montana {coda.base}R Documentation

Concentration of minor elements in carbon ashes


The montana data set consists of 229 samples of the concentration (in ppm) of minor elements [Cr, Cu, Hg, U, V] in carbon ashes from the Fort Union formation (Montana, USA), side of the Powder River Basin. The formation is mostly Palaeocene in age, and the coal is the result of deposition in conditions ranging from fluvial to lacustrine. All samples were taken from the same seam at different sites over an area of 430 km by 300 km, which implies that on average, the sampling spacing is 24 km. Using the spatial coordinates of the data, a semivariogram analysis was conducted for each chemical element in order to check for a potential spatial dependence structure in the data (not shown here). No spatial dependence patterns were observed for any component, which allowed us to assume an independence of the chemical samples at different locations.

The aforementioned chemical components actually represent a fully observed subcomposition of a much larger chemical composition. The five elements are not closed to a constant sum. Note that, as the samples are expressed in parts per million and all concentrations were originally measured, a residual element could be defined to fill up the gap to 10^6.




An object of class data.frame with 229 rows and 6 columns.

[Package coda.base version 0.5.5 Index]