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The sealing capacities of shale, roof, and floor strata are essential for the preservation of shale gas. Sealing capacity development and its influence on shale gas composition and organic matter pore development are important but have not been addressed by existing studies. In this paper, the Upper Ordovician Wufeng-the first member of the Lower Silurian Longmaxi Fm. in the Yangtze region is selected as the study object. We dissected the J1 well in the Jiaoshiba block inside the Sichuan Basin and the Y6 well in the Youyang block outside the Sichuan Basin to analyze the gas components and carbon isotopes in recovered shale gas. In this study, two microscope techniques (i.e., FIB-SEM and FIB-HIM), porosity measurement, TOC content analysis, permeability tests, isothermal adsorption measurements, are utilized. The analytical results show that both the roof and floor strata have vertical sealing effects on the organic-rich shale due to their different physical properties compared to the shale. The shale overburden pressure increases with burial depth, and the adsorbed gas increases with increasing TOC content and thickness: all of these can lead to a decrease in permeability and an increase in self-sealing capacity. This paper determined the formation mechanism of the sealing capacity for shale, roof and floor strata. Furthermore, the control patterns of "sealing capacity strength" on the shale gas source and organic matter pore development are clarified. The main findings are as follows: when the shale, roof, and floor strata have a strong sealing capacity, only a small amount of liquid hydrocarbons can be discharged from the shale, but the natural gas formed due to liquid hydrocarbon cracking is abundant. Under such circumstances, shale gas has a mixed origin of liquid hydrocarbon cracked gas and kerogen cracked gas; the carbon isotopes are inverted; abundant pyrobitumen pores with high porosity and good connectivity are developed. When the sealing capacities are weak, the amount of liquid hydrocarbons discharged from the shale are high, and the amount of natural gas is low. The shale gas is mainly derived from kerogen cracking with weak or no carbon isotope inversion, and kerogen pores are small with poor connectivity. These findings will advance the study of shale gas formation mechanisms and provide a scientific basis for selecting shale gas exploration area. • Due to different physical properties, the roof and floor strata provide a seal for the organic-rich shale. • As the burial depth, TOC content, and the shale thickness increase, the shale has a stronger sealing capacity. • Sealing capacity plays an important role in the characteristics of shale gas and organic matter pore development. [ABSTRACT FROM AUTHOR]

• The factors that affecting urban carbon emissions efficiency (CEE) are explored. • The carbon emissions of 282 cities are estimated with the aid of nighttime light data. • Urban CEE has significant and positive spatial spillover effects. • Industrial agglomeration and collaboration are key to green production efficiency. This paper explores the factors that improve the efficiency of urban carbon emissions. Based on nighttime light data, the carbon emissions of 282 cities in China from 2004 to 2018 are estimated, and the carbon emission efficiency (CEE) is measured. The spatial autocorrelation results show that CEE in Chinese cities has significant and positive spatial spillover effects. The LISA low-low type cluster area of CEE presents an evolutionary trend of westward migration, and eventually formed two low-efficiency centers in the Central Plains city group and the Sichuan-Chongqing city group. The empirical results of the spatial Durbin error model show that urban population expansion, economic growth and R&D investment have effectively improved CEE, but industrial scale and agglomeration adversely affect CEE. In addition, human capital investment and foreign investment have not exerted their due green growth effects. Manufacturing agglomeration had a negative impact on local CEE, but had a warning effect on neighboring regions. Different from the manufacturing industry, the agglomeration of producer services industry can bring significant improvement to CEE, accompanied by a demonstration effect which can promote the CEE in adjacent regions. Further, this paper finds that developing the synergy between manufacturing and producer services industries can significantly restrain the negative effects of industry on CEE. This paper enriches the performance evaluation framework of low-carbon city development in theory, and varies the situations that previous researches only concerned about carbon emissions while ignoring emissions efficiency. This paper is a beneficial policy practice of the coordinated development of economic growth and ecological environmental protection in the regional coordinated development mechanism, which indicates that strengthening industrial collaboration can effectively improve the efficiency of green production in cities. [ABSTRACT FROM AUTHOR]

Coordinating the relationship between the national pipeline network company and the provincial natural gas company is the most crucial contradiction in China's natural gas market reform. This paper innovatively incorporates the comprehensive evaluation method, modified spatial gravity model, and social network analysis method to investigate the regional natural gas market to solve this dilemma. The result of the case study is as follows. (1) The development of the natural gas market in China's provinces is uneven, among which resourceful provinces and eastern provinces are relatively strong. (2) The densely connected areas of the natural gas market are mainly concentrated in the Beijing-Tianjin-Hebei region, the Yangtze-River-Delta region, and the Sichuan-Chongqing region. (3) Our work can clarify the node attributes and different efficacy of provinces. The core provinces all belong to the net spillover block, and they are located at key positions and roles in the obtained spatial correlation network. (4) Market participants, commodity diversification and openness are the prominent factors influencing the proposed spatial correlation network. This paper's major achievement is the reasonable division of five regional natural gas markets. The conclusion can help policymakers clarify the overall natural gas market spatial pattern and provinces' market potential and functions. • This article analyzes the construction plan of regional natural gas market in China. • We builded a comprehensive quality evaluation system for the natural gas market. • We used the modified spatial gravity model to calculate the interprovincial natural gas spatial influence. • We used centrality and structural holes to analyse individual network attributes. • We applied edge-core structure and block model to analyse the overall network structure. [ABSTRACT FROM AUTHOR]

• A zoning method based on ecological indicators and economic indicators is applied. • Ecological and economic situations are highly correlated with topographic conditions. • The coupling coordination degree(CCD) between ecology and economy is calculated. • Economic development is highly positively correlated with CCD. • Targeted regional sustainable development strategies are put forward. The coordinated development of ecology and economy is one of the key issues of sustainable development. A full understanding of the relationship between ecology and economy is necessary for the coordinated development of the two. This paper takes Sichuan Province as the research area and county-level administrative districts as the research unit. Based on the medium value of the ecological quality index and economic growth index of each unit, Sichuan Province is divided into dual pressure zones (DPZ), economic backward zones (EBZ), ecological crisis zones (ECZ), and coordinated development zones (CDZ) and the coupling coordination degree (CCD) of each unit is studied. The results show that: (1) On the whole, the eastern part of Sichuan Province has a better level of economic development, and the southern part of the western region has a higher ecological quality. The ecological quality and economic growth pattern are highly correlated with topographical conditions. (2) The distribution characteristics of the four types of partitions are significantly different. The EBZ are more distributed in the western and southern of Sichuan Province, the ECZ are more distributed in the eastern, the DPZ and CDZ are relatively more sporadic. More than 90% of the partition changed zones are distributed in the eastern area. (3) The CCD of more than 95% units belongs to moderate coordination and high coordination. The overall CCD of the four types of zones has shown an upward trend from 2010 to 2015. Based on the results, Sichuan Province should follow the path of clear waters and green mountains are as good as mountains of gold and silver, and targeted sustainable development suggestions for DPZ, EBZ, ECZ, and CDZ are put forward. This paper provides guidance for formulating regional sustainable development strategies, especially in areas with unbalanced development due to congenital topographical conditions. [ABSTRACT FROM AUTHOR]

• CH 4 and (sub and supercritical) CO 2 adsorption experiments on shales were performed. • The adsorption ratio of CO 2 over CH 4 for tested shale samples ranges from 1.66–8.32. • Langmuir, D-A, D-R and Ono-Kondo models were fitted to the adsorption data. • The favorable models used to fit CH 4 and CO 2 adsorption on shales are recommended. A thorough study of the adsorption behavior of shales to methane (CH 4) and carbon dioxide (CO 2) is critical for carbon dioxide sequestration in shale gas reservoirs and enhanced shale gas recovery. This paper discusses the results of an adsorption study of CH 4 and CO 2 , in single gas environment, on a set of shale samples taken from the Sichuan and Ordos Basins. The results indicated that shale exhibit higher affinity to CO 2 as compared to CH 4 under similar pressure and temperature conditions, and the preferential adsorption ratio of CO 2 over CH 4 varies between 1.66 and 8.32. Furthermore, the experimental data were modeled using Langmuir, Dubibin-Astakhov (D-A), Dubinin-Redushckevich (D-R) and Ono-Kondo models. The accuracy of the models in quantifying CH 4 and CO 2 adsorption on shale was compared using an error analysis technique. For CH 4 , both of Langmuir and D-A models performed satisfactorily with comparable accuracy. For subcritical CO 2 , the performance of the D-A model is the best. However, for supercritical CO 2 , Ono-Kondo model fitted the experimental data the best, which is the proposed model to use. The results of this study can provide the basis for the estimation of the CO 2 sequestration capacity in shale formations. [ABSTRACT FROM AUTHOR]

The main target for hydrocarbon exploration of terrestrial strata in Sichuan Basin is the tight gas sandstone reservoir of the Upper Triassic Xujiahe Formation. Xujiahe Formation in YB area is a major discovery of hydrocarbon exploration in recent years, which is characterized as tight with ultralow porosity, ultralow permeability, and intensive heterogeneity. The tectonic fractures have important influence on accumulation and productivity of gas in the area. In the paper, analysis data of outcrop, core, imaging logging and other experiments were used to determine the characteristics, formation periods and genetic mechanisms of tectonic fractures. There are mainly high-angle and low-angle shear fractures in the area, which caused by tectonic stress. The length of the fractures is mainly 0–4 m from the outcrop and 10–20 cm from the cores and fracture frequencies (number per meter) is mostly 2-7 m−1, 2-4 m−1 respectively. The fracture fillings are mainly calcite, argillaceous and carbonaceous, about 60% of the fractures is unfilled or incompletely filled. Without considering the diagenetic fractures, there are three periods of the fractures: the middle-late Yanshanian tectonic movement, the early-middle Himalaya tectonic movement and the late Himalaya tectonic movement. The first period of the fractures are mainly filled with fine calcite, homogenization temperature of inclusion is 75–85 °C and the maximum effective principal stress of paleostress is 71.64 Mpa. The second period of the fractures are half-filled (or unfilled) with coarse calcite, homogenization temperature of inclusion is 150–175 °C and the maximum effective principal stress of paleostress is 74.91 Mpa. The third period of the fractures are low filling degree and cuts formed fractures clearly, the maximum effective principal stress of paleostress is 86.52 Mpa. For these tectonic movement, there are four sets of the plane "X" shear fractures in the area: NE strike fractures, NW strike fractures, NEE strike fractures, S N strike fractures. There are one set of the profile shear fractures of NWW strike. Finally, the complex fault system of nearly N S, NW and NE strike are formed in YB area. • A new method for comprehensive study of the fracture formation period is provided. • The main fracture formation dating of Xujiahe Formation in YB area as follows: 36–176 Ma and 0.2–36.4 Ma. • There are 3 periods tectonic fractures of Xujiahe Formation and formation period of different fracture types is identified. [ABSTRACT FROM AUTHOR]

