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Lower Paleozoic shale is an important source rock and reservoir for gas in the northwestern Upper Yangtze Plate. The paleoenvironment, and its impact on organic matter enrichment of the shale, plays a vital role in the exploration and development of the resource. Based on the analysis of the results of total organic carbon (TOC), maceral examination, bitumen reflectance (Rb), major elements, trace elements, rare earth elements (REEs), and X-ray diffraction (XRD) of shale samples from the Niutitang and Longmaxi formations, the origin of silica, the paleoenvironment, and the mode of organic matter enrichment of the shale were examined. The shales of the Niutitang and Longmaxi formations have high TOC abundance, with Type I organic matter and high maturity. Quartz and clay minerals dominate the mineral constituents, leading to characterization as siliceous shale. The average SiO 2 content of the shale in the Niutitang and Longmaxi formations is above 70 wt%. Al 2 O 3 and TFe 2 O 3 (total iron) are the next-most abundant major elements, with average values of 12.80 wt% and 1.95 wt% in the Niutitang Formation, and average values of 11.44 wt% and 4.09 wt% in the Longmaxi Formation. Compared with the Upper Continental Crust (UCC), V, Mo and U are the most enriched elements. The average ∑LREE/∑HREE of the shale samples is very low, and the Chondrite-normalized REE distribution pattern shows sloping LREE trends and flat HREE trends towards the right. The total rare earth elements of the shale vary within the range of 147.85–219.60 ppm and 159.90–222.02 ppm in both the Niutitang and Longmaxi formations, suggesting that the shale has not been subject to obvious hydrothermal fluid activities. The correlation diagrams of SiO 2 Al 2 O 3 , SiO 2 -TOC and Si excess -TOC, the diagrams of hydrothermal origins, and the elemental parameters indicate that the silica of the shales from the Niutitang and Longmaxi formations are mainly of biogenic origins, with a lesser contribution from terrigenous detrital sources. The ratios of MnO 2 /TiO 2 and Al 2 O 3 /(Al 2 O 3 +TFe 2 O 3) of the shale samples all show limited variability, illustrating that the shales are mainly deposited on the continental margin. The average chemical alteration index (CIA) values of the Niutitang and Longmaxi formations are 71.25 and 72.77 with little variation, and the average Sr/Cu ratios are 4.38 and 2.22, reflecting a warm and humid paleoclimate for both formations. The average Ni/Co, Th/U, and δU readings of the shale samples of the formations are 10.91, 0.97 and 1.51, and 12.69, 0.43 and 1.75, indicating that the redox conditions during the sedimentation of the formations were anoxic. The positive correlations between TOC and paleoenvironmental proxies reveal a warm and humid climate, and that anoxia had a positive effect on organic matter enrichment. These conditions have laid a geological foundation for the enrichment of shale gas, and that the Upper Yangtze Plate is favorable for future shale gas exploration. • The shales of Niutitang Formation and Longmaxi Formation are both good source rocks. • The silica origin of the shales is primarily biogenic. • The shales were deposited in warm and humid climate with anoxic condition. • The paleoclimate and anoxic conditions had a positive effect on OM accumulation. [ABSTRACT FROM AUTHOR]

