Fig. 5. Example of synthetic zircon age populations computed from thermal modeling.

The kernel density estimate of the zircon age distribution is shown over the duration of the magma injection episode of 1.5 Ma for an incrementally-built intrusion with a magma flux of 9.1 × 10⁻⁶ km³ km⁻² yr⁻¹, using a sill radius of 10 km and andesitic recharge magma⁴⁵. The modeled zircon distribution was randomly sampled 100 times (gray curves) with (a) 300 measured synthetic zircon ages, (b) 100 analyzed zircon ages and (c) 15 synthetic zircon ages. Note the spikiness of the synthetic zircon distribution in (c), which is resulting from under-sampling of the distribution. The black curve in each plot represents a randomly selected distribution to illustrate the impact of under-sampling on the distribution shape. The bandwidth was set to 100 ka.