Molecular parameters of maturation in the Toarcian shales, Paris Basin, France—III. Changes in aromatic steroid hydrocarbons

Pyrolysis-GC/MS analysis of biomass and the bio-oils produced from CO/H 2 O reactions

“…Two dominant steranes, coprostane and cholestane, were produced from sterenes (sterol degradation products) [43] that may be produced during CO/H2O reactions. These two isomers are also known to form via diagenesis or catagenesis of cholesterol; catagenesis formed unstable intermediates and led to formation of isomers [42,44]. As for pyrolysis of the algal feedstock, hydrocarbons (alkanes and alkenes) were produced from pyrolysis or decarboxylation of free fatty acids or algaenans [33].…”

Organic geochemistry of impactites from the Haughton impact structure, Devon Island, Nunavut, Canada

“…Where MPI values were subsequently converted to calculated vitrinite reflectance values, a response factor of 0.65 was adopted to account for the fact that P is from m/z 178 and MPs are from m/z 192, which have different responses for these compounds. Short/long-chain triaromatic steroid ratios (C 21 TA) were calculated as 21T/ (21T + 28TR), where T and TR represent triaromatic steroid peaks (Mackenzie et al, 1981). The polar fraction of the gneiss clast was heated in the presence of the derivatizing agent N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) to convert acids and alcohols to their silyesters and silyethers.…”

Mineral composition and organic geochemistry of the Lower Cretaceous Xiagou Formation source rock from the Qingxi Sag, Jiuquan Basin, Northwest China

“…This indicates that the OM of the Xiagou Formation source rocks came chiefly from planktonic and land plant organisms, with the OM of part of the source rocks from plankton, and algal and bacterial organisms (Adegoke et al 2014). Diagrams of Pr/Ph ratio versus ααα-20R-C 29 /C 27 ratio are applied to analyze OM source and redox condition (Mei and Liu 1980;McKenzie et al 1981). …”