Figure F71. Correlation of dissolved SiO₂ and porosity in sediments at Site 1109. Note the lack of correlation in the first 100 mbsf because of early diagenesis of easily solubilized solid phases containing silica, and an anticorrelation in the volcanic ash-rich interval that provides an important source of this constituent to the pore water. Below 260 mbsf a strong positive correlation exists between porosity and dissolved SiO₂.