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The exploration of high production, natural gas wells (>106 m3/d) has been extremely successful in the Gaoshiti and Moxi areas of the Leshan–Longnvsi paleo‐uplift, in the west‐central Sichuan Basin. This paper focuses on the Sinian and Cambrian reservoirs from the Gaoshiti and Moxi areas, where a dataset of new trace elements in bitumen and potential source rock is reported and where hydrocarbon‐source correlation is attempted based on trace elements characteristics of the 12 potential source rocks and 22 bitumen samples. Results show that the bitumen from the three reservoirs can be distinguished from each other using trace element distribution patterns and redox‐ and provenance‐sensitive elemental ratios. Bitumen in the second and fourth members of the Sinian Dengying Formation were derived primarily from the third member of the source rocks of the Dengying Formation, which represents a self‐sourced paleo‐petroleum system. In contrast, bitumen in the reservoirs of the Cambrian Longwangmiao Formation is derived from the Cambrian Qiongzhusi Formation and third member of Dengying Formation. The trace element method used in this study improves our understanding of the complex hydrocarbon–source relation and confirm the potential target for petroleum exploration in the study area. [ABSTRACT FROM AUTHOR]

• Major elements trace hydrocarbon sources in over-mature petroleum systems. • The Sinian Dengying Formation gas systems in the Sichuan Basin were investigated. • Ti, Al, Fe, Mn, Mg, Ca, Na, K, and P have variable occurrence states. • Mn/Fe ratio and ternary 10Mn–Fe–P diagram are used to trace hydrocarbon sources. • Lower Cambrian shales are the main sources for natural gases. Identifying hydrocarbon sources in over-mature petroleum systems is important and challenging. Here we present a pilot study using inorganic geochemistry to trace hydrocarbon sources in the giant natural gas accumulations within the Sinian (Neoproterozoic) Dengying Formation in the Sichuan Basin, SW China. We investigated the major elements (Ti, Al, Fe, Mn, Mg, Ca, Na, K, and P) as tracers of hydrocarbon sources for the first time. Our results show that the over-mature solid bitumen in the reservoirs contains parts per million amounts of major elements in addition to carbon (i.e., organic matter). Na and K in the bitumen occur mainly in the V–Ni porphyrin form. Al, Fe, and Mn are present in the Fe porphyrin form. The behavior of P is relatively complex, and it may reside mainly in a non-porphyrin organic form. The other elements (Ti, Mg, and Ca) may be present as emulsified "invisible" nano-minerals. The Mn/Fe ratio and ternary 10Mn–Fe–P diagram can be used for hydrocarbon–source rock correlations. Based on the proxies, it is suggested that the lower Cambrian Qiongzhusi Formation was the main source of hydrocarbons in the Dengying Formation. Our data suggest that inorganic geochemistry is an effective method for the study of over-mature hydrocarbons and complements traditional organic geochemical approaches. [ABSTRACT FROM AUTHOR]