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On 1 June 2022, a magnitude 6.1 earthquake struck the southern segment of the Longmenshan fault zone on the eastern edge of the Tibetan Plateau, once again causing casualties and economic losses. Understanding the deep-seated dynamic mechanisms that lead to seismic events in the Lushan earthquake area and assessing the potential hazards in seismic gap areas are of significant importance. In this study, we utilized 118 magnetotelluric datasets collected from the Lushan earthquake area and employed three-dimensional electromagnetic inversion with topographic considerations to characterize the deep-seated three-dimensional resistivity structure of the Lushan earthquake area. The results reveal that the Shuangshi–Dachuan fault in the Lushan earthquake area can be divided into two relatively low-resistivity zones: a western zone dipping southeastward and an eastern zone with a steeper slightly northwestern dip. These two zones intersect at a depth of approximately 20 km, forming an extensional pattern resembling a "Y" shape. The epicenters of both the 2013 and 2022 Lushan earthquakes are primarily located in the upper constricted portion of the pocket-like low-resistivity body at depth. The distribution of seismic aftershocks is confined within the region enclosed by the high-resistivity body, following the pattern of the Y-shaped low-resistivity zone. [ABSTRACT FROM AUTHOR]

Background: Leeches are an integral component of aquatic biocenosis and can be found in a wide range of ecosystems such as freshwater, saltwater, flowing, and still-water ecosystems. It especially plays an important role in the freshwater benthic community and is an important part of the food web. In this study, a leech species was found in the mantle cavity of wild freshwater mussels in Zigong City, Sichuan Province, China, and its identity was determined through morphological analysis and molecular biological analysis. Results: The leech is Hemiclepsis khankiana, a new species of Hemiclepsis that has been discovered in Russia in recent years. Through morphological analysis, the current survey observed that the morphological characteristics of Hemiclepsis khankiana eyespots were significantly different from the first reported description. The first pair of eyespots on the leech were separated and clear, while it had been reduced to unclear shadows in the previous report. The phylogenetic tree based on the COI gene showed that the COI gene sequence obtained in this study was in the same evolutionary branch as Hemiclepsis khankiana (MN295420, MN295421). Genetically, it was most closely related to Hemiclepsis kasmiana (mean COI p-distance = 3.98%). Conclusions: The current study reported on the new distribution range of Hemiclepsis khankiana, which was initially discovered in China. This study indicates that the distribution range of the leech species has expanded, laying a foundation for further studies in China. [ABSTRACT FROM AUTHOR]

The escalation of urbanization in Sichuan Province has resulted in irrational land use and excessive resource exploitation. These developments have consequently diminished the functionality of ecosystem services and exacerbated landscape fragmentation in the region. These challenges pose significant threats to the ecological security of the area. In this study, we computed the ecosystem service value and the landscape ecological risk index of Sichuan Province from 2005 to 2018. We analyzed the spatial autocorrelation between the ecosystem service value and the landscape ecological risk index, constructing a framework for landscape ecological risk assessment and zoning control based on ecosystem service value. The results show the following: (1) Between 2005 and 2018, the total value of ecosystem services in Sichuan Province increased from CNY 10,261.17 × 108 to CNY 10,310.43 × 108, with forest land and grassland being the primary contributors to the ESV. (2) High- and higher-risk areas within the landscape ecology of Sichuan Province are expanding, forming a pattern of high-level risk concentration from west to east. (3) There exists a negative correlation between the ecosystem service value and the landscape ecological risk index in Sichuan Province. (4) In the ecological conservation zone, the principle of low-impact development must be upheld. In the ecological cultivation zone, adjusting the proportion of land use types is necessary to enhance the rationality of the land use structure. The ecological agricultural zone should fully utilize the advantages of agriculture, while the ecological improvement zone requires focused attention to ecological restoration and land remediation. [ABSTRACT FROM AUTHOR]

In order to improve the recovery rate of barite in high-density waste drilling fluid from oil and gas wells, the high-density waste drilling fluid from the centrifuge discharge of shale gas wells in the southern Sichuan area was used as the research object, and the low-density solid phase was removed by the reverse flotation process, and the effect of the new inhibitor junction cold gel on the flotation behavior of barite and low-density solid phase in high-density waste drilling fluid was studied. The corresponding mechanism of action was investigated by wettability and zeta potential tests. The results showed that the flotation process of "one roughing, two cleaning and one scavenging" with the dosage of 700 g/t of sodium dodecyl sulfate and 700 g/t of junction cold gum could obtain a barite concentrate with a combined recovery of 84.99%, a combined grade of ≥95 % and a barite density of ≥4.2 g/cm³. Wettability and zeta potential test analysis showed that the adsorption between gellan gum and barite was carried out in the form of hydrogen bonding, and could hinder the subsequent adsorption of sodium dodecyl sulfate, while the adsorption of low-density solid phase almost did not occur, improving the hydrophilicity of barite and low-density solid phase and the final separation. [ABSTRACT FROM AUTHOR]

Organophosphate esters (OPEs) are emerging pollutants. Currently, research on OPEs in tree rings is still limited. In this study, tree rings of five arbor species from Sichuan Province, China, were sampled to study the occurrence and distribution of six OPEs, which were quantitatively analyzed by gas chromatography–mass spectrometry (GC–MS). The total concentrations of OPEs in all samples ranged from 189.79 (Fir species) to 341.23 ng/g (Toona sinensis), with average concentration of 284.77 ± 46.66 ng/g. So, arbor could be used as good passive samplers for OPEs. The levels of OPEs among five arbor species showed no significant difference (p = 0.668 > 0.05), suggesting that the pollution status of OPEs in a region or country could be roughly assessed by any arbor tree species. In this study area, tris(2-butoxyethyl) phosphate (TBEP) was the dominant OPEs followed by tri(2-chloroethyl) phosphate (TCEP). Tris(2-ethylhexyl) phosphate (TEHP) and tri-n-butyl phosphate (TnBP) showed relatively stable concentrations in each arbor species, while the other four OPEs including TBEP, triphenyl phosphate (TPhP), tri(chloropropyl) phosphate (TCPP) and TCEP had significantly different concentrations. Interestingly, the absorption and accumulation of OPEs by tree rings of arbor species were quite different from that of inorganic elements reported by other studies. [ABSTRACT FROM AUTHOR]

