R8：変成岩とテクトニクス

[R8-12] 後期新原生代－カンブリア紀の超高温変成岩体の熱源：ジルコン中の昇温期メルト包有物の化学組成からの制約

「発表賞エントリー」

*鈴木 康太¹、河上 哲生¹、小木曽 哲²、坂田 周平³ (1. 京都大・院理、2. 京都大・院人環、3. 東京大・地震研)

キーワード：メルト包有物、ガラス包有物、ジルコン、ピストンシリンダー、希土類元素

We performed piston-cylinder remelting experiments of prograde melt inclusions in zircon in an ultrahigh temperature (UHT) granulite from Rundvågshetta, Lützow-Holm Complex, East Antarctica. The diffusion-controlled chemical trend characteristic to rapid heating was absent in the Qz-Ab-Or normative diagram. Therefore, the external heat from the mantle is unlikely involved in attaining the UHT, but rather the radiogenic heat may be the viable heat source in this region. This is supported by the long-lived anatexis (~40 Myr) and the lack of syn-metamorphic igneous activities.