Publication Name: Eastern Australian Basins Symposium III (EABS 2008)
Authors: H. Volk, S.C. George and R. Sykes
Date Published: September 2008
Number of Pages: 4
Abstract:
Source rock maturity parameters such as vitrinite reflectance and parameters based on the molecular distribution of aromatic hydrocarbons and aliphatic biomarkers are influenced by factors such as geothermal history, depositional facies and diagenetic evolution. Nonetheless the thermal maturity of oils is routinely assessed using molecular maturity parameters to estimate the maturity of their source rocks at the time of expulsion. It is therefore important to understand the non-maturity controls on these parameters. One solution is to examine isorank sediments that have experienced variable depositional and early diagenetic histories. We have undertaken geochemical analysis of a set of quasi-isorank coal extracts from the Eocene Mangahewa Formation, the principal source rock unit of the onshore Taranaki Basin, in order to assess the effects of variable marine influence within the depositional environment on a range of aromatic and aliphatic molecular maturity parameters. Understanding the depositional and early diagenetic influences on the molecular maturity parameters applied to Mangahewa-sourced oils will help lead to more reliable assessment of their thermal maturity levels for basin modelling purposes.