The total number of spikelets (TSPN) and the number of fertile spikelets (FSPN) affect the final number of grains per spikelet in wheat. This study constructed a high-density genetic map using 55K single nucleotide polymorphism (SNP) arrays from a population of 152 recombinant inbred lines (RIL) from crossing the wheat accessions 10-A and B39. Twenty-four quantitative trait loci (QTLs) for TSPN and 18 QTLs for FSPN were localized based on the phenotype in 10 environments in 2019-2021. Two major QTLs, QTSPN/QFSPN.sicau-2D.4 (34.43-47.43 Mb) and QTSPN/QFSPN.sicau-2D.5(32.97-34.43 Mb), explained 13.97%-45.90% of phenotypic variation. Linked kompetitive allele-specific PCR (KASP) markers further validated these two QTLs and revealed that QTSPN.sicau-2D.4 had less effect on TSPN than QTSPN.sicau-2D.5 in 10-A×BE89 (134 RILs) and 10-A×Chuannong 16 (192 RILs) populations, and one population of Sichuan wheat (233 accessions). The alleles combination haplotype 3 with the allele from 10-A of QTSPN/QFSPN.sicau-2D.5 and the allele from B39 of QTSPN.sicau-2D.4 resulted in the highest number of spikelets. In contrast, the allele from B39 for both loci resulted in the lowest number of spikelets. Using bulk-segregant analysis-exon capture sequencing, six SNP hot spots that included 31 candidate genes were identified in the two QTLs. We identified Ppd-D1a from B39 and Ppd-D1d from 10-A and further analyzed Ppd-D1 variation in wheat. These results identified loci and molecular markers with potential utility for wheat breeding and laid a foundation for further fine mapping and cloning of the two loci. [ABSTRACT FROM AUTHOR]

Understanding the factors driving ecosystem service (ES) change is essential for maintaining ES functions and achieving sustainable development. Although research on the spatial variations in the effects of driving forces on ESs provides guidance for regional ecological management, the responses of driving forces to environmental conditions have not been adequately investigated, especially in regions with high spatial heterogeneity. By using remote sensing images and socioeconomic data, this paper aims to fill this gap by estimating the spatial distribution characteristics of the effects of driving forces on ESs and their responses to different environmental conditions in Sichuan Province, China. First, the biophysical values of soil conservation (SC) and water yield (WY) were evaluated using ecological simulation models. Second, the spatial distribution of the effects of four driving forces on two services was explored using the geographically weighted regression (GWR) model. Finally, the responses of driving forces to environmental conditions were quantified by using scatter plots. The results revealed that the spatial patterns of SC and WY showed spatial heterogeneity. The effects of driving forces on ESs varied with space. Both positive and negative effects of driving forces were observed in Sichuan Province. Under different biophysical and socioeconomic conditions, the effects of driving forces on ESs showed different change trends, characterized by fluctuating trends and obvious thresholds. In our study area, urban sprawl, impervious surfaces, agricultural expansion, intensive human activities, and complex topographic features contributed to the variations in the effects of driving forces. Our results suggest that the responses of driving forces to different land-use coverage, topographical, NDVI, and socioeconomic conditions should be considered in ecological decision-making. Such research results are expected to manage the driving forces of ESs and serve as a practical reference for local management in order to maintain the functions of ESs and attain sustainable development. [ABSTRACT FROM AUTHOR]

Driving forces are the factors that lead to the observed changes in the quantity and quality of ecosystem services (ESs). The relationship between driving forces and ESs involves considerable scale-related information. Place-based ecological management requires this information to support local sustainable development. Despite the importance of scale in ES research, most studies have only examined the association between ESs and their drivers at a single level, and few studies have examined this relationship at various scales or analyzed spatial heterogeneity. The purpose of this paper is to explore the significance of the scale-dependent effects of drivers on ESs for localized ecological management. The biophysical values of ESs were calculated using several ecological simulation models. The effects of driving forces on ESs were explored using the geographically weighted regression (GWR) model. Variations in the effects of driving forces on ESs were examined at three scales: provincial, ecoregional, and subecoregional scales. Finally, canonical correlation analysis was used to identify the major environmental factors associated with these variations in each ecoregion. Our results show that (1) the distribution of soil conservation and water yield is highly heterogeneous; (2) four driving forces have significant positive and negative impacts on soil conservation and water yield, and their effects on the two services vary spatially (p < 0.05); (3) the impacts of drivers on ESs vary across different spatial scales, with a corresponding shift in the related environmental factors; and (4) in the study area, at the provincial scale, physical, topographical, and biophysical factors were key factors associated with the variations in the relationship between ESs and drivers, and at the ecoregional and subecoregional scales, physical, socioeconomic, topographical, and biophysical factors all contributed to these changes. Our results suggest that significant differences in topographical conditions (e.g., altitude, slope) can be incorporated for exploring the relationship between drivers and ESs and optimizing ecological management at the provincial scale, whereas significant differences in physical and socioeconomic conditions (e.g., urbanization levels, human activity, vegetation coverage) are more meaningful for localized ecological management at the ecoregional and subecological scales. These findings provide a basis for understanding the relationship between drivers and ESs at multiple scales as well as guidelines for improving localized ecological management and achieving sustainable development. [ABSTRACT FROM AUTHOR]

