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| 1 | Initiation and evolution of the South China Sea: an overview显示文摘Different models have been proposed for the formation and tectonic evolution of the South China Sea(SCS), including extrusion of the Indochina Peninsula,backarc extension, two-stage opening, proto-SCS dragging,extension induced by a mantle plume, and integrated models that combine diverse factors. Among these, the extrusion model has gained the most attention. Based on simpli?ed physical experiments, this model proposes that collision between the Indian and Eurasian Plates resulted in extrusion of the Indochina Peninsula, which in turn led to opening of the SCS. The extrusion of the Indochina Peninsula, however, should have led to preferential opening in the west side of the SCS, which is contrary to observations. Extensional models propose that the SCS was a backarc basin, rifted off the South China Block. Most of the backarc extension models, however, are not compatible with observations in terms of either age or subduction direction. The two-stage extension model is based on extensional basins surrounding the SCS. Recent dating results indeed show two-stage opening in the SCS, but the Southwest Subbasin of the SCS is much younger, which contradicts the two-stage extension model. Here we propose a re?ned backarc extension model. There was a wide Neotethys Ocean between the Australian and Eurasian Plates before the Indian-Eurasian collision. The ocean ?oor started to subduct northward at *125 Ma, causing backarc extension along the southern margin of the Eurasian Plate and the formation of the proto-SCS. The Neotethys subduction regime changed due to ridge subduction in the Late Cretaceous, resulting in fold-belts, uplifting, erosion, and widespread unconformities. It may also have led to the subduction of the proto-SCS. Flat subduction of the ridge may have reached further north and resulted in another backarc extension that formed the SCS. The rollback of the?at subducting slab might have occurred *90 Ma ago; the second backarc extension may have initiated between 50 and 45 Ma. The opening of the Southwest Subbasin is roughly simultaneous with a ridge jump in the East Subbasin, which implies major tectonic changes in the surrounding regions, likely related to major changes in the extrusion of the Indochina Peninsula. | Weidong Sun | 2016 | Acta Geochimica2016，35，3： | 22 |
| 2 | Adakitic rocks associated with the Shilu copper–molybdenum deposit in the Yangchun Basin,South China,and their tectonic implications显示文摘South China is famous for the extensive magmatism and polymetallic mineralization that took place there in the Mesozoic. Shilu is a large porphyry–skarn Cu–Mo deposit in the Yangchun Basin, South China. The lithology of the Shilu intrusion is granodiorite and quartz diorite, both of which are high-K calc-alkaline series, with high Sr([400 ppm) content along with low Y and Yb contents. Most of the samples have characteristics of adakite except for a few samples that have slightly higher Y and Yb contents, which may be plausibly explained by crustal contamination. Laser Ablation Inductively Coupled Plasma Mass Spectrometry zircon U–Pb dating revealed ages between 106.6 ± 1.3 and 103.9 ± 0.5 Ma, with multiple magmatic pulses. Molybdenite Re–Os isochron age of 102.2 ± 2.9 Ma(MSWD = 9.4) was determined, which is identical to the youngest zircon U–Pb age(103.9 ± 0.5 Ma) within error.The Shilu intrusion has high oxygen fugacity as indicated by high zircon Ce^(4+)/Ce^(3+) and Eu_N/Eu_N* ratios. Considering the geochemical characteristics(high Sr, and low Y and Yb contents), high oxygen fugacity, and copper mineralization of the Shilu intrusion, it was most likely formed by partial melting of a subducted young oceanic slab. Whole-rock Sr–Nd isotope-, zircon Hf isotope-, and whole-rock trace element analyses show that Shilu adakitic magmas may have interacted with type II enriched mantle and/or crustal materials during ascent. South China was affected by the Pacific tectonic regime to the east and the Neo-Tethys tectonic regime to the south in the Cretaceous. Based on the Pacific Plate drifting and rotation history, it is hard to explain how the Pacific Plate would have subducted and melted, forming adakitic rocks in the Shilu region. Considering the tectonic history of Southeast Asia and the South China Sea, the Neo-Tethys trench should have been much closer to the South China Block in the Cretaceous, and thus have had a greater impact on the South China Block. Based on the subduction direction, time of subduction,and distance between the Neo-Tethys subduction zone and the Shilu deposit, subduction of the Neo-Tethys ridge is the best mechanism for explaining the Shilu adakitic rocks and Cu–Mo mineralization. | Lipeng Zhang Yongbin Hu Jinlong Liang Trevor Ireland Youliang Chen Rongqing Zhang Saijun Sun Weidong Sun | 2017 | Acta Geochimica2017，36，2： | 15 |
