This study examines the effect of local media sentiment on corporate green innovation based on a textual analysis of China's provincial official party newspapers from 2007 to 2018. The results show that the negative sentiment in official media positively influences firms' green innovation, measured by the number of green patents and green patent citations. This positive effect is more pronounced when firms have weaker internal or external governance structures, when the regional punitive measures are less stringent, or after the incentive measures are implemented, suggesting that official media plays a governance role in corporate green innovation. Further analysis shows that the negative sentiment from market-oriented media impedes green innovation and does not affect the relationship between official media sentiment and green innovation. Taken together, our findings reveal the real effects of local media negative sentiment on technological progress and pollution controls through its pressure on firms to engage in green innovation.

The progression from initial back-arc rifting to back-arc opening in ancient orogenic collages is important for reconstructing subduction histories, constraining tectonic switching, and understanding crustal growth and evolution. However, it is difficult to constrain this transition in ancient arcs. The Qinling-Dabie orogenic belt is one of the most important orogenic belts in eastern Asia, yet the history of Paleozoic accretionary processes in this belt remains equivocal, owing to a poor understanding of back-arc opening processes in the Erlangping unit. In this study, we present whole-rock geochemical analyses of mafic dikes in the Erlangping unit, along with U-Pb ages and Hf-O isotope compositions of zircon from these dikes. Zircon secondary ion mass spectrometry (SIMS) dating of these mafic dikes yielded U-Pb ages of 453 ± 3 Ma. The mafic dikes are calc-alkaline and are characterized by high K2O contents (1.16−3.16 wt%). They have enriched ([La/Yb]N = 4.3−14.9) light rare earth elements (REEs) and relatively flat heavy REE ([Dy/Yb]N = 0.9−1.5) patterns, and they exhibit enrichment in large ion lithophile elements (LILEs) but depletion in high field strength elements (HFSEs), resembling arc-like magmatism. These mafic dikes are characterized by relatively enriched initial 87Sr/86Sr (0.7049−0.7059), chondritic to slightly radiogenic εNd(t) (−0.36 to 1.33), and radiogenic whole-rock and zircon εHf(t) (+7.2−7.6 and +7.5−7.8, respectively). The zircons have δ18O values (5.0‰ ± 0.1‰) similar to those of normal mantle zircon. Accordingly, we interpret that the mafic dikes were derived from an enriched lithospheric mantle source metasomatized by subducted Proto-Tethys (Shangdan) ocean material. In contrast, previously reported ca. 440 Ma gabbros from the Erlangping unit are tholeiitic and have lower incompatible trace-element concentrations with less enrichment in LILEs and less depletion in HFSEs than the mafic dikes presented here. Whole-rock Nd and zircon Hf isotopic compositions suggest that these Silurian gabbros were derived from partial melting of a more depleted mantle with the involvement of asthenosphere, and they have a close geochemical affinity with back-arc basin basalts. In addition, trace-element ratios and geochemical modeling suggest higher melting pressures for the mafic dikes than the gabbros. The geochemical differences show systematic variations from island-arc basalt into back-arc basin basalt types, which is consistent with the magma source evolution of the Mariana Trough. Thus, we interpret that the ca. 454 Ma mafic dikes were emplaced when the infant arc split, and they record initial back-arc rifting in the Erlangping unit, whereas the Silurian gabbros subsequently formed during the opening of the back-arc basin. Our study provides a paradigm for deciphering the evolution of back-arc basins through the study of spatiotemporal geological and geochemical variations of mafic intrusions in ancient accretionary orogens.

Using textual analysis of Chinese listed firms’ filings, we construct a new firm-level measure of manager risk perception. The measure identifies the extent of risk perceived by managers. We validate our measure by showing that it varies over time and across industries, correlates with aggregate economic policy uncertainty and firm-level stock return volatility, and relates cross-sectionally with firm characteristics. Managers with higher risk perception leads to a lower level of firm investment.

Promoting green investment is the inevitable choice for sustainable economics against climate change. We examine how the COVID-19 pandemic affected corporate green investment. Using a sample of publicly listed firms in China, we document the negative and significant effect of the COVID-19 pandemic on corporate green investment. Further analyses suggest that the COVID-19 pandemic impeded corporate green investment by exacerbating firms’ financial constraints. We also find that the COVID-19 pandemic had no significant effect on total investment, suggesting that the pandemic shock only changed investment structure. In summary, our findings reveal the real effects of the COVID-19 pandemic on green development at the firm level.