Conventional triaxial loading and unloading tests were carried out on sandstone samples in the Zigong area, of Sichuan Province, China. The changes in the elastic modulus of the unloading curves under different confining pressures were calculated, and the evolution law of the nonlinear properties of rock was analyzed. The results show that the rock is subjected to nonlinear damage during initial compaction, the elastic phase, destruction, and postpeak unloading. Moreover, the nonlinear behaviors of rock are restrained by the confining pressures. On this basis, a nonlinear stress-strain relationship affected by the average stress is proposed to describe nonlinear behaviors in the initial compaction stage. According to the test data, the evolution laws of various energies inside the rock during loading and unloading cycles are obtained. The results show that the external work is transformed into elastic energy and damage dissipated energy. Based on the energy analysis, the energy balance equation is established according to the law of energy conservation. By deriving the energy balance equation, the damage evolution equation of sandstone under triaxial loading is solved to establish a continuous constitutive model. The calculation results of the model are compared with the test results from two aspects of loading and postpeak unloading. The comparison results show that the proposed model, which reflects the whole stress-strain process and nonlinear properties of rock, could also describe the stress-strain relationship at the postpeak unloading stage to some extent. [ABSTRACT FROM AUTHOR]

The geographical detector model (GDM) is based on the spatial variance analysis of geographical strata of variables to assess the association between the independent variables ( X) and dependent variables ( Y). The independent variables of the GDM must be discretized into classes. However, current discretization methods employ univariate analysis, which may lead to inaccurate results. The aim of this study was to develop a novel bivariate optimal discretization approach, known as the multiscale discretization (MSD) method. The objective of the MSD method is to determine an appropriate set of thresholds for X , thereby minimizing the variance of Y within the spatial partitions determined by the discrete X. We successfully applied the MSD method to assess the relationship between the precipitation and enhanced vegetation index on the African continent, as well as the habitat range of pandas in Ya'an County, Sichuan Province, China. The results demonstrate that the MSD is a feasible, robust, and rapid method for converting continuous data into discrete data, with globally optimal discretization results. Furthermore, the MSD method can evaluate the degree of association between X and Y more accurately, and can optimize the results of the GDM. [ABSTRACT FROM AUTHOR]

At approximately 3:50 a.m. (UTC + 8) on August 21, 2020, a massive rainfall-induced landslide occurred in Zhonghaicun, Fuquan town, Hanyuan County, Sichuan Province, China, forming an approximately 40.85 × 104 m3 landslide accumulation, burying eight houses and approximately 100 m of roads, and causing long-term traffic interruptions. The landslide was comprehensively evaluated through field investigation, UAV photography, borehole drilling, and laboratory tests. According to movement and accumulation characteristics, the landslide is divided into the main sliding zones (the source area, impact sliding area, shoveling-accumulation area, and accumulation area) and landslide-affected zones. The deformation and failure of the Zhonghaicun landslide are related to the lithology (existence of a weak interlayer), geomorphology (microrelief changes), and antecedent rainfall. However, the main trigger of the landslide is continuous rainfall, which increases the landslide saturation and pore water pressure and reduces the mechanical strength of the weak layer. The landslide failure mode is complex. The upper slope is affected by rainfall and loses stability first. Under the impact of the sliding mass, sliding of the lower slope is triggered. This study of the Zhonghaicun landslide characterizes the evolution process of a complex rainfall-induced landslide and provides ways to mitigate landslide disasters. [ABSTRACT FROM AUTHOR]

Tunnels stand as indispensable pillars of transportation infrastructure, assuming a central and transformative role in fostering the sustainable evolution of urban. The excavation process of tunnels presents a spectrum of geological challenges, encompassing the potential for instability and collapse. Ensuring the stability of the tunnel is a top priority in tunnel construction. The destabilization leading to collapse in certain tunnels is intricately connected to the structural planes of the rock mass. Accurately obtaining the distribution of structural planes within the rock mass is the necessary basis for maintaining the stability of the tunnel. The conventional Monte Carlo method generates each parameter of stochastic structural planes separately without considering the correlations between the parameters. To address this limitation, we propose a stochastic structural plane generation method based on deep generative model (DGM). The model takes the measured factual structural plane data as input, and the neural network realizes the generation of structural plane data with automatic learning of the distribution law of structural planes and the correlations between each parameters without assuming the probability distribution of stochastic structural planes in advance. This method has been used for stochastic structural plane generation of the rock mass in the Yuelongmen tunnel located in Mianyang City, Sichuan Province. The validation results show that the proposed DGM‐based method automatically captures the correlation between structural plane parameters while ensuring the greater accuracy of the generated structural planes. [ABSTRACT FROM AUTHOR]

We examine seismic anisotropy beneath eastern China by analysing shear wave splitting of teleseismic SKS, SKKS and PKS phases recorded at 402 permanent and temporary stations. In general, our fast directions are approximately oriented in the E–W direction. The delay times vary greatly between 0.5 and 1.9 s. The delay times at stations in the Sichuan basin are less than 0.8 s, which could explain the fossilized anisotropy in the lithospheric mantle and little deformation after the formation of stable block. The fast directions in the Qinling–Dabie orogenic belts orient NWW–SEE, E–W and NEE–SWW, and are roughly parallel to the strikes of orogens that may indicate that the anisotropy contribution comes mainly from the lithospheric mantle. The fast directions mostly oriented in the nearly E–W direction, are generally subparallel to the absolute plate motion directions beneath the North China Craton and South China Block, suggesting it is primarily related to drag induced by the asthenospheric flow. [ABSTRACT FROM AUTHOR]

