『Abstract
Evidence for the dissolution of biogenic silica at the base of
pelagic sections supports the hypothesis that much of the chert
formed in the Pacific derives from the dissolution and reprecipitation
of this silica by hydrothermal waters. As ocean bottom waters
flow into and through the crust, they become warmer. Initially
they remain less saturated with respect to dissolved silica than
pore water in the overlying sediments. With the diffusion of heat,
dissolved ions, and to some extent the advection of water itself,
biogenic silica in the basal part of the sedimentary section is
dissolved. Upon conductively cooling, these pore waters precipitate
chert layers. The most common thickness for the basal silica-free
zone (20 m) lies below the most common height of the top of the
chert interval above basement (50 m). This mode of chert formation
explains the frequent occurrence of chert layers at very shallow
subbottom depths in pelagic sections of the Pacific. It is also
consistent with the common occurrence of cherts≦150 m above basement.』
Introduction
Methods
The model
Results
Conclusions
Acknowledgments
References cited