Environmental Engineering Reference
In-Depth Information
TABLE 1
General Characteristics and Environmental Aspects of the Marine and
Marginal-Marine Seilacherian Ichnofacies
Ichnofacies
Environmental constraints
Settings
Variably sorted, periodically exposed
sandy substrates, deposition rates low.
Food present as detritus. Softgrounds
to stiffgrounds.
Supratidal to upper intertidal positions,
subject to moderate- to low-energy
marine and/or eolian settings such as
beach backshore and dunes, washover
fans and supratidal flats.
Psilonichnus
Moderately to well-sorted, shifting
sandy substrates with variable
sedimentation and erosion rates. Food
mainly held in suspension, sieved
organics present in shallow water.
Softgrounds to stiffgrounds.
Lower intertidal to shallow subtidal
settings, in moderate to high-energy
conditions such as foreshore, shoreface
(above fair-weather wave base), tidal
inlets and channels, sandy shoals and
bars, and sandy deep-sea fans.
Skolithos
Relatively low-energy, semicohesive
muddy substrates with intercalated silt
and sand. Sedimentation and erosion
rates low. Food deposited on or buried
in the sediment. Softground near
surface, deep tiers encounter
stiffgrounds.
Permanently subtidal settings lying
below fair-weather wave base, but above
storm wave base. Common to fully
marine quiet-water conditions such as
offshore, shelf and open epeiric
embayments.
Cruziana
Fine-grained, cohesive muddy to
sandy substrates, locally showing
oxygen deficiency. Sedimentation rates
very low. Food deposited on substrate.
Shallow tiers in softgrounds, deep tiers
in stiffgrounds and firmgrounds.
Low-energy subtidal settings near to or
below storm wave base. Settings are
generally free of turbidites. Common
environments include silled basins,
restricted lagoons, continental shelves
and upper continental slopes.
Zoophycos
Pelagic and hemipelagic cohesive
muddy substrates reflecting very slow
sedimentation. Commonly
interstratified with sandy turbidites.
Patchy distribution of food confined
mainly at surface and shallow tiers.
Predominantly softgrounds.
Basinal subaqueous settings ranging
from bathyal to abyssal, typically low
energy but oxygenated. Settings include
lower slope, submarine canyon and
basin-floor (abyssal plain)
environments.
Nereites
Marine- or marginal-marine-generated
omission surfaces on firm but unlithified
substrates. Reflects recolonization of
dewatered, compacted and/or incipiently
cemented media. Commonly associated
with erosional exhumation.
Firm, compacted, semi-lithified
substrates characterized by very slow
sedimentation. Food dominantly held in
suspension.
Glossifungites
Xylic [woody] substrates characterized
by slow sedimentation. Food mainly in
suspension, with some organisms
adapted to consuming wood.
Marine omission surfaces on peat/coal
deposits and driftwood pavements. Not
applied to single wood clasts. Typical of
erosion in peat-forming areas (e.g.,
estuarine margin, delta plain or back-
barrier settings).
Teredolites
Hard, lithified substrates characterized
by erosion and non-deposition. Food
predominantly held in suspension.
Marine-influenced omission surfaces on
lithified media such as rocky coasts,
beachrock, hardgrounds, reefs or bone
beds and coquinas. Not applied to
individual bones, shells or clasts.
Trypanites
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