• Geological disasters in hilly areas are related to Land-Use and Land-Cover Changes. • The number of geological disasters in the cultivated land area is the largest. • The point density of geological disasters and vegetation coverage is limited. • Geological disasters are more likely to occur in the period of heavy rainfall. • The closer geological disaster to river, the greater probability/scale of occurrence. Sichuan hilly area is located in southwest China, which have many hilly area, is a densely populated, economically active, frequent geological disasters area. In this paper, Neijiang City in the region is taken as the test sample. This article, which analyzes Land-Use and Land-Cover Changes (LUCC), meteorological and hydrological data from 2015 to 2020, takes Neijiang City in this region as the research object. We explored the relationship between geological disasters such as collapse and landslides that often occur in the natural ecological environment with LUCC and meteorological and hydrological factors, using GIS spatial analysis and statistical analysis methods. The research results indicate that geological disasters mainly occur in farmland areas. The density of geological disaster points is highest within urban areas, making them the most prone to geological disasters. Geological disasters are more densely distributed in the area within 600 to 800 m from the river. There is a strong correlation between the average rainfall amount and the probability of geological disasters occurring. This study provides a scientific basis for the geological disaster risk assessment, prevention and control in this region. It has certain reference significance for the ecological environment governance, land resources planning and management in other similar regions. [ABSTRACT FROM AUTHOR]

Geology, stratigraphy, drilling, logging, biomarker studies and apatite fission tracks were used to study Sinian- Ordovician mudstone and reservoir bitumen extracted from exploration wells located in central and southeastern Sichuan. This analysis confirms the source rocks were located in a reducing sedimentary environment, with organic matter such as bacteria and algae. The bitumen found in Sinian-Ordovician reservoirs in central Sichuan and Sinian reservoirs in southeastern Sichuan were mostly derived from Cambrian mudstones. The reservoir bitumen found in Cambrian rocks in southeastern Sichuan are from a mixed Cambrian-Silurian source. The apatite fission track combined with the Easy% Ro model were used to reconstruct the hydrocarbon-generation history of Cambrian source rocks in the Dingshan 1 well in southeastern Sichuan. The comparison between the Gaoke 1 well located in central Sichuan and the Dingshan 1 well demonstrates the maturation time and oil and gas generation stage from Cambrian source rocks in southeastern Sichuan is younger than the source rocks from central Sichuan. The source rock formations underwent tectonic uplift and reburial for secondary hydrocarbon-generation. The research methods provided can assist in oil exploration of deep and old hydrocarbon-bearing strata with a multi-stage evolution and tectonically superimposed features in the Chinese Qinghai-Tibet plateau basin, or similar basins worldwide. [ABSTRACT FROM AUTHOR]

Efficient exploration and development of shale gas require the identification of reservoirs with abundant hydrocarbon accumulation and high brittleness. However, realistic descriptions and seismic visibility of these reservoir properties have not been thoroughly investigated due to the complex elastic responses of organic shale. This study develops a new rock-physics-based framework incorporated with proposed effective reservoir parameters to evaluate hydrocarbon accumulation and brittleness in shale gas reservoirs. The developed rock physics model quantitatively relates the elastic characteristics of organic shale to the controlling factors of gas enrichment and brittleness that are realistically represented by the proposed effective reservoir parameters. Moreover, the rock physics template (RPT) computed using the proposed model represents a powerful tool to reveal implicit correlations between the effective reservoir parameters and elastic attributes in organic shale. In a real data application related to the Longmaxi shale gas reservoir in the Sichuan Basin, the constructed RPT provides reliable estimates of effective reservoir parameters using seismic-inverted elastic attributes, with the results being validated by logging data from gas-producing wells. Furthermore, reservoir classification based on the RPT and effective reservoir parameters offers a practical way to identify geological and engineering sweet spots, yielding valuable insights into reservoir qualities associated with gas enrichment and brittleness for locating promising shale gas areas. The predicted results indicate that high-quality shale gas reservoirs exhibit a structure-related distribution with potential geological significance. • A rock-physics-based framework for shale gas characterisation. • Effective reservoir parameters for realistic representations of reservoir properties. • Advanced modelling scheme by a step-by-step modelling strategy. • RPT reveals correlations between reservoir parameters and seismic attributes. • Reservoir classification provides insights into shale gas reservoir qualities. [ABSTRACT FROM AUTHOR]

Analyzing the distribution characteristics and influencing factors of cultivated land in complex geomorphic areas is significant in evaluating the agricultural farming environment and formulating cultivated land protection measures. This study extracted cultivated land information based on multi-source remote sensing data, and analyzed the geomorphic differentiation of cultivated land distribution and climate response from 2000 to 2020 using the Gini coefficient, spatial autocorrelation analysis and geographic detector. The results show that cultivated land is mainly distributed in low-altitude hills and low-altitude small undulating mountains, and secondarily in low-altitude alluvial and proluvial plains and platforms. Moreover, from 2000 to 2020, the cultivated land in the high-altitude and high-altitude undulating mountains and medium and high-altitude undulating mountains in the Northwest Plateau of Sichuan showed an upward trend, while the cultivated land in the Sichuan Basin mainly increased from the north and south to the middle of the basin. In addition, the highest temperature has the strongest ability to explain the spatial heterogeneity of cultivated land. From the calculation results of the influence coefficient of a single climatic factor and the combined effect of multiple climatic factors, the main factors that affect the distribution of cultivated land are different in different geomorphological regions. Finally, it is proposed to formulate a long-term strategy for agricultural production to adapt to climate change in complex geomorphic areas in order to reduce the negative impact of environmental change on agricultural production. [ABSTRACT FROM AUTHOR]

