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Parabadiella is considered the earliest trilobite representative in South China and was originally recovered from the mid-upper part of the Guojiaba Formation, in Liangshan section. Previous studies suggested that the earliest brachiopod co-occurred with the oldest trilobite, and the Parabadiella–Eoobolus association from the Xihaoping Member (Cambrian Series 2, Stage 3), in southern Shaanxi was considered the first trilobite–brachiopod assemblage zone in South China. Therein, brachiopods occur together with trilobites recovered in Well JS103 seemingly extending the First Appearance Datum deeply in the lower Cambrian at the central Yangtze Platform. Well JS103 is a shale gas exploration well that targets the lower Cambrian Jiulaodong Formation in southern Sichuan Basin. The uppermost fossiliferous layers are siliciclastic rocks nearly 10 metres thick. Here, two distinct trilobite zones are found, including the lower Parabadiella Zone and the upper Wutingaspis–Eoredlichia Zone. Additionally, the lowermost part of the Guojiaba Formation is poorly fossiliferous, and ranges from 200 to 250 metres in thickness. Thus, the discovery of the brachiopod–trilobite assemblage provides new insights into the biostratigraphy in Sichuan and is of great potentials for biostratigraphic correlation of the siliciclastic rocks in the western margin of the Yangtze Platform. [ABSTRACT FROM AUTHOR]

Lacustrine shale has garnered significant attention due to its significant resource potential. The Jurassic shale in the Sichuan Basin is an important target for lacustrine shale exploration in China. However, previous studies have predominantly focused on the Da'anzhai member of the Ziliujing Formation, and little attention has been paid to the shale of other strata. This paper aims to address this gap by investigating the Jurassic Dongyuemiao member in the Sichuan Basin. The study systematically characterizes the geological properties of the Dongyuemiao shale system, reconstructs the paleosedimentary environment, identifies the key factors influencing organic matter (OM) enrichment and physical properties, and assesses its resource potential through comparative analysis. Our results show that the Dongyuemiao shale was deposited in an oxic and semi-humid sedimentary environment characterized by intense weathering conditions. The enrichment of OM in the shale is primarily controlled by redox conditions and salinity, with redox conditions playing the most crucial role in OM accumulation. In terms of pore system characterization, clay mineral-associated pores dominate the pore types in the Dongyuemiao shale, while two types of organic matter-associated pores are also widely observed. The development of framework grain-associated pores is limited and only present in certain siliceous and carbonate minerals. The shales of the Dongyuemiao member and the Da'anzhai member exhibit slight differences in TOC content. However, the kerogen in the Dongyuemiao member displays higher hydrocarbon generation potential, and the Dongyuemiao shale exhibits more favorable pore structure parameters. Overall, the Dongyuemiao shale does not exhibit any significant disadvantages compared to the Da'anzhai shale. Therefore, it deserves greater attention in future exploration endeavors. The research findings presented in this paper provide a solid theoretical foundation for expanding the exploration scope of lacustrine shale in the Sichuan Basin. [ABSTRACT FROM AUTHOR]

China's helium resource is highly dependent on overseas imports. Organic-rich and U/Th-rich shale reservoirs generally contain helium, and although the helium content is low, the total reserve is large. Therefore, the effective development and utilisation of shale-type helium resources is a realistic way to improve the security of helium resources in China. In this study, the generation mechanism, helium source and content, migration modes and pathways, controlling factors of enrichment, distribution pattern, and resource potential of the helium were analysed, using the Wufeng-Longmaxi shale in the Sichuan Basin and its periphery. Furthermore, countermeasures were proposed for shale-type helium exploration and development. The results show that the Wufeng-Longmaxi shale has a high content of U and Th and a good ability to generate helium. The helium is generated by a typical crustal source of helium and is characterised by self-generation, self-storage, and wide distribution. The helium resource potential is a product of its content and the resources of the associated natural gas. The continuous supply of helium and effective preservation are the main geological factors that control the enrichment of shale-type helium. The preliminary evaluation results show that the reserves of helium in proven shale gas reserves are 10.8×108 m3 in the Sichuan Basin and its periphery, where the extra-large helium fields are likely to be discovered. Additionally, 0.0912×108 m3 of helium was produced, along with the annual production of shale gas. To avoid the waste of helium and to improve the self-supply ability, it is suggested that research on the resource potential, enrichment mechanism, and distribution pattern of shale-type helium should be carried out as soon as possible, and helium extraction techniques for helium-bearing natural gas should be studied. [ABSTRACT FROM AUTHOR]

