the Barbados hemipelagics. When six of the data points, which were obtained from
Taylor and Leonard (1990), were removed from the regression, the R2 value of the
remaining 19 samples increased from 0.20 to 0.50, predicting a permeability-porosity
relationship of log (k)=-24.24 + 11.3 In. Although statistically this makes the six data
points outliers, a closer look at the lithological descriptions, grain size data and CaCO3
percentages suggest that the hemipelagics samples used by Taylor and Leonard (1990)
are likely to be different from the rest of the hemipelagics sediments representative of
Barbados because samples used by Taylor and Leonard (1990) represented calcareous
muds whereas other samples represented claystones.
Even though many of the samples from Barbados, Nankai, and Costa Rica fall in
the depositional classification of"hemipelagics", they are not well represented by the
same permeability-porosity relationship (log (k) = -19.91+4.9n, R2 = 0.5). The Barbados
permeability-porosity relationship predicts similar values of permeability to Nankai and
Costa Rica relationships at porosities between 0.55-0.70 (Table 2-1). However, at lower
porosities the Barbados permeability relationship predicts lower values than those of
Costa Rica and Nankai. Because Barbados permeabilities are constrained by a small
range of porosities, one should be cautious outside the porosity range of the laboratory
results. The log-linear relationships for Nankai and Costa Rica plot roughly parallel to
each other with slightly lower permeabilities at Costa Rica for a given porosity than at
Nankai (Figure 2-6). The R2 value obtained for Nankai was 0.79 while for Costa Rica it
was 0.70 suggesting reasonable correlation between permeability and porosity at these
two locations. The R2 value obtained for the log linear relationships for the calcareous
oozes were less than 0.5 while for the siliceous oozes it is greater than 0.5 (Figure 2-6).