In-situ geochemical and isotopic analyses of zircon and monazite can provide compelling and detailed insights into the source and evolution of their hosting granite. Here we investigated the U-Th-Pb and Hf/Nd-O isotopic signatures of zircon and monazite in two petrological zones (i.e., fine- to medium-grained zone and medium-grained zone) of the Laojunshan granite pluton in the Qinling Orogen, central China, to better constrain their source nature and evolution processes. Co-existing magmatic zircon and monazite in both zones gave identical crystallization ages of ca. 113 Ma. In the fine- to medium-grained zone, both magmatic and xenocrystic zircons were identified, which respectively have epsilon(Hf)(t) values of -6.5 to -5.0 and - 17.4 to +5.1, and delta O-18(VSMOW) values of +5.25 parts per thousand to +5.78 parts per thousand and + 5.17 parts per thousand to +9.15 parts per thousand. The age distribution pattern and HfO isotopic characteristics of the xenocrystic zircons are similar to those of detrital zircons from the wall rock, i.e., meta-sedimentary rocks in the Kuanping unit. Monazite grains in this zone have relatively low SiO2, ThO2 but high CaO contents, dominated by cheralite-type substitution. These monazites have epsilon(Nd)(t) values of -5.8 to -4.6 and delta O-18 values of +3.79 parts per thousand to +5.66 parts per thousand, except one grain (epsilon(Nd)(t) = -10.4 to -9.6, delta O-18 = +9.22 parts per thousand to +9.81 parts per thousand), which is likely a xenocrystic crystal assimilated from wall rocks. The identical UPb age but contrasting NdO isotopic compositions between the xenocrystic monazite and the magmatic monazite grains indicate that the former might have experienced solid-state recrystallization process and completely lost radiogenic Pb. Both zircon and monazite geochemical and isotopic signatures consistently indicate that crustal assimilation occurred in the fine- to medium-grained granite zone. In contrast, in the medium-grained zone, only magmatic zircons and monazites were identified. The magmatic zircons have epsilon(Hf)(t) values of -3.2 to +2.7, and delta O-18 values of +4.65 parts per thousand to +6.36 parts per thousand. The magmatic monazites are characterized by huttonite-type substitution with high SiO2, ThO2 but low CaO contents. Their epsilon(Nd)(t) values vary from -5.7 to +1.6 (mostly < -4.4) and delta O-18 values from +4.65 parts per thousand to +6.36 parts per thousand. Given that the isotopic features of zircons and monazites in this zone are consistent with their whole-rock isotope features and no inherited/xenocrystic grains were observed, the zircons and monazites should record the source isotope compositions. The presence of highly radiogenic Nd isotopes in monazite coupled with its normal mantle-like O isotopes suggest minor involvement of juvenile mantle-derived components in the magma source. Accordingly, we advocate combined study of zircon and monazite, which can better track granite source nature and evolution processes than individual mineral.

