Crystallization processes of quartz in a granitic magma; Implications for the magma chamber processes of Okueyama granite, Kyushu, Japan

花崗岩質マグマにおける石英の結晶化プロセス; 北部九州,大崩山花崗岩体のマグマ溜りプロセスに対するインプリケーション

湯口 貴史*; 加藤 丈典*; 小北 康弘  ; 渡邊 みのり*; 山嵜 勇人*; 加藤 あすか*; 伊藤 大智*; 横山 立憲   ; 坂田 周平*; 大野 剛*

Yuguchi, Takashi*; Kato, Takenori*; Ogita, Yasuhiro; Watanabe, Minori*; Yamazaki, Hayato*; Kato, Asuka*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Ono, Takeshi*

Cathodoluminescence (CL) characterization combined with titanium concentration of quartz crystals in granite is a prevalent tool for deciphering the crystal growth of quartz in granitic magmas. The CL pattern yields to the internal structure, and the titanium concentration allows crystallization temperature determination based on TitaniQ geothermometry. This study is conducted using two approaches, 1) observations of quartz crystals based on thin sections and 2) observations based on multiple sections of separated quartz, revealing to obtain both the overall characteristics of quartz crystals within a magma chamber and the 3D internal structure and growth characteristics of quartz grains. Petrological restrictions such as zircon in quartz deduced from thin-section observations permit suitable geothermometer use and appropriate TiO activity estimation, and thus, accurate quartz crystallization temperature determination. The difference in CL characteristics and crystallization temperature among the lithofacies in granite contributes to clarifying the spatiotemporal magma chamber processes.