Rhizome Chuanxiong (RCX), the dried rhizomes of Ligusticum striatum DC., is a geoauthentic TCM herb distributed in Sichuan province of China that possesses efficacy in promoting blood circulation, removing blood stasis and alleviating pain. Rhizome Chuanxiong total alkaloids (RCXTAs) are one of the major characteristic constituents of RCX with the effects of antimigraine, neuroprotective, cardioprotective and other cardiovascular and cerebrovascular diseases. Over the past years, rapid development of technology has advanced some aspects of RCXTAs. The aim of this review is to illustrate the recent advances in the chemical analysis and biological activities of RCXTAs, and to highlight new challenges. [ABSTRACT FROM AUTHOR]

Gas-bearing property evaluation and main controlling factor analysis have remained a concern in shale gas research. The application of principal component analysis, an important mathematical statistical method, in gas-bearing property evaluation and main controlling factor analysis of the Longmaxi shale in the Weirong area, Sichuan Basin, was examined. The Longmaxi shale exhibits high heterogeneity, manifested in the organic matter abundance, mineral composition, and pore structure. Seven geological factors, including the temperature, pressure, TOC content, clay content, brittle mineral content, pore volume, and specific surface area (SSA), were selected in principal component analysis. Four principal components with geological significance, such as mineral composition, formation condition, pore structure, and organic matter abundance, were extracted through principal component analysis, and further constituted a comprehensive factor. Shale gas-bearing properties were evaluated according to the score of the comprehensive factor. The Longmaxi shale could be identified as exhibiting good, medium, and poor gas-bearing properties based on the comprehensive factor scores of these samples. According to each geological factor's contribution to the comprehensive factor, combined with geological analysis, it could be considered that gas-bearing properties are primarily controlled by pore volume, SSA, and clay content, followed by TOC content, brittle mineral content, temperature and pressure. [ABSTRACT FROM AUTHOR]

• Long-ranging hypobradytelic cyanobacteria dominate the Maidiping microbial assemblage. • Obruchevella with distinct cross-partitioning is preserved with exceptional fidelity. • We propose two possible explanations for the morphological variation of Obruchevella. • Filament diameter is the key character in the taxonomy of Obruchevella. Phosphatization is known for its remarkably detailed preservation of cellular and subcellular microfossils through diagenetic phosphate replacement of the original organic materials. Thin-sections of the Ediacaran-Cambrian transition Maidiping Formation from borehole core Jinshi 103 from southern Sichuan Province, China, exhibit a newly discovered, diverse assemblage of helically coiled microfossils. The four genera recovered include three-dimensional preserved Obruchevella and fragments of cyanobacteria Siphonophycus and Oscillatoriopsis and coccoidal fossils Archaeophycus. The fossil assemblage was dominated by long-ranging hypobradytelic (exceptionally slow evolutionary rate) cyanobacteria. A large number of exquisitely preserved Obruchevella can be identified, including O. minor , O. parva , O. delicata , O. meishucunensis , and O. magna , which exhibit a variety of morphologies, ranging from tangled masses to well-developed helixes, from cocoons with thick mucilaginous sheaths to elongated spring-like forms. Preserved with exceptional fidelity, these Obruchevella species display distinct cross-partitioning and support affinities with modern helical cyanobacteria, such as Arthrospira or Spirulina. Based on traditional taxonomic parameters, such as filament diameter, helix diameter, and winding pattern, two possibilities for the morphological variety of the spiral rings of Obruchevella are proposed. Overall, the Maidiping fossil assemblage provides new paleontological data on the Ediacaran-Cambrian transition and opens an important window into the evolution of early ecosystems at the time of metazoan radiation. [ABSTRACT FROM AUTHOR]

