Molecular hydrogen isotopic compositions of petroleum n-alkanes and its geological significance in the Mahu Sag, Junggar Basin, NW China

• Mahu Sag source rocks are classified into P 1 f (saline lacustrine) and P 2 w (freshwater to brackish lacustrine). • δ 13 C and δ 2 H can effectively classify oil type and determine oil sources. • The crude oils are classified into three groups: P 1 f -derived, P 2 w -derived, and mixed oils. • Depositional environment is the primary factor controlling the δ 2 H composition of n -alkanes in oils. • High maturity of the crude oil can affect the hydrogen isotopes of n -alkanes in the oil. The Ma