| 3 | Effects of biochar-based fertilizers on nutrient leaching in a tobacco-planting soil显示文摘Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural soils. We conducted a soil column leaching experiment to study the effects of BF on the leaching of total nitrogen(TN), total phosphorus, and total potassium(TK) in tobacco soils. The distribution characteristics of NH_4^+-N, available P, and available K in soil profiles were analyzed after the application of BF. Biochar was prepared by pyrolysis of fluecured tobacco stems. It was applied at four levels, 0%, 3%,9%, and 15%(w/w), respectively, to the compound fertilizer. Compared with the control, the leaching loss of soil TN decreased by 8.36%, 6.72%, and 6.45%, and the loss of soil TK decreased by 9.18%, 9.31% and 11.82% in the 3%,9%, and 15% BF treatments, respectively. However, BF had no significant effect on the P leaching due to the low movement of P in the soil profile. In addition, the BF addition increased the immobilization of NH_4^+-N, available P, and available K in the soil profile. These results indicate that addition of BF to a tobacco-planting soil reduced nutrient leaching, and suggest that BF could be an effective method of applying biochar to agriculture fields. | Yunlong Li Jianzhong Cheng Xinqing Lee Yi Chen Weichang Gao Wenjie Pan Yuan Tang | 2019 | Acta Geochimica2019，38，1： | 13 |
| 4 | Re–Os dating of molybdenite and in-situ Pb isotopes of sulfides from the Lamo Zn–Cu deposit in the Dachang tin-polymetallic ore field, Guangxi, China显示文摘The Dachang tin-polymetallic district, Guangxi,China, is one of the largest tin ore fields in the world. Both cassiterite-sulfide and Zn–Cu skarn mineralization are hosted in the Mid-Upper Devonian carbonate-rich sediments adjacent to the underlying Cretaceous Longxianggai granite(91–97 Ma). The Lamo Zn–Cu deposit is a typical skarn deposit in the district and occurs at the contact zone between the Upper Devonian limestone and the granite.The ore minerals mainly consist of sphalerite, arsenopyrite,pyrrhotite, galena, chalcopyrite, and minor molybdenite.However, the age of mineralization and source of the metals are not well constrained. In this study, we use the molybdenite Re–Os dating method and in-situ Pb isotopes of sulfides from the Lamo deposit for the first time in order to directly determine the age of mineralization and the tracing source of metals. Six molybdenite samples yielded a more accurate Re–Os isochron age of 90.0 ± 1.1 Ma(MSWD = 0.72), which is much younger than the reported garnet Sm–Nd isochron age of 95 ± 11 Ma and quartz fluid inclusions Rb–Sr isochron age of 99 ± 6 Ma. This age is also interpreted as the age of Zn–Cu skarn mineralization in the Dachang district. Further, in this study we found that in-situ Pb isotopes of sulfides from the Lamo deposit and feldspars in the district's biotite granite and granitic porphyry dikes have a narrow range and an overlap of Pb isotopic compositions(^(206) Pb/^(204) Pb =18.417–18.594,^(207) Pb/^(204) Pb = 15.641–15.746, and^(208) Pb/^(204) Pb = 38.791–39.073), suggesting that the metals were mainly sourced from Cretaceous granitic magma. | Hai Zhao Wenchao Su Peng Xie Nengping Shen Jiali Cai Ming Luo Jie Li Zhian Bao | 2018 | Acta Geochimica2018，37，3： | 11 |
