Crystallization processes of quartz in a granitic magma: Cathodoluminescence zonation pattern controlled by temperature and titanium diffusivity. (1st May 2020)

• Record Type: Journal Article
• Authors: Yuguchi, Takashi; Ogita, Yasuhiro; Kato, Takenori; Yokota, Rintaro; Sasao, Eiji; Nishiyama, Tadao
• Is Part Of: Journal of Asian earth sciences. Volume 192(2020)
• Publication Date: 2020-05-01
• Subjects: Quartz -- Cathodoluminescence characterization -- Oscillatory zonation -- TitaniQ thermometer -- Diffusion-controlled growth -- Toki granitic pluton; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2020.104289
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: Sequential growth events of Quartz crystals occurred within granitic magmas. There are three types of internal structure in quartz crystals under CL imagines. Oscillatory zonation of quartz can be developed according to diffusion-controlled growth. Temperatures for the formation of oscillatory zonation range from 850 °C to <700 °C. Crystallization of quartz can lead to the cooling of granitic magmas. Abstract: Quartz from a granitic pluton is found to have formed through sequential growth events under different mechanisms and crystallization temperatures, which can provide new insights into magmatic processes of granitic magmas that were eventually consolidified into plutons. The events were identified using (1) the description of crystal shape and occurrence, (2) the study of the internal structure with cathodoluminescence (CL), and (3) derivation of the crystallization temperatures based on TitaniQ thermometry. The magmatic quartz crystals from the Toki granite, central Japan, are characterized as having the following internal structures: oscillatory zonation, no-oscillatory zonation with luminescence gradation (gradational zonation), and heterogeneous CL. The quartz crystals with oscillatory zonation were formed in the temperature range of about 800 °C to below 700 °C, which is referred to as oscillatory zoning temperature (OZT) conditions. The CL zonation pattern was controlled by the temperature conditions and titanium diffusivity in the melt (magma). The crystallization process of quartz within the Toki granite reveals the cooling processes of the granitic pluton; the lithofacies with a high frequency of oscillatory-zoned quartz underwent slower cooling under the OZT conditions than those in other lithofacies.