• Resource-Richness Analogy Approach used in less explored reservoirs is proposed. • Genesis-Statistics Assessment Approach for heterogeneous tight oil is proposed. • The parameter criteria of lacustrine tight oil resource assessment are established. • In-place tight oil resources in China's major basins are estimated of 12.6 × 109 t. • 15 most favorable plays are outlined with in-place resources of 5.3 × 109 t. Large-scale commercial development of shale gas and tight oil resources in North American and continuous discoveries of tight oil in China lead to the recognition of the importance of assessment on tight oil resources. Based on the characteristics of China's tight oil reservoirs and exploration status, this paper discusses a workflow focusing on in-place resource evaluation. In the workflow, a Resource-Richness Analogy Approach (RR-AA) is proposed for assessment of tight oil resources in less explored areas, a Genesis-Statistics Assessment Approach (GS-AA) for lacustrine tight oil resources with strong heterogeneity and regions where more delicate assessment is required, and an EUR Analogy Approach (EUR-AA) for assessment on recoverable tight oil by fully using available EUR data of production wells. After analyzing the geological characteristics of the formation of tight oil in the Ordos, Bohai Bay, Songliao, Junggar, Sichuan and other major Basins, the distributions of essential parameters such as reservoir thickness, area and porosity have been defined, and the parameter evaluation criteria have been established. Finally, the tight oil resource potentials in the major basins in China have been evaluated using one of the three methods and the prospective areas of high resource abundance are outlined in each of basins. The results from this study show that China's tight oil resources have a large potential and good exploration future. The estimated in-place tight oil resources are 12.580 × 109 tons, mainly distributed in the Ordos, Songliao, Bohai Bay and Junggar Basins. 15 most favorable zones are proposed having in-place resources of 5.296 × 109 tons. [ABSTRACT FROM AUTHOR]

• Zircon fission track analyses of the pre-Cretaceous sandstones are reported. • ZFT data constrain the low-temperature evolution or sediment provenance. • The westward decreasing trend in age represents a Mesozoic intracontinental orogeny. • Sediments source from the Qinling orogen due to its multistage evolution. The Xuefeng Intracontinental Tectonic System (XITS) is a large-scale compressional tectonic system in the central South China block. It is characterized by northeast-trending fold-thrust belts involving the Xuefeng zone, the Chevron syncline fold-thrust zone, the Chevron anticline fold-thrust zone and the Central Sichuan basin. This paper reports detrital zircon fission track (ZFT) analyses of the sandstones sampled from Neoproterozoic to Middle Jurassic sequences, and further discusses their relation with low-temperature tectonic evolution and sediment provenance. The totally annealed ZFT data of 452–377 Ma from the Neoproterozoic and Devonian sandstones were related to an Early Paleozoic low-temperature exhumation of the Jiangnan orogen due to intracontinental orogeny in the South China block. Those annealed ZFT components from Triassic to Jurassic sandstones, grouped 236–189 Ma, 189–142 Ma, and 142–124 Ma decreasingly from east to west structurally imply a northwestward progressively squeezing by the Xuefeng intracontinental orogeny as a result of the Paleo-Pacific subduction. The unannealed age components (411 Ma, 362–377 Ma, 270–216 Ma, and 209–183 Ma) of the Upper Triassic to Middle Jurassic sandstones, are comparable to the multistage tectonic evolution of the Qinling orogen through subduction, accretion and collision and are therefore indicative of sample potential provenance. [ABSTRACT FROM AUTHOR]

Nucleic acid constituents are the main functional ingredients in edible fungi, therefore understanding the nucleic acid constituents of edible fungi often eaten on the table by the Chinese people is of significant value. In this study, Sichuan Provincial Center for Disease Control and Prevention collected 147 samples of edible fungi (including certain species that the Chinese often eat) from different parts of the Sichuan Basin. A new UPLC-QqQ/MS method has been developed to determine the 17 nucleic acid constituents in these 147 samples, including guanosine, adenosine, uridine, cytidine, inosine, thymidine, xanthosine dehydrate, 2′-deoxyguanosine, 2′-deoxyadenosine, 2′-deoxyuridine, 2′-deoxycytidine, 2′-deoxyinosine, guanosine 5′-monophosphate, adenosine 5′-monophosphate, uridine 5′-monophosphate, cytidine 5′-monophosphate, and inosine 5′-monophosphate. Finally, similarity assessment of the main edible fungus was performed using vectorial angle cosine method, and hierarchical cluster analysis was used to classify all the 147 samples. The results showed that some edible fungi have high similarities, especially in Lentinula edodes (Berk.) Pegler, the monogenic nucleotides content of which (55.84 ± 8.4 mg/100 g) is far greater than any other edible fungus, which is directly related to its taste. For quality control, this paper proposed to use the reference values of total nucleic acid compounds in edible fungi computed by percentile threshold method. This is the first time a comprehensive evaluation of nucleic acid constituents of different edible fungi of daily consumption was conducted for a large region, and the results is conducive to the quality evaluation and quality control of edible fungus. Unlabelled Image • Developed a new UPLC-/MS method for the determination of 17 nucleic acid constituents • The similarity was assessed by vectorial angle cosine and hierarchical cluster analysis. • The reference values of total nucleic acids in each species computed by percentile threshold method. • Can be applied for quality evaluation and quality control of edible fungus [ABSTRACT FROM AUTHOR]

Abstract Multiphase (adsorbed and free) liquid water that is accumulated in shale matrix pores (i.e., pore water) substantially affects the storage and transport of gas in shale. Traditionally used macroscopic parameters (e.g., initial, irreducible, mobile and clay bound water saturations) are not sufficient to describe the microdistribution characteristics and mobility of pore water in the complex porous shale matrix. In this paper, a new classification was proposed in which the pore water is composed of adsorbed and free parts, of which the latter is subdivided into capillary bound and mobile water. The components of pore water have the following features: during the centrifugation process, (a) adsorbed water is essentially immobile, while free water is potentially mobile; (b) capillary bound water is gradually transformed into mobile water with increased centrifugal pressure difference; and (c) the maximum mobile water amount is numerically equal to the free water amount. Based on the classification, an effective technique, which integrates centrifugation, water imbibition and low temperature nitrogen adsorption methods with the modified Li's adsorption ratio equation (2018), was established to quantitatively evaluate the microdistribution characteristics (adsorbed and free amounts and their ratios) and the mobility (mobile amount, potential and capacity) of pore water in marine shales from the southern Sichuan basin in China. Furthermore, the mechanism of controlling the microdistribution and mobility of pore water is analyzed with respect to the microscopic pore structure characteristics and material compositions of shales. The primary results demonstrate that (1) adsorbed and free water amounts obtained by centrifugation tests range from 5.145 to 31.282 mg/g (adsorbed) and from 7.880 to 49.751 mg/g (free); the weight ratio of adsorbed water is 0.268–0.629. (2) The mobile potential and mobile capacity of pore water are represented by the free water amount and mid-value pressure difference, respectively. A positive relationship between these two parameters occurs in the studied shales. (3) Pore microstructure characteristics of shale mainly impact the microdistribution and mobility of pore water in the shale matrix. The adsorbed water amount is closely associated with the specific surface area of pores, while the free and mobile water amounts are controlled by the pore volume. The ratios of adsorbed and free water depend on the size and morphology of pores for certain state parameters. The mobile ratio is impacted by pore complexity, which indicates that as the complexity increases, the mobile ratio decreases. The study provides significant insight into the microdistribution and mobility of pore water in gas shale matrix. Highlights • A new classification was proposed for the components of pore water. • A technique was established to evaluate the microdistribution characteristics and the mobility of pore water in shales. • Mechanism of controlling the microdistribution and mobility of pore water was analyzed. [ABSTRACT FROM AUTHOR]

• The forest productivity of mixed plantations was 18–39.5% greater than that of pure plantations. • Understory vegetation diversity in MCC was significantly higher than in PCL and PCF, by 15.8–20% and 13.2–35.7%, respectively. • The water conservation capacity of MCC is significantly higher (by 19.4–42.9%) than that of PCL and PCF. • Performance against the soil fauna diversity index was similar in all three stands. Many studies of biodiversity-ecosystem functioning (BEF) relationships indicate that mixed plantations can enhance ecological benefits by enabling ecological niche differentiation between species. However, few studies explore multi-dimensional evidence to fully evaluate the integrated ecological benefits of mixed plantations. This paper aims to assess the stand characteristics and ecological benefits of different forest types, drawing on multiple lines of evidence (trees, shrubs, herbs, soil fauna, and soils) to understand the effects of mixed plantations on integrated ecological benefits. Our study focused on pure Cunninghamia lanceolata (Chinese Fir) plantations (PCL), pure Cryptomeria fortunei (Chinese Cedar) plantations (PCF), and mixed C. lanceolata - C. fortunei plantations (MCC), which are common in the mountainous areas of the Sichuan Basin in southwestern China. We analysed the growth status, spatial structure, understory vegetation diversity, soil fauna characteristics, and physical and chemical soil properties found in plots representing these three forest types. The results showed that productivity was significantly higher in the MCC than in PCL or PCF, by 39.5% and 18%, respectively. Mixed plantations showed higher stand growth rates, but this effect was limited by interspecific competition. The results further showed that mixed plantations promote forest growth by allocating spatial locations between different tree species. In addition, the spatial stand structure in the mixed plantations was more stable than that in the two pure plantations, and the management potential of the mixed plantations was greater. Understory vegetation in MCC was significantly more diverse than in PCL and PCF, by 15.8–20% and 13.2–35.7%, respectively. Moreover, mixed plantations performed better in terms of soil water and soil fertility. Interestingly, we found no difference in soil fauna diversity between mixed and pure plantations. We conclude that, overall, planting mixed plantations can enhance the integrated ecological benefits of afforestation and may be an essential strategy for ensuring that plantations can cope with climate extremes. [ABSTRACT FROM AUTHOR]

Hydropower is an essential resource for the future clean energy transition, in which an accurate assessment of the hydropower cost is vital for promoting its share in the energy market. The purpose of this paper is to comprehensively reassess the cost of hydropower from a new perspective, in which the total static investment cost of a hydropower base is allocated among multiple functions. An allocation coefficient is proposed based on indicators of economic value and physical volume of multi-function hydropower bases. The economic value of each function is evaluated using approaches including the shadow project, market valuation, and emergy evaluation methods. Meanwhile, the physical volume is obtained through a multi-objective optimization of cascade reservoir operation considering an ecological constraint. Four main functions consisting of hydropower generation, flood control, agricultural irrigation, and residential water supply of hydropower bases in Sichuan are investigated. The results show that the allocation coefficients under both economic and physical indicators vary significantly among hydropower bases, and change slightly over the years. The average comprehensive allocation coefficient of hydropower is 57.26% (range from 29.83% to 77.41%), and the hydropower cost can be reduced by 59% from the current level. The reassessed hydropower cost can lay a solid foundation for market pricing. Attention should be paid to the multi-functionality characteristics of hydropower bases to achieve fair sharing of cost and benefit. • A new approach is proposed from the perspective of allocation among multiple functions for hydropower cost assessment. • A comprehensive allocation coefficient combining economic and physical indicators has been developed. • The indicator of storage capacity is expanded based on the multi-objective optimization of cascade reservoir operation. [ABSTRACT FROM AUTHOR]

