Figure 4: CL images and measured SIMS δ18O traverses across selected quartz crystals from the YTT.
From: Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz
Grey shading on the Cathodoluminescence (CL) images defines distinct textural and compositional domains. Numbered red squares on the CL images correspond to analysis spots on the inset δ18O plots. Insets: Grey shading on graphs indicates textural domains and horizontal red bars indicate individual δ18O zone averages. Orange bars indicate high- and low-δ18Oquartz from basement granitoids of the Toba region. Error bars = 1σ. Crystals (a–f) (part 1) display an overall core to rim decrease in δ18O values, while crystals (g–o) (part 2) show no significant core to rim variation in δ18O value. Individual analysis points that deviate from the crystal average in (g–o) are considered outliers, and are potentially due to small inclusions of foreign material in the analysis.
