Convenient analysis of chemical composition of clay fraction of sediment by electron probe microanalyzer

We developed a convenient sample preparation method applicable to electron probe microanalysis (EPMA) of the clay fraction of sediment. The clay fraction separated from original sediment by elutriation was pasted evenly on an area of about 1 cm ¥ 1 cm on a copper plate. After the sample had dried at room temperature, it was subjected to EPMA analysis using the maximum electron beam diameter (30 μm). This method provides adequate results, consistent with those obtained by X-ray fluorescence in the case of intensely hydrothermally altered sediments collected from a seafloor hydrothermal field. The major merit of this method is the small amount of clay fraction required (about 10 mg), which saves time in sample preparation. We call this method the "Cu-EPMA method."