Fig. 4: Silicon isotope and geochemical trends in solids and pore fluids.
From: Coastal El Niño triggers rapid marine silicate alteration on the seafloor
a In-situ δ30Si of authigenic clays and bulk sediment of the Peruvian shelf in 2017 and bulk sediment analyses from the shelf in 2013. Error bars are 2 SD of individual measurements. Horizontal line is the average modeled authigenic clay δ30Si signature following the coastal El Niño (see also Table S10, Fig. S4). Note that the ‘diatom’ endmember, which upon dissolution, determines the pore fluid δ30Si from which the authigenic clays precipitate. The trend to lower authigenic clay δ30Si is likely due to increasing maturation of an amorphous gel-like precursor phase to smectite as described in Baldermann et al.12. b Ge versus Si concentrations for the Peruvian margin compared to pore fluids from other continental margin areas21,22,35,56. c Peruvian margin δ30Si versus Ge/Si ratios in pore fluids (symbols as in b). Error bars are 2 SD of individual measurements. Most samples fall on mixing lines between dissolving primary silicates (here feldspar), dissolving diatoms and/ or seawater (sw). Seawater δ30Si is from Grasse et al.57,58. Only samples from the shelf in 2017 deviate from this trend to higher δ30Si and Ge/Si ratios indicating extensive authigenic clay formation (see text).
