Influence of organic-matter occurrence on hydrocarbon-generation timing in source rocks: Evidence from the Shahejie Formation, Dongying Sag, China - Peng-Yan Du; Jin-Gong Cai; Hui-Min Liu; Qian Chao; Zheng Li; Xu Li; Xue-Jun Wang; Jia-Zong Du; Xiang Zeng (Journal of Asian Earth Sciences, 2026)