Data report: quantitative analysis of grain size distribution for coarse sediments in an accretionary prism: an example from the Cascadia accretionary prism

Abstract

Grain size distributions of coarse sediments from a shallow depth of an accretionary prism were examined by two-dimensional image analysis using thin sections. The analyzed samples were obtained during Integrated Ocean Drilling Program (IODP) Expedition 311. Statistical parameters such as kurtosis, skewness, and correlation coefficients of exponential and power functions show no relationship with depth and porosity. There is an inverse relationship between the correlation coefficients of exponential and power functions, indicating that some grain size distributions can be classified. The correlations also relate to sediment textures. Samples with rounded and isolated grains have a higher correlation coefficient with the exponential function. Angular grains and a denser packing texture represent a lower correlation coefficient with the exponential function.

On the consolidation state of sediments from the accretionary prism offshore Vancouver Island, North Cascadia Margin

“…The grain-size analysis revealed that most samples are either clayey silt or silty clay (Table 3, Fig. 4) as no sand-rich samples remained for our analyses, consistent with the major lithologies defined from visual core descriptions (Table 1) and onboard data (Wang et al 2007;Hashimoto and Minamizawa 2009). Sand-rich samples were mostly taken at sea as they were often gas hydrate-bearing and underwent gas hydrate-specific analyses (Torres et al 2008).…”