Infrared stimulation spectra of sediments containing feldspars

High resolution infrared stimulation spectra have been measured for feldspar-bearing samples from a sequence of intertidal Holocene sediments at Downholland Moss, Lancashire, U.K. To allow comparison, spectra were also measured for a range of well characterized feldspar specimens. The spectra from sediment samples show a broad resonance peaking at similar to 1.44 eV with an average FWHM of 0.196 +/- 0.028 eV. Fitting the sum of two Gaussian functions to the stimulation spectra of both sediment samples and mineral specimens indicate that two component bands at 1.442 eV (860 nm) and similar to 1.6 eV (similar to 775 nm) are present. The position of the low energy band at 1.44 eV is independent of feldspar composition in the suite of feldspars studied. The ratio of the 1.6 to the 1.44 eV band appears to increase with increasing potassium content of the feldspar samples, although this is not exclusively the case. It is the relative intensities of these two bands which results in the asymmetry observed in the spectra of some feldspars. (C) 1997 Elsevier Science Ltd.