• Abrupt high δ13C -CO2-DIC in the hot springs occurred before earthquakes. • The carbon isotopic spikes are caused by fractionation due to tectonic activity. • The δ13C -CO2-DIC of hot springs changed markedly before and after the earthquakes. • The elevated carbon isotopic levels may be a signal for the subsequent earthquakes. Geothermal springs are controlled by deep faults, which are the major causes of earthquakes. A series of geochemical indicators of hot springs, such as carbon dioxide content (CO 2), carbon isotope and noble gas isotope etc., have been used for earthquake monitoring and early warning at home and abroad. Given that previous studies have failed to establish an inevitable link between the carbon isotopic variations of hot springs and seismic activities, in this study, mass spectrometry techniques were used to analyze the carbon isotopes of gaseous CO 2 and noble gas isotope in hot springs, thermal water, and newly formed travertines from western Sichuan before and after an Ms 4.8 earthquake (i.e., 7.14 earthquake). The results showed that the carbon isotope level of the hot spring system increased significantly before the earthquake, i.e., δ13C CO2 = -2‰ to 3.3‰, δ13C DIC = 2.2‰ to 6.6‰ (DIC = dissolved inorganic carbon in geothermal water), R/R A = 0.90–1.83, and δ13C travertine = 1.76‰ to 5.75‰. These indicators decreased markedly 1 week after the earthquake, whereas the helium isotope ratio of R/R A did not exhibit a noticeable change (δ13C CO2 = -3.9‰ to 0.4‰, δ13C DIC = 1.6‰ to 4.1‰, R/R A = 0.68–1.87). Combined with previous thermodynamic calculation and experimental results on carbon isotope fractionation of the CO 2 –calcium carbonate system, we suggest that the high carbon isotope characteristics of hot springs are caused by carbon isotope fractionation following the release of CO 2 from fault carbonate decomposition owing to tectonic activity, not by a mixture of different carbon sources. A high carbon isotopic delivery path in geothermal water, from released CO 2 to DIC and then to travertine, was observed. The new mechanism proposed in this paper reveals the intrinsic relations between the changes of the hot spring geochemical properties and deep tectonic activities, and the variations of these geochemical parameters before and after earthquakes may assist in capturing seismic precursors. A post-peak earthquake warning model has thus been preliminarily proposed, however, long-term monitoring data are required to reduce some uncertainties. [ABSTRACT FROM AUTHOR]

In this paper, the genesis of dolomite in Longwangmiao Formation is analysed through field investigation and geochemical methods, and dolomization model is established, which is very important for the next reservoir prediction in Longwangmiao Formation. According to the crystal size, the Longwangmiao Formation dolomite can be divided into two types: microcrystalline dolomite (MID) and macrocrystalline dolomite (MAD). Both types of dolomite have higher Al content than lime mudstone, indicating that during the deposition process of the Longwangmiao Formation, terrigenous materials are continuously mixed into the sediment, which significantly affects the geochemical characteristics of the Longwangmiao Formation. The rare earth element (REE) composition of the two types of dolomite is consistent with that of lime mudstone (LM), with an obvious δCe positive anomaly and no δEu anomaly, which is a typical distribution pattern of marine carbonate sediments. The microcrystalline dolomite has a higher Na element content, lower δ13C value, and higher δ18O value, suggesting that it is formed in a highly saline evaporation environment. Most of the macrocrystalline dolomite has a residual grain texture. The elements, as well as the isotopic geochemical characteristics of the dolomite, are consistent with those of lime mudstone, indicating that macrocrystalline dolomite is formed early and inherits the geochemical characteristics of the precursor limestone. We believe that the dolomitization model of the Longwangmiao Formation is an evaporative concentration + reflux seepage model. In the late sedimentary period of the Longwangmiao Formation, the sea level declined and a large area of lagoon appeared in the restricted and semi-restricted platform. As the evaporation and concentration continued, precursor minerals such as high-magnesium calcite and aragonite mud experienced chemical precipitation. In this process, a large amount of Ca2+ was consumed, resulting in an increase in the Mg2+/Ca2+ ratio. Then, the precursor minerals underwent dolomitization, and microcrystalline dolomite began to form. At the same time, owing to the difference in density between the high-salinity concentrated seawater and the pore water existing in the early limestone, the concentrated seawater flowed back and penetrated downward, causing the dolomitization of the underlying strata, and then the formation of macrocrystalline dolomite. The degree of dolomitization was mainly affected by the development degree of the granule beach and the thickness of the strata. • The highlights of this article are as follows: • This paper provides a case study of terrigenous clastic dolomite. • This paper analyses the genesis of the dolomites of Longwangmiao Formation and establishes a dolomitization model. • We analysed a large number of samples and provided basic geochemical data for Longwangmiao Formation. [ABSTRACT FROM AUTHOR]

• Rural renewable energy construction is entry point and foothold for implementing the rural revitalization strategy. • While promoting rural energy development, we should solve the problem of rural dirty and messy. • Build a comprehensive rural space integrating leisure agriculture. At present, rural areas in China have problems such as poor living environment, shortage of facilities, and industrial disappointment. They still use the concept and strategy of urban planning and design to manage the rural areas, which leads to the rural planning results become empty shells, which is time-consuming and laborious, but does not bring practical use to the improvement of rural life. The purpose of this paper is to better implement the rural revitalization strategy, more scientifically guide the beautiful rural construction, and more effectively restore the rural vitality. Based on the strategy of beautiful village planning under the background of rural revitalization strategy, this paper takes Shuanglongqiao Village, Fengming Town, Xichong County, Sichuan Province as the empirical research object, and comprehensively applies research methods such as literature inquiry, on-site investigation and comparative analysis. Firstly, the paper puts forward the background of rural revitalization strategy and the concept of beautiful rural planning. Based on the theory and practice of beautiful rural planning at home and abroad, it analyzes the guiding significance and enlightenment of these theories and practices on beautiful rural planning. And further reflect on the concept and strategy of planning and construction of beautiful villages; then, in combination with national policies, profoundly analyze the scientific connotation of rural revitalization strategy, on this basis, comprehensively analyze the requirements of rural revitalization strategy for beautiful rural construction, and then combine with rural planning The characteristics of the compilation system of urban planning, and the basic strategies of beautiful rural planning under the background of rural revitalization strategy. Finally, combined with the characteristics of the village and the construction needs, the paper summarizes the planning strategies suitable for the development needs and village characteristics of Shuanglongqiao Village under the background of rural revitalization strategy. On the basis of previous studies, this paper comprehensively interprets the scientific connotation of rural revitalization strategy, and conducts summative research on beautiful rural planning. It hopes to refine some beautiful rural planning concepts and strategies, and other similar Shuanglongqiao villages under the background of rural revitalization strategy. The beautiful village planning provides a new perspective and also provides some experience in building practices in other villages. [ABSTRACT FROM AUTHOR]

Since the Guideline of Strengthen Preservation and Development of Traditional Village enacted, the traditional villages gradually gain academic concern and many achievements are acquired. But the study about outdoor wind environment is still insufficient. In this paper, the outdoor wind environment of Liyuanba Village in Bazhong City of Sichuan Province – a typical traditional village in the northeastern Sichuan Basin, is simulated by CFD methods. According to the simulation result, the outdoor wind environment in winter is comfortable for people in general, but there are still eddies and corner flows in some areas. To improve the outdoor wind environment, the suggestions such as changing the direction of courtyard and building are put forward. Furthermore, the optimization is also simulated and these two simulation results are compared in the end. [ABSTRACT FROM AUTHOR]

• Microstructures of the outcrop/core kerogen were systematically characterized. • Differences in chemical structure between the outcrop/core kerogen were identified. • Realistic 2D/3D molecular models of the outcrop/core kerogen were constructed. • Validity of the proposed molecular models was verified by gravimetric adsorption. • Effect of the kerogen microstructure on CH 4 adsorption behavior was investigated. It has been known that adsorbed gas, mainly CH 4 , serves as the dominant source of shale gas yield in the middle and later stages of reservoir exploitation. Therefore, it is of great significance to study the microstructure of kerogen (organic matter rich in shale) and its effect on CH 4 adsorption characteristics. In this paper, for the first time, a comparative study was conducted to experimentally characterize the microstructure of both outcrop and core kerogen samples from Longmaxi Shale, Sichuan Basin, SW China, using 13C NMR, FTIR, and XPS. Great differences in the chemical structure such as carbon skeleton (e.g. , aromaticity, aliphatic branch) and heteroatoms (e.g. , distribution and proportion of various types of functional groups) between the two kerogen samples have been identified. Molecular models of the outcrop and core kerogen samples were constructed based on the experimental data, that is, C 237 H 219 O 21 N 5 S 4 for the former and C 239 H 175 O 27 N 5 S 4 for the latter. CH 4 adsorption isotherms obtained from gravimetric adsorption test and molecular simulation using proposed kerogen molecular models are in reasonable agreement with each other, especially at low-pressure range. Interestingly, the adsorption capacity of CH 4 in the core sample is found higher than that in the outcrop sample under the same condition, indicating the effect of kerogen microstructure on CH 4 adsorption behavior. As a result, to precisely evaluate the adsorbed gas content in shale gas reservoirs, it is strongly recommended to use a core sample rather than an outcrop sample. [ABSTRACT FROM AUTHOR]

