Distribution, occurrence and identification of dibenzofuran, benzo[b]naphthofurans and their alkyl derivatives in Gippsland Basin source rocks

Abstract

Dibenzofuran, benzo[b]naphthofurans and a series of their alkylated isomers were identified in coal, coaly shale, and shale extracts from the Gippsland Basin (Victoria, Australia). The dibenzofuran series include C₀-C₄ dibenzofurans, and the benzo[b]naphthofuran series are composed of benzo[b]naphthofuran, methylbenzo[b]naphthofurans, and possible dimethylbenzo[b]naphthofurans. Seventeen C₂ dibenzofurans isomers (including six new isomers) were tentatively identified in rock extracts from the Gippsland Basin. The distribution and contents of C₀-C₄ dibenzofurans are different for Eocene and Paleocene rocks, providing a source rock age diagnostic correlation tool. Biological origin is the main factor that controls the abundance and distribution of dibenzofuran, benzo[b]naphthofuran and their alkylated isomers, based on investigation of source-, environment- and maturity-derived parameters. Variations in the C₁ dibenzofurans/dibenzofuran ratio and the benzo[b]naphtho[2,1-d]furan/benzo[b]naphtho[1,2-d]furan ratio may reflect local paleoclimate changes in the Gippsland Basin.