METHODOLOGY: HIGH- RESOLUTION ANALYSIS OF NATURALLY OCCURING COARSE- GRAINED SEDIMENT THROUGH LASER DIFFRACTOMETRY

Determination of grain size is one of the most essential measures in a sedimentologic study. Grain size distributions are an important source of information when interpreting the sedimentary environment. Detailed methodological measurements of very fine-grained sediments by laser diffraction have been reported to yield an uncertainty of ~5% at 2 sigma. These methodological procedures have been followed in this study for laser diffraction measurements on the Malvern Mastersizer 2000. The methodology for the fine-grained material was replicated with coarse-grained material as a standard for comparison and included quantifying the methodological uncertainty of each method so the overall accuracy of the grain size determination can be assessed. During this replication, it was found that the machine parameters needed to be altered to accommodate the larger grain size while maintaining uncertainty levels. Based on this, standardized sample preparation procedures and machine operating parameters for laser diffraction analysis of naturally occurring coarse grained sediments have been derived. This enriched methodology study will heighten the resolution of grain size as a sedimentologic proxy and allow for an efficient and accurate means of grain size analysis.