Owing to the lack of conventional oil resources, oil shale from the Triassic Yanchang Formation in the southern Ordos Basin has attracted unprecedented attention. The origin of organic matter and the paleo-sedimentary environment of oil shale are discussed. Based on the results of total organic carbon (TOC), total sulfur (TS), rock pyrolysis, organic elements, vitrinite reflectance (Ro), biomarkers, major elements, and trace elements of oil shale from Yishicun Profile, Tongchuan City. The oil shale from the Chang 7 sub-unit has high TOC (0.29–24.68%) and low TS content (0.13–0.61%), exhibiting middle-grade criterion and extra-low sulfur quality. The Ro, together with discrimination diagrams of C 2 9steraneββ/(ββ + αα)-αααC 2 9sterane20 S/(20 S + 20 R) and OEP-CPI, suggests that the oil shale has reached maturity. C 27 − C 29 regular steranes distribution, (C 19 + C 20 tricyclic terpane)/C 23 tricyclic terpane, and C 23 tricyclic terpane/(C 23 tricyclic terpane + C 30 hopane) all indicate that the parent materials of the organic matter in the oil shale are algae, phytoplankton, and terrestrial plants. The Pr/Ph, V/Cr, V/(V + Ni), U/Th, δU, and TOC-TS-TFe 2 O 3 ternary diagrams indicate that oil shale mainly deposits in reducing environment with a relatively poor preservation conditions. TS content, gammacerane/αβ-C 30 hopane, gammacerane/0.5C 31 αβ(22 R + 22 S), and Equivalent Boron accurately explain that marine transgression did not occur and the paleosalinity of the lake indicates predominantly fresh water. The paleoproductivity of the lake during oil shale sedimentation is very high in terms of U and Mo concentrations and Ba/Al ratio. After quantitative calculation, the lake is classified as an extremely eutrophic lake. The water depth of oil shale sedimentation varies from 26.00 to 108.6 m, indicating a semi deep- deep lake. [ABSTRACT FROM AUTHOR]

Antitaxial fibrous veins are commonly developed in low permeability shale in orogenic belts and sedimentary basins. We review work on antitaxial fibrous veins, provide a classification, and discuss a formation mechanism. On the basis of crystal morphologies within veins, generalized fibrous veins can be categorized into stretched, syntaxial and antitaxial veins, and the antitaxial veins are fibrous veins in the strict sense. Typically, individual antitaxial fibrous veins consist of a median zone and two fibrous zones. According to detailed petrographic observations, four different types of solid inclusions within antitaxial fibrous veins were distinguished. Only solid inclusions occurring within blocky or elongate-blocky crystals in the median zone reliably indicate crack events. Other types of solid inclusions do not show clear evidence of crack-seal mechanism. The initial opening of antitaxial fibrous vein is considered to result from hydrofracturing caused by fluid overpressure. The origins of fluid overpressure mainly include hydrocarbon generation, tectonic compression and mineral transformation (such as illitization of smectite and hydration of anhydrite to gypsum), or a combination of these factors. The crack-seal mechanism cannot fully explain the formation mechanism of fibrous veins, and it may be only responsible for the median zone of antitaxial fibrous veins. The growth of fibrous crystals occurs at vein-wall interface without fracturing. Petrographic observations show that fluid pressure, force of crystallization, and sometimes tectonic compression synchronously drive fibre growth. The goal of further work should be to quantitatively determine fluid pressure and force of crystallization during fibre growth. • Different solid inclusions and their formation mechanism were identified. • Opening of antitaxial fibrous veins results from hydrofracturing. • Fibre growth was mainly driven by fluid pressure and force of crystallization. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Daban Thrust belt contains fibrous calcite veins bearing hydrocarbons. [•] C and O isotopes indicate basinal fluids precipitated calcite veins. [•] Th and R 0 indicate temperatures of 140–196°C and pressures of 150–200MPa. [•] Overpressure and development of fractures caused expulsion of basin fluids. [ABSTRACT FROM AUTHOR]

Abstract: Phosphating prior to coating for steel is usually needed. In this paper, an innovative cleaner production has been developed for steel surface treatment using Zn–Mn phosphating solution in which there was no nitrite. The mass of the Zn–Mn layer deposited in this new process was about 1.1gm−2 when the temperature ranged from 3 to 35°C. The corrosion time for the color phosphating layer in the copper sulfate spot test was in the range of 72–145s. Adhesion test showed that the coating layers achieved a higher adhesion load than those produced by conventional methods. Washing using water was not necessary in this cleaner phosphorization, which usually follows phosphorization in traditional processes of steel phosphorization. Consequently, wastewater discharge was reduced greatly. [Copyright &y& Elsevier]

