4.2. Stable carbon isotope composition
The δ13C values of kerogen, expelled oil, bitumen, and gaseous hydrocarbons are listed in Table 1 and Fig. 4.
The δ13C values of kerogen and bitumen in the original sample (Ro = 0.75) were -26‰ and -27.6‰, respectively. With an increase in Ro , the δ13C values of kerogen were -25.5‰, -25.3‰, -25.4‰, -26.1‰, -25.6‰, -25.4‰, and -25.2‰, with a mean of -25.5‰. In general, there was a tendency first to become lighter and then heavier. When Ro = 1.93%, the carbon isotope of kerogen was the lightest, with a value of -26.1‰.
Table 1 The δ13C values of kerogen, expelled oil, bitumen and gaseous hydrocarbons at different simulated temperatures