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Objective The Lower Cambrian organic-rich shale is an important marine shale exploration target in western Hubei and southern Guizhou. Understanding the chronostratigraphic relationships and their underlying causes of organic-rich shale intervals in different areas is crucial for shale gas exploration. Methods In this study, we conducted cyclostratigraphic analyses using natural gamma-ray logging data from the Lower Cambrian well ND1 in western Hubei and the well HY1 in southern Guizhou and determined the primary astronomical periods. Using previously reported zircon ages as anchoring points, we constructed an astronomical time scale for the Lower Cambrian. Using a sedimentary noise model, relative sea-level changes in the Lower Cambrian were reconstructed. Results Our results reveal that wavelengths of 36 m and 9 m in well ND1 and 16.6 m and 4 m in well HY1 correspond to orbital 405 kyr and 100 kyr cycles, respectively. Furthermore, we calculated the durations of the Niutitang Formaion in well Niedi-1 and the Jiumengchong Formation in well HY1 to be 3.30 and 2.64 Myr, respectively, The astronomical age scales of two options are presented. In Option 1, the top of the Niutitang Formation in well ND1 serves as the starting point for the anchor point, with an age interval of 535.20±1.70 Ma to 538.50±1.70 Ma. Option 2 employs the top of the Jiumengchong Formation in well HY1 as the starting point of the anchor point, with the corresponding age interval spanning from 535.20±1.70 Ma to 537.84±1.70 Ma. Through correlation sea-level change curves (DYNOT and ρ1) with eccentricity cycles and sedimentary cycles, our results indicate that sea-level changes correspond to 1.2 Myr obliquity modulation cycles and two sedimentary sequences (SQ1 and SQ2). Comparing the total organic carbon (TOC) content of the Lower Cambrian organic-rich shale with orbital eccentricity, sedimentation rates, and sea-level changes, our findings reveal that the intervals with high TOC value correlate with the maximum eccentricity of 405 kyr, whereas those with low TOC value correspond to the minimum value in well ND1. In addition, the high TOC value corresponds to both the high sea level period and the low sea level period. Conclusions Because of the chaotic behavior of the solar system, accurately predicting the mechanism that drives organic-rich shale during the Early Cambrian is impossible. Assuming that the maximum eccentricity corresponds to the maximum organic carbon content at that time, strong seasonal variations have triggered the enrichment of black shale over a more extended period. Furthermore, the comparison between relative sea-level changes and organic carbon content reveals no causal relationship between sea-level fluctuations and the enrichment of organic matter. [ABSTRACT FROM AUTHOR]

The breakthrough of bauxite natural gas in the Taiyuan Formation in the Longdong area of the Ordos Basin makes bauxite natural gas gradually become a new exploration direction. However, the complex sedimentary conditions and diverse developmental strata of the Linxing region present difficulties for the exploration of bauxite gas. In this research, samples of bauxite cores from significant drilling sections in the Linxing area were obtained for comprehensive geochemical, mineralogical, and pore structure analysis. This study investigates the impact of sedimentary environments on the physical properties of bauxite reservoirs within the Benxi Formation, focusing on lithofacies categorization, mineral composition, and pore structure. This study established a lithofacies categorization system that iron minerals, aluminum minerals + titanium minerals, clay minerals as three end‐member components. The study identified four lithofacies types: pure bauxite, clayey bauxite, mixed bauxite, and bauxite mudstone. According to geochemical analysis, the bauxite rock in the study area is deposited in a semi‐enclosed bay with terrestrial freshwater input. The physical properties of bauxite reservoir in the study area are relatively poor, among which the physical properties of bauxite reservoir are the best. Authigenic minerals like pyrite are often filled in dissolution pores. The constraint of sedimentary environment on bauxite reservoir is mainly manifested as the influence on the formation of diaspore mineral framework, and its acidity and alkalinity are very important for the formation of diaspore. Hence, diaspore commonly forms in the shallow lake environments characterized by pure bauxite rock, exhibiting favorable reservoir conditions. This research examines the impact of mineral composition on bauxite reservoirs through the lens of lithofacies and sedimentary environments. The variations in bauxite rock reservoirs across distinct sedimentary environments have been elucidated. It provides a new guidance for the exploration of natural gas in Benxi Formation bauxite in Ordos Basin. [ABSTRACT FROM AUTHOR]