Neoproterozoic evolution of the Yangtze Craton has long been debated. The Douling complex, representing one of the oldest crystalline basements, records Neoproterozoic high-grade metamorphism and may provide pivotal clues into a reliable Neoproterozoic configuration of the Yangtze Craton. However, its metamorphic evolution and tectonic significance have not been well constrained. In this contribution, we conduct an integrated study of petrography, zircon U-Pb age and Hf-O isotopic compositions for two garnet amphibolites and one gneiss from the Douling complex. Phase equilibrium modeling and conventional geothermobarometry calculation define peak P-T conditions of 9-10 kbar and 670-690 degrees C, and shape a clockwise P-T path. Zircon grains from the gneiss mostly reveal core-rim structure. The cores display oscillatory zoning, high Th/U ratios and trace element contents, as well as HREE-enriched patterns, high 176Lu/177Hf ratios and 818O values, consistent with a magmatic origin. They yield a weighted mean 206Pb/238U age of 868 +/- 9 Ma, which is taken as the protolith age. The cores have strongly positive sigma Hf(t) values of 7.0-15.6 and young two-stage Hf model ages of ca. 1310-760 Ma, indi-cating that the protolith was dominantly sourced from prompt reworking of Meso-Neoproterozoic juvenile crust. On the other hand, the zircon overgrowth rims in the gneiss exhibit no zoning patterns, low Th/U ratios and trace element contents, flat HREE patterns and pronouncedly negative Eu anomalies, variable 176Lu/177Hf ratios and comparable sigma Hf(t) values to the magmatic cores, indicating their coeval formation with garnet and plagioclase under amphibolite-facies metamorphism and might be generated by dissolution-reprecipitation. Zircon crystals from the two amphibolites perform weak zoning patterns, low Th/U ratios and trace element contents, high formation temperatures, flat to weakly enriched HREE patterns, insignificantly and/or clear negative Eu anomalies, and low 176Lu/177Hf ratios and sigma Hf(t) values, suggesting that they may form near the peak stage of amphibolite-facies metamorphism. Metamorphic zircon in the three samples yield homogeneously high 818O values (10.81 +/- 0.17%o, 11.45 +/- 0.40%o, 10.92 +/- 0.08%o), indicating the participation of external fluid origi-nated from surrounding metasedimentary rocks. These metamorphic zircon grains together yield a weighted mean age of 817 +/- 4 Ma (MSWD = 0.63), which is taken as the best estimated age for the upper amphibolite -facies metamorphism in the Douling complex. Considering the widespread contemporaneous magmatism in the northern Yangtze Craton, we propose that the Douling complex recorded a tectonic regime switch from compression to extension at ca. 830-820 Ma, in response to outboard oceanic subduction on the periphery of the Yangtze Craton and then tectonic extension and collapse of the thickened lithosphere.

The North Qinling (NQ) orogen is a typical high-pressure (HP) and ultrahigh-pressure (UHP) terrane involved in multiple orogenies, whose exhumation processes have yet been well constrained. Six plagioclase-bearing felsic dikes were collected for zircon petrochronological study to place precise age constraints on the end of the UHP metamorphism. The felsic dikes show no to strong deformation and consist mainly of K-feldspar, plagioclase, and amphibole, with minor biotite and muscovite. Zircons from these dikes have euhedral shape and exhibit weak, planar, or oscillatory zoning. They possess very low Th/U ratios, steep heavy rare earth element enriched pat-terns, and variable Eu anomalies, with Ti-in-zircon temperatures between ca. 600 and 660 degrees C. Therefore, the zircon crystals precipitated from the felsic dikes under relatively low pressure and high temperature conditions. These felsic dikes jointly yielded a weighted mean age of 490 +/- 2 Ma (MSWD = 0.39). This age is indistin-guishable from the peak HP-UHP metamorphic age of 492 +/- 4 Ma within analytical errors for the NQ unit. The resultant exhumation rate is averaged at about 3.2 cm/yr, and the minimum is about 0.8 cm/yr from the peak UHP metamorphic to at least the middle crust depth. The NQ terrane thus is a fast exhumation HP-UHP terrane. Considering the regional tectonic evolution, the contemporary jump of ocean subduction slab is likely triggering the rapid exhumation. Our results show that zircon petrochronology of felsic dikes is a powerful tool for con-straining the early exhumation of HP-UHP rocks involving in complex metamorphic processes.

This paper explores the effect of carbon trading on low-carbon transformation of high energy consumption enterprises in China. Based on the mechanism of interaction and restriction among high energy consumption enterprises, carbon verification agencies and the government, a tripartite evolutionary game model is constructed. The three-dimensional dynamic system is built to analyze the behavior patterns of the three parties. The evolution path of the tripartite game is visualized, and the low-carbon transformation states of high energy consumption enterprises in different situations are described. The results show that the high energy consumption enterprises, verification organization and the government cannot reach the optimal game equilibrium (low-carbon transformation, verification and supervision) temporarily when seeking their own interests. The corresponding measures should be taken with different situations of the tripartite game. No matter what strategy the government chooses, the low-carbon transformation could be promoted by carbon trading through carbon verification mechanism.

