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The Sichuan Basin was a part of the Yangtze Carbonate Platform (YCP) during the Cambrian–Ordovician, and marine carbonates were deposited in the basin during this interval. Although previous studies have evaluated the paleogeography, paleoclimate and paleoecology of this basin, they have primarily focused on the paleoecology and biological evolution in the basin; however, analysis of paleogeography and paleoclimate is lacking. This study integrated outcrop sedimentological and magnetic fabric data to document sedimentary differentiation and anisotropy of magnetic susceptibility (AMS) within the YCP. The aims of this study were to infer paleowind directions during each epoch of the Cambrian–Ordovician and to constrain the paleogeographic location of the YCP. The northwestern, central and southeastern sides of the YCP were characterized by high-energy deposition (e.g. sub-angular to rounded intraclasts), medium-energy deposition (e.g. sub-angular to sub-rounded intraclasts) and low-energy deposition (e.g. angular to sub-angular intraclasts), respectively. The centroid D-Kmax values for the Early, Middle and Late Cambrian were 116° ± 52°, 145° ± 57° and 159° ± 62° from the present north, respectively; corresponding values for the Early, Middle and Late Ordovician were 169° ± 70°, 139° ± 73° and 91° ± 68° from the present north, respectively. Sedimentary differentiation and AMS results indicated that the prevailing wind directions during the Early Cambrian, Middle Cambrian, Late Cambrian, Early Ordovician, Middle Ordovician and Late Ordovician were 296° ± 52°, 325° ± 57°, 339° ± 62°, 349° ± 70°, 319° ± 73° and 271° ± 68° from the present north, respectively. The present study provides evidence for the location of the YCP during the Cambrian–Ordovician via the correspondence between the paleowind directions over the YCP and the trade winds in the Northern and Southern hemispheres. The novelty of this study lies in the following aspects: (1) it integrates microfacies and AMS analyses to establish paleowind patterns; (2) it constrains the paleo-hemispheric location of the YCP during the Cambrian–Ordovician; and (3) it provides a reference for further studies of the paleoclimate and paleogeography of the YCP during the Cambrian–Ordovician. [ABSTRACT FROM AUTHOR]

China hosts rich shale gas resources. The Longmaxi Formation (LF) in the Sichuan Basin is one of the important regions for shale gas exploration and extraction. Here, we investigate the pore structure and factors influencing the gas-bearing characteristics of the pores in the shale reservoirs in the LF. We employed scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), gas content testing, gas saturation testing based on nuclear magnetic resonance (NMR), overburden porosity and permeability analysis, distribution of pore size, specific surface area (SSA) analysis, and geochemical analysis. Our results show that the organic matter of the shale in the LF in the study area is highly favorable to shale gas conditions; the brittleness of the regional shale generally increases with an increase in depth. The pores in the LF mainly include organic matter-hosted pores, intergranular pores, intragranular pores, and microfissures, with mesopores dominating. Meanwhile, the gas content also increases with an increase in depth. The pore structure in the study area is affected by organic matter content and mineral components, with the development of organic matter-hosted pores. The porosity and the SSA are positively correlated with the total organic carbon (TOC), whereas clay minerals have an adverse effect on the SSA of pores in the study area. Higher TOC and vitrinite reflectance (Ro) indicate higher gas content. It can be inferred that as the content of brittle minerals increases, particles break to form storage spaces as the depth increases, causing the gas content to increase. Higher SSA and total pore volume indicate higher volume of adsorbed gas. The bound water in rocks tends to reduce the content of desorbed gas. Our results suggest high potential for shale gas extraction in this region. [ABSTRACT FROM AUTHOR]