Effects of Maturation on the Indigenous D/H Signatures of Individual Hydrocarbons in Sediments and Crude Oils from the Vulcan-Sub Basin and Perth Basin (Western Australia)

We have measured the stable hydrogen isotopic composition of selected aliphatic hydrocarbons from a series of Late Jurassic sediments from the Vulcan sub-Basin region covering a wide maturity range (% Ro = 0.6 - 1.6). The D/H of n -alkanes, pristane and phytane show similar trends of deuterium (D) enrichment to those seen in a previous study undertaken on sediments from Western Australia (Dawson et al., 2005, Organic Geochemistry, 36, 95-104). Samples of similar thermal histories from the different regions show similar offsets between the average D/H value of n -alkanes and isoprenoids. Furthermore, the D/H of hydrocarbons from a post-mature sediment (% Ro = 1.6) indicate that the enrichment of D in isoprenoids continues at higher maturities. The results indicate these measurements will be useful for evaluating the thermal history of highly-mature sedimentary organic matter.

Personnel

K. Grice, R. Alexander, D. Dawson

Funding

ARC (QEII), APAI