Generate Near Table (Analysis)—ArcMap | Documentation (arcgis.com)
Then just the histogram of the near table (NEAR_DIST field) ? Histograms—Help | ArcGIS for Desktop
I will give this a try. Thank you
location would use up X and Y, leaving Z for isotope values, unless your locations are along a straight line, then you could use "distance from" some location for the X values.