Maceral percentages and bitumen, oil, and oil-drop abundances were determined by visual estimate during linear traverses. This method is more reliable than the point-count technique where the abundance of these components is less than ~10%. The maceral classification used is given in Table T1. Other descriptions of maceral classifications can be found in Standards Association of Australia (SAA) (1981), International Committee for Coal Petrology (ICCP) (1971, 1994, 1997), and in Taylor et al., (1998). Of these, only the SAA system and that used here combine the vitrinite and huminite macerals into a single group. However, the classification used here retains those terms within the huminite group that are essentially textural and are related to the extent of gelification. Gelification is due either to processes associated with peat formation or subsequent compaction following burial. Table T2 summarizes the cutoff values used to describe maceral abundance for dispersed organic matter (DOM) and coal as well as for the abundance of rock types and minerals, such as pyrite and glauconite.
Observations were also made on mineral matter fluorescence. Apart from a small number of minerals, such as dolomite and zircon, that fluoresce due to the presence of trace elements, most fluorescence from minerals is due to the presence of small amounts of dispersed and adsorbed bitumens. At low levels of maturation, mineral fluorescence is generally weak and becomes stronger within the oil window. For marine rocks, fluorescence intensity tends to decrease markedly close to the oil thermal limit but persists into the wet gas window in source rocks of terrestrial origin. A patchy distribution of mineral fluorescence is also characteristic of the more mature source rocks that contain organic matter that is terrestrial in origin. Weak to absent mineral fluorescence is generally an indication that a sediment unit is supermature (Ro >3.0%) but is also characteristic of red-bed units where iron oxides cause quenching of the fluorescence emitted. Observations of the alteration of mineral fluorescence with time of irradiation are also made. Data on alteration are reported only where unusual features are noted.