Grain size analysis of sediments from the northern Andaman Sea: Comparison of laser diffraction and sieve-pipette techniques

Abstract

A comparison has been made of sand, silt, and clay percentage of 118 samples from the Ayeyarwady continental shelf, northern Andaman Sea, measured by the sieve-laser diffraction technique and by classical sieve-pipette methods. Clay and silt percentages determined by Malvern Mastersizer 2000 Laser Particle Size Analyzer are 37% and 157% of pipette clay and pipette silt percentages, respectively. Clay particles separated by the settling technique and having an apparent size of less than 2 mu m when measured with laser diffraction show that 99% of the particles have an upper size range between 4.8 and 7.7 mu m. A calibration relationship between pipette and laser diffraction techniques has been developed for the northern Andaman Sea. A clay particle size of 2 mu m defined by the pipette technique corresponds best to a size of 6.2 mu m defined by laser diffraction. For the laser data, when 6.2 mu m is taken as the boundary between silt and clay, the results are comparable to pipette analysis. Use of the calibration relationship enables one to make use of the rapid laser diffraction size analysis technique for routine sediment texture analysis with high precision.