Isotopic compositions and biomarkers in crude oils from the Tarim Basin: Oil maturity and oil mixing

► n-Alkane C, H isotopic compositions of Tarim Basin oils were analyzed. ► Hydrogen and carbon compositions of n-alkanes classify the oils into two groups. ► δ13C values of n-alkanes shows good correlations with the maturity indices. ► δD values of n-alkanes in most oils are also influenced by the oil maturity. ► Isotopic compositions and biomarkers of the oils suggest two oil mixing processes.