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Eco-compensation is an important policy tool to trade off economic development and environmental protection in a watershed. This study introduced the gross ecosystem product (GEP) accounting system to identify the eco-compensation provider (ECP) and eco-compensation receiver (ECR) of a river basin. Then, a cooperative game model and a non-cooperative game model between the ECP and the ECR were established, in which system dynamics was incorporated into the game theoretical analysis to aid selection of the optimal compensation scheme. The study further demonstrated the model applications by taking the Tuojiang River Basin as a case. The results showed that the accounted GEP increased from CNY 32.2 billion in 2018 to CNY 35.5 billion in 2020, with a growth rate of 10.2%. Deyang City, as an ECP, had a cumulative difference of CNY 11.759 billion between its accounted GEP and actual GEP output over the three years. Neijiang City, Zigong City, and Luzhou City were taken as the ECR, receiving the GEP revenues as CNY 11.289 billion, 7.661 billion, and 1.497 billion, respectively. Chengdu City changed from the ECP to the ECR and ultimately to the ECP. However, Ziyang City and Meishan City changed from the ECP to the ECR. The eco-compensations increased to varying degrees during 2018–2020 in both game scenarios, with ECP payments and ECR revenues increasing by 16.5% and 4.6% in the non-cooperative game and by 5.0% and 50.8% in the cooperative game. Particularly, the eco-compensation obtained by the cooperative game had better environmental and economic performance, as there was a total of CNY 7.049 billion being saved. However, there was no savings of compensation by the non-cooperative game. It is expected that the results may provide insight into the design of the eco-compensation standard for a river basin. [ABSTRACT FROM AUTHOR]

This study employed an input-output approach to measure household CO2 emissions (HCEs) in Sichuan province, China from 2010 to 2017. A ZSG-DEA model with a factor constraint cone was built, to allocate such emission allowances to provincial subordinate cities and investigate their spatiotemporal heterogeneity. Using Tapio decoupling analysis, this study further examined the nexus between regional economic performance and HCEs. The results indicated that HCEs in Sichuan province initially increased and then decreased, peaking at 69.60 million tons in 2015. The structure of the HCEs changed from coal- to petroleum-dominated from 2010 to 2017. Indirect emissions from consumption-related sectors accounted for 60% of the total HCEs, including food, transportation, communication, and accommodation. The capital city of Chengdu, with the largest economic scale, overwhelmingly dominated the total household CO2 emissions, whereas Panzhihua, a heavy-industry-dominated city, had the highest HCEs per capita. The Tapio decoupling results suggested that seven cities, led by Chengdu, had strong decoupling statuses, indicating that these cities performed well in the trade-off between economic growth and HCEs reduction. These results indicated that HCEs had a head effect centered on cities with advanced urbanization, but there was a virtuous cycle between CO2 emissions reduction and economic development. Given the spatial and temporal heterogeneity of HCEs, differentiated policymaking on emissions reduction is the key to facilitating green transformations. [ABSTRACT FROM AUTHOR]

