During the Early-Middle Ordovician, the Upper Yangtze Platform experienced extensive development of a distinctive set of mixed siliciclastic-carbonate deposits known as the Meitan Formation. To conduct a comprehensive study of the relationship between mixed sedimentation and sea-level changes, the Hailong section, situated at the southwest margin of the Upper Yangtze Platform in SW China, was selected as the study area due to its typical mixed sedimentary sequence. This section was effectively compared with sections in other regions. Clustering analysis of the point-count groups from the Honghuayuan and Meitan Formations revealed nine microfacies that developed during this period. Such a diverse range of microfacies provides the evidence of frequent sea-level changes in the Yangtze Platform throughout this period. Specifically, two sea-level rises were identified during the early TS.2b and early TS.3b, with the early TS.2b event occurring globally. Furthermore, four sea-level falls were observed in the late TS.2b, TS.2c, TS.3a, and late TS.3b periods. The late TS.2b sea-level fall was globally significant. From TS.2c onwards, distinct variations in sea-level changes among the Yangtze Platform, North China, Baltoscandia, Australia, and North America emerged due to alterations in the paleogeographic pattern. By comparing the sea-level curves in the Upper Yangtze Platform with the diversity curves of chitinozoans, acritarchs, and brachiopods, it became evident that environmental changes played a crucial role in the Great Ordovician Biodiversification Event (GOBE), especially during the Floian. The rising sea level and increased detrital materials fostered the development of diverse habitats, prompting organisms to adapt to varying environments. In general, rising sea levels favored increased brachiopod diversity, while falling sea levels favored enhanced planktonic diversity among chitinous and acritarch species. By shedding new light on the relationship between Ordovician sea-level changes and biodiversification in the Yangtze region, this study offers a fresh perspective on the subject from the microfacies analysis.

Energy resources exploration has been taking place in the Southern North China Basin (SNCB) for decades, but no big breakthroughs have been made. A case study focusing on the Lower Permian Shanxi Formation in the Taikang Uplift of the SNCB is presented in this paper; based on the practice of shale gas exploration, we summarize the geological characteristics, geochemical characteristics, mineral characteristics, and pore type and analyze the exploration potential shale gas. The type of organic matter in the studied strata is mainly type III, the vitrinite reflectance (Ro) is between 2.1% and 3.4%, the average total organic carbon content is 1.66%, the mineral of shale is mainly composed of quartz and clay, and the main reservoir space types are mineral pores and microfractures. Through comprehensive evaluation, the sedimentary environment, organic matter abundance, physical properties, and mineral composition control the shale gas accumulation in the studied area.

To advance the understanding of Mesoproterozoic sedimentary facies and delineate their distribution patterns in the Ordos Basin, this study systematically analyzes the sedimentary characteristics and stratigraphic architecture of the Mesoproterozoic sequences using integrated datasets, including core samples, well logs, seismic profiles, and field outcrops. The results indicate that the Mesoproterozoic Changcheng System, shaped by rift-related processes, displays a southwest-to-northeast thinning trend, culminating in stratigraphic pinch-out. Three Facies associations are identified: rift-related sandstone-shale and volcanic eruption facies (dominated by sandstones with abundant basaltic eruptives in the Changcheng rift trough), shoreface sandstone facies (primarily lower shoreface subfacies with quartz sandstones and mudstones), and fluvial facies (sandstone-siltstone sequences). During the Jixian System, post-Changcheng “compensatory sedimentation” led to a significantly reduced depositional area dominated by tidal flat environments. A southwest-to-northeast facies transition progresses from shelf facies (siltstones interbedded with shales and bioclastic limestones) through mid-ramp facies to tidal flat and mixed tidal flat facies, collectively forming a carbonate tidal flat system dominated by siliceous-banded dolomites. The Mesoproterozoic succession in the Ordos Basin thus records an evolutionary trajectory from rift basin infilling (“leveling”) to the development of a shallow marine clastic-carbonate platform during the Jixian System, reflecting progressive tectonic stabilization and paleoenvironmental transitions.