Sm-Nd Epsilon Grid (felsic igneous rocks)

This is an interpolated grid of Sm-Nd epsilon values, based on whole-rock Nd isotopic analyses from felsic magmatic rocks, particularly focusing on I- and A-type granites and volcanic rocks. 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 seven-class interval binning and colour scheme applied to the source point data in the Sm-Nd Isotope Data layer (classification 2).本数据集为Sm-Nd ε值（Sm-Nd epsilon values）插值网格，基于长英质岩浆岩的全岩钕同位素分析数据构建，重点聚焦I型与A型花岗岩及火山岩。本次插值所用的点位数据，为2021年2月时收录于《同位素图集（Isotopic Atlas）》中的Sm-Nd数据的长英质火成岩子集。2021年2月后新增至《同位素图集》的点位数据未纳入本网格。本网格由Esri的ArcMap空间分析插值工具生成，采用自然邻域算法（Natural Neighbor algorithm），像元大小为0.01度。本网格提供两种分级方案：其一为遵循Champion（2013）提出的詹克斯自然间断点分级法（Jenks natural breaks classification）的10级分级（分级方案1），参考数据集链接为http://pid.geoscience.gov.au/dataset/ga/77772；其二为与Sm-Nd同位素数据图层中原点位数据一致的七级区间分箱及配色方案（分级方案2）。