| 5 | Geological cycling of potassium and the K isotopic response:insights from loess and shales显示文摘Shales are a major sink for K into seawater delivered from continental weathering,and are potential recorders of K cycling.High precision K isotope analyses reveal a[0.6%variation in δ^41K values(41K/39K relative to NIST SRM 3141a)from a set of well characterized postArchean Australian shale(PAAS)samples.By contrast,loess samples have relatively homogenous δ^41K values(-0.5±0.1%),which may represent the average K composition of upper continental crust.Most of the shales analyzed in this study have experienced K enrichment relative to average continental crust,and the majority of them define a trend of decreasing δ^41K value(from-0.5to-0.7%)with increasing K content and K/Na ratio,indicating cation exchange in clays minerals is accompanied by K isotope fractionation.Several shale samples do not follow the trend and have elevated δ^41K values up to-0.1%,and these samples are characterized by variable Fe isotope compositions,which reflect post-depositional processes.The K isotope variability observed in shales,in combination with recent findings about K isotope fractionation during continental weathering,indicates that K isotopes fractionate during cycling of K between different reservoirs,and K isotopes in sediments may be used to trace geological cycling of K. | Weiqiang Li Shilei Li Brian L.Beard | 2019 | Acta Geochimica2019，38，4： | 8 |
| 6 | Geochemistry and Zircon U–Pb age of the Yao'an pseudoleucite porphyry,Yunnan Province,China显示文摘The Yao'an Pb–Ag deposit, located in the Chuxiong Basin, western Yangtze Block, is an important component of the Jinshajiang–Ailaoshan alkaline porphyry–related polymetallic intrusive belt. This complex suite of rock bodies includes a vein of pseudoleucite porphyry within deposits of syenite porphyry and trachyte.The pseudoleucite is characterized by a variable greyish,greyish-white, and greyish-green porphyritic texture. Phenocrysts are mainly pseudoleucite with small amounts of alkali feldspar and biotite. In an intense event, leucite phenocrysts altered to orthoclase, kaolinite, and quartz.Both the pseudoleucite porphyry and the syenite porphyry samples were typical alkali-rich, K-rich, al-rich rocks with high LaN/YbNratios; enriched in light rare earth elements and large-ion lithophile elements, and depleted in high field strength elements; and with strongly negative Ta, Nb, and Ti(TNT) anomalies and slightly negative Eu anomalies—all characteristics of subduction-zone mantle-derived rock.We obtained a LA-ICP-MS zircon U–Pb age of 34.1 ± 0.3 Ma(MSWD = 2.4), which is younger than the established age of the Indian and Eurasian Plate collision.The magma derived from a Type-II enriched mantle formed in a post-collisional plate tectonic setting. The geochemical characteristics of the Yao'an pseudoleucite porphyry are powerful evidence that the porphyry'sdevelopment was closely linked to the Jinshajiang–Ailaoshan fault and to the Indian-Eurasian collision. | Chundi Sun Peng Wu Die Wang Shenjin Guan Xiaojun Jiang Longyan Jiang Longyan Wang | 2017 | Acta Geochimica2017，36，2： | 8 |
| 7 | The enhanced element enrichment in the supercritical states of granite–pegmatite systems显示文摘In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them. | Rainer Thomas Paul Davidson Karen Appel | 2019 | Acta Geochimica2019，38，3： | 8 |
| 8 | Spatial prediction of landslide susceptibility using GIS-based statistical and machine learning models in Wanzhou County,Three Gorges Reservoir, China显示文摘Landslide susceptibility mapping is vital for landslide risk management and urban planning.In this study,we used three statistical models[frequency ratio,certainty factor and index of entropy(IOE)]and a machine learning model[random forest(RF)]for landslide susceptibility mapping in Wanzhou County,China.First,a landslide inventory map was prepared using earlier geotechnical investigation reports,aerial images,and field surveys.Then,the redundant factors were excluded from the initial fourteen landslide causal factors via factor correlation analysis.To determine the most effective causal factors,landslide susceptibility evaluations were performed based on four cases with different combinations of factors('cases').In the analysis,465(70%)landslide locations were randomly selected for model training,and 200(30%)landslide locations were selected for verification.The results showed that case 3 produced the best performance for the statistical models and that case 2 produced the best performance for the RF model.Finally,the receiver operating characteristic(ROC)curve was used to verify the accuracy of each model's results for its respective optimal case.The ROC curve analysis showed that the machine learning model performed better than the other three models,and among the three statistical models,the IOE model with weight coefficients was superior. | Ting Xiao Kunlong Yin Tianlu Yao Shuhao Liu | 2019 | Acta Geochimica2019，38，5： | 8 |
