Lu-Hf Model Age (T2DM) Grid (igneous)

This is an interpolated grid of Lu-Hf two-stage model ages, based on (primarily zircon) Lu-Hf isotopic analyses from igneous rocks. The data provides an estimate of the timing of extraction from the mantle of the middle to lower crustal source regions from which the melts were generated. The point data used for the interpolation is the median magmatic T2DM data of the summary Lu-Hf dataset held in the Isotopic Atlas as of February 2021. Point data added to the Isotopic Atlas after February 2021 is not represented in this grid. The grid was generated with Esri's ArcMap Spatial Analyst interpolation tool using the Natural Neighbor algorithm and 0.01 degree cell size. Two classifications are provided for this grid; a Jenks natural breaks classification with ten classes (classification 1) as per Champion (2013) http://pid.geoscience.gov.au/dataset/ga/77772, and; the same three-class interval binning and colour scheme applied to the source point data in the Lu-Hf Isotopes - Summary Data layer (classification 2).