The marine-continental transitional shale is widely distributed in the Lower Permian Shanxi Formation of the southeast Ordos Basin. The primary factors controlling organic matter accumulation of the Shanxi shale are still obscure. In this study, we used mineralogy and organic geochemistry, coupled with major and trace element geochemistry to analyze the paleoenvironment and their effects on organic matter enrichment, and established the accumulation model of organic matter in the Shanxi transitional shale. Results show that the mineralogical composition of the Shanxi shale is dominated by clay and quartz (averaging of 62.8 and 33.3%, respectively). The Shanxi shale has relatively high TOC contents and thermal maturity (Ro) (averaging of 1.25% and 2.66%, respectively), and predominantly contains type III kerogen. The significantly low paleoproductivity indicates that this factor plays not the primary role of organic matter accumulation. Ti and Al concentrations indicate a strong terrestrial input, simultaneously bringing abundant terrestrial organic matter, which is favourable for its enrichment. The warm and humid climate condition enhanced higher plant growth and provenance weathering. The δU, U/Th, V/Cr and Ni/Co values show dysoxic-oxic environments, suggesting relatively poor preservation conditions for organic matter. Comprehensive analysis shows that the terrestrial organic matter input, paleoclimate and redox conditions are the primary factors controlling the organic matter accumulation of the Shanxi shale. • The paleoproductivity is significantly low during the Shanxi shale deposition. • The terrestrial detrital input is strong, carrying abundant terrestrial organic matter. • The paleoclimate and redox conditions triggered organic matter accumulation to some extent. • An accumulation model of organic matter in the Shanxi Formation was established. [ABSTRACT FROM AUTHOR]

Solid bitumen is ubiquitous in the Sinian Dengying Formation dolomite, a crucial gas reservoir in the Sichuan Basin. We use biomarkers and Re–Os geochronology, coupled with burial-thermal evolution history to trace the source and formation timing of the solid bitumen, and to reconstruct the petroleum system evolution in the Dengying Formation of the Beiba Dome, northern Sichuan Basin. The bitumen reflectance (Rb) values of solid bitumen range from 1.92 to 3.95%, with the solid bitumen showing no fluorescence, indicating that the solid bitumen in the Dengying Formation dolomite has a high thermal maturity, which consequently belongs to pyrobitumen formed by thermal cracking of crude oil. The isoprenoids and terpanes indicate that the solid bitumen was sourced from a marine shale deposited under a reducing environment. The C 27 –C 29 regular sterane distribution of the solid bitumen is consistent with the Lower Cambrian Guojiaba Formation (Є 1 g) organic-rich shale, indicating that the solid bitumen was derived from the Є 1 g shale, rather than dolomite or shale within the Dengying Formation. The burial-thermal evolution history indicates that initial oil generation began in the Late Cambrian to the Early Silurian. Since the Early Permian, the Є 1 g organic-rich shale re-entered the oil generation window, and formed a giant paleo-oil accumulation during the Late Triassic. Thermal cracking of crude oil occurred from the Late Triassic to the Early Cretaceous forming the extensive solid bitumen. The Re–Os isotopes of solid bitumen yield two similar isochron ages of 128.1 ± 7.3 Ma and 126.2 ± 8.0 Ma, which represents the timing of thermal cracking termination, i.e. the final timing of dry gas generation. This work highlights that the Re–Os geochronology has great potential to constrain the absolute timing of evolution of the petroleum system. • The solid bitumen belongs to pyrobitumen with a highly thermal maturity, formed by thermal cracking. • The solid bitumen was derived from the Lower Cambrian Guojiaba Formation organic-rich shale. • The solid bitumen was formed in the Early Cretaceous, which represents the timing of thermal cracking termination. [ABSTRACT FROM AUTHOR]

