Page 67 - Maldonado_Stanley_1976

60
SMITHSONIAN CONTRIBUTIONS TO TRE EARTH SCIENCES
Stra i t of S ici ly
lonian and Balearic Margins
Basi n
(Siope)

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500 1000 2000 2500
DEPTH IN METERS
FIGURE 37.-Percent of bioturbated strata in cores versus depth in different Strait of Sicily
environments. Regression line and correlation coefficient shows dose relation between depth and
degree of benthic activity. Data from core KS 110 was not used in the calculation. (Explanation
in text.)

sediment type and depth described in the previous sects the I 00% abscissa a t about 700 m. The neritic-
section. Benthic organisms are closely depth con- bathyal cores shallower than this depth are com-
trolled and the resulting degree of bioturbation pletely bioturbated (examples: cores LY II-4 in
should closely correlate with depth. Bioturbation is Figure 34 and KS 105 in Figure 35). Even in
a function of the number of organisms, type of ac- coarse-grade sediments of the shallow platform,
tivity, and rate of sedimentation. Inasmuch as the bioturbation is an important factor (Figure 24AJ
first two appear so closely related to depth, we sup- B); in some cases, however, the coarse texture of
pose that the other factor, less important than sediments in shallow water cores masks biogenic
the rate of biologica! activity, is the rate of structures.
sedimentation.
There is a generai decrease in the relative
The regression line shown on Figure 37 inter- amount of bioturbated core section between about