Introduction

The study of disseminated organic matter in sediments to determine characteristics of the depositional environment dates back to the early work in palynology. The basic reasoning is that the organic material contained in sediments derives from living organisms, and much of that material is autochthonous. Preservation of organic matter in sediments is primarily a function of the effects of the surface, depositional, and diagenetic environments upon the dead organism or parts thereof. The types of organisms and the chemical and biological alterations following death determine the types of particulate organic matter (macerals) found in the sediments. As a consequence, the maceral spectra derived from a sedimentary rock may have a strong autochthonous component which often can be used to extract information about the environment of deposition (Darrell & Hart, 1970; Hart, 1971, 1975, 1976, 1979a,b, 1986; Hart et al., 1989; LeNoir & Hart, 1986, 1988; Wrenn & Beckman, 1981, 1982). It should also be stressed that land-derived palynomorphs and other organic particles can indicate sedimentary environments due to sorting in the marine realm (Traverse & Ginsburg, 1966).

The descriptive classification system used to identify the macerals (Hart, 1979, 1986; see also Hart and Hart et al., Chaps. 9 & 17 this volume) divides them into phytoclasts (plant-derived), zooclasts (animal-derived), protistoclasts (protistan-derived) and scleratoclasts (fungalderived), using the five-kingdom system of classification of organisms of Whittaker (1969). Based on the preservational state of cell walls, each of these biological categories consists of well-preserved (little evidence of biodegradation); poorly preserved (minor biodegradation); infested (cell walls highly disrupted by organic attack); amorphous structured (remnant cell structure only); amorphous non-structured (blocky phytoclast mass or fluffy protistoclast mass).