| 9 | Geochemical characteristics of soil selenium and evaluation of Serich land resources in the central area of Guiyang City,China显示文摘Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluated.Major conclusions are as follows:(1) the Se content in surface soil of the central area of Guiyang City was 0.17–2.89 mg kg^(-1), and the average was 0.78 mg kg^(-1), which were respectively 2.6 and 3.9 times of the national background value of soil and the world background value of soil.The Se content in deep soil was 0.11–1.48 mg kg^(-1), and the average was 0.44 mg kg^(-1), which were respectively 1.5 and2.2 times of the national background value of soil and the world background value of soil. The soil Se content decreased with the increase in the soil depth on the vertical profile, and the surface soil had a higher Se content.(2)Distribution of Se content was mainly affected by parent material, physicochemical properties of soil and other components, soil type, and land use type. Parent material played a key role, as the soil Se content was mainly originated from parent rock and increased with the background value of Se in parent rock, physicochemical properties of soil and other components had certain influences upon the Se content. Se was shown to have a significant linear positive correlation with S and organic carbon but no significant correlation with p H value. Se content varied with different types of soil as follows: skeleton soil > yellow soil > paddy soil > limestone soil > purple soil. Land use type also hadcertain influences upon the soil Se content as follows: dry land > construction land > garden plot > grassland =garden plot > forest land.(3) Taking 0.4 mg kg^(-1)B x(Se) <3.0 mg kg^(-1) as the standard for Se-rich soil, Se-rich soil of the study area covered an area of 2224 km^2 and 92.5% of the total area; the remaining is general soil. The study area had no Se-excess soil. Therefore, the central area of Guiyang City has a high proportion of Se-rich land, a large area of Serich land resources, and a moderate selenium enrichment strength, which have been rarely seen anywhere and provide advantageous resources for the development of Se-rich featured agriculture. | Ziping Pan Shaolin He Chaojin Li Wei Men Chengzhi Yan Fang Wang | 2017 | Acta Geochimica2017，36，2： | 8 |
| 10 | Geochronological and geochemical constraints on the Cuonadong leucogranite, eastern Himalaya显示文摘First comprehensive investigations of the Cuonadong leucogranite exposed in North Himalayan gneiss dome of southern Tibet are presented in this study.The SIMS U–Pb ages of oscillatory zircon rims scatter in a wide range from 34.1 to 16.0 Ma, and the Cuonadong leucogranite probably emplaced at 16.0 Ma. High-precision ^(40)Ar/^(39)Ar dating on a muscovite sample yields an essentially flat age spectrum with consistent plateau and isochron ages, indicating that the Cuonadong leucogranite cooled below 450 °C at 14 Ma. Based on the youngest zircon U–Pb age and muscovite^(40)Ar/^(39)Ar age, the Cuonadong leucogranite experienced rapid cooling with a rate of 119 °C/Myr from 16 to 14 Ma. The geochronological data of this undeformed leucogranite also suggest that the ductile extension of the South Tibetan Detachment System in the eastern Himalaya ceased by ca. 14 Ma. Furthermore,the initial Sr–Nd isotopic compositions and Nd model ages demonstrate that the leucogranite was derived from metapelitic source within the Greater Himalayan Crystalline Complex. The distinct Ba depletion with high Rb/Sr ratios and negative Eu anomalies make it clear that the leucogranite melts were generated by breakdown of muscovite under fluid-absent conditions. | Jiajia Xie Huaning Qiu Xiujuan Bai Wanfeng Zhang Qiang Wang Xiaoping Xia | 2018 | Acta Geochimica2018，37，3： | 7 |
| 11 | Air–water CO2 flux in an algae bloom year for Lake Hongfeng,Southwest China:implications for the carbon cycle of global inland waters显示文摘The carbon cycle of global inland waters is quantitatively comparable to other components in the global carbon budget. Among inland waters, a significant part is man-made lakes formed by damming rivers. Manmade lakes are undergoing a rapid increase in number and size. Human impacts and frequent algae blooms lead to it necessary to make a better constraint on their carbon cycles. Here, we make a primary estimation on the air–water CO_2 transfer flux through an algae bloom year for a subtropical man-made lake—Hongfeng Lake, Southwest China. To do this a new type of glass bottles was