Abstract: A suite of dolomite-dominated carbonate reservoirs is developed in the Sinian Dengying Formation in the Huangling anticline in the eastern part of the intracratonic rift, western Hubei Province. Investigating the formation environment and genetic mechanism of dolomites is crucial for determining the developmental mechanism of carbonate reservoirs and facilitating conventional oil and gas exploration in the study area. This study employed various analytical techniques, including cast thin sections, cathodoluminescence thin sections, field emission scanning electron microscopy, carbon and oxygen isotope analyses of carbonate rocks, major and trace element analyses, whole-rock mineral analyses, and determination of the degree of order of dolomite. Using these techniques, this study analyzed the chemical composition and mineralogical characteristics of dolomites from the Dengying Formation on the periphery of the Huangling anticline. Furthermore, this study explored the formation environment, developmental mechanism, and modification process of dolomites. The results indicate that the dolomites from the Dengying Formation contained the same proportions of CaO and MgO molecules and low Sr content, aligning with the characteristics of penecontemporaneous dolomites. The analytical results of trace elements and carbon and oxygen isotopes confirm that the dolomites formed in a marine environment with low Fe and Mn contents. The average paleoseawater salinity (Z) of 128.41, average temperature of 21.32 ℃, and average diagenetic temperature of 49.36 ℃ created the favorable environmental conditions for forming penecontemporaneous dolomites. Additionally, the dolomite from the Dengying Formation exhibited significantly lower δ¹⁸O compared to the Dengyingian seawater, degrees of order ranging from 0.61 to 0.99, and a peak frequency distribution between 0.8 and 0.9, indicating that the dolomite experienced a progressively deepening burial modification process. The whole-rock mineral analyses reveal that the content of dolomite was positively correlated with its degree of order, suggesting that a high degree of dolomitization corresponded to a higher degree of order during burial modification. Therefore, this study holds that dolomites in the Dengying Formation were originally formed by penecontemporaneous dolomite. Through prolonged burial modification, micritic dolomite with a low degree of order experienced recrystallization, gradually transitioning into very finely crystalline/finely crystalline dolomite, accompanied by an elevated degree of order. Ultimately, dolomites of a penecontemporaneous-burial modification origin formed in the study area.