Biogenic silicate accumulation

While rapid burial enhances preservation, the type of sediment produced is determined by the relative particle composition of the deposit. For example, rapid burial of biogenic silicate by clay minerals helps protect the shells against dissolution, but the resulting deposit is classified as an abyssal clay, rather than a siliceous ooze, if the sediment is less than 30% by mass BSi. Thus, prediction of the sediment type likely to be found at a given location requires knowledge of the relative magnitudes of the accumulation rates of all particle types. 

Only 15.5% of biogenic silicate is hydrolyzed during the journey from the surface to the bottom in seawater, thus ca. 84.5% can be deposited on the bottom. The silicate release rate at the sediment-seawater interface is quite a bit lower than its accumulation rate from water to sediment. They are the main reasons for a constantly low silicate concentration in sea water and Si-limitation in phytoplankton primary production. In one... 

Schneider, R. R., P. J. Muller, and M. Zabel. 1996. "Biogenic opal in the eastern South Atlantic patterns of surface water productivity, sedimentary accumulation, and benthic silicate fluxes in relation to oceanic and fluvial nutrient supply." In OPALEO On the Use of Opal as a PaleoProductivity Proxy, ed. O. Ragueneau, A. Leynaert, and P. Treguer (Brest, France), pp. 98-103. 

Figure 3 Seabed silica-preservation efficiency plotted as a function of sediment accumulation rate in Antarctic Ross Sea deposits. As sediment accumulation rates increase, the amount of time that siliceous material is exposed to the highly undersaturated bottom waters at the sediment-water interface decreases, which enhances the preservation of biogenic silica in the seabed.

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