RECONSTRUCTION OF IN-SITU PORE-WATER COMPOSITIONS OBTAINED BY AQUEOUSLEACHING OF DRILL CORE - AN EVALUATION USING MULTIVARIATE STATISTICALDECONVOLUTION

A method for reconstructing pore-water compositions from aqueous leach ate data obtained from milled and dried drill core is described, The m ethod uses principal component analysis (PCA) to construct an abstract model of the aqueous leachate data which separates out the contaminat ing components, arising from rock dissolution and drilling fluid conta mination, from the pore-water residual solutes component, Iterative ta rget factor analysis (TFA) is used to quantify this pore-water compone nt based on the assumptions that halides in the aqueous leachate are m ainly attributable to the pore-water and that the lithium tracer in th e drilling fluid is not present in the pore-water, The method is teste d on a simulated data set and on data obtained from a deep borehole in Sellafield, Cumbria. The results demonstrate that the proposed method , although requiring further development, has potential use as a power ful investigative tool in a wide range of environmental applications.