• Three ANN methods are utilized in the process of force finding of cable domes. • Four finite element models of cable domes are established to validate the feasibility of ANN-aided force finding methods. • Prestress of cable domes with single and multiple self-stress states can be accurately predicted by ANNs. Force finding of cable dome structures is a sophisticated and indispensable procedure in terms of their unique structural stiffness derived from self-equilibrium stress to the tension cables and compression struts. Owing to the limitation of traditional force finding methods, the process is often time-consuming and challenging. To address this issue, a general machine learning-aided computational framework for conducting a reliable force finding process is established. Several commonly used force finding methods for cable dome structures are summarized at first. Then the paper introduces the fundamental principle of the artificial neural network (ANN) methods including Back Propagation neural network (BPNN), Radial Basis Function neural network (RBFNN) and General Regression neural network (GRNN), and proposes to combine ANN methods with finite element analysis (FEA) to the force finding of cable dome structures. Additionally, the Geiger, Kiewitt, Levy and hybrid cable dome structures (Tianquan Gymnasium in Sichuan Province, China) are taken as examples of case validation, solved by ANN-aided force finding methods respectively. The results indicate that the proposed computational framework is capable of searching for the feasible prestress whether or not considering the external load such as self-weight. Among ANNs in this case study, GRNN can be applied in the calculation of not only basic cable dome structures with both single and multiple integral self-stress states, but also intricate cable dome structure in practical engineering projects with optimal accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Although there is a growing body of literature on the COVID-19 pandemic and the implemented strategies that have imposed additional risks in tackling emergencies by increasing socio-economic vulnerabilities, studies on human evacuation behavior during lockdowns are lacking. This paper contributes to evacuation and emergency research by examining seismic evacuation decision-making by surveying the areas affected by the Luding earthquake on 5 September 2022, when most parts of Sichuan province were experiencing strict pandemic restrictions. Using these data and per the emergency evacuation decision-making mechanism, we developed six hierarchical series of logistic regression models. Our major results suggest that 1) Socio-demographic parameters have shown different correlations with the study's dependent variables in each stage of those hierarchical models, 2) Respondents at home at the time of the earthquake were more likely to identify the earthquake risk than those who stayed outdoors; the former group showed less willingness to evacuate, 3) Rural residents have perceived higher earthquake risks than urban residents, and 4) Loss of job, change in income due to COVID-19 restrictions, and difficulty accessing daily supplies during the lockdown affected the residents' risk assessment and evacuation decision-making negatively. Insights into these aspects are expected to contribute to a better understanding of evacuation behavior during double disasters by modifying emergency response regulations and providing the residents with information about emergencies during pandemic restrictions. • Examining Emergency Decision-Making Mechanism (EDMM) during a vast Covid-19 epidemic lockdown • Epidemic prevention regulations and access to earthquake information significantly affected the residents' earthquake risk perception, evacuation decision-making, and risk identification, respectively. • Access to disaster information has played a critical role in risk recognition. • Rural residents felt more vulnerable to the earthquake than urban residents. [ABSTRACT FROM AUTHOR]

In shale plays, the in-situ effective stress is continuously being perturbed because of the production which impacts field operations. Therefore, mechanical properties of the formation and its response to stress field changes, with respect to mineral variations, is of great significance for the proper design of horizontal drilling and hydraulic fracturing. In this paper, clay-rich, calcareous and siliceous black shales are classified based on their XRD analysis, from the Wufeng and Longmaxi Formations in the Sichuan Basin of the Upper Yangtze Plate. Uniaxial quasi-static and cyclic loading tests, acoustic emissions, and CT scanning are combined to study mechanical behavior and fracturing mechanisms of the shale layer samples that own different mineral components. The results show that the strength and deformation response of the samples is a function of their mineral composition. The damage from cyclic loading is gradually accumulated in the samples which ultimately leads to fatigue and sample failure. The compressive strength of the samples under cyclic loading is lower than in the uniaxial quasi-static conditions. Furthermore, the fracturing of rock under uniaxial quasi-static loading mainly occurs after the peak strength is achieved while in cyclic loading, when a certain stress level is reached, fracturing begins, the damage accumulates up to the peak stress and the rock suddenly fails. Based on CT images from the samples after rupture, failure modes of the clay-rich, calcareous and siliceous black shales mainly constitute extensional and shear fractures, with some conjugate shearing. In comparison with uniaxial quasi-static loading, the fracture volume of the clay-rich, calcareous and siliceous black shales after cyclic loading increases by 12.2%, 25.9% and 32.9%, respectively. Overall, this study explains how cyclic loading that can be applied in the field via changing the injection pressure and other stimulation parameters, can effectively improve the complexity of the shale fracture network and lead to higher productivity of the formation. • Quasi static loading and cyclic loading are employed in the mechanical test. • The compressive strength of the cyclic loading is lower than that of uniaxial quasi-static loading. • The fracture volume of the cyclic loading is higher than that of uniaxial quasi-static loading. [ABSTRACT FROM AUTHOR]

Taking multimodal transport network as the research object, a quantitative method of risk propagation based on improved percolation theory is proposed. This paper analyzes the applicability and limitations of the percolation theory for this problem, and improves such four aspects of nodes and edges as the state, the initial load, the percolation probability and the evaluation index of percolation effect, so that they are universal to the risk propagation of the transport network. Taking Sichuan–Tibet​ region as an example for empirical analysis, this paper simulates and analyzes the risk propagation law of the multimodal transport network under different attack types and load preferences. The results show that the risk propagation effect in the multimodal transport network will become stronger with the increase of attack scale and attack intensity, and it will show an exponential growth trend with the increase of attack scale. When other conditions are the same, the order of strength of the three kinds of attack law according to the risk propagation effect is: the intentional attack based on the loads > the random attack > the intentional attack based on the failure probability; the risk propagation effect of the load with preferences is stronger than that without preferences. Therefore, managers can control the risk of multimodal transport network in Sichuan and Tibet from the perspective of controlling attack types and balancing load preference. The research improves the method of risk propagation simulation, makes up for the shortcomings of existing research which neglects the subjectivity of load and the dynamics of risk propagation, and makes it closer to the reality, which is of strong practical value and theoretical significance. • We discusses the limitations of the percolation theory application in the multimodal transport network, and proposes a universal improvement method. • This paper proposes that the subjectivity of load has a certain influence on the risk propagation effect in the network. In order to quantify the subjectivity of load, we use the FMEA, the triangular fuzzy number and the prospect theory to improve the percolation probability, and integrate the subjectivity of load into the redistribution process of load. • This paper proposes the method of combining the static index and the dynamic index to measure the percolation effect, so as to explore the dynamics of risk transmission. • This paper makes an empirical analysis of the multimodal transport network in Sichuan–Tibet region of China, and analyzes the law of risk propagation in the network from such two aspects as the attack type and the load preference, which is of strong practical value. [ABSTRACT FROM AUTHOR]

• Villagers exhibit endowment effects of varying intensity through withdrawal from rural homesteads (WRH). • As the degree of villagers' non-agricultural activities increase the endowment effect is more intense. • Emotional attachment to rural homesteads, property right status, and substitutability of rural homesteads affect villagers' endowment effects. • The endowment effect accompanying WRH should become an important factor for WRH policymakers. The withdrawal from rural homesteads (WRH) refers to a mechanism to encourage villagers to withdraw from their vacant homesteads or give up their occupied homesteads (including the houses built on them) voluntarily and move into high-rise buildings with compensation. WRH aims to address inefficient utilization of rural land in China. However, the endowment effect, a behavioral tendency for villagers to value rural homesteads more highly when they own them relative to when they do not, may affect the process of implementing WRH policy. Based on survey data from 878 villagers in Chengdu, Sichuan Province, this paper estimates endowment effects for different types of villagers whose rights to their rural homesteads could be withdrawn. It then makes an empirical analysis on the differences and influencing factors of villagers' endowment effects related to WRH via a binary logistic model querying emotional attachment , property right status , and substitutability of rural homesteads. The results show 70.62 % of sampled villagers exhibit an intensive endowment effect after WRH. Meanwhile, as non-agricultural economic activities increase, villagers' endowment effects intensify. In terms of influencing factors, emotional attachment and cognition of inheritance rights strengthen the degree of pain experienced by villagers when they withdraw from their rural homesteads, thereby enhancing endowment effects. Property certificates and cognition of disposal rights negatively affect villagers' endowment effects. From the perspective of villagers' differentiation, cognition of mortgage rights intensifies the feelings of security within rural homesteads for full-time agricultural households, thereby intensifying endowment effects. Substitutability of villagers' livelihood positively affects endowment effects in full-time agricultural households and negatively affects endowment effects in non-agricultural households. This paper concludes by discussing the land use policy implications of these findings. [ABSTRACT FROM AUTHOR]

• Trace elements are innovatively used in the study of hydrothermally altered pyrobitumen. • Hydrothermal minerals cause enrichment of some trace elements in altered pyrobitumen. • The enrichment of trace elements varies with the optical texture change of pyrobitumen. • The hydrothermal activity is not limited to the vicinity of deep faults. The hydrothermal activity in the Ediacaran Dengying (DY) Formation in central Sichuan has modified the reservoirs and paleo-oil reservoirs; however, these modifications are not specific due to the challenges in recovering the hydrothermal scale. This paper classified pyrobitumen in the DY Formation into five categories by optical textures and analyzed the physical structure and trace element composition of the different pyrobitumen using scanning electron microscope, reflectance, and trace elements. Finally, the responses of the trace element concentrations and optical textures of the pyrobitumen to hydrothermal alteration were discussed and used to restore the hydrothermal scale in the central Sichuan Basin. The results show that isotropic, fine-grained, medium-grained, coarse-grained mosaic, and fibrous pyrobitumen develop in the DY Formation. As the optical texture of the pyrobitumen changes from isotropic to mosaic to fibrous, the order degree of aromatic lamella in pyrobitumen gradually increases, the maturity, the maximum reflectance, and the bireflectance of pyrobitumen gradually increase. Except for isotropic pyrobitumen, anisotropic pyrobitumen is subject to varying degrees of hydrothermal alteration. The hydrothermal alteration on pyrobitumen is primarily in the form of material exchange, precipitating illite, salt, and barium-enriched minerals in pyrobitumen pores and enriching some elements (Ba, Cr, Nb, and Sr) in the pyrobitumen. As the optical texture changes from isotropic to mosaic to fibrous, the element enrichment degree gradually increases. Medium-grained mosaic, coarse-grained mosaic, and fibrous pyrobitumen are widely observed in central Sichuan. Therefore, hydrothermal modification on the DY reservoirs and paleo-oil reservoirs is not limited to the deep faults but widely develop in central Sichuan, and should be an essential part of the further study of hydrocarbon accumulation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fluorescent carbon dots was prepared at room temperature(R-CDs). • A flow injection fluorescence method for nitrite was developed using R-CDs probe. • Changes in nitrite content during pickling of Sichuan pickles were evaluated. In this paper, highly fluorescent carbon dots were synthesized from sodium ascorbate and polyethyleneimine at room temperature (R-CDs). The proposed green synthesis method was energy-saving, environmentally friendly and easy online. R-CDs exhibit an optimal emission peak of 490 nm under excitation at 380 nm with a quantum yield of 32 %. R-CDs morphology, composition, and properties were characterized using TEM, FTIR, XPS, UV-vis and fluorescence spectroscopy. The study revealed that nitrite quenched the fluorescence of R-CDs under acidic conditions. Subsequently, this discovered reaction of R-CDs and nitrite was combined with flow-injection technology, and a simple, precise and automatic fluorescence strategy for nitrite determination was accomplished. The response to nitrite was linear in 5–300 μg·L−1 concentration range and the limit of detection was 2.85 μg·L−1 (3.3 S/ k). This method was applied to nitrite determination in Sichuan pickles during the pickling process and results were consistent with the standard method, demonstrating its feasibility in practical applications. [ABSTRACT FROM AUTHOR]

