Figure 4.

Comparison of crystallization ages and Ti-in-zircon temperatures with thermal history derived from also considering diffusion durations. (a) Ti-in-zircon crystallization temperatures versus ²³⁸U-²³⁰Th ages for zircon crystals from the Soufriere Volcanic Center (SVC), Lesser Antilles (redrafted using data in [66]). Dataset includes zircon rim analyses from dacitic eruptions (Belfond lava; black triangles) and cogenetic enclaves of plutonic material (red squares). Error bars shown are 1-sigma. See [66] for additional details. (b) Time–temperature history recorded in the zircon crystals from the Kaharoa eruption, New Zealand, modified from [22]. Each crystal is represented by a different symbol (open symbols represent surface analyses) and all measured ²³⁸U-²³⁰Th ages are plotted with their 1-sigma uncertainties at the corresponding Ti-in-zircon temperature. Points yielding ²³⁸U-²³⁰Th activity ratios within error of secular equilibrium are plotted at 350 ka. The widths of the peaks in temperature correspond to the diffusion durations calculated at 700°C and the temperature between peaks is arbitrarily set below the lowest recorded crystallization temperature. For reference, the grey shaded regions indicate the range of zircon saturation temperatures for the Kaharoa eruption, the estimated rheological lock-up temperature, and the solidus temperature. Note that the zircon saturation temperature is calculated based on the bulk magma composition, and given the diversity of ages and trace-element compositions of zircon in the Kaharoa samples, it is likely that some zircon crystallized in local environments with different zircon saturation conditions. See [22] for additional details.