All of the samples contain some organic matter, and for most it was possible to measure at least 25 fields of vitrinite for reflectance. A high proportion of the vitrinite appears to represent drifted logs. Within most of these, tissue preservation is excellent. Variations in vitrinite reflectance relate mainly to tissue type. It is also possible that the species of wood preserved has an influence on the values obtained. To minimize the effects of tissue type, measurements were largely restricted to the cell contents in most cases. Some vitrinite is preserved in a form similar to telocollinite, and this form was also found to show marked reflectance variations that are also presumed to relate to tissue or wood type.
Vitrinite preserved as smaller particles of dispersed organic matter has reflectances generally similar to those obtained on the larger particles. This is presumed to be because the smaller particles selectively represent the cell filling, corpocollinite.
Liptinite is generally a minor component in the organic matter assemblage. Marine phytoplankton preserved as lamalginite represents the most widely distributed form of liptinite, but lamalginite is a minor component. Abundant foraminiferal tests are present in many of the samples, but this abundance of fossil remains is not matched by an abundance of marine-sourced organic matter. Terrestrially sourced liptinite is also present but is most abundant in samples that are either terrestrial in origin or represent intraclasts of terrestrial origin.
Samples of coal and shaly coal are present in the deeper part of the Hole 1109D section. These may represent hypautochthonous peats. Two samples are dominated by fusinite and semifusinite. These may represent forest fire episodes in the source areas for the organic matter. Material interpreted as air-fall tuffs is abundant in a high proportion of the samples, but its presence cannot be correlated with the presence of forest fire charcoal. Variation of vitrinite reflectance is not systematic with either depth or location, and it appears that the formation temperatures of 10°-80°C, and/or the time over which the organic material has been exposed to these temperatures, have not been sufficient to cause an increase in vitrinite reflectance levels. Vitrinite texture is relatively sensitive to the depth of cover, and it is normally possible to detect systematic variation in the ratio of textinite to ulminite in the top 500 to 700 m of the section. This did not prove possible in the present case. It seems unlikely that this is due to cover loss, and it is more probable that it has been caused by selective preservation of the more strongly gelified tissues. Thus, the relative lack of textinite may by due to the depositional setting rather than to the extent of gelification that has occurred either as a process during peat formation or during the early stages of compaction.