Clumped isotope thermometry is an effective tool which allows to understand the post-depositional alteration, including recrystallization and solid-state reordering, of carbonate rocks. However, as both processes are controlled by elevated temperatures, it is frequently a challenge to distinguish between the relative importance of these two processes in deeply buried carbonate successions (depth > 5000 m or formation temperature > 150°C). In this paper, we have established a clumped isotopic framework of paired dolomite and calcite in order to decipher the relative influence of solid-state reordering versus recrystallization and consequently offer an improved understanding of the mechanisms involved. The material studied was derived from two deeply buried successions (Jurassic-Ediacaran) drilled in the central Sichuan Basin of South China. The calcite and dolomite minerals from these cores were separated using buffered acetic acid, and based on a two-component mixing model, the carbon, oxygen and clumped isotopic (Δ 47) compositions of the two endmembers were determined. Based on an evaluation of solid-state reordering models, we conclude that micritic carbonates (dolomite and calcite) from the Jurassic to the Cambrian have been altered during burial by the geothermal gradient as determined by vitrinite reflectance. The Ediacaran micritic dolomite records a hydrothermal event in the transition between the Ediacaran and Cambrian. In contrast, the clumped isotopic temperature of Ediacaran saddle dolomites reflects subsequent hydrothermal activity during the Silurian and Devonian and shows compositional variations controlled by cooling rates. This study highlights the utility of the theoretical framework based on paired dolomite and calcite records to untangle overprinted signals of clumped isotopes in ancient carbonate rocks and gives insight to better understand the complexity of alteration processes in deeply burial carbonate successions. [ABSTRACT FROM AUTHOR]

In the process of hydraulic fracturing of shale gas horizontal wells in the Weiyuan area of Sichuan, China, casing deformation (CD) is a frequent problem that has seriously affected the benefits of shale gas development and remains to be solved for many years. In this paper, based on the analyses of Multi-finger Imaging Tool-24 (MIT-24) data, microseismic data, and the relationship between CD and engineering parameters, we confirm that the wellbore morphology in all CD sections in the Weiyuan area is consistent with shear deformation characteristics and clarify the cause of all CD: hydraulic fracturing leads to increased fluid pressure in well-intersecting faults and large fractures (F-Fs), inducing their shear slip, and eventually leads to asymmetric compression on the casing by strata on both sides of F-Fs, i.e., CD. On this basis, we propose a set of methods to control (or moderate) the shear slip of F-Fs by reducing the additional fluid pressure in target F-Fs during hydraulic fracturing to prevent CD, including multi-cluster perforations, temporary plugging F-Fs and fracturing fluid flowback. We also analyze the theoretical basis, feasibility and workflow of these methods. These methods have been tested in 44 horizontal wells in the Weiyuan area, of which the result is a radical decrease in the CD rate of the single well (from 54% to 9.1%), indicating that the slip of F-Fs and the resulting CD during hydraulic fracturing can be controlled and providing a reference for the prevention of hydraulic fracturing-induced earthquakes. • All CD during hydraulic fracturing of shale gas in the Weiyuan area is caused by induced shear slip of F-Fs. • Temporary plugging can reduce the additional fluid pressure in target F-Fs so as to prevent CD. • The integrated technical methods have been proved to be effective in preventing CD in field application. [ABSTRACT FROM AUTHOR]

Breakthroughs in shale gas exploration in the Upper Ordovician-Lower Silurian strata of the Upper Yangtze Platform have attracted interest in its sedimentary-tectonic evolution, but the tectonic background of the northern margin of the Upper Yangtze Platform remains unclear. In this paper, the Wufeng-Longmaxi formations on the northern margin of the Upper Yangtze Platform were investigated. Based on geochemical and mineralogical analyses of the tuffs/K-bentonites of the Wufeng Formation and the barite in the Longmaxi Formation, as well as previous research results, it was concluded that the northern margin of the Upper Yangtze Platform was in an extensional tectonic background during the Late Ordovician-Early Silurian. Detailed analysis revealed that, (1) the U–Pb zircon age of the tuff in the Bajiaokou section in South Qinling is 443.91 ± 0.92 Ma. The Zr/TiO 2 –Nb/Y diagram of the tuffs/K-bentonites indicates that their protoliths were alkaline-subalkaline basalt and andesite series rock. Based on the Th–Hf/3-Ta, Th–Tb*3-Ta*2, and TiO 2 –Nb/3-Th diagrams, there are undiscovered intraplate tension calc-alkaline basalts in the northern Yangtze Platform or the southern Qinling region, which provided volcanic clastic materials to the Ziyang, Lan'gao, Chengkou, Yichang and other regions. (2) Scanning electron microscopy revealed that the barite crystals in the Longmaxi Formation exhibit dissolution features and have a large particle size. Energy spectrum analysis of these barite crystals revealed that they have C, O, S, and Ba contents of 8.48 wt%, 22.98 wt%, 13.09 wt% and 55.44 wt%, so they are speculated to have been formed via cold methane seep genesis in a weak extensional tectonic setting. The 87Sr/86Sr ratios of the barite revealed that different types of barite were simultaneously formed in this area under the influences of hydrothermal and cold methane seeps. (3) The analysis of the heavy minerals in the Lower Silurian strata in the Bajiaokou section revealed that the provenance in the South Qinling area changed significantly during the late Early Silurian. Based on the above analyses, the northern margin of the Upper Yangtze Platform was in an extensional tectonic setting during the Late Ordovician-Early Silurian. The distribution of the total organic carbon content indicated that the extensional tectonic background provided good conditions for the enrichment and preservation of organic matter. The results of this study provide an understanding of the regional sedimentary-tectonic pattern and evolution of the Yangtze Platform during this period, as well as a reference for future shale gas exploration in this region. • The tectonic background of the Late Ordovician-Early Silurian was studied. • The northern margin of the Upper Yangtze Platform is an extensional background. • The extensional tectonics caused the cold seepage events. • The extensional fault controlled the distribution of volcanic clastic sediments. • Organic matter accumulation was influenced by the extensional fault depression. [ABSTRACT FROM AUTHOR]

Caprock sealing ability is one of the key geological factors to ensure the stable and safe operation of the underground gas storage (UGS). Gypsum salt rock is the high-quality caprock for oil and gas reservoirs, however, the effect of cyclic stress on its sealing capacity is still unclear, which restricts the construction progress of this kind of UGS. Therefore, taking the H UGS in the Sichuan Basin in China as an example, this paper analyzes the initial sealing capacity of gypsum salt caprock using cast thin section, conventional physical property test, nuclear magnetic resonance and breakthrough pressure tests. On this basis, study the variation characteristics of physical and mechanical parameters of gypsum salt caprock under cyclic stress using cyclic stress loading and unloading experiment, and then analyze the evolution law of its sealing capacity. The results show that gypsum salt caprocks of H UGS can be used as a good tight caprock with the porosity less than 1.0%, permeability less than 0.005 mD, breakthrough pressure greater than 6.0 MPa and triaxial compressive strength greater than 210 MPa. In addition, the physical properties of gypsum salt caprock become worse and the sealing capacity increases under cyclic stress, and physical and mechanical changes of gypsum salt caprock mainly occur in the first 30 cycles accounting for about 75%. Moreover, with the increase of cycles, the Poisson's ratio increases by 88% while the change range of elastic modulus is only 6.4%, indicating that gypsum salt caprocks mainly expands laterally and still maintain good elasticity. However, when the cycle times reach a certain threshold of 1002, the cumulative plastic strain of gypsum salt rock will become larger and larger until fracture. And the gypsum salt caprocks can be effective cover in the 184 cycles of loading and unloading with the maximum pressure threshold of 18 MPa and minimum pressure threshold of 1 MPa. This research results can provide theoretical guidance for cap rock stability analysis and operation parameter design of gas reservoir. • The variation characteristics of physical and mechanical parameters of gypsum salt caprock under cyclic stress were analyzed • The gypsum salt caprock is dominant by the compaction of pores and microcracks and mainly occur in the first 30 cycles. • The damage variables are defined from the perspective of energy, and the fatigue life of gypsum rock is 1002 times. • The sealing capacity of the gypsum salt caprock gradually increases with the process of cyclic loading and unloading. [ABSTRACT FROM AUTHOR]

• Discovery of women's leadership roles as rescuers, decision makers and breadwinners. • Empowering women's leadership will reduce vulnerability and advance resiliency. • Supporting gender equality engagement for communities affected by disasters. • Examination of women's leadership at three post-disaster stages of their lifespans. Community engagement in disaster risk reduction activities assists women to discover and build their capacity for leadership before, during, and after disaster. In the study of the entire process after an extreme event, previous research has been scarce in the examination of women of different ages' capacities of engagement, leadership, and resilience. Developed during 10 years of ongoing research after the Wenchuan earthquake, this paper employs qualitative research methodology that scrutinizes women's leadership at different stages of their lifespans during all the post-disaster stages (emergency rescue, short-term reconstruction, and long-term recovery and mitigation) that took place after the Wenchuan earthquake, in the rural areas of Sichuan Province, China. This paper discovers that (1) during the emergency rescue stage, women became rescuers augmenting and supporting the urgent response; (2) during the short-term reconstruction stage, women served as decision makers guiding the reconstruction of housing and communities; and (3) during the long-term recovery and mitigation stage, many women took on the role of breadwinner, managing the family livelihood and long-term development. From the perspective of built environment, this paper argues that women's leadership in managing existing and obtaining new resources (internal and external), in parallel effort alongside the official missions, not only strengthened the men's dominant aftermath efforts, but also promoted gender equity engagement in post-disaster reconstruction and recovery as well as powerfully advanced resilience capacity at individual, family, and community levels. [ABSTRACT FROM AUTHOR]

The propagation characteristics and influencing factors of hydraulic fractures can be analyzed through fracturing experiments. However, there are almost no fracturing experiments in which acid fluids were considered, for the acid resistance of the equipment is always imperfect. In this paper, a physical modeling experimental equipment for acid fracturing was designed and introduced, in which corrosion protection and alternate injection were realized. The carbonate rock for acid fracturing experiment was collected from Sichuan Basin, China, which was tight with a little cavity developed. Acid fracturing experiments, in which HCL, guanidine gum and guanidine gum with an acid fluid were used as the fracturing fluids, were conducted to analyze the characteristic of acid-etched fractures. The results showed that: Acid fluid etched the fracture surface, especially in the near-wellbore area; Acid fluid would open microfractures and pores easily, and leaked into these spaces, which decreased the propagation distance of the primary acid-etched fracture; High viscosity guanidine gum was first injected and then with low viscosity acid fluid, then the latter one was transported to distal area by viscous fingering, which would lead to a better fracturing effect; Due to the acid-rock reaction, the morphology of acid-etched fracture was obviously different from hydraulic fracture, and two kinds of acid-etched fracture morphology were proposed according to the sequence of acid fluid and guanidine gum. In this paper, the characteristics of acid-etched fractures were investigated by four groups of acid fracturing experiments, which could provide a reference to optimize acid fracturing effect. • An improved acid fracturing physical modeling experimental equipment in which acid injection is allowed is developed. • Peculiar mechanical characteristics in acid fracturing are investigated and compared with hydraulic fracturing. [ABSTRACT FROM AUTHOR]

