Zircon growth process in granitic pluton by 3D cathodoluminescence patterns, U-Pb ages, titanium concentration, and Th/U ratios; Case study of the Okueyama granite, Kyushu, Japan

Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*

no journal, , 

This study proposes a new method for elucidating zircon growth processes in the Okueyama granitic pluton, Kyushu, Japan. Our method, which combines 3D growth patterns, U-Pb ages, titanium concentration, and Th/U ratios, contributes to the petrology and mineralogy to understand the growth of zircon crystals within a magma chamber. Simultaneous determination of zircon U-Pb ages and titanium concentrations for the granite gives the variations in the temporal and thermal conditions during zircon growth, thus, developing a t-T history of the granitic magma before its solidification. The simultaneous determination of zircon U-Pb ages and Ti concentrations in the granite also enable us to associate the Th/U ratio with the crystallization temperature. Therefore, the decrease in zircon Th/U ratios as decreasing the temperature indicates the progression of fractional crystallization as the cooling of the magma chamber.