A new carbonate-specific quantification procedure for determining elemental concentrations from portable energy-dispersive X-ray fluorescence (PXRF) data

摘要

Portable energy-dispersive X-ray fluorescence (PXRF) analyzers are routinely used to generate large elemental datasets in sedimentary strata. These data provide the basis for assessing stratigraphic changes in geochemistry, bulk mineralogy, and paleo-redox conditions. The manufacturer provided procedure used to calculate elemental concentrations from PXRF photon counts that was developed for siliciclastic mudrocks. This quantification is, however, routinely applied to other sedimentary rocks, such as carbonates, which often have very different elemental concentrations and rock textures. The current study reports elemental concentration data from 57 limestone and dolomite rock samples measured by both PXRF and conventional geochemical analyses including inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma - optical emission spectrometry (ICP-OES), and wavelength-dispersive X-ray fluorescence (WD-XRF). Carbonate samples were subdivided into two groups. The calibration set (N = 43) is used to establish a carbonate-specific PXRF quantification procedure, and to investigate the effects of different sample preparation techniques. The validation set (N = 14) is used to evaluate the applicability of both the newly developed carbonate-specific quantification procedure and the existing mudrock quantification procedure for the carbonate rock suite.