designed for content and isotopic analysis of DIC and other environmental parameters. At the early stage of algae bloom,CO_2 was transferred from the atmosphere to the lake with a net flux of 1.770 g·C·m^(-2). Later, the partial pressure(pCO_2) of the aqueous CO_2 increased rapidly and the lake outgassed to the atmosphere with a net flux of 95.727 g·C·m^(-2). In the remaining days, the lake again took up CO_2 from the atmosphere with a net flux of 14.804 g·C·m^(-2). As a whole, Lake Hongfeng released 4527 t C to the atmosphere, accounting for one-third of the atmosphere/soil CO_2 sequestered by chemical weathering in the whole drainage. With an empirical mode decomposition method, we found air temperature plays a major role in controlling water temperature, aqueous pCO_2 and hence CO_2 flux. This work indicates a necessity to make detailed and comprehensive carbon budgets in man-made lakes. | Faxiang Tao | 2017 | Acta Geochimica2017，36，4： | 7 |
| 12 | The formation of porphyry copper deposits显示文摘Copper is a moderately incompatible chalcophile element.Its behavior is strongly controlled by sulfides.The speciation of sulfur is controlled by oxygen fugacity.Therefore,porphyry Cu deposits are usually oxidized(with oxygen fugacities > AFMQ +2)(Mungall 2002;Sun et al.2015).The problem is that while most of the magmas at convergent margins are highly oxidized,porphyry Cu deposits are very rare,suggesting that high oxygen fugacity alone is not sufficient.Partial melting of mantle peridotite even at very high oxygen fugacities forms arc magmas with initial Cu contents too low to form porphyry Cu deposits directly(Lee et al.2012;Wilkinson 2013).Here we show that partial melting of subducted young oceanic slabs at high oxygen fugacity(>AFMQ +2) may form magmas with initial Cu contents up to >500 ppm,favorable for porphyry mineralization.Pre-enrichment of Cu through sulfide saturation and accumulation is not necessarily beneficial to porphyry Cu mineralization.In contrast,remelting of porphyritic hydrothermal sulfide associated with iron oxides may have major contributions to porphyry deposits.Thick overriding continental crust reduces the 'leakage' of hydrothermal fluids,thereby promoting porphyry mineralization.Nevertheless,it is also more difficult for ore forming fluids to penetrate the thick continental crust to reach the depths of 2—4 km where porphyry deposits form. | Weidong Sun Jin-tuan Wang Li-peng Zhang Chan-chan Zhang He Li Ming-xing Ling Xing Ding Cong-ying Li Hua-ying Liang | 2017 | Acta Geochimica2017，36，1： | 7 |
| 13 | In-situ sulfur isotope and trace element of pyrite constraints on the formation and evolution of the Nibao Carlin-type gold deposit in SW China显示文摘The fault-controlled Nibao Carlin-type gold deposit,together with the strata-bound Shuiyindong deposit,comprise a significant amount of the disseminated gold deposits in southwestern Guizhou Province,China.Five main types and two sub-types of pyrite at the Nibao deposit(Py1a/Py1b,Py2,Py3,Py4,Py5)were distinguished based on detailed mineralogical work.Py1,Py2and Py3 are Au-poor,whereas Py4 and Py5 are Au-rich,corresponding to a sedimentary and hydrothermal origin,respectively.Through systematic in situ analyses of NanoSIMS sulfur isotopes,the framboid pyrite Py1a with negative δ^34S values(-53.3 to-14.9%)from the Nibao deposit were found to originate from bacterial sulfate reduction(BSR)processes in an open and sulfate-sufficient condition while the superheavy pyrite Py1b(73.7–114.8%)is probably due to the potential influence of closed-system Rayleigh fractionation or the lack of preservation of deepsea sediments.Data of Py2 and Py3 plot within the area of S isotope compositions from biogenic and abiogenic sulfate reduction.In view of few coeval magmatic rocks in the mining district,the near zero δ^34S values of the Au-rich pyrites(Py4 and Py5)may discount the potential involvement of magmatic but metamorphic or sedimentary origin.LA-ICP-MS and TEM work show that Au in ore-related pyrite is present as both nanoparticles and structurally bound.LA-ICP-MS analyses show that the Au-rich pyrite also contains higher As,Cu,Sb,Tl and S than other types of pyrite,which inferred a distal manifestation of deep hydrothermal mineralization systems. | Jinxiang Li Chenghai Zhao Yong Huang Yuzhou Zhuo Jinwei Li | 2019 | Acta Geochimica2019，38，4： | 7 |
