It should be noted that hand picking of the samples means that these data overstate the amount of organic matter in the whole cores. Even where hand picking of samples was not undertaken, the most organic-rich layers were selected. A summary of the type of organic matter present is given in the comments column of Table T3.
Photomicrographs of the organic matter are shown in Plates P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, and P14. A high proportion of these plates illustrate the woody tissues that form the most abundant type of organic matter. The plates also illustrate the coals found, DOM, and rare oil drops.
The photomicrographs of the samples (all plates) were taken either using white light with the polar removed from the light train or in fluorescence mode using a BG3 excitation filter and the plane slip illuminator. Photographs were taken using lenses with nominal magnifications of 10x, 20x, and 50x. The 10x objective lens is an "air" immersion lens, and the 20x and 50x lenses use oil immersion, but all those used were taken with the 50x lens. Where matching pairs of reflected white light and reflected fluorescence mode are used, the pairs are in registration or are close to being in registration.
Using microscope techniques, crushed fragments of large pieces of wood tend to report as coal. The distinction between some DOM and coal must also include information relating to the preparation of the samples. However, with the present set of samples where true coals are present, these are finely bedded (in samples from Hole 1109D below 650 mbsf) and are easily distinguished from fragments of drifted logs. Thus, Plates P9 and P10 illustrate samples of coal, whereas Plates P1, P2, P3, P4, P5, and P6 illustrate fragments of drifted logs. Plate P11, figure 3 and figure 4, illustrate a peat intraclast, and even within a core sample, it is difficult to be certain that larger occurrences of coal do not represent intraclasts. However, it is normally the case that intraclasts show some degree of deformation. Hence, the coals illustrated in Plates P9 and P10 are considered autochthonous.
Most DOM occurs as small particles as in Plate P12. Most of the small particles of organic matter can be assumed to be allochthonous. However, many of the structures found where DOM is more abundant (as in Plate P12) are suggestive of an in situ origin. The telovitrinite in Plate P13, figure 3 and figure 4, are similar to root structures.
Although most samples were deposited in marine conditions, most of the organic matter is terrigenous in origin. The drifted logs could be relatively rare events, and so those samples containing them may not be representative. However, the lithologies that contain larger numbers of particles of DOM are also dominated by higher plant-derived phytoclasts. Phytoplankton are present in some samples but are typically a minor part of the organic matter population.
Overall, the organic matter assemblage is dominated by vitrinite (see plates). Liptinite is the second most abundant maceral group. The most common form of liptinite is suberinite, and most of this is associated with the large wood fragments that are dominant in the majority of samples. The coal and shaly coal samples contain a diverse range of liptinite and represent the highest liptinite content other than suberinite. Small amounts of cutinite are present mostly as DOM. Plate P13, figure 1 and figure 2, show well-preserved leaf cuticle, but such good preservation is unusual. Although most of the samples were undoubtedly deposited under marine conditions, liptinite derived from phytoplankton is relatively rare and has been reported as lamalginite. Most of the lamalginite occurs as thin-walled tests.
Inertinite is widely distributed, but most represents fungal tissues preserved as funginite (Plate P14, figure 3 and figure 4). This maceral was previously referred to as sclerotinite, but the members of ICCP, meeting at Wellington in 1987, agreed to the change in terminology. The presence of funginite indicates some decay of the tissues under aerobic conditions. Funginite comes from Basidiomycete and Ascomycete fungi, and these do not survive immersion in water, especially saline water. In two samples, the organic matter consists almost entirely of fusinite and semifusinite. This represents the residues from forest fires. Both of these samples are overlain and underlain by samples that lack fusinite and semifusinite. They appear to represent relatively rare forest fire events. The fusinite and semifusinite in the sample from Hole 1115A shows a high mean reflectance of 3.44%, with a range from 1.38% to 5.24%.