Several conclusions may be
drawn from this study. First, the absence of a gradient in the 18O
in the upper portion of Sites 1003 through 1007 is consistent with the idea that
advection of water through this region is removing the geochemical gradients
normally produced by diffusion and carbonate diagenesis. However, we cannot rule
out the possibility that the observed geochemical patterns are a result of high
rates of sedimentation in the upper portion of the profile.
Second, increases in 18O
of the pore water with depth are not traceable to diffusion from an underlying
source high in
18O
but result principally from recrystallization of existing metastable carbonate
sediments to low-Mg calcite and dolomite. The increases in
18O
of the pore waters are most prominent in the sites closest to the platform and
are reduced at Site 1006, reflecting higher rates of carbonate recrystallization
closer to the platform.
Third, pore waters
throughout the flushed zone show elevated 18O
values at the sites closest to the platform, suggesting the fluids from the
platform top are influencing the salinity of bottom waters.