17:15 〜 18:45
[MIS23-P04] 飛騨帯の変成炭酸塩岩研究から読み解く脱炭酸反応
★招待講演
キーワード：飛騨帯、変成炭酸塩岩、脱炭酸
In the Hida Belt, metacarbonate rocks widely occur accompanying gneissose rocks, and the protolith has been regarded to be continental platform carbonates1–3. Most metacarbonate rocks consist mainly of calcite (i.e., calcite marble) with a minor amount of clinopyroxene, quartz, and titanite4,5. In contrast, dolomitic marble, which consists mainly of Mg-calcite and dolomite, is rare5,6. Microscale analyses of carbon and oxygen stable isotopes (δ13C and δ18O) in calcites from these metacarbonate rocks revealed distinct isotope zoning at the calcite crystal grain boundaries7. More recently, a systematic isotope study found a large isotope variation (δ13C = −4.4 to +4.2‰ [VPDB], δ18O = +1.6 to +20.8‰ [VSMOW])4. This includes significantly low δ13C values of a carbonate-silicate rock (−4.4 to –2.9‰), indicative of CO2 release via decarbonation reactions.
The process of decarbonation, particularly due to granitic intrusion into continental platform carbonates within continental arc settings, has been identified as an important pathway for CO2 release to the atmosphere8–10. The clinopyroxene-bearing leucogranite in the Hida Belt, so-called 'Inishi-type' migmatite, is believed to have formed through the interaction between granitic intrusion and metacarbonate rocks11,12. This specific interaction might provide crucial insights into the mechanisms of decarbonation in continental margin/arc.
Reference
1 Isozaki, 1996, Isl. Arc 5, 289–320. https://doi.org/10.1111/j.1440-1738.1996.tb00033.x
2 Isozaki, 1997, Isl. Arc 6, 2–24. https://doi.org/10.1111/j.1440-1738.1997.tb00038.x
3 Sohma & Kunugiza, 1993, Mem. Geol. Soc. Japan 42, 1–20 (in Japanese with English abstract).
4 Harada et al., 2021a, Isl. Arc 30, e12389. https://doi.org/10.1111/iar.12389
5 Kano, 1998. Shigen-Chishitsu 48, 77–92 (in Japanese with English abstract). https://doi.org/10.11456/shigenchishitsu1992.48.77
6 Harada & Tsujimori, 2024, Prog. Earth Planet. Sci. 11, 6. https://doi.org/10.1186/s40645-024-00609-y
7 Wada, 1988. Nature 331, 61–63. https://doi.org/10.1038/331061a0
8 Lee & Lackey, 2015, Elements 11, 125–130. https://doi.org/ 10.2113/gselements.11.2.125
9 Lee et al., 2013, Geosphere 9, 21–36. https://doi.org/10.1130/GES00822.1
10 Ramos et al., 2020. GSA Today 30, 5. https://doi.org/10.1130/GSATG432A.1
11 Harada et al., 2021b, Lithos 398–399, 106256. https://doi.org/10.1016/j.lithos.2021.106256
12 Kano, 1992. Shigen-Chishitsu, 42, 379–390. https://doi.org/10.11456/shigenchishitsu1992.42.379
The process of decarbonation, particularly due to granitic intrusion into continental platform carbonates within continental arc settings, has been identified as an important pathway for CO2 release to the atmosphere8–10. The clinopyroxene-bearing leucogranite in the Hida Belt, so-called 'Inishi-type' migmatite, is believed to have formed through the interaction between granitic intrusion and metacarbonate rocks11,12. This specific interaction might provide crucial insights into the mechanisms of decarbonation in continental margin/arc.
Reference
1 Isozaki, 1996, Isl. Arc 5, 289–320. https://doi.org/10.1111/j.1440-1738.1996.tb00033.x
2 Isozaki, 1997, Isl. Arc 6, 2–24. https://doi.org/10.1111/j.1440-1738.1997.tb00038.x
3 Sohma & Kunugiza, 1993, Mem. Geol. Soc. Japan 42, 1–20 (in Japanese with English abstract).
4 Harada et al., 2021a, Isl. Arc 30, e12389. https://doi.org/10.1111/iar.12389
5 Kano, 1998. Shigen-Chishitsu 48, 77–92 (in Japanese with English abstract). https://doi.org/10.11456/shigenchishitsu1992.48.77
6 Harada & Tsujimori, 2024, Prog. Earth Planet. Sci. 11, 6. https://doi.org/10.1186/s40645-024-00609-y
7 Wada, 1988. Nature 331, 61–63. https://doi.org/10.1038/331061a0
8 Lee & Lackey, 2015, Elements 11, 125–130. https://doi.org/ 10.2113/gselements.11.2.125
9 Lee et al., 2013, Geosphere 9, 21–36. https://doi.org/10.1130/GES00822.1
10 Ramos et al., 2020. GSA Today 30, 5. https://doi.org/10.1130/GSATG432A.1
11 Harada et al., 2021b, Lithos 398–399, 106256. https://doi.org/10.1016/j.lithos.2021.106256
12 Kano, 1992. Shigen-Chishitsu, 42, 379–390. https://doi.org/10.11456/shigenchishitsu1992.42.379