The humic source gas is heavier than the sapropelic source gas in the carbon isotope. The methane carbon isotope will become heavier if the Carboniferous source gas is mixed. The C 2 /C 3 index in the ...

The maceral composition of coal-rock kerogen is predominantly of humic type, with a small amount of sapropelic type. The carbon isotopes of methane (δ 13 C 1) values range from −37.60 to −16.00‰, with ...