| Abstract: | A series of recent peat samples from tropical, sub-tropical and temperate locations were investigated using coal petrographical and organic geochemical techniques. Maceral and biomarker compositions were examined to see if they correlated or diverged from the known environment of deposition of the peats.The proportion of humotelinite was related to the water depth and the frequency of dry periods. The pH and trophic level have a modifying influence on the preservation of tissues. Furthermore, the proportions of sclerotinite in the peats seem to reflected the oxygen status in the mire, which was also mirrored in the abundance of humic and fulvic acids.A facies diagram was calculated for the peat samples to see how maceral indices would fare in interpreting their known environments of deposition. The results proved to be generally unsuccessful as the herbaceous and woody peats did not always give the predicted high humodetrinite and humotelinite compositions, respectively.The aliphatic hydrocarbon fraction from the extracts of the peat samples show that mainly odd-numbered n-alkanes are present. Diterpenoids, triterpenoids and hopanoids were found in most samples and were mainly unsaturated in nature. The relative proportion of hopanoids in pears appears to be related to bacterial activity in acidic environments. De-A-triterpenoids were also detected in the peat stage of diagenesis.In an angiosperm dominated peat type (Mariscus), polycyclic aromatic triterpenoids were present in the aromatic fraction of the extract. Their occurrence and proportion appears to be related to the degree of humification. In a Taxodium peat, mono-, di-and triaromatic diterpenoids were detected. The presence of these aromatic biomarkers indicate the rapid formation of these compounds in the peat stage, mainly mediated by microbial activity. |
