Grain-size analysis is useful for characterizing a wide variety of physical properties of marine sediment. Grain size and sorting affect porosity and permeability (e.g., Boggs, 1995; Fetter, 2001), and they are also related to the geotechnical properties of sediment. For instance, the relation between void ratio and applied effective stress can be strongly influenced by grain size, as are physiochemical and mechanical factors during consolidation. Clays, especially highly colloidal ones, experience greater reduction in void ratio under a given increase in effective stress than do silty clays or silts (Mitchell, 1993). The presence of abundant clay can also inhibit crushing of diatoms and calcareous tests during consolidation, which contributes to the maintenance of porosity (Hein, 1991). Grain size also affects Atterberg limits, bulk density, shear strength, permeability, and pore pressure transients in response to cyclic loading (Hein, 1991).
Leg 190 of the Ocean Drilling Program (ODP) targeted the Nankai convergent margin, southwest Japan, for the purpose of understanding the complex relations among deformation, diagenesis, and fluid flow. To this end, we clustered samples for studies of mineralogy next to those for geotechnical and geochemical analyses. The first objective of this report is to summarize the grain-size data for the sample clusters so that the results of geotechnical tests can be interpreted more effectively. A second objective is to document a method for using a laser particle counter for performing grain-size analysis with fine-grained sediment.