Figure 3

Gas compositions from a marine shale under isothermal anoxic helium flow in sequential heating cycles at 50°C, 250°C, and 350°C. Sample: the Floyd shale in Fig. 1 at 1578 m; TOC = 4.42; S1 = 2.3; S2 = 10.5; S3 = 0.39; Tmax = 450. Yield: 57.4 μg (C₁–C₅)/(g rock) at 50°C; 78.9 μg (C₁–C₅)/(g rock) at 250°C; 12 μg (C₁–C₅)/(g rock) at 350°C. The C₁–C₅ products contained no olefins below 350°C, and 33% vol C₂–C₄ olefins at 350°C. C₅olefins were not isolated in our analytical procedure. Olefins are not included in Yield.