The emplacement of the Late Permian Emeishan large igneous province (ELIP) in the Upper Yangtze craton, SW China, is considered to be a crucial factor that triggered the end-Guadalupian biodiversity crisis. However, the contribution of ELIP remains debated because of its relatively modest known size. The restricted assessment of its areal extent is, in part, due to the lack of study of the potential volcanic rocks concealed beneath younger strata. Here we present the first geochemical and isotopic variations and detailed spatial distribution of Late Permian basaltic rocks penetrated by deep exploratory boreholes in the Sichuan Basin. The Late Permian basaltic rocks are mainly distributed in the western and northeastern parts of the Sichuan Basin and are positioned at the same stratigraphic level as the Emeishan flood basalts. Petrography, whole-rock trace elements and Sr-Nd-Pb isotopic compositions demonstrate that these rocks are alkaline basalts and have oceanic island basalt - like characteristics, indicating a similar origin as the Emeishan flood basalts. The trace element and isotope ratios suggest that the basaltic magmas in the western Sichuan Basin were derived by low degrees of partial melting of a garnet-bearing source. In contrast, the basalts in the northeastern part of the basin were generated by higher degrees of melting of a shallower mantle source in the spinel-garnet transition zone. Varying amounts of contamination by lower continental crustal melts are suggested by rough correlations between isotope and immobile trace element ratios. The spatial changes in composition and origin of the basaltic rocks in the Sichuan Basin can be interpreted as the result of varying extents of Emeishan mantle plume-lithosphere interaction under different lithospheric stress backgrounds, such that the reactivation of pre-existing basement faults controlled the emplacement of basaltic magma in the periphery of the ELIP. Our work reveals a substantially broader extent of the ELIP in buried sedimentary strata, which might have contributed to the abrupt end-Guadalupian climatic change. [Display omitted] [ABSTRACT FROM AUTHOR]

The prediction of geothermal high-temperature anomalies along the plateau railway will be helpful in the construction of the project and its later management. Taking the Sichuan–Tibet railway as the study area and based on Landsat8 thermal infrared images, map data, and measured data regarding the cause and distribution of geothermal high-temperature anomalies, through correlation analysis, we selected six impact factors including the LST, combined entropy of geological formation, fault density, buffer distance to rivers, magnetic anomaly, and earthquake peak acceleration as the input maps of the model. The index-overlay information model, the weights of the entropy information model, and the weights of the evidence information model were established to quantitatively predict the geothermal anomaly in the study area, and the prediction maps were divided into four classes. The results show that the weights of the evidence information model achieved a high prediction accuracy; the success index and the ratio of the high anomaly area reached 0.0053% and 0.872, respectively, and the spatial distribution of the geothermal points is basically consistent with the prediction results. This research can act as a reference for the design and construction of the Sichuan–Tibet railway. [ABSTRACT FROM AUTHOR]

• A long deep seismic reflection image captured a non-modified syn -Rodinian orogen resting beneath the Sichuan basin, western China. • Contemporaneous continental recycling that assembled the Rodinia Supercontinent is clearly recorded. • Continental recycling in the Neoproterozoic Era still experiences more extensive crustal extraction than the counterparts of modern Earth. Owing to most tectonic events in Precambrian have been modified by intensive post-Precambrian overprinting, the question how exactly crustal recycling operated on earlier Earth remains an open one. Here, we report a SE-striking, 175 km-long deep seismic reflection profile that traverses the Sichuan basin, China. The image shows a well-preserved syn -Rodinian orogen resting beneath flat lying sedimentary cover of the basin. Relative to the counterparts of modern Earth, this orogen shows a structurally complex Moho geometry composed of multiple layers of basaltic sills, exhibiting extensive crustal extraction. The outlined crustal architecture further depicts that growth of the upper plate arose dominantly through tectonothermal processes, while coeval ductile underthrusting and overthrusting drove contemporaneous crustal shortening of the lower plate. Together with accretionary stacking above, these processes coevally generated a crustal thickness to ~ 30 km. This well-preserved syn -Rodinian orogen provides direct evidence for understanding contemporaneous continental recycling that assembled the Rodinia supercontinent. Near-vertical, deep seismic reflection profiling is an effective technique for mapping complicated subsurface structures. In this study, the obtained high-resolution deep seismic reflection image captured a non-modified syn -Rodinian orogenic belt resting beneath flay lying sedimentary cover of the Sichuan basin, western Yangtze block, China. Structural interpretation and associated tectonic implications tell us: (1) the Yangtze block was actually a tectonic collage of microcontinents accreted during Neoproterozoic Rodinian assembly, (2) contemporaneous crustal recycling is featured with extensive crustal extraction, and (3) crustal growth was dominantly driven by tectonothermal events in the upper plate of the convergent zone and crustal shortening in a way of coeval underthrusting and overthrusting in the lower plate, a scenario that has shown no big difference with the counterparts of modern Earth. This well-preserved Neoproterozoic orogenic belt provides direct evidence for helping understand the continental recycling that assembled the Rodinia Supercontinent. [ABSTRACT FROM AUTHOR]

