Organic petrology of oil shales

Oil shales are a diverse group of rocks that may become an important source of liquid fuel and chemical feedstocks. The bulk of the organic matter in oil shales is generally exinite derived from a variety of organisms ranging from terrestrial higher plants to freshwater and marine algae. In this study reflected light and fluorescence mode petrography provide data not readily available through chemical, transmitted light and palynological studies. The petrographic studies elucidate the mode of preservation and mineral-maceral relationships usually destroyed during mineralization and pyrolysis. Previous petrographic terminology for algal components is revised and two new terms, lamalginite and telaginite, are defined. Type of exinite is used to classify oil shales into three primary and six secondary groups. Telalginite derived from Reinschia and Pila, both related to the extant green alga Botryococcus braunii, is the major exinite in torbanite which is formed in shallow lakes associated with coal forming swamps. The reflectance of vitrinite in torbanite decreases as the alginite content increases. Lamosites are freshwater, laminated oil shales and are divided into Rundle type and Green River type. Australian Tertiary lamosites belong to the Rundle type and contain discrete lamalginite derived in part from the colonial green alga Pediastrum, the freshwater dinoflagellate Septodinium, and the acritarch Cleistosphaeridium. Botryococcus telalginite and huminite are minor constituents. Green River lamosite contains layered lamalginite with minor bitumen and huminite. Differences between the two forms of lamalginite in the Rundle and Green River type lamosites indicate that the environments of deposition were not the same for both types. Australian Tertiary lamosites were deposited in fresh to brackish water, probably nearshore lakes. Recognition of phytoplanktonic algae, but not benthonic or mat-forming algae, suggests that the bulk of the exinite in these lamosites was d