The Jiajika rare-metal deposit located in western Sichuan Province (China) is renowned as the largest lithium deposit in Asia, and the No. 134 pegmatite dike is the largest lithium pegmatite under mining conditions in the area. On the basis of a detailed characterization of textures and minerals in the Jiajika No. 134 pegmatite, two zones (the barren Zone I and the spodumene Zone II) and three subzones (Zone II was subdivided into microcrystalline, medium-fine grained and coarse-grained spodumene zones) have been identified. The detailed mineralogical characteristics of lithium minerals and other indicator minerals from each zone were evaluated by EPMA for illustrating the magmatic–hydrothermal evolution and the cooling path of the Jiajika No. 134 pegmatite. From the outer zone inwards, grain size gradually increased, the typical graphic pegmatite zone was absent, and spodumene randomly crystallized throughout nearly the whole pegmatite body. This evidence indicated a Li-saturated melt prior to pegmatite crystallization, which could be the main cause of the super-large-scale Li mineralization of the Jiajika No. 134 pegmatite. A comparison of the Cs content between primary beryl in the Jiajika No. 134 pegmatite and other important Li-Cs-Ta pegmatites in the world indicates that No. 134 pegmatite shows a high degree of fractional crystallization. The evolution of mica species from muscovite to Li-micas from Zone I to Zone II marks the transition from the magmatic to the hydrothermal stage in pegmatite evolution. The absence of individual lepidolite and the relatively limited scale of alteration of spodumene (<10 vol%) suggest that the activity of the hydrothermal fluids in the system is limited, which contributes to the preservation of the easily altered Li ores and is also an important controlling factor of the super-large-scale Li mineralization of the pegmatite. Spodumene–quartz intergrowth (SQI) usually occurs partly along the rims of the spodumene grains in the Jiajika No. 134 pegmatite. Combined with the pegmatite mineral equilibria, the results of fluid inclusion studies of the pegmatite and the metamorphic conditions in the area, a constrained P-T path of the magmatic–hydrothermal crystallization of the Jiajika No. 134 pegmatite is proposed. The unusual steeply sloped cooling path of the No. 134 pegmatite could be attributed to the fast pressure drop triggered by the intrusion of a pegmatitic melt along the fractures surrounding the Majingzi granite, which could also be the dominant evolution process for other spodumene pegmatites with similar SQI features in the world. The feature of limited internal geochemical fractionation suggested by mineral-scale geochemical analyses of spodumene and micas, combined with the clear textural zoning of the No. 134 pegmatite, can best be ascribed to the effect of undercooling during pegmatite formation. This effect might be one of the non-negligible rules of pegmatite petrogenesis, and would significantly upgrade the potential of Li mineralization by minimizing diffusional Li transfer to the country rocks. [ABSTRACT FROM AUTHOR]

The Zhawulong ore field hosts lots of rare-element pegmatite dikes and is an important producing area for lithium resources in the Songpan–Ganzê orogenic belt (SGOB), east Tibet. This paper aims to evaluate the sources and ore-forming processes for granite and pegmatite in the Zhawulong ore field, as well as the petrogenetic links between these rocks, using petrography, whole-rock major and trace-element analysis, and Sr–Nd–Hf isotope analysis. In this ore field, pegmatites are common as dike swarms that emanate from the external and/or internal contact zone of the Zhawulong granitic pluton and strata of the Triassic Xikang group, showing close spatial relationships. Measured values of K/Rb vs. Zr, Hf, and Cs contents indicate geochemical affinities between granite and pegmatite, which suggests that the pegmatite was generated by processes involving high fractional crystallization from the residual parental magma of the host granite. Additionally, the granite have high (87Sr/86Sr) i values (0.711064 to 0.716105), negative ε Nd (t) values (−9.6 to −9.1) and ε Hf (t) values (−32.6 to −2.0), and ancient Nd and Hf model ages (1.2–3.1 Ga), which indicate a continental crustal source. Metasedimentary rocks of the Xikang group are rich in Li (~95 ppm), Rb (~124 ppm), Nb (~15 ppm), and Cs (~17 ppm), and their rare-earth element (REE) patterns show moderate enrichment in light REEs and a negative Eu anomaly (Eu/Eu* = ~0.64), revealing characteristics similar to those of granite. The coeval nature and close spatial relationships between the Zhawulong granite and other syn-orogenic S-type granites indicate that the formation of this granite was related to crustal melting. The petrology and geochemical signatures of the Zhawulong rare-metal-bearing granite–pegmatite imply that it was generated by the partial melting of metasedimentary rocks during the Late Triassic orogeny assembly and was further enriched in Li through processes involving high fractional crystallization. Unlabelled Image • The pegmatite was formed via fractional crystallization of residual granitic magma. • The granite derived from the partial melting of the Triassic flysch sediments in the deep crust. • Triassic flysch sediments provide the potential rare-metal materials for pegmatite. • Zhawulong Li deposit in the SGOB was correlated with the late Triassic orogeny. [ABSTRACT FROM AUTHOR]