## 5 Discussion  
### Source Rock Characteristics  
Two types of source rocks have been identified in the northern Kuqa Foreland Basin, consistent with the previous studies of [PERSON] et al. (2019) [4] and [PERSON] et al. (2021) [5]. One source is Jurassic coaly source rocks, and the second is Triassic lacustrine source rocks. According to the source rocks evaluation in previous studies (Table 6), the Triassic source rocks (T\({}_{3}\)_h_) are predominantly by Type II\({}_{2}\) and III organic matters, and the average TOC value is 1.84 wt%, the average S\({}_{1}\) + S\({}_{2}\) value is 14.07 mgHC/g rock, HI values are in the range of 16 mgHC/gTOC-189 mgHC/g TOC, and T\({}_{\max}\) values are in the range 439-469 \({}^{\circ}\)C. The Jurassic source rocks (J\({}_{2}\)_kz_, J\({}_{1}\)_y_, and T\({}_{3}\)_t_) are predominantly Type III with minor Type II organic matters, and the average TOC is 18.32 wt%, the average S\({}_{1}\) + S\({}_{2}\) value is 27.61 mg HC/g rock, HI values are in the range of 12 mgHC/gTOC-901 mgHC/gTOC, and T\({}_{\max}\) values are in the range of 405-546 \({}^{\circ}\)C. Both types of source rocks display predominantly good to excellent petroleum-generation qualities. The Pr/Ph ratios for the Triassic source rocks are generally less than 1 (Table 2), indicating that nearly all of the source rocks were deposited under anoxic conditions [17; 95; 96]. The Pr/Ph ratios for the Jurassic source rocks are greater than one (Table 2), indicating that the sedimentary environment of the source rocks changed from the reduced deep lacustrine facies to the shallow marsh and near-shore-shallow lacustrine facies [17; 97; 98]. The cross plots of Pr/n-C\({}_{17}\) vs. Ph/n-C\({}_{18}\) and C\({}_{27}\)/C\({}_{29}\) regular steranes vs. Pr/Ph show that the source rocks are mainly generated from freshwater swamp-saline lake environments. The Triassic sources appear to have been influenced more by saline-hypersaline lake compared with the Jurassic source rocks (Figure 7B,C). The relative abundances of C\({}_{27}\)-C\({}_{28}\)-C\({}_{29}\) regular steranes are a common parameter indicative of the input of organic matter [23; 99; 100]. Higher levels of C\({}_{29}\) steranes occur in higher plants, showing an inverted \"L\" shape of C\({}_{27}\)-C\({}_{28}\)-C\({}_{29}\) regular steranes distribution in the Jurassic source rocks (Figure 4A-C). Higher relative levels of C\({}_{27}\) sterane (or C\({}_{28}\) sterane) occur in the aquatic inputs, showing a \"V\" shape of C\({}_{27}\)-C\({}_{28}\)-C\({}_{29}\) regular steranes distribution in the Triassic source rocks (Figure 4D) [99]. Gammacerane is a pentacyclic triterpene that originated from tetrahymanol, and the latter is formed by a protist or other bacterium that replaces lipid compounds [17; 101]. The gammacerane/C\({}_{30}\) hopane ratio is greater than 0.11 in all the source rock extracts (0.12-0.26), indicating the potential water column stratification [102]. The occurrences of gammacerane may also be influenced by hypersaline depositional environments [17; 103]. In summary, the Triassic source rocks are predominately composed of lacustrine source rocks, and the Jurassic source rocks are predominately composed of coaly source rocks.