| 14 | Zircon SHRIMP U–Pb age of Late Jurassic OIB-type volcanic rocks from the Tethyan Himalaya: constraints on the initial activity time of the Kerguelen mantle plume显示文摘This work presents zircon U–Pb age and wholerock geochemical data for the volcanic rocks from the Lakang Formation in the southeastern Tethyan Himalaya and represents the initial activity of the Kerguelen mantle plume. SHRIMP U–Pb dating of zircons from the volcanic rocks yielded a ^(206) Pb/^(238) U age of 147 ± 2 Ma that reflects the time of Late Jurassic magmatism. Whole rock analyses of major and trace elements show that the volcanic rocks are characterized by high content of Ti O_2(2.62 wt%–4.25 wt%) and P_2O_5(0.38 wt%–0.68 wt%), highly fractionated in LREE/HREE [(La/Yb)N= 5.35–8.31] with no obvious anomaly of Eu, and HFSE enrichment with no obvious anomaly of Nb and Ta, which are similar to those of ocean island basalts and tholeiitic basaltic andesites indicating a mantle plume origin. The Kerguelen mantle plume produced a massive amount of magmatic rocks from Early Cretaceous to the present, which widely dispersed from their original localities of emplacement due to the changing motions of the Antarctic, Australian, and Indian plates. However, our new geochronological and geochemical results indicate that the Kerguelen mantle plume started from the Late Jurassic. Furthermore, we suggest that the Kerguelen mantle plume may played a significant role in the breakup of eastern Gondwanaland according to the available geochronological, geochemical and paleomagnetic data. | Yuruo Shi Chenyang Hou J. Lawford Anderson Tianshui Yang Yiming Ma Weiwei Bian Jingjie Jin | 2018 | Acta Geochimica2018，37，3： | 6 |
| 15 | Carboniferous Alaskan-type complex along the Sino–Mongolian boundary,southern margin of the Central Asian Orogenic Belt显示文摘We present zircon ages and geochemical data for the Hongshishan Carboniferous Alaskan-type mafic–ultramafic complex exposed in the Beishan area along the Sino–Mongolian boundary, southern margin of the Central Asian Orogenic Belt. This complex mainly consists of dunite,harzburgite, lherzolite, wehrlite, and gabbro, which intrudes Early Carboniferous volcanic rocks and reveals a zoned structure. Zircons of a gabbro sample yielded a 206Pb/238 U age of 357 ± 4 Ma, reflecting the time of Early Carboniferous magmatism. Zircon ages were also obtained for an andesite(322 ± 3 Ma) and a basaltic andesite(304 ± 2 Ma).High initial Nd isotope whole-rock values suggest that the Hongshishan gabbro [e_(Nd(t))= +9.6-+10.2] and basalt[eNd(t)= +10.0-+10.8] were derived from a depleted mantle source. Slightly lower eNd(t)values for the ultramafic rocks [eNd(t)= +8.5-+8.7] suggest some interaction of the parental magma with the continental crust. In contrast, the Late Carboniferous Quershan samples in this area represent subduction-related arc volcanic rocks with Adakite-like compositions. The early Carboniferous Hongshishan Alaskan-type complex was interpreted to represent the remnants of a magma chamber that crystallized at the base of a mature island arc, whereas the Quershan island arc volcanic rockssuggest the resurrection of the subduction process after arccontinent collision and uplift of the roots of the arc. | Yuruo Shi Linlin Li Alfred Kroner Jing Ding Wei Zhang Zengbao Huang Ping Jian | 2017 | Acta Geochimica2017，36，2： | 6 |
| 16 | Quantification of photosynthetic inorganic carbon utilisation via a bidirectional stable carbon isotope tracer显示文摘The amount of bicarbonate utilised by plants is usually ignored because of limited measurement methods.Accordingly, this study quantified the photosynthetic assimilation of inorganic carbon(CO_2and HCO_3^-) by plants. The net photosynthetic CO_2assimilation(PN), the photosynthetic assimilation of CO_2 and bicarbonate(PN'),the proportion of increased leaf area(fLA) and the stable carbon isotope composition(δ^(13)C) of Orychophragmus violaceus(Ov) and Brassica juncea(Bj)under three bicarbonate levels(5, 10 and 15 mm NaHCO_3)were examined to determine the relationship among PN,PN' and fLA. PN', not PN,changed synchronously with fLA.Moreover, the proportions of exogenous bicarbonate and total bicarbonate(including exogenous bicarbonate and dissolved CO_2-generated bicarbonate) utilised by Ov were 2.27 % and 5.28 % at 5 mm bicarbonate, 7.06 % and13.28 % at 10 mm bicarbonate, and 8.55 % and 17.31 % at15 mm bicarbonate, respectively. Meanwhile, the proportions of exogenous bicarbonate and total bicarbonate utilised by Bj were 1.77 % and 3.28 % at 5 mm bicarbonate,2.11 % and 3.10 % at 10 mm bicarbonate, and 2.36 % and3.09 % at 15 mm bicarbonate, respectively. Therefore, the dissolved CO_2-generated bicarbonate and exogenous bicarbonate are important sources of inorganic carbon for plants. | Hongtao Hang Yanyou WU | 2016 | Acta Geochimica2016，35，2： | 6 |