The casing deformation problems during hydraulic fracturing process in shale gas wells seriously affect multi-stage hydraulic fracturing treatment and cause significant impact on efficient exploitation of shale gas in Sichuan, China. But by now, the mechanism of these casing deformation problems has not been completely understood. The tests of the casing deformation show that the shear failure is the main type of casing deformation. Combined with the detected seismic data, the fault slip caused by hydraulic fracturing is identified as the main reason for casing deformation in shale gas wells. A deep understanding of fault reactivation and slip is significant important. Hence, a semi-analytical model for calculating induced stress along the fault caused by hydraulic fracture is established in this paper. Based on the induced stress along the fault, semi-analytical models for calculating two types of fault slip are established, including the reactivated zone located at one fault tip and the reactivated zone located away from fault tips. Additionally, the effects of fluid pressure, dip angle of fault, scale of fluid stimulated area and the friction coefficient on fault slippage are discussed. At last, the method for calculating fault slippage proposed in this paper is applied in field and the calculated result is consistent with the field data. The semi-analytical model proposed in this paper provides a reasonable way for identifying casing deformation in shale gas wells or other wells which need hydraulic fracturing treatments. [ABSTRACT FROM AUTHOR]

As an institutional innovation in the market-oriented reform of China's energy sector, the policy effect of energy consumption license transaction (ECPT) is still lack of research. The pilot provinces of energy market-oriented reform are relatively scattered. Therefore, this paper aims to evaluate the spillover effect and regional differences of ECPT, so as to make up for the lack of research on China's market-oriented energy reform. Results show that ECPT has inhibitory effects on energy consumption and energy intensity. In addition, ECPT can reduce energy consumption and energy intensity in neighboring areas. The policy effect of ECPT shows the characteristics of strengthening with the evolution of time. Foreign trade, industrial structure and technological progress are the paths for ECPT policies to promote energy transformation. The implementation effect of ECPT shows significant regional differences, which has a significant role in promoting the energy transformation of Henan and Sichuan. Therefore, the central government must ensure the continuity of energy market-oriented reforms to release long-term policy dividends. Pilot provinces should not only play the role of domestic regional energy-saving cooperation, but also strengthen foreign trade and technological innovation to promote energy transformation. • ECPT has an obvious inhibitory effect on energy consumption and energy intensity. • ECPT has the spillover effect of energy saving on neighboring provinces. • The long-term effects of ECPT are stronger than the short-term effects. • Foreign trade, industrial upgrading and technological progress are the mechanisms. • The effect of ECPT shows significant heterogeneity in different pilot provinces. [ABSTRACT FROM AUTHOR]

Chinese mole shrew (Anourosorex squamipes, Soricidae) is a small mammal, with a large population in the low mountain basin area of Sichuan, China, and it is one of the main pests in farmland. We exposed A. squamipes to cat（a natural predator） and rabbit（a non-natural predator） odors, and compared their behaviors and hypothalamus c-fos mRNA expression. This paper explored the behavioral changes in predator odor stress of A. squamipes , which reveals the shrews' stress response mechanism to natural predators. In this study, 36 Chinese mole shrew individuals were exposed to different odors for a short time (10 min) under laboratory conditions. Distilled water was used as the control group (CG), rabbit urine odor as the non-predator group (NG), and cat urine odor as the predator group (PG). SuperMaze animal behavior video analysis system was used to observe and record anti-predation behavior data. The real-time fluorescence quantitative nucleic acid amplification detection system (QPCR) was used to determine the expression of hypothalamic c-fos genes. The results showed that 1) both male and female shrews were significantly stimulated by cat odor, and their time of concealment, sniffing, wariness, and escape behavior showed significant increases, showing that the shrews responded strongly to the odors of a natural predator and showed clear anti-predation behavior. 2) different odor stimuli resulted in different expression of c-fos mRNA in the shrews' hypothalamus, and there was no significant difference between the rabbit odor treatment group and that of the control group. The expression of c-fos mRNA in the cat odor was significantly higher than other two groups, indicating that the stress response of A. squamipes to natural predator is closely related to the expression of c-fos mRNA. The result shows that A. squamipes can recognize the scent of predators and regulate their own behavior by promoting the expression of c-fos mRNA in the hypothalamus, thereby increasing the investment into anti-predation defense strategies. [Display omitted] • The shrew responded strongly to the odors of a natural predator and showed clear anti-predation behavior. • The stress response of the shrew to natural predators is closely related to the expression of c-fos mRNA. • The shrews can recognize the scents of a predator and regulate their own behavior by promoting the expression of c-fos mRNA in the hypothalamus. [ABSTRACT FROM AUTHOR]

• An optimization of eco-industrial structure considering economy-society-ecology. • A multi-objective optimization model meeting three dimensional objectives is built. • The hybrid ACO-PSO algorithm is applied to solve the model. • Optimized scenarios realize overall development of economic-social-ecological benefits. • The optimized scenarios with different tendencies promote different benefits. The establishment of ecological economic system has become the key to realize the transformation of China's economy from high-speed development to high-quality development. This paper considers the multiple goals of economic, social, and ecological benefits to achieve sustainable development. Firstly, it establishes an indicator system affecting economic, social, and ecological benefits to guide the construction of the subsequent model. Secondly, this study constructs a multi-objective optimization model for ecological industrial structure. According to the different emphasis of objectives, a hybrid approach based on ant colony optimization and particle swarm optimization (ACO-PSO) is implemented to solve the optimal solution set of feasible schemes. Finally, Sichuan Province is selected as the case study area, and three scenarios including economic oriented scenario, employment protection scenario and environment-friendly scenario are screened and analyzed. The results show that: (1) After reasonable optimization and adjustment of the industrial structure, it realizes the overall development of economic benefits, social benefits, and ecological benefits. The comprehensive benefits of sustainable development have been significantly improved. (2) The optimized scenarios with different tendencies promote different benefits. Decision makers can make better choices based on the diverse needs of the different development stage. [ABSTRACT FROM AUTHOR]

The construction and operation of the Sichuan-Tibet railway require constructing extensive supporting facilities along its route. Sichuan-Tibet transportation corridor features high mountains and deep valleys where land resources suitable for such purposes are very limited. As a result, safe utilization of the torrential fan along the railway becomes essential. Focus on buildings at the torrential fan, this paper aims to develop a vulnerability model that can assess their maximum potential damage and support the planning and development of the torrential fan. The model was developed based on 51 building damage data collected at 11 torrential fans. The hazard intensity was defined by the geometric configuration of torrential fans and the location of assessed buildings. In addition, a physical experiment was carried out to study the shielding effect of building groups. The results show that the shielding effect range is about 25 times the building size, and the maximum reduction in impact force can reach 60%. The advantage of the proposed vulnerability assessment model is that it only requires the spatial information of the site that can be easily derived from the satellite image. In addition, the model can reflect the complex torrential process and the shielding effect of building groups. This study provides an alternative approach to building vulnerability assessment. It supports the planning and development of torrential fans when constructing the supporting facilities for the railway construction and operation. • The intensity of torrential hazards at each building is defined by the fan's geometric configuration and the assessed building's position. • The proposed model is easily adaptable since the required data is widely accessible from the satellite image. • The shielding effect of building groups when subject to torrential hazards is considered in this vulnerability assessment model [ABSTRACT FROM AUTHOR]

• The desorption mechanism of oil from the nano-micro pores was studied. • The oil is desorbed when the particle self-rotation speed is faster than the critical speed. • When the inlet flow rate increased, the particle self-rotation speed increased, which could strengthen the desorption process. To realize the harmless treatment and resource recycling of oily shale cuttings, the most important step is to desorb the oil phase from the pores of the cuttings. The desorption treatment must overcome the capillary force and viscous resistance inside the pores. This paper discusses a cyclone oil desorption technology. The particles of the oily shale cuttings in the swirl field generated by the cyclone will have high-speed self-rotation, thus providing sufficient centrifugal forces that separate the phase oil from the pores. The critical speed of such self-rotation for the desorption of oil phase in pores of particles was analyzed using mechanical formula, and the distribution of particle self-rotation speed in the cyclone was calculated and simulated. We collected shale cutting samples from the Sichuan shale gas field in China. Experiments were conducted to observe the changes in the porosity and oil content of the cuttings before and after cyclone desorption treatment. The results show that the particle self-rotation in the cyclone can effectively achieve the oil phase desorption from the particle pores. For the shale cuttings in the experiments, when the particle self-rotation speed is faster than the critical self-rotation speed of 507 rad/s, the oil phase in the particle pores can be desorbed. When the inlet flow rate is between 55 m3/h − 95 m3/h, the particle self-rotation speed is faster than the required critical self-rotation speed. As the inlet flow rate increases, the particle self-rotation speed in the cyclone also increases, which generates better desorption effects. [ABSTRACT FROM AUTHOR]

The Nb-Ta-Zr-Hf-REY-Ga mineralization in the Late Permian coals in southwestern China has been well investigated by several studies and has generally been attributed to alkaline pyroclastics coupled with input from hydrothermal fluids. The Late Triassic is one of the important coal-forming periods but the critical element mineralization in coals of this geological age has not been well documented. In this paper, the mechanism of Nb-Ta-Zr-Hf-REE-Ga-Th-U mineralization in the K5 coal seam of the Upper Triassic Xujiahe Formation from the Gaosheng Mine, Sichuan Basin, southwestern China, was investigated. The K5 coal is a high-ash, low-sulfur, and low-volatile bituminous coal. The minerals in this coal include illite, kaolinite, quartz, and, to a lesser extent, anatase, calcite, chamosite, bassanite, and pyrite, along with traces of ankerite, rutile, and zircon. Compared with the averages of common world hard coals, the studied coals are enriched in critical elements including Zr (247 ppm), Hf (5.56 ppm), Nb (23 ppm), Ta (1.55 ppm), rare earth elements and yttrium (REY, 168 ppm), Ga (18.3 ppm), Th (14.1 ppm), and U (6.18 ppm) (all on a whole coal basis). The Al 2 O 3 /TiO 2 ratios, Eu anomalies, and the relationships of Al 2 O 3 /TiO 2 vs. Zr/TiO 2 and Nb/Yb suggest that the sediment-source rocks of the Gaosheng coals were Neoproterozoic and Early-Middle Triassic felsic-intermediate igneous rocks from the southeastern Qinling and Longmenshan Orogens, along with the Hannan and Micangshan-Dabashan Uplifts. Other probable sources are contemporaneous felsic-intermediate pyroclastics from the Late Triassic volcanic areas around the Sichuan Basin (i.e., East Kunlun Orogen, West Qinling Orogen, and East Tibetan Plateau). The relationships of Al 2 O 3 /TiO 2 vs. Zr/Al 2 O 3 , Al 2 O 3 /TiO 2 vs. Nb/Al 2 O 3 , Ga/Al 2 O 3 , and Al 2 O 3 /TiO 2 vs. LREY/Al 2 O 3 further indicate that the elevated concentrations of Nb(Ta)-Zr(Hf)-REY-Ga in the Gaosheng coal are probably sourced from both the erosion of sediment-source regions and contemporaneous pyroclastics. The illite-kaolinite aggregates with a vermicular texture and authigenic illite, quartz, anatase, pyrite, calcite, ankerite, barite, and REE-rich minerals, REY distribution patterns, as well as elemental variation trends of the coal seam, collectively indicate that the studied coals were likely influenced by multiple-stage infiltration of various solutions. These solutions leached the fresh pyroclastics and products of erosion derived from granites in the sediment-source regions, leading to redistribution of the critical elements (e.g., Zr, Nb, and HREY) between the roof, floor, and parting mudstones and the coal benches. The concentrations of (Nb,Ta) 2 O 5 , (Zr,Hf) 2 O 5 , and Ga in the coals are 107, 1093, and 57.6 ppm, respectively, close to or higher than the marginal grade of conventional ore deposits for these elements, and thus the Gaosheng coals have potential as raw materials for the recovery of the critical metals Nb, Ta, Zr, Hf, and Ga. [Display omitted] • The coal contains elevated concentrations of Nb, Ta, Zr, Hf, REE, Ga, Th, and U. • The sediment-source region of the coals was felsic-intermediate igneous rocks. • Elevated concentrations of critical elements in coal due to products of erosion and pyroclastics. • The coals are likely influenced by the multiple-stage infiltration of acid solutions. • The acid solutions leached the fresh pyroclastic and terrigenous materials. [ABSTRACT FROM AUTHOR]

