Semeniuk & Semeniuk: Wetland sedimentary fill - particles, sediments, classification 
Table 5 
Categories of sediments transitional between sand and mud (fabric nomenclature after Dunham 1962) 
Sediment fabric category 
Wetland sediment type 
composed wholly of sand grains in grain-support 
fabric (= grainstone fabric of Dunham 1962) 
sand 
composed of sand grains in grain-support fabric 
with interstitial mud (= packstone fabric of 
Dunham 1962); categorisation of interstitial mud 
follows Figure 12A 
peaty sand, diatomaceous muddy sand, calcilutaceous muddy sand, 
kaolinitic muddy sand, organic matter enriched diatomaceous muddy 
sand, organic matter enriched calcilutaceous muddy sand. 
composed of sand grains floating in a mud-support 
fabric (= wackestone fabric of Dunham 1962); 
categorisation of mud follows Figure 12A 
sandy peat, sandy diatomite, sandy calcilutite, sandy kaolinitic mud, 
sandy organic matter enriched diatomite, sandy organic matter 
enriched calcilutite 
composed wholly of mud-sized particles 
(= mudstone fabric of Dunham 1962); 
categorisation of mud follows Figure 12A 
peat, diatomite, calcilutite, kaolinitic mud, organic matter 
enriched diatomite, organic matter enriched calcilutite 
In regards to the gradation between quartz sand and 
mud-sized components (i.e., quartz sand and peat, 
diatomite, calcilutite, or kaolinitic mud), the 
intermediates are peaty quartz sand (Fig. 5G) and sandy 
peat, diatomaceous (muddy) quartz sand and sandy 
diatomite, calcilutaceous (muddy) quartz sand and sandy 
calcilutite, and kaolinitic muddy sand and sandy 
kaolinitic mud, respectively (Table 5). There also are 
intermediates between intraclast sand and calcilutite (Fig 
5K) and diatomite intraclast sand and diatomite. A 
simplified classification and nomenclature of the fabric 
classes and hence sediment classes for the mixtures 
between sand and mud is presented in Figure 12B. Fabric 
rather than percentage boundaries are used to separate 
the classes of muddy sand and sandy mud because the 
category of "grain-support" will have different size of 
interstitial space, and hence different sand to mud ratio, 
dependent on grain shape and sphericity ( e.g ., Plates I & 
II of Dunham 1962). While the descriptor terms "peaty", 
"diatomaceous", and "calcilutaceous" carry implication 
that these sediment types are muddy sands, we suggest 
that the term "muddy" be inserted between the 
descriptors referring to the mud fraction and the term 
"sand", e.g., calcilutaceous muddy sand. If the mud-sized 
fraction is left undifferentiated as to its particle types, the 
sediments may be termed "muddy sand" or "sandy 
mud". If the composition of the muddy component of the 
sediment is known and has been classsified as to its 
position on the ternary diagram, the category of the 
"mud" in the muddy sand can be adfixed to the sediment 
name, e.g., organicmatter enriched diatomaceous muddy 
sand. Analyses of the fine-grained interstitial material 
from some 50 wetland sediments are superimposed on 
the ternary diagram in Figure 13B to illustrate the 
variability in composition of the interstitial material in 
these types of wetland sediments. 
The "muddy" sands are intermediate sediment types 
between wetland sands and biogenic muds and usually 
form where peat, diatomite, or calcilutite accumulations 
are interspersed with the influx of quartz sand from 
wetland basin margins (Fig. 4H), or at the basal 
transitional infiltrational zone where the fine-grained 
wetland sediment fill stratigraphically rests on the 
underlying basement sand (Fig. 14). In the cases of peaty 
quartz sand, diatomaceous quartz sand, and 
calcilutaceous quartz sand, the mud-sized components 
are interstitial to the grain-support sand framework. In 
the cases of sandy peat, sandy diatomite, sandy 
calcilutite, and sandy kaolinitic mud, quartz sand is 
dispersed in the mud-support matrix. 
While phytoliths are not abundant enough in the 
sediments encountered in this study to constitute an end- 
member wetland sediment type, locally they comprise 
the dominant interstitial fine-grained component of 
muddy sands. In this context, these sediments are termed 
phytolithic muddy sand. 
The range of common wetland sediments encountered 
in this study is listed in Table 6. 
Table 6 
Range of most common wetland sediments encountered in this 
study 
peat 
diatomite 
calcilutite 
kaolinitic mud 
quartz sand 
quartz silt 
skeletal gravel and sand 
peat intraclast gravel and sand 
carbonate intraclast gravel and sand 
diatomite intraclast gravel and sand 
peaty quartz sand 
sandy peat 
diatomaceous muddy quartz sand 
sandy diatomite 
calcilutaceous muddy quartz sand 
sandy calcilutite 
kaolinitic muddy quartz sand 
sandy kaolinitic mud 
diatomaceous peat 
organic matter enriched diatomite 
sandy organic matter enriched diatomite 
calcilutaceous peat 
organic matter enriched calcilutite 
sandy organic matter enriched calcilutite 
organic matter enriched diatomaceous calcilutite 
sandy organic matter enriched diatomaceous calcilutite 
organic matter enriched kaolinitic mud 
organic matter enriched diatomaceous kaolinitic mud 
phytolithic muddy sand 
161 
