The distributions and geochemical implications of methylated 2-methyl-2-(4,8, 12-trimethyltridecyl)chromans in immature sediments

Methylated 2-methyl-2-(4,8,12-trimethyltridecyl)chromans are salinity-sensitive biomarkers that have been detected in immature – early mature petroleum and sediments. In this study, the occurrence distribution patterns of were investigated a set lacustrine sediments from Nördlinger Ries southern Germany marine South China Sea. Among all 2-methyl-2-(4,8,12-trimethyltridecyl)chroman isomers detected, 8-Me-2-methyl-2-(4,8,12-trimethyltridecyl)chroman presented with high abundance deposited hypersaline environments, while absent samples normal environments. contrast, 5,7,8-triMe-2-methyl-2-(4,8,12-trimethyltridecyl)chroman was more enriched This study also showed ratio 5,7,8-triMe-/5,8-diMe-2-methyl-2-(4,8,12-trimethyltridecyl)chroman can be applied as potential salinity indicator on account positive correlation other indicators. an alternative paleosalinity when is or present quite low abundance. The content may affected by freshwater supply lithology. Molecular simulations 5,8-diMe-2-methyl-2-(4,8,12-trimethyltridecyl)chroman has higher thermal dynamic stability than 7,8-diMe-2-methyl-2-(4,8,12-trimethyltridecyl)chroman. Thus, 5,8-diMe-2-methyl-2-(4,8,12-trimethyltridecyl)chroman/7,8-diMe-2-methyl-2-(4,8,12-trimethyltridecyl)chroman maturity parameter for at stage.