Using a large sample of publicly listed firms in China, we examine the relation between local financial agglomeration and corporate green innovation. We document that local financial agglomeration positively affects corporate green innovation output. This positive effect is more pronounced when firms have better environmental performance, when the market‐level sentiment for corporate environmental responsibility is higher, or prior to the implementation of a green credit policy in China. Further analysis reveals that local financial agglomeration enhances corporate green investments and the quality of green innovation. Collectively, our findings reveal the real and environmental effects of local financial agglomeration.

The late Mesozoic tectonic domain of Southeast China transitioned from compression to extension because of the Paleo-Pacific plate rollback. However, the precise timing of the initiation of extensional tectonics remains unclear. This work focuses on the E–W-trending granite belt and the growth strata of Early Cretaceous red beds in Southeast China to establish the extensional tectonic model in Southeast China. The petrogenesis of four granitic plutons from the E–W-trending granite belt in NE Jiangxi is traced on the basis of zircon U–Pb ages and whole-rock major and trace element abundances to elucidate lithosphere evolution in the study area. U–Pb zircon dating reveals the granite emplacement at 130–135 Ma. Geochemical results demonstrate that all granite intrusions can be identified as A-type granites derived from crustal and a few mantle sources respectively through lithospheric thinning and magma upwelling under the extension background. Field observation shows the enlargement of the sedimentary area of the early Cretaceous Huizhou Formation (Fm.) in the Huangshan Basin closely after (or simultaneously) 139 Ma Shiling volcanic activities. The dip angles of the lower part of Huizhou Fm. vary from 49° to 25° towards the basin centre, and the thickness exhibited a slightly increasing trend towards the lower part within the same bed. These phenomena are consistent with the shape of the growth strata. A model, in which the NE–SW-oriented structure lines transfer to the E–W-trending tectono-magmatic belts by meeting and inheriting the previous E–W-trending tectonic axis, is established in the present work. Lithospheric thinning, magma upwelling, and crustal remelting occur within an oblique extension stress field since ca. 140 Ma. Consequently, these phenomena are influenced by the Paleo-Pacific plate rollback and the inheritance of a structural framework from the regional basement series.

Oceanic arcs are known as the critical sites to generate new continental crust. However, additional processes are needed to transform mafic oceanic crust to mature continental crust. Ascertaining the petrogenesis of granitoids therein is vital to understand such a maturation process. In this study, we carried out a combined study of in-situ zircon U-Pb dating and Hf-O isotopic analyses, as well as whole-rock geochemical and Sr-Nd isotopic compositions for the Changwan granitoids in the Erlangping oceanic arc unit of the Tongbai orogen. This intrusion mainly consists of biotite granite with subordinate trondhjemite. LA-ICPMS and SIMS zircon U-Pb dating yielded identical U-Pb ages of ca. 460 Ma, representing the intrusion ages. Whole-rock analyses demonstrated that the Changwan granitoids have relatively high SiO2 (72.71-77.14 wt%) and Al2O3 (12.61-14.24 wt%), but low MgO (0.31-0.74 wt%) contents and Mg# (32.0-40.2). The relatively high K2O (2.81-3.63 wt%) contents and K2O/Na2O values (0.76-1.03) of the granitic samples suggest they belong to middle-K weakly peraluminous I-type granite, while the trondhjemitic samples with low K2O (1.06-1.96 wt%) and K2O/Na2O values (0.23-0.42) are tholeiitic to middle-K series. In both cases, the samples show arc-type trace element distribution patterns. They are characterized by depleted Sr-Nd-Hf isotopic compositions with (Sr-87/Sr-86)i of 0.7038-0.7050, epsilon(Nd)(t) of +0.52 ~ +2.85, zircon epsilon(Hf)(t) of +3.4 ~ +9.6, and relatively low zircon delta O-18 values of 4.71 +/- 0.17-4.97 +/- 0.18 parts per thousand. These isotopic fingerprints suggest the Changwan granitoids were derived from a relatively depleted source that had been hydrothermally altered under high temperature conditions. The most likely candidate is the accreted Erlangping lower oceanic crust which might have been heterogeneously modified in a supra-subduction zone. This is further verified by the trace element modeling on potential mafic source rocks enriched in incompatible elements in the Erlangping unit. We suggest that the high K2O/Na2O granitic samples were derived from K-rich segment of the Erlangping lower oceanic crust whilst the low K2O/Na2O trondhjemites from K-poor part. Therefore, our results show that partial melting of enriched oceanic crust in supra-subduction zone plays an important role for crust maturation in accretionary orogens.