Floral color polymorphism can provide great insight into species evolution from a genetic and ecological standpoint. Color variations between species are often mediated by pollinators and are fixed characteristics, indicating their relevance to adaptive evolution, especially between plants within a single population or between similar species. The orchid genus Pleione has a wide variety of flower colors, from violet, rose-purple, pink, to white, but their color formation and its evolutionary mechanism are unclear. Here, we selected the P. limprichtii population in Huanglong, Sichuan Province, China, which displayed three color variations: Rose-purple, pink, and white, providing ideal material for exploring color variations with regard to species evolution. We investigated the distribution pattern of the different color morphs. The ratio of rose-purple:pink:white-flowered individuals was close to 6:3:1. We inferred that the distribution pattern may serve as a reproductive strategy to maintain the population size. Metabolome analysis was used to reveal that cyanindin derivatives and delphidin are the main color pigments involved. RNA sequencing was used to characterize anthocyanin biosynthetic pathway-related genes and reveal different color formation pathways and transcription factors in order to identify differentially-expressed genes and explore their relationship with color formation. In addition, qRT-PCR was used to validate the expression patterns of some of the genes. The results show that PlFLS serves as a crucial gene that contributes to white color formation and that PlANS and PlUFGT are related to the accumulation of anthocyanin which is responsible for color intensity, especially in pigmented flowers. Phylogenetic and co-expression analyses also identified a R2R3-MYB gene PlMYB10, which is predicted to combine with PlbHLH20 or PlbHLH26 along with PlWD40-1 to form an MBW protein complex (MYB, bHLH, and WDR) that regulates PlFLS expression and may serve as a repressor of anthocyanin accumulation-controlled color variations. Our results not only explain the molecular mechanism of color variation in P. limprichtii, but also contribute to the exploration of a flower color evolutionary model in Pleione, as well as other flowering plants. [ABSTRACT FROM AUTHOR]

Ten Longmaxi shale samples were collected from the Jiaoshiba area, China, where 5 billion cm3/year of shale gas is produced. The samples were evaluated to characterize the pores of various shale lithofacies. Three shale lithofacies were determined in the Jiaoshiba area, Sichuan Basin, China, based on the shale mineral components, namely, siliceous lithofacies (SL), argillaceous lithofacies (AL), and mixed lithofacies (ML). Field emission scanning electron microscopy (FE-SEM), which was performed under high and low voltages, GRI porosity, and carbon dioxide and nitrogen adsorptions were used to investigate the bulk-shale porosity, pore type, pore size, pore morphology, and pore volume among the lithofacies. Lithofacies affects the shale total organic carbon (TOC), bulk-shale porosity, pore size, shape, and volume. SL and ML contain high porosity, high TOC, abundant organic-matter (OM)-hosted pores, and high OM porosity, whereas AL contains few OM pores and has low TOC and low porosity. In the same lithofacies, samples with various TOC values exhibit different pore morphologies. For SL, the low-TOC sample has a round and elliptical OM pore forms, whereas the high-TOC samples show linear and narrow pore shapes that are probably associated with gas expulsion. In ML, the higher TOC is related to spherical or near-spherical OM pores, whereas the OM pore shape collapses in the low-TOC shale. Therefore, lithofacies affect the shale reservoir, and the characteristic and evolution of OM pores should be considered as constraints in shale lithofacies. In SL, sections with a higher TOC value are prime targets despite the high expulsion efficiency, which does not affect the enrichment and high yield of the shale gas. Sections of ML and low-TOC SL should be considered as potential targets because of higher OM porosity and low expulsion efficiency, whereas sections of AL engender risk in exploration and development of shale gas. • Lithofacies controlling porosity, mineral and OM pore diameters, OM porosity were researched. • OM pore types in different lithofacies were determined. • Pore preservation of rigid minerals calcite, dolomite, quartz were investigated. • Expulsion efficiency implication for shale gas enrichment was clarified. • An available method was introduced to determine the high production sections. [ABSTRACT FROM AUTHOR]

The trace fossil Zoophycos is characteristic of the Lower Devonian in the Longmenshan area of southeastern China. Three distinct storm-generated or induced types of sedimentary sequences bearing Zoophycos have been identified in shallow marine deposits of the Bailiuping Formation and the Yangmaba Formation. The type A deposit is composed of siltstoneswith shell concentrations andwave ripples and small Zoophycos at the top. The type B deposit is characterized by fine-graded sandstone with long wavelength hummocky cross-stratification and black gray mudstone as well as the largest and densest Zoophycos at the top. The type C deposit has graded bioclastic limestone with short wavelength hummocky cross-stratification, muddy wackestone and large Zoophycos at the top. Based on the features of the types of Zoophycos, the distribution zone of the Zoophycos ichnogenus that preserved in tempestite sequence was built between the fair weather wave base and storm wave base in the Lower Devonian. This research suggests that the distribution patterns of Zoophycos formed in storm-induced deposits may not provide significant clues for the estimation of relative water depths. The hydrodynamic conditions and sedimentation rate are two important environmental factors of the development of the Zoophycos in the Lower Devonian shallow marine deposits where it was mainly affected by storms between the fair weather and storm wave bases. The abundance of Zoophycos at the top of locally frequent storm deposits could indicate a fairly opportunistic behavior and they were formed in the early HST deposit, which had a relatively stable environment with low energy and higher sedimentation rate. [ABSTRACT FROM AUTHOR]

