Distribution of aromatic biomarkers in pyrolysates of coccolithophore

Abstract

Analyses of the original and pyrolytic products of coccolithophore at various temperatures suggest that the contribution of coccolithophore to the formation of large immature oil reservoirs should attract keen interest. Through biochemical processes algae can change inorganic sulphur into organic sulphur, which could be one of the most important precursors of organic sulphur compounds in oil and source rocks. When Methylphenanthrene Index (MPI) and Methylphenanthrene Ratio (MPR) indices were used to evaluate the evolution degree of source rocks and oil maturity, other maturity indices must be used together for correction. In low maturity, the relative abundances of dibenzothiophene (DBT), fluorine (F) and dibenzofuran (DBF) can be used to identify the oxidation-reduction environments.

Stable carbon isotope compositions of isoprenoid chromans in Cenozoic saline lacustrine source rocks from the Western Qaidam Basin, NW China: Source implications

“…There is a large variation in the relative abundances of different groups of aromatic hydrocarbons in the sample profile (Figure 3), and this reflects the dynamics of the depositional environments and biological inputs. For example, the variations in the relative abundances of long-chain alkylbenzenes in the source rocks may indicate changes in the productivity of halophiles [6] and other brackish water plankton [20]. The detection of aryl isoprenoids suggests the presence of photosynthetic sulfur bacteria, and the occurrence of euxinic conditions in the photic zone of water body [21][22][23][24].…”

Evolutive characteristics of aromatics under high pressure and temperature of deep lithosphere

“…All ratios of the methyl-substituted aromatics to their corresponding non-substituted aromatics increase at first and then decrease with the increasing maturation during the evolvement of ingredient [15] . Methylphenathrene index (MPI) ( Table 1) increases with maturation (R o < 1.5%) and follews a decreasing one [16] , which is probably because the demethylation predominates in the high maturation stage and the methylation and rearrangement do in the low thermal maturation stage [17] . However, the MP/P ratios of the experimental products show an increasing trend with temperature and pressure increasing (Table 1), which suggests that increasing pressure significantly retards demethylation of methylphenanthrene, but accelerates the methylation of phenanthrene.…”

“…(iii) Distributions of perylene, benzofluoranthene and benzopyrene. The ratios of both perylene to benzofluoranthene (PER/BFL) and perylene to benzo[e] pyrene (PER/B(e)PY) ( Table 1) are proposed as the very effective indexes of thermal maturity [12,17] . With increasing pressure, temperature from 400 to 500℃, both ratios decrease sharply, and then vary to a small extent until 700℃.…”

The Characteristics of Organic Matter from the Triassic Clays of nw Margin of the Holy Cross Mts (Poland) — Preliminary Report

“…Other groups of organic compounds present in the clays include long-side chain alkylbenzenes, alkyltoluenes and branched long-side chain alkylbenzenes. Organic compounds of this type have been previously described in sedimentary organic matter (Fan et al 1991;Ellis et al 1996;Zhou et al 2001). Their genesis, however, remains unclear (Sinninghe Damsté et al 1988;Zhou et al 2001).…”