Sm-Nd Residence Time Grid (felsic igneous rocks)

This is an interpolated grid of Nd residence time values, based on whole-rock Nd isotopic analyses from felsic magmatic rocks, particularly focusing on I- and A-type granites and volcanic rocks. The data provides an estimate of the duration for material residing in the crust prior to its last melting event. The point data used for the interpolation is the “felsic igneous rock” subset of the Sm-Nd data 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 nine-class interval binning and colour scheme applied to the source point data in the Sm-Nd Isotope Data layer (classification 2).