This paper reports the geochemical and mineralogical compositions of the Late Permian No. 25 Coal (semi-anthracite) and its host rocks (roof and floor strata) from the Guxu (Gulin–Xuyong) Coalfield, Sichuan Province, China. The coal is characterized by medium-sulfur content (average 2.73%) and has an average ash yield of 20.95%. In contrast to other Late Permian coals from southwestern China that are enriched in Sc, V, Cr, Co, Ni, and Cu, the No. 25 coal does not contain an abundance of these transition elements but is rich in lithophile elements Be, Y, Nb, Zr, Hf, and U. The elevated concentrations of trace elements in the No. 25 Coal were probably derived from the felsic–intermediate rocks at the top of the Emeishan basalt sequence, rather than from the Emeishan mafic basalts. The floor strata of the No. 25 Coal can be divided into two sub-sections. The upper sub-section of the sequence immediately below the No. 25 Coal consists of material with a felsic–intermediate composition probably derived from terrigenous sources and the lower sub-section is composed of mafic tuff. The terrigenous mineral matter in the No. 25 coal appears to have the same sediment-source region as the upper sub-section of the floor strata, based on their similar geochemical compositions. The roof strata of the No. 25 Coal are more quartzose, and were probably derived from a different sediment-source region. The mineral matter in the coal is dominated by kaolinite and, to a lesser extent, calcite and pyrite; the roof and floor strata each have quite different mineralogy, with kaolinite dominant in the latter and illite, kaolinite and quartz in the former; pyrite contents are variable both in the coal and in the host rocks. The floor strata and the coal have been affected by hydrothermal solutions, leading to the enrichment of rare earth elements and yttrium (REY), Nb, Ta, Zr, Hf, and U. The REY in the coal and floor strata, as well as the Nb, Ta, Zr, Hf, and U in the floor strata, represent potentially economic rare metal resources. [ABSTRACT FROM AUTHOR]

In this paper, the core shale samples from the Lower Longmaxi Formation (LF) in the southwest of the Sichuan Basin of China are carried out laboratory experiments to investigate the wettability and adsorption characteristics. The influences of the wettability on the development of the shale gas reservoirs were discussed. And the influences of the kerogen and the pure mineral on the methane adsorption capacity were discussed. The differences between the methane adsorption capacity of the pure mineral and the mixed minerals were also discussed. The results show that the spontaneous imbibition rate of the LF shale samples tended to rise firstly and then become stable with the increasing of the time; The spontaneous imbibition rate of water was higher than the spontaneous imbibition rate of oil; The methane adsorption capacity on the kerogen and the pure minerals first increased rapidly and then increased slowly and tended to be stable with the increasing of the pressure; The methane adsorption capacity on the kerogen was much larger than the different pure minerals; And among the different pure minerals, the order of the methane adsorption capacity is that: illite > chlorite > quartz; The water molecules would reduce the methane adsorption capacity on the Kerogen; The methane adsorption capacity of the mixed minerals can be approximately equal to the sum of the methane adsorption capacity of the pure minerals calculated by the mass ratios. The water blocking damage in the shale formation can’t be assessed according to the water blocking damage evaluation system of the conventional oil and gas reservoirs. The mixed wettability, the influence of the water on the methane adsorption capacity and water-induced cracks should be considered in the water blocking damage evaluation system of the shale reservoir. [ABSTRACT FROM AUTHOR]

The Emei Shan stands on the southeast side of the Longmen Shan. It marks the southeastern most edge of the eastern margin of the Tibetan Plateau (EMTP) and towers above the Sichuan Basin to its east, with the highest peak being 3099 m. A large number of structural and thermo-chronological studies have been published focused on the Longmen Shan orogen, which is considered to be the northern part of the EMTP. However, for the southern part of the EMTP where the Emei Shan lies, its tectonics and uplift history are still poorly understood. This paper dates five granite samples from the Emei Shan batholith using the apatite fission track (AFT) method. The boundary faults of the Emei Shan and structural deformation in adjacent region are also investigated and mapped in detail. (1) In Miocene time, compressional stress from the eastward extrusion of the EMTP caused large-scale thrusting and mountain uplift along narrow Longmen Shan in northern EMTP, in contrast to southern EMTP where a broad and gentle Yaan−Emei Shan fold belt absorbed most of the stress. By Pliocene time, the southeastward extrusion of the Tibetan Plateau caused the transpressional stress and rotated the Chuandian fragment along the Xianshuihe−Xiaojiang fault belt. As a consequence, the Emei Shan region was intended northeastwards into the Sichuan Basin, bounded by two strike-slip faults on its north and southeast sides. (2) The AFT results show the Emei Shan uplifted since ∼25–20 Ma ago. The threshold and main stage of uplift of the Emei Shan possibly lagged behind the Longmen Shan of approximately 5 Myr. As the leading edge of fold belt, uplift of the Emei Shan indicated the eastward propagation of the EMTP was time-transgressive from Late Oligocene to Middle Miocene. [ABSTRACT FROM AUTHOR]

The distinctive features of the Lower Devonian rocks of the Longmenshan area in southwestern China are brachiopod shell concentrations, especially in the Bailiuping, Ganxi and Xiejiawan Formations, where brachiopod shell concentrations occur widely throughout. Depending on the dominant skeletal elements, six types of shell concentrations can be distinguished: Protochonete , Acrospirifer , Howellella , Orientospirifer , polyspecific shell and polyspecific fragments concentrations. According to the shell features, taphonomic signature, host sediments and their relationships, four genetic models of the various shell concentrations are described in this paper. The genetic processes and distributions along an onshore–offshore area were clarified on the base of taphonomic analysis. Pavements of opportunistic species of Protochonetes are autochthonous assemblages living in quieter, deeper, more offshore waters near the maximum storm wave base. The pavements are the result of reduced sedimentation; the substrate was silty and water-saturated with variable turbidity soupy-mud. Transport by high-energy processes is interpreted as the final formation process of polyspecific fragments concentrations with most extensive scope from intertidal zone to the maximum storm wave base. The Acrospirifer , Howellella , and Orientospirifer concentrations have been stirred by storm wave action and quickly buried after short transport tempestite model. They are most easily preserved around the average storm wave-base. The polyspecific shell concentrations, which include large bivalves are autochthonous assemblages living in shallow and relatively quieter water near shore environments. Autochthonous assemblages of the opportunist Protochonetes bailiupingensis occurring in the Bailiuping Formation of the Longmenshan area not only record of storm events, but are also important features to identify and correlate the Bailiuping Formation in the field. [ABSTRACT FROM AUTHOR]

The fold-and-thrust belt in the eastern Sichuan basin is represented by a series of subparallel chevron anticlines. Under the orogenic tectonic setting within the South China Block in Meso-Cenozoic period and the influence of the multi-layer detachment fault, the deformation of the thrust belt exhibits remarkably layered and large-scale intracontinental thrusting structural characteristics. In this paper, we focus on the structural geometry and deformational mechanisms using the latest two-dimensional (2D) and three-dimensional (3D) seismic reflection data in combination with well and outcrop data. The multi-layer detachment faults, especially the upper gypsum-bearing detachment in the Middle Triassic Jialingjiang Formation and lower detachment with gypsum or shale in the Lower–Middle Cambrian system, directly control the deformational styles of the study area. Interpretation of seismic sections indicates that the fold-and-thrust belt has various deformational styles during folding, including fault-propagation fold, fault-bend fold, and detachment fold with box-fold or pop-up structural geometry. Regional location and structural boundaries play significant roles in controlling the deformational styles, and distinct differences exist among the different anticlines. The Huayingshan anticline located at the front of the thrust belt shows intense structural deformation with northwestward thrusting direction and a relatively weak opposite southeastward thrusting. In addition, the anticlines exhibit structural differences along strike and the fold-and-thrust belt in the northern segment is influenced by the North China Block. [ABSTRACT FROM AUTHOR]

The Mianning–Dechang (MD) REE belt of Sichuan, China is one of the most important REE belt in China, which includes Maoniuping, the third largest REE deposit in the world and a series of large to small REE deposits. Mineralization styles varied across the belt, as well as within different parts of the same deposit. Styles include vein-stockworks, pegmatites, breccias and disseminated REE mineralization. Based on geological, geochemical and inclusion studies, this paper proposes a new model for carbonatite hosted REE mineralization. The results show that ore-forming fluid is derived from carbonatite magma, which has high temperature, pressure and density, and is characterized by high K, Na, Ca, Sr, Ba, REE and SO 4 contents. The supercritical ore fluid underwent a distinctive evolution path including phase separation, exolution of sulfate melt and unmixing between aqueous fluid and liquid CO 2 . Rapid geochemical evolution of a dense carbonatite fluid causes REE mineralization and associated alteration to occur within or proximal to the source carbonatite. Veins, pegmatites and carbonatite comprise a continuum of mineralization styles. Veins occur in the outer zone of the upper levels of the deposit. Pegmatites occur in the inner zone of upper levels, whereas disseminated REE ore occurs at the base of the carbonatite. High water solubility in the carbonatite magma and low water, high REE in the exsolved ore-forming fluids, imply that a giant carbonatite body and deep magma chamber are not necessary for the formation of giant REE deposits. [ABSTRACT FROM AUTHOR]

