The Large Lakes Observatory at the University of Minnesota Duluth hosts the Continental Scientific Drilling (CSD) Facility X-ray Fluorescence (XRF) Lab. Funded by the National Science Foundation and the University of Minnesota, this lab provides essential analyses of core samples for geoscience researchers.
The ITRAX XRF Corescanner provides nondestructive elemental analysis of most elements from Aluminum (atomic number 13) to Uranium (92). Stratigraphic resolution can vary between 0.2 mm to 2 cm. Fine resolutions are more time consuming but may be desired for detailed studies of (for example) finely laminated sedimentary core samples, whereas relatively homogeneous samples are typically analyzed at a courser resolution (5-10 mm). The elements detected depend on concentrations present in the sample, the sample matrix, the dwell time at each sample point, and the selection of X-ray tube. A 15-second dwell time generally yields good results for most common elements. However, the scanner can be configured for dwell times ranging from 1 second for high stratigraphic resolution studies of abundant elements to 2 minutes for lower stratigraphic resolution studies of trace elements. Three X-ray tubes with different anodes are available (chromium, molybdenum, and rhodium). The Cr tube is more effective for lower weight elements (< Ti), the Mo tube is more effective for higher weight elements (> V), and the Rh tube yields similar results to the Mo tube, but provides better analytical capabilities for studies of Mo and neighboring elements. In all configurations, results are reported in counts and are semi-quantitative unless calibrated with standard reference materials.
The core scanner produces high-quality digital X-radiographic core images with 16-bit grayscale density and 0.2 mm resolution. Time required varies from 30 to 60 minutes per meter, depending on core thickness and density.
Materials and Preparation
Suitable materials for analysis are unsampled split cores, u-channels from cores, discrete samples, and whole cores (for radiographic imaging only). Maximum core dimensions are 180 cm length, 12 cm width, and 6 cm height (thickness). The sample surface must be carefully cleaned and leveled prior to scanning.
Current rates for XRF analyses are based on a per-section fee for sample preparation and setup and a per-hour fee for instrument time (both rates apply to a single scan). X-radiographic imaging requires additional instrument time, but no additional preparation time if undertaken at the same time as the XRF scan. Please contact the facility for up-to-date pricing.