Journal of the Royal Society of Western Australia, 87(4), December 2004 
Table 7 
Classification of the main wetland sediments and their origin 
Sediment How formed 
Primary end-member sediments 
peat 
diatomite 
calcilutite 
kaolinitic mud 
quartz sand 
quartz silt 
skeletal gravel and sand 
intrabasinal accumulation of plant material 
intrabasinal accumulation of diatoms 
intrabasinal accumulation of disintegrated charophytes and invertebrate skeletons 
extrabasinal delivery of fine-grained sediment by fluvial or aeolian processes 
extrabasinal delivery of fine-grained sediment by fluvial or marginal sheet wash 
processes 
extrabasinal delivery of fine-grained sediment by fluvial or aeolian processes 
intrabasinal accumulation of invertebrate skeletons 
Secondary (derivative) sediments 
peat intraclast gravel and sand desiccation, baking, cracking, reworking and accumulation of peat mainly along 
wetland margins 
carbonate intraclast gravel and sand desiccation, cementation, cracking, reworking and accumulation of carbonate sediments 
mainly along wetland margins 
diatomite intraclast gravel and sand desiccation, cracking, reworking and accumulation of diatomite mainly along wetland 
margins 
Mixtures of end-member sediments 
peaty quartz sand mixing by sheet wash or bioturbation of peat and quartz sand either along wetland 
margins or along the base of the wetland fill; the occurrence of interstitial organic 
matter indicates that the sediment has formed under anoxic subaqueous or waterlogged 
conditions 
sandy peat 
diatomaceous quartz sand 
sandy diatomite 
calcilutaceous quartz sand 
sandy calcilutite 
kaolinitic muddy quartz sand 
and sandy kaolinitic mud 
diatomaceous peat 
organic matter enriched diatomite 
and sandy organic matter enriched diatomite 
calcilutaceous peat 
organic matter enriched calcilutite 
and sandy organic matter enriched calcilutite 
organic matter enriched diatomaceous 
calcilutite, and sandy organic matter 
enriched diatomaceous calcilutite 
organic matter enriched kaolinitic mud 
organic matter enriched diatomaceous 
kaolinitic mud 
mixing by sheet wash or bioturbation of peat and quartz sand either along wetland 
margins or along the base of the wetland fill 
mixing by sheet wash or bioturbation of diatomite and quartz sand either along wetland 
margins or along the base of the wetland fill 
mixing by sheet wash or bioturbation of diatomite and quartz sand either along wetland 
margins or along the base of the wetland fill 
mixing by sheet wash or bioturbation of calcilutite and quartz sand either along wetland 
margins or along the base of the wetland fill 
mixing by sheet wash or bioturbation of calcilutite and quartz sand either along wetland 
margins or along the base of the wetland fill 
mixing by sheet wash, fluvil processes, or bioturbation of kaolinitic mud and quartz 
sand either along wetland margins or along the base of the wetland fill 
accumulation of organic matter with diatoms, dominated by organic matter 
accumulation of organic matter with diatoms, dominated by diatoms 
accumulation of organic matter jointly with calcilutite, dominated by organic matter 
accumulation of organic matter jointly with calcilutite, dominated by calcilutite 
accumulation of organic matter, diatoms and calcilutite 
accumulation of organic matter and kaolinitic mud 
accumulation of organic matter, diatoms, and kaolinitic mud 
phytolithic muddy sand 
accumulation of phytoliths and mixing of this fine-grained material with sand either by 
sheet wash or bioturbation along the margins of wetlands 
sedimentary structures such as vesicular structures, 
fenestral structures, breccioid structures, and burrow 
structures, and the mixing of interlayered sediment. This 
is the zone where there is development and accumulation 
of second cycle intrabasinal sediments such as carbonate 
intraclast gravel and sand, peat intraclast gravel and 
sand, and skeletal intraclast gravel and sand, and 
extrabasinal quartz sand aprons and tongues, and 
marked lithological interlayering between extrabasinal 
and intrabasinal sediments. During times of 
exceptionally low water levels, the features of wetland 
sediments that reflect processes of desiccation and 
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