In this paper, sea-level fluctuations during the Carnian Pluvial Episode (CPE) are investigated. A revision of published data from multiple successions worldwide indicates a sea-level drop that occurred in different geodynamic settings after the onset of the first of multiple carbon-isotope perturbations that characterize the CPE. New stable isotope data, zircon U-Pb geochronology, carbonate petrology, conodont and foraminifer biostratigraphy from the Carnian of the Sichuan Basin and comparison to the well-dated coeval successions of the Dolomites allow pinpointing with unprecedented precision this sea-level fall and determine that it occurred after the onset of the first, but prior to the third negative δ 13 C shift of the CPE. These lines of evidence indicate that such sea-level oscillation was eustatic. Facies analysis and sequence stratigraphy of units deposited during the ensuing sea-level rise in the Sichuan and Dolomites, further show that a Tethys-wide crisis of microbial carbonate production and drowning of carbonate platforms were followed by a recovery of marine calcification, widely testified by the deposition of oolitic bodies. Whereas a Tethys-wide recovery of microbial carbonate production is documented at the end of the Carnian, this increase in chemical calcification occurred earlier, at the beginning of the Tuvalian, and suggest that global transformations in carbonate systems coincident with the CPE were complex and share commonalities with other times in the geological record when a similar evolution was linked to ocean acidification. • New bio-, chrono-, chemostratigraphic and sedimentological data on the CPE. • Tethys wide correlation of carbonate platform successions across the CPE. • Correlations and sequence stratigraphy highlight an eustatic sea-level fall. • Results suggest global fluctuations in carbonate production during the CPE. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pure microbial carbonates and marine fibrous cements can record the original Precambrian seawater chemistry. • Carbonate rocks of the Ediacaran Dengying Formation were deposited from seawater under suboxic conditions with high salinity. • Seawater oxygen concentration increased and salinity decreased gradually during the deposition of the Dengying Formation. • The suboxic and high-salinity seawater contributed to the development of the Precambrian microbial carbonates. Abundant microbial carbonates with well-preserved primary textures occur in the upper Ediacaran Dengying Formation in the Sichuan Basin, southwest China, providing an opportunity to study the paleoceanographic conditions and the origin of Precambrian microbial carbonates. However, paleoenvironmental studies of these microbial carbonates are relatively rare, especially with respect to the comparison between the upper and lower parts of the Dengying Formation. In this paper, we present new analyses of carbon and oxygen isotopes and major, trace, and rare earth elements (REEs) for carbonate rocks from the Dengying Formation, in order to reveal the paleoceanographic redox and salinity conditions of the seawater from which these rocks were deposited. These rocks have shale-normalized REE and Y patterns that display weak negative Ce anomalies, weak positive Eu anomalies, and moderate middle REE enrichment, indicating the suboxic seawater for their deposition. From the lower to upper parts of the Dengying Formation, negative Ce anomalies become more prominent, while positive Eu anomalies and middle REE enrichment weaken, suggesting a gradual increase in the seawater oxygen concentration. The heavier oxygen isotopes of the carbonate matrixes and fibrous cements in the second member of the lower part of the Dengying Formation reflect a higher seawater salinity, conforming to the thick evaporates in the second member. The elevated oxygen content and decreased salinity in the seawater promoted the emergence of metazoans that inhibited the growth of microbes, causing the decreasing development of microbial carbonates in the upper part of the Dengying Formation compared to the lower part. [ABSTRACT FROM AUTHOR]

The terrain along the Tibet Railway is primarily steep mountains and valleys with complex geological structures. The occurrence of the Mainling earthquake indicates that the intensity of seismicity in the eastern structural junction area has strengthened, and the potential risk of earthquake-induced disasters such as landslides and debris flows is also increasing. The earthquake engineering community generally recognizes that the prediction of near-field strong ground motion can reduce the disasters caused by future large earthquakes and can guide earthquake prevention, disaster reduction and seismic design along the Sichuan–Tibet railway. The M6.9 Mainling earthquake affected the stability of Sedongpu Glacier near the epicentre. A glacier avalanche occurred under the coupling of multiple factors, including post-earthquake and precipitation events. The waveform and response spectra of a strong earthquake are key input parameters for investigating the seismic triggering mechanisms of landslides and glacier avalanches and accurately reproducing the dynamics of such disasters. In this paper, the concept of the equivalent Green's function is introduced, and various source parameter uncertainties are fully considered. The waveform and response spectra of the Mainling earthquake at Sedongpu Glacier are simulated, and the most likely seismic waveform is comprehensively assessed from multiple perspectives. This work can provide reliable acceleration waveform input for the analysis of ground motion damage and the study of earthquake-induced disaster mechanisms at important locations along the Sichuan–Tibet railway and provide a scientific reference for earthquake prevention and disaster reduction along the railway. • The concept of equivalent Green's function is proposed. • The waveform containing many practical and complex information for seismic damage analysis • It expands the application range of empirical Green function method. • It could help to study the mechanism of earthquake induced geological hazards. [ABSTRACT FROM AUTHOR]

Deep shale gas reservoirs, compared to shallow and intermediate shale gas reservoirs, usually exhibit lower fracture complexity, smaller stimulated volume, poorer conductivity, and faster production decline when the same injection scheme and construction parameters are used. As a result, specific injection scenarios for deep shale reservoirs must be investigated. In this paper, a series of laboratory fracturing tests were conducted to investigate the influence of injection scenarios on deep shale hydraulic fracture initiation and propagation. The black shale of the Lower Silurian Longmaxi formation in the Sichuan Basin was adopted, and four different injection schemes (constant fluid rate injection, cyclic injection, shut-in intermittent injection, and low-frequency pulse pressurization injection) were utilized in these experiments. The energy evolution during hydraulic fracturing with different injection schemes was analyzed by an array of acoustic emission (AE) sensors. Furthermore, the internal fracture geometry of the shale specimens after failure was determined using high-resolution CT scanning. Two parameters, fracture bulk density and fractal dimension were defined to quantitatively characterize the post-pressure fracture complexity. The results indicate that the rock breakdown pressure rises rapidly as the injection rate increases, for conventional monotonic rate injection. Although increasing the injection rate can serve the purpose of increasing the net pressure in the seam and enhancing the fracture complexity, it makes it easier to approach the equipment pressure limit. Unlike conventional hydraulic fracturing, which mainly induces tensile fractures near the wellbore, cyclic fracturing is more likely to cause fatigue damage to the rock, resulting in the formation of subcritical microcracks, which gradually grow into macroscale fractures. In addition, the cyclic injection method can reduce the rock breakdown pressure by approximately 24% compared with the conventional continuous injection method. The shut-in intermittent injection method can also reduce the breakdown pressure of shale by 22%, but this method is not conducive to enhancing the fracture complexity. Pulse fracturing creates the most complex fracture morphology among the four injection schemes tested. The rapid changes in wellbore pressure over a short time can easily result in the formation of multiple fractures around the borehole. Our experimental results and theoretical analysis can provide theoretical support for the optimization of injection schemes for deep shale hydraulic fracturing. • Laboratory tests were conducted to investigate the influence of injection scenarios on deep shale hydraulic fracturing. • All the experiments were monitored by an array of AE sensors. • The internal fractures geometry of the shale specimens after failure was determined by high-resolution CT scanning. • The cyclic fracturing can reduce the breakdown pressure by about 24% compared with the conventional continuous injection method. [ABSTRACT FROM AUTHOR]

Sichuan basin is a superimposed basin of marine sediment and continental sediment in Southwest China. The great potential of the deep reservoir in Sichuan basin motivated geophysical studies on the deep structure in this area. Limited by the penetration depth of seismic exploration, the gravity inversion is widely applied to study the deep structure and the density properties. This paper inverted the 3D density distribution of Sichuan basin based on gravity inversion with reweighted regularized conjugate gradient algorithm. The proposed algorithm was tested and verified with two synthetic models. For the application in Sichuan basin, an initial model based on former studies was built to reach a reasonable model in the shallow part structure. The inversion result gave the 3D density structure of Sichuan basin with 60 km in depth. It illustrated the basic layered structure and the horizontal inhomogeneous features from the sedimentary layer to the deep crust. The density features of 7–12 km in depth revealed the basement structure with three parts, which was consistent with the velocity structure on the whole. The high density feature of Dazu area might indicate the local mantle uplift. • 3D density of Sichuan basin is inverted with the reweighted regularized algorithm. • 3D density shows the layered structure and lateral heterogeneity of Sichuan basin. • Basement and deep crust of Sichuan basin are mainly divided into three parts. • High density in the deep part of Dazu area may indicate local mantle uplift. [ABSTRACT FROM AUTHOR]

Microseismic monitoring is a widely used technique in coal mine safe production. Microseismic events classification is one of the most important steps in microseismic monitoring. CNN has been proven to be the potential tool to identify microseismic events automatically. When the noise is serious and the signal is weak, the recognition ability of CNN is limited. Some scholars use denoising methods, such as wavelet transform, to enhance the signal-to-noise ratio (SNR) of the input data. However, the effective signal will be broken if the incorrect threshold parameters are set in this wavelet transform-based denoising method. In this paper, we intend to make the data volume of the time-frequency graph obtained by WPT as the input of CNN. But it may lead to a dimensional disaster if taking the time-frequency domain signals as input directly. To utilize the effective information extraction and reduce the data dimension, we propose a dual-channel CNN model by combining time domain information and wavelet packet decomposition coefficients (T-WPD CNN). The wavelet packet decomposition coefficients highlight the characteristics of the signal and suppress the characteristics of noise. In addition, the coefficients have the same dimension as the original signal. These advantages are useful for enhancing the performance of CNN. Two field datasets are used to test the network. One from Australia and another from Jiayang coal mine, Sichuan, China. The feature map of the convolutional layer with different inputs are shown to illustrate the influence effect of raw time domain signal and WPD coefficient on the classification performance. The final results show that the T-WPD CNN is superior to the traditional CNN method in accuracy and robustness. • The network combines time-domain information and wavelet packet decomposition coefficients of the microseismic data. • The more obvious feature map of the microseismic is extracted, which makes the classification performance better. • The wavelet packet decomposition coefficients can avoid the dimensional disaster of the input data. [ABSTRACT FROM AUTHOR]

[Display omitted] • The shale gas resource potential of the Longmaxi Formation was evaluated by using mud gas isotope logging technology. • The reservoir properties of shale were evaluated based on gas isotope fractionation effects. • The shale gas in the Changning area belongs to late kerogen cracking gas. • The lower part of the Longmaxi Formation has a better shale gas exploration potential. The Longmaxi Formation in the Sichuan Basin is one of the most important shale gas producing formations in China. Previous studies of shale gas were mostly carried out on based on laboratory analyses and did not provide effective guidelines for shale gas exploration. In this paper, we present a large amount of carbon isotopic data from mud gas isotope logging and rock-cutting headspace gas in wellsites. The δ13C 1 values showed a significant decrease at the bottom of the Longmaxi Formation. The δ13C 1 and δ13C 2 values in the Changning area were observed to be heavier than those in the Weiyuan and Jiaoshiba areas. The second half of the N216H27-3 horizontal well had obvious outgassing and carbon isotope fractionation effects. This indicates that the bottom of the Longmaxi Formation has better shale gas exploration potential. The shale gas of the Longmaxi Formation in the Changning area belongs to late kerogen cracking gas, where exploration prospects are poorer than those in the Weiyuan and Jiaoshiba areas. There were more oil cracking gas resources and better reservoir conditions at the end of the N216H27-3 horizontal well; therefore, drilling should be continued at this site. [ABSTRACT FROM AUTHOR]