China's industrial parks have made great contributions to its economic growth with their rapid development. However, the resources and environment related issues have been challenging their sustainability to different degree. There still exist the following challenges in evaluating the sustainability of industrial systems due to the existing researches ignoring one or more related issues, including (1) ignorance of ecosystem's contributions to industrial activities, (2) neglect of quality differences between different resources, energies and labors, (3) involving subjectivity of human, (4) inadequate consideration of emissions' impact, and (5) lacking consideration on recycling and reuse benefit derived from industrial symbiosis. Therefore, they are isolated to some degree and lack completeness and systematization. This study aimed to deal with the five issues by adopting classic EA (emergy analysis) method (Overcoming issues 1–3.), quantifying emissions' impact in terms of emergy with some modified parameters (Addressing issue 4.) and proposing indicators to evaluating recycling and reuse benefit (Focusing on issue 5.). Then one proposed emergy method and the related indicator system for assessing the sustainability of industrial parks were set up. Next, an industrial park in Sichuan, China, as a case, was research using the proposed method and indicator system. The study results show that, according to the classic emergy based indicators, this industrial park has relatively high economic competition ability (EYR = 1.14), relatively low environmental press (ELR = 29.31), and relatively strong sustainability (ESI = 0.0388) compared to other industrial parks in China. However, its low economic efficiency and low wastes recycling/reuse degree still seriously challenge its sustainability with the local mineral resources exhaustion in the future. In terms of modified emergy indicators, emissions' impact further raises its environmental load by 3.42% and reduces its sustainability level by 2.70%. Finally, some corresponding suggestions are put forward. [ABSTRACT FROM AUTHOR]

[Display omitted] • Various heavy metals existed in the sediment and the mutual correlation is complex. • Aquatic plants and benthic fauna absorbed different heavy metals selectively. • Eriocheir sinensis could be the potential indicator for Zn and Cr in the sediment. • Erigeron acer could be the Zn hyperaccumulator. As a highly toxic contaminant, heavy metals have been proven to be widely distributed in the water and sediments of the global oceans, rivers, and lakes. Due to the functional differences in urban areas, the extent, characteristics, and hazards of heavy metal pollution in rivers are also different. To monitor and eliminate heavy metal pollution in rivers, indicators and hyperaccumulators perform crucial roles. In this study, heavy metal concentrations in the water, sediment, benthic faunae and aquatic plants of the Jiang'an River (which flows through Chengdu city, Sichuan Province, P.R. China) were investigated, followed by heavy metal correlation analysis of different media to identify potential bioindicator and hyperaccumulator. The results demonstrated that, none of the heavy metals were detected in the water. However, the 6 heavy metals in the surface sediments showed dramatic spatial regional differences, with Ni-As, Ni-Pb, Ni-Cr, Cr-Cu and Cr-Zn being highly significantly correlated. Furthermore, heavy metal contents in surface sediments were highly significantly correlated with the enrichment capacity of Eriocheir sinensis , Polypogon fugax , and Setaria viridis , and significantly correlated with Erigeron acer. Moreover, all plants were poorly enriched with Pb, which may be related to the morphology of Pb in the sediments. Besides, Eriocheir sinensis is a potential indicator of Zn and Cr in the sediments, and Erigeron acer is a possible Zn hyperaccumulator. This research confirms that heavy metals migrated in the water–sediment-benthic-plant system. Therefore, this study can provide a theoretical foundation for river monitoring and administration in Chengdu city and Sichuan Province. [ABSTRACT FROM AUTHOR]

Abstract: The Himalayan Mianning–Dechang REE belt, western Sichuan, SW China, is approximately 270 km long and 15 km wide, and contains total reserves of >3 Mt of LREE, including one giant (Maoniuping), one large (Dalucao) and a number of small-medium REE deposits (Muluozhai, Lizhuang) and occurrences. The belt is tectonically located within a continental collision zone, i.e., the eastern Indo-Asian collision zone. REE mineralization is associated with Himalayan carbonatite–alkaline complexes, which consist of carbonatitic sills or dykes and associated alkaline syenite stocks. Available dating data define a Himalayan metallogenic epoch (40–10 Ma). The magmatic–hydrothermal REE systems were controlled by Cenozoic large-scale strike-slip faulting and the resultant tensional fissure zones, developed in a transform phase from a transpressional to a transtensional regime. Alteration is characterized by fenitization, which formed fenite halos enveloping the REE orebodies. Associated REE mineralization occurs as complex vein systems consisting of various veinlets, stringer and stockwork zones, and breccia-pipe systems. The REE orebodies show various shapes from plate-like, lenticular to pipe-like in different districts. Ore types are dominated by pegmatitic, carbonatitic, breccia, and stringer (stockwork), and disseminated ores, mainly composed of barite + fluorite + aegirine-augite + calcite + bastnaesite assemblages. Bastnaesite precipitation (275–325 °C) appears in three assemblages: early clastics-bearing barite + arfvedsonite + calcite + bastnaesite; intermediate quartz + fluorite + barite + bastnaesite; and late fluorite + barite + bastnaesite assemblages. These were followed by low-temperature pyrite + galena + sphalerite assemblages. Fluid inclusion studies indicate that gangue quartz and fluorite hosts numerous melt/fluid inclusions with a large proportion of sulfate (i.e., BaSO4, K2SO4, and CaSO4), in addition to CaCO3 and CaF2, yielding abnormally high (up to 750 °C) but wide-ranging homogenization temperatures (750–125 °C). The similarity of Sr–Nd isotopic compositions for gangue minerals with those of the host carbonatite–syenite suggests that ore-forming fluids, especially the F−, HCO3 2−, SO4 2− components, were derived from carbonatite–syenite magmas. The O–D–C isotopic data from gangue calcite, fluorite and quartz indicate that the fluids were of orthomagmatic origin, but also involved mixing with an external fluid. On the basis of our synthesis, we propose a possible genetic model for REE mineralization, in which the hydrothermal system temporally underwent a complicated evolution from separation of high-T sulfate-bearing NaCl–KCl brine resulting in effective precipitation of REE-fluorocarbonate and sulfate, to subsequent mixing with low-temperature meteoric water precipitating minor sulfide assemblages. Spatially, this sequence of events generated a three-tier REE mineralized architecture, in which pipe-like breccia orebodies grade downwards from shallow to deep structural levels into large veinlet ore systems, and veinlet-disseminated orebodies. [Copyright &y& Elsevier]