This research proposes a new method of estimating pore-throat size distribution that converted based on nuclear magnetic resonance (NMR) T 2 spectra, so as to more accurately explore the pore-throat structures of tight reservoirs. In this work, one of the most potential shale formations, Yanchang shales in the Ordos basin, NW China, was targeted. Take Chang 2 Member as an example, the experimental parameters were comprehensively analyzed, including petrological property analysis, NMR, and constant-rate mercury injection porosimetry (MIP). This research compared the pore-throat size distributions which are converted from NMR T 2 spectra using a conventional method, an empirical formula method, and the new method. The research found that the results obtained through the linear relationship of the conventional method showed low accuracy, and the fitting coefficients vary from 0.5339 to 0.8238. Although the empirical method lacks physical significance and mathematical derivation, the fitting coefficients are from 0.8565 to 0.9886, which is referable. The new method brought in the physical significance of formula derivation and took into account the distribution characteristics of experimental data, resulting in higher fitting coefficients of 0.9928–0.9999. Based on the fitting results, the new method is more reasonable and feasible, which can be used for conversion of pore-throat size distribution through NMR T 2 spectrum to obtain the NMR pore-throat structure. • A new method of estimating pore-throat size distributions from NMR T 2 was proposed. • Estimated pore-throat size distributions from NMR T 2 by different methods were compared. • The newly proposed method first incorporates the distribution of data. [ABSTRACT FROM AUTHOR]

Bedding-parallel fibrous gypsum veins, which are widely developed in the Neogene Qingshuiying Formation of the Ningnan Basin, a Tertiary basin located in the northeastern margin of the Tibetan Plateau, provide valuable information on stress field, fluid origin and host rock deformation during their formation. The systematic petrographic observation and isotope analysis of both of veins and wall rocks were carried out to investigate the formation mechanism of bedding-parallel fibrous gypsum veins. The distribution of fibrous gypsum veins shows vertical heterogeneity, and mainly occurs in the middle and lower part of the Qingshuiying Formation with relatively high gypsum content. Single fibrous gypsum veins consist of a median zone and two fibrous zones. The median zone is characterized by blocky gypsum crystals and multiple host rock fragments formed by crack-seal events. The fibrous zone is composed of parallel gypsum fibres a high angle to the vein walls, indicating shear component. Vein opening is considered to be the result of fluid overpressure caused by horizontal compression in low-permeability mudstone during basin inversion. Fibrous gypsum crystals grow continuously without obvious growth competition between adjacent crystals. This indicates that growth of gypsum fibres occurs in limited space, even without fractures. The main driving force for vein dilation is force of crystallization of gypsum fibre growth, and fluid pressure also has a certain contribution. The sulfur and strontium isotopes of gypsum veins exhibit a high degree of consistency with wall rocks, which indicates the material of the fibrous gypsum veins is derived from the wall rock. A suitable growth model of bedding-parallel fibrous gypsum veins in the Ningnan Basin is established, which explains the process of vein interaction, and the formation of V-shaped or U-shaped solid inclusions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Diversed cooling histories evolved among different places in the southwestern Ordos Basin. • Cooling events started at Late Jurassic and lasted till Cretaceous with the peak rate at Miocene. • These histories were mainly controlled by the Qinling-Qilian Orogen and the Tibetan Plateau event. Differential tectonothermal evolutionary history of the southern part of the Western Ordos Basin, the southern part of the Liupanshan Mountains, and the northwestern part of the Weibei Uplift was revealed since Late Jurassic by integrating low-temperature thermochronology of apatite fission-track, apatite (U-Th-Sm)/He and zircon (U-Th)/He along with vitrinite reflectance. Inverse modeling results suggest four cooling stages among these three regions since Late Jurassic. Uplift-cooling in the Southwestern Ordos Basin commenced simultaneously with that in the South Liupanshan Mountains in Late Jurassic at ~164–160 Ma. During Late Cretaceous, the entire southwestern region uplifted and cooled since ~118 Ma in the Southwestern Ordos Basin and in the Northwest Weibei Uplift, and since ~105 Ma in the South Liupanshan Mountains. During Early Cenozoic, the Southwestern Ordos Basin and the Northwest Weibei Uplift continued uplift-cooling, while parts of the South Liupanshan Mountains subsided. Since Miocene, a rapid uplift-cooling event of the South Liupanshan Mountains commenced at ~24 Ma, and at ~8 Ma for the Southwestern Ordos Basin and the Northwest Weibei Uplift. In general, the differential evolutionary process of the southwestern North China Plate began in Late Jurassic, continued in Cretaceous and reaching a cooling peak during Miocene with heterogeneous start-time and cooling rate of different sub-units, and mainly controlled by the regional uplift-cooling event of the Qinling-Qilian Orogen in Late Jurassic - Early Cretaceous and by the Qinghai-Tibet Plateau event since Paleocene. [ABSTRACT FROM AUTHOR]