We identify 21 predetermined country-level factors that explain marked variations in weekly COVID-19 morbidity and mortality across 91 countries between January and the end of 2020. Besides factors commonly associated with infectious diseases (e.g., population and tourism activities), we discover a list of country characteristics that shape COVID-19 outcomes. Among demographic-geographic factors, the male-to-female ratio, population density, and urbanization aggravate the severity of COVID-19, while education, temperature, and religious diversity mitigate the impact of the pandemic on morbidity and mortality. For the political-legal dimension, democracy and political corruption are aggravating factors. In contrast, female leadership, the strength of legal systems, and public trust in government significantly reduce infections and deaths. In terms of socio-economic aspects, GDP per capita, income inequality, and happiness (i.e., life satisfaction) lead to worse COVID-19 outcomes. Interestingly, technology advancement increases morbidity but reduces mortality. For healthcare factors, SARS (severe acute respiratory syndrome) experience and healthcare infrastructure help countries perform better in combating the pandemic.

The capital market in China has progressed rapidly within the realm of ESG and sustainability. This study investigates whether and how ESG investing works in China. The portfolio-level analysis shows that both high- and low-level ESG portfolios can earn higher abnormal returns, which implies a non-linear relationship between ESG and portfolio excess returns. In stock-level analysis, the effect of ESG on future stock returns varies by pillar and sector. Governance and social pillars work in opposite directions to predict returns. In the secondary (tertiary) sector, higher ESG scores predict lower (higher) returns. Furthermore, we find that higher ESG performance is associated with worse future profitability, which impairs firm value, and lower cost of equity capital, which increases firm value.

基于中国A股上市公司数据,文章实证分析了企业披露绿色发展信息对权益资本成本的影响以及不同所有权性质下这种影响效应的差异.研究发现:绿色发展信息披露与权益资本成本呈"倒U型"关系,该结论在一系列稳健性检验下仍然成立.与非国有控股企业相比,这种"倒U型"关系在国有控股企业中表现的更为显著.进一步研究发现,绿色发展信息披露与权益资本成本的"倒U型"关系在重污染行业和高成长性企业中更为显著,但在不同经济发展状况的地区之间并没有产生显著差异.

Cretaceous syntectonic growth strata in terrigenous basins in Southeast China have scarcely been reported in previous studies. This work focusses on the growth strata of the Early Cretaceous red beds in the East Yangtze Block (EYB), especially in the Huangshan Basin in southern Anhui Province, to help determine the Late Mesozoic tectonic domain and the precise timing of the initiation of extensional tectonics in Southeast China. Field observations show that the dip angles of the red conglomerate‐bearing sandstones from the lower part of the Huizhou Fm. vary from 49° to gentle dips towards the basin centre and that the visible and estimated thickness within a single bed increases slightly downward from the upper to the lower part. These characteristics indicate that the sedimentary area of the Early Cretaceous Huizhou Formation (Fm.) has undergone an extensional process with the expansion and deepening of the sedimentary basin by rotation of the border surface (limb) and thus deposited the extension growth strata simultaneously with (or closely after) the 139 Ma Shiling volcanic activity. Caused by a NW‐SE‐oriented extensional stress field since ca. 140 Ma, a model in which NE‐SW‐oriented tectonic lines transform to E‐W‐trending tectono‐magmatic belts by intersecting and inheriting the previous E‐W‐trending tectonic fabrics is established in the present work. Consequently, these phenomena are influenced by Palaeo‐Pacific Plate rollback and the inheritance of a structural framework from the regional basement strata and deformation series.

