Organic Geochemical Characteristics, Source-Rock Quality, and Remaining Hydrocarbon Potential of the Lin 1–Lin 2 Members of the Linhe Formation, Xinglong Structural Belt, Hetao Basin

To evaluate the organic geochemical characteristics, source-rock quality, and remaining hydrocarbon potential of the Lin 1–Lin 2 source rocks in the Xinglong structural belt, Hetao Basin, 20 samples from eight wells were analyzed using TOC, rock pyrolysis, chloroform-extractable bitumen “A”, kerogen microscopic components, vitrinite reflectance, GC, and GC–MS. TOC ranges from 0.11 to 3.12 wt.% (mean 1.46 wt.%), and S1 + S2 from 0.21 to 20.92 mg HC/g rock; 55% of samples are fair or better and 45% are good to excellent source rocks. Organic matter is predominantly Type II1–II2. Mean Ro values of 0.99–1.28%, together with Tmax values of 425–454 °C and PI, indicate generally mature source rocks. Maceral, n-alkane, and sterane data indicate mixed aquatic–terrestrial organic matter with a relatively greater aquatic contribution. Pr/Ph values below 1.0 in 19 of 20 samples indicate generally reducing conditions, while the gammacerane/C30 hopane ratio and its positive relationships with the C35 homohopane index and TOC support variable water-column stratification and enhanced preservation. In the regional evaporitic context, these data support episodic evaporative concentration. Overall, the source rocks are predominantly oil-prone, and some mature, organic-rich samples retain appreciable remaining pyrolysable hydrocarbon potential, supporting their significance for deep hydrocarbon exploration.