Fuzi is a well-known traditional Chinese medicine developed from the lateral roots of Aconitum carmichaelii Debx. It is rich in alkaloids that display a wide variety of bioactivities, and it has a strong cardiotoxicity and neurotoxicity. In order to discriminate the geographical origin and evaluate the quality of this medicine, a method based on high-performance liquid chromatography (HPLC) was developed for multicomponent quantification and chemical fingerprint analysis. The measured results of 32 batches of Fuzi from three different regions were evaluated by chemometric analysis, including similarity analysis (SA), hierarchical cluster analysis (HCA), principal component analysis (PCA), and linear discriminant analysis (LDA). The content of six representative alkaloids of Fuzi (benzoylmesaconine, benzoylhypaconine, benzoylaconine, mesaconitine, hypaconitine, and aconitine) were varied by geographical origin, and the content ratios of the benzoylmesaconine/mesaconitine and diester-type/monoester-type diterpenoid alkaloids may be potential traits for classifying the geographical origin of the medicine. In the HPLC fingerprint similarity analysis, the Fuzi from Jiangyou, Sichuan, was distinguished from the Fuzi from Butuo, Sichuan, and the Fuzi from Yunnan. Based on the HCA and PCA analyses of the content of the six representative alkaloids, all of the batches were classified into two categories, which were closely related to the plants' geographical origins. The Fuzi samples from Jiangyou were placed into one category, while the Fuzi samples from Butuo and Yunnan were put into another category. The LDA analysis provided an efficient and satisfactory prediction model for differentiating the Fuzi samples from the above-mentioned three geographical origins. Thus, the content of the six representative alkaloids and the fingerprint similarity values were useful markers for differentiating the geographical origin of the Fuzi samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • T-OAE changed the hydrological conditions during the sedimentary process of the Da'anzhai member. • OM accumulation controlled by relatively reducing environment and low salinity conditions. • T-OAE affects organic matter-associated pores development by promoting water column productivity. The Da'anzhai Member of the Lower Jurassic Ziliujing Formation of the Sichuan Basin is one of the most important targets for lacustrine shale oil exploration in China. Organic matter (OM) content is a critical factor when considering the exploration and production potential of lacustrine shale reservoirs. However, the complexity of the lacustrine paleoenvironment necessitates a fuller understanding of OM accumulation mechanisms. The Early Jurassic (∼183 Ma) Toarcian Oceanic Anoxic Event (T-OAE) occurred concurrently with the deposition of the Da'anzhai Member. However, the control of sedimentary differentiation triggered by the T-OAE on the formation of lacustrine shale oil reservoirs remains a matter of debate. In this study, we used total organic carbon (TOC) analysis, X-ray diffraction (XRD), major and trace element analyses, field emission scanning electron microscopy (FE-SEM), mercury intrusion capillary pressure (MIP) measurements, and nitrogen adsorption (NA) analysis to investigate the Da'anzhai Member in the Langzhong region of the Sichuan Basin. Our results demonstrate that the deposits of the Da'anzhai Member accumulated in a warm and humid oxygenated environment under freshwater to brackish salinities. OM accumulation in the Da'anzhai Member was largely controlled by redox and salinity conditions. The pore systems of the analyzed samples of the Da'anzhai Member were diverse but dominated by clay mineral-associated pores. The T-OAE appears to have modified the redox conditions and salinity of the lacustrine environment, in which sediment of the middle part of the Da'anzhai Member accumulated by influencing paleoclimate and hydrological conditions, resulting in the enrichment of OM in contemporaneous sediment. Furthermore, the onset of T-OAE affected the productivity of the water column, inducing changes in the kerogen type that favored the formation of organic pores. In summary, T-OAE influenced the exploration and production quality of lacustrine shale by engendering OM enrichment and organic pore formation. Our study provides new insights into the effects and influence of OAEs on the accumulation in lacustrine shale oil reservoirs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanoscale clay mineral-related pores dominate the pore system of the Da'anzhai shale. • TOC content, kerogen type, clay mineral content, and porosity are key controlling factors for oil content in shales. • Real (S 1-1 /TOC) and maximum ((S 1-1 + S 1-2)/TOC) movable oil index derived from multistep pyrolysis can be used to evaluate oil mobility. • Oil mobility is mainly influenced by the thermal maturity, physical properties, mineral composition, and oil occurrence state. Early Jurassic lacustrine shales in the Sichuan Basin contain significant resources potential and are one of the most important exploration targets in China. However, studies of these shales are limited and controlling factors on oil contents are poorly known despite the importance of such studies in evaluating favorable exploration targets and risks. In addition, effectively evaluating oil mobility is challenging in lacustrine shale exploration. Herein, lacustrine shales of the Lower Jurassic Da'anzhai Member from the Sichuan Basin are investigated through a series of experiments, including thin sections, field emission scanning electron microscopy, total organic carbon (TOC), X-ray diffraction, nitrogen adsorption, mercury intrusion capillary pressure, routine and multistep pyrolysis, and organic petrographic analysis. Our results show that four lithofacies can be identified in the Da'anzhai shale: organic-lean mixed shale with bioclastics (LM), organic-lean argillaceous shale with siliceous mineral concretions (LCM), laminated organic-rich mixed shale with bioclastics (RM), and laminated organic-rich argillaceous shale (RCM). The pore system is dominated by clay mineral-related (CM) pores, with significant contribution from nanopores. The TOC content is the primary factor that influences oil content, with kerogen type, clay mineral content, and porosity also having important effects. The influences of these factors on oil content are mainly controlled by the oil occurrence states and pore structures. The internal and surficial parts of the organic matter and the widely distributed nanoscale CM pores are the main storage spaces for oil. Oil mobility in the four shale lithofacies varies considerably: the oil mobility of the RCM shale is the greatest, and differences in oil mobility are mainly due to thermal maturity, physical properties, mineral composition, and oil occurrence state. Overall, RCM shale is the most favorable lithofacies for exploration in the Da'anzhai shale. The real movable oil index (S 1-1 /TOC×100) and the maximum movable oil index ((S 1-1 + S 1-2)/TOC×100) derived from multistep pyrolysis data can be used to evaluate oil mobility. Our findings may provide new insights into the evaluation of oil resource potential and the exploration of lacustrine shale. [ABSTRACT FROM AUTHOR]