Plagiogranites are a volumetrically minor component of oceanic crust and ophiolites, but offer an opportunity to probe the processes and mechanisms by which felsic crusts were produced from the mafic oceanic crusts. The Qinling-Tongbai orogenic belt in central China is a typical composite orogenic belt that records the amalgamation processes between the North China Block and the South China Block. The Erlangping unit represents an accretionary oceanic unit in the Qinling-Tonbai orogenic belt and contains minor plagiogranites, which have received little attention. In this study, we carried out an integrated study of U–Pb geochronology and Hf–O isotopes in zircon, as well as whole-rock isotope and geochemical analyses for felsic rocks in the Erlangping unit. These rocks occur as dikes to stocks intruding ambient basalts. They have relatively high Na2O and Al2O3, moderate MgO and low K2O contents, and are classified as oceanic plagiogranites. Zircon U–Pb geochronology yielded formation ages of ca. 465 Ma. Zircon δ18O compositions (4.4–5.1‰) are lower than or similar to those of zircons from normal mantle. The low TiO2 content, elevated Zr/Hf, and light rare-earth element (LREE) enrichments in these rocks indicate that these plagiogranites were generated by partial melting of hydrothermally altered oceanic crust. These samples have more depleted whole-rock εNd(t) (+4.4 to +5.1) and zircon εHf(t) (+10.5 to +12.8) values than the basaltic wall-rocks, implying they were derived from a newly accreted oceanic arc. Taking into account the tectonic framework of the broader Qinling Orogenic belt, a subduction-induced magma flare-up in the Ordovician could have triggered the anatexis of the existing Erlangping oceanic arc, and in turn generated these plagiogranites. Partial melting of oceanic crust that has been enriched in a subduction system may be an important mechanism for the formation and maturation of continental crust in oceanic arc settings.

This study constructs a media-based investor sentiment index based on a textual analysis of China's leading financial newspapers. We employ both the Word2Vec technique and the dictionary method to measure the aggregate textual tone in the media news. Based on a sample of publicly listed A-share firms in China, we document that media-based sentiment is positively (negatively) related to the cross-section of stock returns over a short (long) horizon. Further analysis shows that higher information quality, measured by more analyst coverage, better audit opinions and non-governmental ownership could mitigate the effects of sentiment. Overall, our findings imply that media news contains important information for measuring the overall investor sentiment that drives the future stock price up in the short term and then down in the long term.

为预测和评价山东蓬莱石家金矿床的深部找矿远景,延长矿山服务年限,着重论述了该矿床的原生晕地球化学特征,对矿床的深部找矿潜力进行了探讨.原生晕元素组合特征分析表明,石家金矿床的矿体及近矿晕元素组合为Au、Ag、Cu、Pb、Zn、S、Te,前缘晕为Hg、As、Sb、Ba,尾晕为Mo、W、Sn.元素异常形态特征显示,326号矿脉南段以前缘晕和近矿晕为主,北段以前缘晕和尾晕为主,近矿晕元素异常较弱,矿体总体具有向南侧伏的特点.原生晕轴向分带序列在36线和84线均呈现反分带和前缘晕、尾晕共存的特点,结合地球化学参数在垂向上呈振荡波动变化的特征,说明矿体由多期次成矿作用叠加形成,同时预示矿体向深部还有一定延伸或有盲矿体存在.综合分析认为,326号矿脉南段为成矿的有利部位,深部仍有较大的找矿空间;矿体北段深部矿化减弱,但出现了前缘晕、尾晕元素的共存,预示深部可能还有盲矿体存在.

