Datasets defining elements

In react, dataset isotope.dat contains polynomial coefficients that define temperature functions for the fractionation factors of species, minerals, and gases. The factors describe fractionation relative to a reference species chosen for each element. The reference species for oxygen and hydrogen is solvent water, H2O. CO2 and H2S, in either aqueous or gaseous form, serve as reference species for carbon and sulfur. 

The values are reported as averages however, this in not meant to infer that apatite chemistry displays a normal distribution about a mean, but is displayed as such for simplicity sake. Sufficient analyses of mafic pegmatites were not present in the literature to be included. The compilation represents over 1000 analyses and is not meant to be all-inclusive. The following abbreviations are used N is the number of analyses represented (however, not all elements were analyzed for in all analyses) Avg is the mean Std is lo standard deviation about the mean, and - indicates that sufficient data within a petrogenetic group are not available in the present dataset to appropriately define. 

Within the software architecture the volumetric dataset is organized in terms of voxels. These are near cubic elements that arise from each image pixel. This latter is the basic building block for the voxel to which a Hounsfield value (in case of CT) or an intensity value (in case of MR) is assigned each voxel has also a defined spatial position and dimension in the volume. 

Some velocity models are built using voxels (volume elements) that define homogeneous 3D regions. Other models combine different datasets using interpolation rules that assign weights based on the location of the point of interest relative to the data points. 

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