The High Temperature Titration of Amorphous Silica

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A new and novel technique will be developed for the determination of amorphous silica in marine sediments. It is based on the high temperature titration of amorphous silica with added calcium carbonate according to the reaction: SiO2 + CaCO3 ----- CaSiiO3 + CO2. The proposed research will proceed along three lines: 1. Further development of the method. Preliminary pyrolysis experiments were done at 500oC for three days. Subsequent work was at 700oC for one hour. These new conditions necessitate the repetition of many experiments to determine the optimum temperature and time and the dependence of the reaction on mineralogy, water content etc. for the optimum conditions. 2. Revaluation of the marine silica budget. Preliminary work indicates that calcareous oozes and continental shelf sediments are much more important sinks than previously believed. 3. The use of the &18O of the product CO2 as a measure of the &18O of amorphous silica and the paleocean from which it was deposited. //