⓎ⏕ࡋ࡚࠸ࡓ⪃࠼ࡽࢀ࡚࠸ࡿ[1]ࠋ ᡃࠎࡢ◊✲ࢢ࣮ࣝࣉ࡛ࡣࠕᡃࠎࡢඹ㏻♽ඛࡣࠊH2ࢆ㔞Ⓨ⏕ࡉࡏࡿࢥ࣐ࢳࢺࢆẕᒾࡍࡿ ᾏᗏ⇕Ỉ⎔ቃ࡛ㄌ⏕ࡋࡓࠖࡍࡿ௬ㄝᇶ࡙ࡁ ◊✲ࢆ⾜࡞ࡗ࡚ࡁࡓࠋᮏⓎ⾲࡛ࡣࠊࡇࡢࣔࢹࣝ ࡑࡢ᳨ド◊✲ࡘ࠸࡚⤂ࡍࡿࠋ 2. 㧗 㧗ᅽỈᒾ▼ᛂᐇ㦂⏕⏝ྍ⬟࢚ ࢿࣝࢠ࣮⇕ຊᏛࣔࢹࣜࣥࢢ ࢥ࣐ࢳࢺ⇕Ỉࡢᛂ࠾ࡅࡿ H2 Ⓨ⏕ ⋡ ࢆ ᳨ ド ࡍ ࡿ ᐇ 㦂 ࢆ ⾜ ࡗ ࡓ ࠋ ᐇ 㦂 ࡣ ࠊ JAMSTEC ᡤ᭷ࡢ㧗 㧗ᅽỈᒾ▼ᛂ⨨ࢆ⏝ ࠸ࡓ㸦Figure 1㸧ࠋᐇ㦂࡛ࡣࡲࡎࠊ⌧ᅾࡢᆅ⌫ ࡣᏑᅾࡋ࡞࠸㠀ኚ㉁ࡢࢥ࣐ࢳࢺࢆ㓟㑏ඖ㞺ᅖẼไᚚᆺ㟁Ẽ⅔ࢆ⏝࠸࡚ 1600Υ࡛ྜᡂࡋ Figure 1. A hydrothermal reactor used in this
S5
-19-ࡓࠋࡑࡢᚋࠊྜᡂࢥ࣐ࢳࢺࡢ⢊ᮎᶍᨃᾏ Ỉࢆ 100–350Υࠊ500 Ẽᅽ࡛⣙ 3 ࢝᭶㛫ᛂࡉࡏ ࡓࠋᶍᨃᾏỈࡣ CO2ࢆྵࡲ࡞࠸ሙྜ CO2ࢆ 㔞ྵࡴሙྜ㸦400 mmol/kg㸧ࡢ୧᪉࡛⾜ࡗࡓࠋ ࡲࡓࠊ⇕ỈᄇฟᏍ⏕ᜥࡍࡿᚤ⏕≀ࡣᾏỈ⇕ ỈࡢΰྜࡼࡾⓎ⏕ࡍࡿ㓟㑏ඖ㠀ᖹ⾮≧ែ ࡽ㓟㑏ඖ࢚ࢿࣝࢠ࣮ࢆᚓ࡚௦ㅰࢆ⾜ࡗ࡚࠸ࡿ ࡇࡽࠊཎጞᆅ⌫⇕Ỉ⣔ࡢ⇕ỈᾏỈࡢΰྜ ᇦ㸦ࢳ࣒ࢽ࣮ෆ㒊࡞㸧࠾ࡅࡿ⏕⏝ྍ⬟ ࢚ࢿࣝࢠ࣮ศᕸࡢ⇕ຊᏛィ⟬ࢆ⾜ࡗࡓࠋ 3. ⤖⤖ᯝ⪃ᐹ ᐇ㦂࡛ࡣࠊᶍᨃᾏỈ୰ࡢ CO2ࡢ᭷↓ࢃ ࡽࡎࢥ࣐ࢳࢺࡀ⺬⣠ᒾࡋࠊCO2ࢆྵࡴ᮲௳࡛ࡣḟ㖔≀ࡋ࡚Ⅳ㓟ሷ㖔≀ࡀከࡃᙧᡂࡍࡿ ࡇࡀ☜ㄆࡉࢀࡓࠋࡲࡓࠊᾏỈ CO2ࢆྵࡲ࡞࠸᮲௳ࡢᐇ㦂࡛ࡣࠊ300Υࡢ⇕Ỉ୰ࡢ H2⃰ᗘࡣ 20 mmol/kg ௨ୖ࡛࠶ࡾࠊ⌧ୡࡢ㠀ᖖ H2ᐩࡴ⇕Ỉࡢ H2⃰ᗘ༉ᩛࡍࡿࡶࡢ࡛࠶ࡗࡓ [2]ࠋ୍᪉ࠊ ᾏỈ CO2ࢆྵࡴ᮲௳ࡢᐇ㦂࡛ࡣࠊ ᗘࡀୗࡀࡿࡘࢀ࡚⇕Ỉ୰ࡢ H2⃰ᗘࡀୗࡀࡿࡶࡢࡢࠊ350Υ ࡢᐇ㦂࡛ࡣ⇕Ỉ୰ࡢ H2⃰ᗘࡣ 