“…It is known that the ratio composition of C 27 -C 29 regular steranes (named cholestane, ergostane, and stigmastane) in crude oil does not change significantly through the maturation process, and thus, a ternary diagram of these steranes can be used to distinguish oils from different source rocks or different organic facies in the same source rock (Peters et al, 2005;Peters, Snedden, Sulaeman, Sarg, & Enrico, 2000). Some studies have used this diagram to evaluate depositional environments and the sources of organic matter (Huang & Meinschein, 1979;Maravelis, Chamilaki, Pasadakis, Vassiliou, & Zelilidis, 2017;Riboulleau et al, 2007); however, some data show that there are obvious overlaps between crude oils from various settings (Moldowan, Seifert, & Gallegos, 1985). On the other hand, a plot of C 27 /C 29 or C 27 /(C 27 + C 29 ) regular steranes against pristane/phytane can be utilized to investigate input sources and redox conditions during sedimentation (Hossain, Sampei, & Roser, 2009;Peters & Moldowan, 1993;Sawada, 2006).…”