Environmental Engineering Reference
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ooze accumulated slowly as a pelagic rain, typically at rates of a few centime-
ters per thousand years. Yet, some oozes were redistributed by persistent bottom
currents (e.g.,
Surlyk and Lykke-Andersen, 2007
) or rapidly redeposited by
mass-movement processes (
Bromley and Ekdale, 1987
), including turbidity
currents (
Uchman, 2007
), to ocean depths that in some cases were below the
CCD. Thus, despite “pelagic” and “deep water” monikers, the carbonate
deposits addressed herein accumulated via multiple processes, under a signifi-
cant range of water depths and in a wide array of marine environments (
Fig. 1
;
Table 1
).
Zoophycos
Ichnofacies
Cruziana
Ichnofacies
Unnamed
association
Glossifungites
and
Trypanites
ichnofacies
Chalk redeposition along
oversteepened slopes
Periodically storm-
influenced inner
shelf
Bottom
currents
Periodically
oxygen-deficient
epeiric seas
Periodically
winnowed/
scoured shelves
with omission
surfaces
Slope-fan-basin
calciturbidites
Oxygenated
middle-outer
shelves
Deep sea
(slope, basin
floor and bank
tops above
CCD)
Arenicolites
Ichnofacies(?)
Zoophycos
Ichnofacies
Nereites
Ichnofacies
FIGURE 1
Various chalk and deep-marine carbonate depositional regimes and associated ichno-
facies.
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