2~3 mmol/kg ⛬ᗘࠊ⋞Ṋᒾࢆẕᒾࡍࡿ⇕Ỉࡢ H2⃰ᗘࡼࡾࡶ୍ ᱆⛬㧗࠸್ࢆ♧ࡋࡓ [3]ࠋࡋࡓࡀࡗ࡚ࠊཎጞᆅ⌫ࡢᾏỈࡢ CO2⃰ᗘࡀ࠶ࡿ⛬ᗘᖜࢆᣢࡗ࡚࠸ࡓ ࡋ࡚ࡶࠊࢥ࣐ࢳࢺࢆẕᒾࡍࡿ㧗 ࡢ⇕Ỉάືᇦ࡛ࡣࠊ⺬⣠ᒾస⏝ࡼࡾ㠀ᖖ H2⃰ᗘࡢ 㧗࠸⇕ỈࡀⓎ⏕ࡋ࡚࠸ࡓ⪃࠼ࡽࢀࡿࠋࡇࡢࡇࡣࠊཎጞᆅ⌫࠾࠸࡚ప ᆺࡼࡾࡶ㧗 ᆺࡢ⇕ Ỉάືᇦࡢ᪉ࡀཎጞⓗᚤ⏕≀⏕ែ⣔ࢆᨭ࠼ࡿ࣏ࢸࣥࢩࣕࣝࡀ㧗ࡗࡓࡇࢆ♧ࡋ࡚࠸ࡿࠋࡉࡽࠊ ⏕⏝ྍ⬟࢚ࢿࣝࢠ࣮ィ⟬ࡽࡣࠊෞ⋤௦ࡢࢥ࣐ࢳࢺ⇕Ỉ⣔࠾ࡅࡿ H2ࢆ⏝ࡍࡿ࣓ࢱࣥ ⏕ᡂࡸ㓑㓟⏕ᡂ࢚ࢿࣝࢠ࣮ࡀ⇕Ỉ 1 kg ᙜࡓࡾ 0.5 kJ ௨ୖ㠀ᖖ㧗ࡃࠊ⌧ᅾࡢ H2ࢆ௦ㅰ⏝ ࡍࡿ࣓ࢱࣥ⏕ᡂ⳦ࡀ⏕ᜥࡍࡿᾏᗏ⇕Ỉ⣔࡛Ⓨ⏕ࡍࡿ࣓ࢱࣥ⏕ᡂ࢚ࢿࣝࢠ࣮ࡼࡾࡶ㧗࠸ࡇࡀࢃ ࡗࡓࠋࡋࡓࡀࡗ࡚ࠊෞ⋤௦ࡢࢥ࣐ࢳࢺࢆẕᒾࡍࡿᾏᗏ⇕Ỉ⣔࡛ࡣࠊH2ࢆ௦ㅰ⏝ࡍࡿ ᚤ⏕≀ࡀㄌ⏕ࡋ࠺ࡿࡇࡀ࢚ࢿࣝࢠ࣮ㄽⓗ♧ࡉࢀࡓ [4]ࠋࡇࡢ୍㐃ࡢᐇ㦂⇕ຊᏛࣔࢹࣜࣥࢢ ᇶ࡙ࡃ◊✲ࡣࠊࠕᡃࠎࡢඹ㏻♽ඛࡣࠊH2 ࢆ㔞Ⓨ⏕ࡉࡏࡿࢥ࣐ࢳࢺࢆẕᒾࡍࡿᾏᗏ⇕ Ỉ⎔ቃ࡛ㄌ⏕ࡋࡓࠖࡍࡿࣔࢹࣝࡀጇᙜ࡛࠶ࡿࡇࢆ♧ࡋ࡚࠸ࡿࠋ ཧ⪃ᩥ⊩
[1] K Takai et al., Paleontol. Res., 2006, 10, 269.
[2] T. Shibuya et al., Prog. Earth Planet. Sci., 2015, 2, 46. [3] H. Ueda et al., Prog. Earth Planet. Sci., 2016, 3, 33.
[4] T. Shibuya et al., Geochim. Cosmochim. Acta, 2016, 175, 1.
Figure 2. A microphotograph of komatiite synthesized at 1600 °C.