The investigation of characteristics of biomarker assemblages and their precursors in Damintun ultra-high wax oils and related source rocks

Abstract

This paper discusses the characteristics of biomarkers in Damintun ultra-high wax oils and related Paleogene source rocks as well as the type of organic matter and the maceral composition in the source rocks. An overall comparison between Damintun ultra-high wax oils and the well-known Gippsland/Taranaki high-wax oils is made in order to discuss the generation of these oils. Damintun high-wax oils contain high concentrations of sesquiterpenoids but relatively low concentrations of diterpenoids. This is in contrast to the high concentration of diterpenoids derived from resins of southern hemisphere conifers in the Gippsland/Taranaki high-wax oils (Noble et al., 1986; Weston et al., 1989). α-Cedrene, cuparene and cedrol were identified in Damintun high-wax oils, source rock extracts and pyrolysates and in saponification products of the asphaltenes and kerogens. This suggests a contribution of Cupressaceae and Taxodiaceae conifers to the Damintun source rock formations. The organic matter of the Damintun S 4 source rock (the principal source rock for ultra-high wax oil) is mainly of type III, with the organic carbon content ranging from 0.96 to 10.49% and the extractable organic matter varying from 100 to 1660 ppm. As supported also by maceral composition in the source rocks, Damintun ultra-high wax oils were mainly generated from particular types (i.e. Gymnospermae and Angiospermae) of terrestrial higher plant remains incorporated into the source formations.