A large number of thermal springs are widely distributed along the deep suture zones and faults in the north section of the Sanjiang Orogenic belt in southeast Tibetan Plateau, connecting the two high-temperature hydrothermal areas in southern Tibet and western Sichuan. Whether the genesis of all geothermal water in the north section of the Sanjiang Orogenic belt is consistent is still an unanswered question. In order to fill the research gap of the high temperature geothermal system in this region, in this study, we classified the geothermal springs into three geothermal fields (Jinsha, Lancang, and Nujiang geothermal fields) and attempted to find clues by comparing the hydrochemical and isotopic characteristics of geothermal fluids in the three geothermal fields. The δ2H and δ18O composition of geothermal springs suggest that all thermal springs are replenished by the meteoric water. Low content of trace elements and low degree of oxygen isotope shift indicate that the partial melting of the crust at a depth of about 20 km mainly provide heat for all thermal springs in the geothermal fields through conduction. But due to the difference of tectonic conditions, there are two formation patterns of geothermal waters in the study area, one was controlled by regional faults, the other was controlled by the folded complex. The geothermal waters controlled by regional faults were heated after deep circulation, and the reservoir temperatures calculated by the Silica-enthalpy mixing model are 175–200 °C and 200–225 °C, respectively. But the geothermal waters controlled by the folded complex were heated after shallow circulation, and the reservoir temperature is only 100–125 °C. Upon rising to the surface, the geothermal waters mixed with cold groundwater to different degrees. The dissolution of Na/K-silicates and carbonate rocks controlled the formation of Na-HCO 3 and Ca·Mg-HCO 3 type water, respectively. But dissolution of halite and gypsum (or anhydrite) in some areas can lead to further diversity of hydrochemical species, resulting in the formation of Na-Cl, Na-HCO 3 ·Cl, Ca·Mg-SO 4 and Na-HCO 3.SO 4 type waters. • The crustal partial melting mainly provides heat for geothermal waters through conduction. • Two formation patterns of geothermal waters are formed due to the difference of tectonic condition. • Geothermal water controlled by regional faults was heated after deep circulation. • Geothermal water controlled by complex fold was heated after shallow circulation. • Reservior temperatures of the two patterns are calculated as 175–225 °C, 100–125 °C respectively. [ABSTRACT FROM AUTHOR]

• We assessed the performance of rice production in Southwest China during 2004–2016. • The share of indirect energy consumption reached 75.46%. • Direct carbon emissions contributed to 55.20% of the total carbon emissions. • The structure of rice production was optimized to different degrees. • No clear improvement in relationships was observed between different factors. Global warming, energy consumption (EC), and food security have led to increasing concern about carbon emissions (CEs) from agriculture, especially CEs from rice cultivation in China. However, there are few studies on CEs from rice production in Southwest China (SWC) (including Yunnan Province (YNP), Sichuan Province, Guizhou Province, and Chongqing Municipality (CQM)), which has complex topography and climatic conditions. Here, a set of indicators based on yield, economic output, EC, and CEs were proposed to describe the performance of rice production in SWC during 2004–2016. The research results reflected that (1) the share of indirect EC of rice production was 75.46% in SWC, more than 90% of which originated from nitrogen fertilizer, compound fertilizer, and pesticides; (2) direct CEs contributed to 55.20% of the total CEs in SWC during the study period, and fertilizer production and utilization were the largest contributor (45.03%) to CEs in this area, followed by paddy fields (38.61%); (3) CQM had the worst performance in SWC in terms of CE intensity of economic output and profit from land use; (4) YNP had the greatest EC intensity based on yield, the greatest CE intensity based on sowing area and yield, and the worst production structure and comprehensive performance; and (5) the structure of rice production was optimized to different degrees in SWC, but no obvious improvement was seen in relationships between yield, economic output, EC, and CEs in this area. Therefore, measures should be taken to reduce the EC intensity and CE intensity of rice production in YNP, and rice plantation methods with high yield and fine quality should be emphasized in the other three administrative regions. [ABSTRACT FROM AUTHOR]

• Community change characteristics of Abies faxoniana was studied. • With the change of relative basal area value (RBAV) of A. faxoniana , dominant trees changed markedly. • Tree diversity was significant negatively correlated with RBAV of A. faxoniana. • Betula albosinensis was significant negatively correlated with A. faxoniana in basal area. • Studying changes of RBAVs of dominant trees centered on target species is feasible. To detect the community change characteristics of Abies faxoniana , we carried out a field survey in a forest where A. faxoniana was present in the Wanglang Nature Reserve, Sichuan Province, China. We used the quadrat method to collect the data, and studied the composition and changes of dominant tree species, changes of tree diversity and community structure centered on A. faxoniana , as well as the interspecific correlation and population structure related to this species. The results indicated that in different communities, A. faxoniana had different relative basal area values (RBAVs). With the increase of the RBAV of A. faxoniana , the community was changed from non-dominant A. faxoniana , to mixed community of A. faxoniana and other species, to single dominant community of A. faxoniana ; the tree diversity showed a trend of decrease, but the community structure had no obvious change. Betula albosinensis had a significantly negative correlation relationship with A. faxoniana in basal area. A. faxoniana in the area we sampled was a growing type population in general. We summarized the community change process of A. faxoniana as the substitution process of dominant tree species in community and decline in tree diversity. Based on this study, the method of studying the changes of RBAVs of dominant trees in different plots centered on the target species is feasible in studying the community change characteristics. This study could provide a basis for revealing community dynamic which is important for forest restoration practices. [ABSTRACT FROM AUTHOR]