The Shangdan Ocean represents the eastern branch of the Proto-Tethys Ocean, which is important to decipher the evolution of the Central China Orogenic Belt. However, its evolution is still in debated. In this contribution, we carried out an integrated study of zircon U-Pb ages, whole-rock geochemistry, as well as zircon Hf-O isotope compositions for the Lajimiao mafic complex in the Shangdan Suture Zone in the North Qinling orogen. The Lajimiao mafic complex is composed of coarse-grained gabbros to norite-gabbros (Group 1) in the inner and fine-grained diorites (Group 2) in the outer part. The Group 1 samples are comprised predominantly of salite to augite (Mg-# = 75-80), magnesi-hornblende (Mg-# = 65-67) and Ca-rich plagioclase (An = 45-67); the Group 2 samples are comprised predominantly of magnesi-hornblende (Mg-# = 60-66) and plagioclase (An = 28-53). New SIMS and LA-ICP-MS U-Pb dating of zircon grains from a gabbro and a diorite sample yielded similar weighted mean ages of 412 +/- 4 Ma and 414 +/- 2 Ma, indicating that they were formed simultaneously. The Group 1 samples have relatively low SiO2 (49.56-50.78 wt%), high MgO (6.67-7.70 wt%) and Fe2O3T (7.46-9.61 wt%) contents, while the Group 2 samples have relatively high SiO2 (57.74-59.53 wt%), low MgO (3.28-3.42 wt%) and Fe2O3T (5.76-7.01 wt%) contents. They both belong to calc-alkalic series and enriched in large ion lithophile elements (LILEs), light rare earth element (LREEs) and depleted in high field strength elements (HFSEs), which are typical of arc-related rocks. The Group 2 diorites exhibit relative enrichment in light rare earth element (LREE) ((La/Yb)(N) = 10.9-13.1) with slightly negative Eu anomalies (Eu/Eu* = 0.82-0.93), compared to the Group 1 samples ((La/Yb)(N) = 5.2-9.6; Eu/Eu* = 0.91-1.43). Both of them have enriched initial Sr (0.7049-0.7054), and chondritic to slightly depleted Nd (epsilon(Nd)(t) = -0.09 similar to +1.50), but depleted whole-rock and zircon Hf isotopic compositions (epsilon(Hf)(t) = 7.81-8.10 and 8.2-9.1). The Hf-Nd isotopic systems are decoupled with positive Delta epsilon(Hf) values (5.22 to 5.92) (Delta epsilon(Hf) = epsilon(Hf)(t) - (1.59 x epsilon(Nd)(t) + 1.28)). The zircon grains display higher delta O-18 values of 6.3 to 6.5 parts per thousand than those of the normal mantle zircon. Whole-rock Pb isotopic compositions of the studied samples are of 15.610-15.624 for Pb-207/Pb-204, 38.027-38.178 for Pb-208/Pb-204, and 18.100-18.269 for Pb-206/Pb-204. These geochemical features indicate that the Lajimiao mafic complex was derived from relatively depleted mantle that had been metasomatized by 2-5% subducted zircon-barren oceanic sediments. Combining with regional geological, geochronological, mineralogical, and geochemical data, the Lajimiao mafic complex was suggested to be generated by partial melting of a phlogopite-bearing mantle source at relatively low pressure in an arc setting. We suggested that the generation of the Lajimiao mafic complex was induced by the subduction of Shangdan Ocean during the early Devonian and thus the eastern branch of ProtoTethys Ocean might have not been closed until that time. (C) 2021 Elsevier B.V. All rights reserved.

An integrated study of whole-rock elements, Sr-Nd isotopes, and zircon U-Pb ages and Hf-O isotopes was carried out for the "Grenvillian" granites from the North Qinling unit, central China. The results not only place clear constraints on the petrogenesis of these granites, but also give insights into the geodynamic evolution of the Qinling orogen during the assemblage of supercontinent Rodinia. LA-ICPMS zircon U-Pb dating of three representative granites from the Dehe, Fangzhuang, and Zhaigen outcrops yielded formation ages of ca. 940-900 Ma. These muscovite-bearing granites have high silica contents (72-79 wt%) and are weak to strong peraluminous (ASI = 1.01-1.15). They exhibit arc-like trace element distribution patterns with enrichment of LREE and LILE (e.g., Rb, K, Pb) but depletion in HFSE (e.g., Nb, Ta, Ti). Besides, they show variable initial Sr-87/Sr-86 ratios of 0.704 to 0.729 and relatively low eNd(t) values of 3.2 to 6.1, as well as variable zircon epsilon(Hf)(t) and delta O-18 values (8.1-+2.6, 7.9 parts per thousand-12.0 parts per thousand). These results suggest their derivation from partial melting of a heterogeneous source that dominated by supracrustal components. Furthermore, a few inherited grains give negative epsilon(Hf)(t) values of 9.4 to 18.4 with two-stage Hf model ages up to 2.9 Ga, suggesting the involvement of minor Archean crustal components. Along with their peraluminous features, high zircon delta O-18 values, and enriched Sr-Nd isotope compositions, these granites were unambiguously derived from partial melting of metasedimentary rocks and thus are of S-type affinity. Geothermometric and compositional approaches suggest these S-type granites were likely generated by dehydration melting of metagraywacke- and/or metapelite-dominated sources. They might be formed in an accretionary orogen associated with the Rodinia-assembly during the early Neoproterozoic, through which the outboard North Qinling terrane was eventually adjacent to the South China Block.