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Data report: clay mineralogical composition of northern Cascadia margin sediments, IODP Expedition 3111
The clay mineralogical semiquantitative composition of 186 samples of hemipelagic sediments, turbiditic sediments, and authigenic carbonates from Integrated Ocean Drilling Program Sites U1325–U1329, northern Cascadia margin, were determined by X-ray diffraction analyses. Oriented aggregates of clay-sized fractions were analyzed to estimate the relative percentages of smectite, illite, chlorite, kaolinite, and illite/vermiculite mixed layers. Illite/vermiculite mixed layers were observed for the first time in this area. Clay mineral assemblages show only modest long-term variations with no significant differences among Sites U1325–U1329. Variations in clay mineral assemblages are supposed to be mostly related to differences between hemipelagic sediments and turbiditic sediments. The sampling resolution and the age control are not good enough to define or recognize any climate control indicators in the clay mineral record.