• The supply and demand of two ESs was examined at multiple scales. • UDR was proposed to explore the mismatch between supply and demand of both ESs. • The supply-demand mismatch varied with the three examined scales. • The urbanization rate was the dominant factor influencing the mismatch of ESs. • No significant trade-off between two ESs was identified. Ecosystem services (ESs) are produced in a particular social-ecological context, which is significantly affected by the scale. The mismatch between the supply and demand of the ESs is a common phenomenon at a specific scale or during a certain time period. However, systematic research on the supply and demand of ESs and their mismatch at multiple spatial and temporal scales has rarely been reported. In this study, we estimated the supply, demand and mismatch of two ESs, namely, the carbon sequestration and grain provision, for the Yangtze River Delta Urban Agglomerations (YRDUA) at three different spatial scales, i.e., city, provincial and urban agglomerations. Their temporal dynamics were also examined during the period of 2000–2010. We proposed the indicator of Unsatisfied Demand Rate (UDR) to evaluate the mismatch of the ESs. The results suggested that the spatial pattern of the supply and demand of both ESs had a high level of heterogeneity at the different scales, and relatively stronger dynamics were found at the relatively larger scale. The areas supplying high ESs did not usually overlap those consuming high ESs. We found that the scale effect on the mismatch showed different characteristics for the carbon sequestration and grain provision. Although natural factors increasingly exerted an impact on the mismatch of both ESs, measured by the proposed UDR, during the decade, the socioeconomic factors, especially the urbanization rate, were the dominant influencing factors. In addition, we tested the trade-off between the carbon storage and grain provision, and no significant trade-off or synergy was identified, except for individual cities. The selection of indicators for measuring ecosystem provision might be the major reason influencing trade-offs. This gives a better understanding of the interactions among multiple services. In all, our findings could provide comprehensive information for the management of ESs and decision-making. [ABSTRACT FROM AUTHOR]

Climate change and anthropogenic activities are increasingly threatening estuarine and coastal zones. These effects lead to complex positive and negative feedback among sustainable development pillars of human, society, economy and environment according to the integrated sustainability perspective. Only limited studies have calculated comprehensive impact assessments of land conversions between land and sea, invasive species expansion, and inundation impacts on natural wetlands under future scenarios. To fill-in this research gap, this study aims to conduct a long-term temporal analysis (1960–2015) of land use and land cover change (LULC), and future ecosystem service value (ESV) loss for intertidal wetlands predicted in the Yangtze River Estuary (YRE). The results show that, over recent decades, impervious constructed areas and Spartina alterniflora-covered saltmarsh have increased to 10.7% and 2.61%, respectively, whereas native species saltmarshes and tidal flats have decreased to 0.04% and 1.1%, respectively. The total ESV increased significantly during 1960–2000 but significantly declined during 2000–2015. The highest total ESV was US$ 3.8 billion in 2010, considering the approximate contributions of natural and artificial wetlands. Similarly, the ESV of the S. alterniflora saltmarshes reached US$ 0.7 billion in 2015. The total intertidal wetlands area could decrease to 8071–8248/ha by 2100. The total ESV of intertidal wetland ecosystems would decrease by approximately one billion dollars between 2015 and 2050. An enhanced understanding of the economic impacts regarding coastal management, restoration, and conservation is of profound importance for improving coastal resilience, sustainable development, and adaptation of coastal societies to climate change in the Yangtze River Estuary. • The total ESV increased significantly during 1960–2000 but significantly declined during 2000–2015. • The highest ESV in total was US$ 3.8 billion in 2010. • The ESV of the S. alterniflora saltmarshes reached US$ 0.7 billion in 2015. • Under the SRES A2 scenario, the intertidal wetlands area maximally decrease to 8071–8248/ha in 2100. • The total ESV of natural wetland ecosystems decreased by approximately US$ 1 billion in 2015–2050. [ABSTRACT FROM AUTHOR]