| 17 | Nitrous oxide (N_2O) emissions from a mesotrophic reservoir on the Wujiang River,southwest China显示文摘Aquatic ecosystems have been identified as a globally significant source of nitrous oxide(N_2O) due to continuous active nitrogen involvement, but the processes and influencing factors that control N_2O production are still poorly understood, especially in reservoirs. For that, monthly N_2O variations were monitored in Dongfeng reservoir(DFR)with a mesotrophic condition. The dissolved N_2O concentration in DFR displayed a distinct spatial–temporal pattern but lower than that in the eutrophic reservoirs. During the whole sampling year, N_2O saturation ranging from 144% to 640%, indicating that reservoir acted as source of atmospheric N_2O. N_2O production is induced by the introduction of nitrogen(NO_3^-, NH_4^+) in mesotrophic reservoirs, and is also affected by oxygen level and water temperature. Nitrification was the predominate process for N_2O production in DFR due to well-oxygenated longitudinal water layers.Mean values of estimated N_2O flux from the air–water interface averaged 0.19 μmol m^(-2)h^(-1) with a range of 0.01–0.61 μmol m^(-2)h^(-1). DFR exhibited less N_2O emission flux than that reported in a nearby eutrophic reservoir, but still acted as a moderate N_2O source compared with other reservoirs and lakes worldwide. Annual emissions from the water–air interface of DFR were estimated to be 0.32×10~5 mol N–N_2O, while N_2O degassing from releasing water behind the dam during power generation was nearly five times greater. Hence, N_2O degassing behind the dam should be taken into account for estimation of N_2O emissions from artificial reservoirs, an omission that historically has probably resulted in underestimates. IPCC methodology should consider more specifically N_2O emission estimation in aquatic ecosystems, especially in reservoirs, the default EF5 model will lead to an overestimation. | Xiaolong Liu Siliang Li Zhongliang Wang Guilin Han Jun Li Baoli Wang Fushun Wang Li Bai | 2017 | Acta Geochimica2017，36，4： | 6 |
| 18 | Geological significance of nickeliferous minerals in the Fule Pb–Zn deposit, Yunnan Province, China显示文摘The Fule Pb–Zn deposit is located in the Sichuan–Yunnan–Guizhou Province, and it is an important and giant low temperature metallogenic domain in China.In our research area, the Pb–Zn deposits are mainly hosted in the Permian Yangxin Formation and are composed of dolostone and limestone. The distance between the ore bodies and the Permian Emeishan basalt ranged from 50 to160 m. In this study, the nickel rich minerals, including vaesite, polydymite and millerite, were reported for the first time in the Fule deposit. These minerals occurred as xenomorphic mineral aggregate and were sporadically distributed in the sphalerite–galena–calcite vein, which is the main ore type in the deposit. Our study indicated that the paragenetic sequence of minerals in the Fule deposit is the following order: polydymite → vaesite→ millerite → sphalerite → galena → tetrahedrite(tennantite).The geological occurrence characteristics of those nickeliferous minerals suggested that the Permian Emeishan basalt is a possible barrier layer of Pb–Zn ore-forming fluid, and it is an important source for the Ni and part of the Cu in the deposit. The Sichuan–Yunnan–Guizhou Pb–Zn mineralization province is a world-class production base of Pb and Zn, in which the Permian Emeishan basalt and Pb–Zn deposits have uniformly spatial distribution, but the relationship of mineralization between them is still under debate. This report provides new evidence forunderstanding the relationship between Pb–Zn mineralization and Permian Emeishan basalt in the Sichuan–Yunnan–Guizhou Pb–Zn mineralization province. | Zhenli Li Lin Ye Yusi Hu Zhilong Huang | 2018 | Acta Geochimica2018，37，5： | 6 |
| 19 | The mixing of multi-source fluids in the Wusihe Zn–Pb ore deposit in Sichuan Province, Southwestern China显示文摘The Sichuan-Yunnan-Guizhou(SYG)metallogenic province of southwest China is one of the most important Zn-Pb ore zones in China,with^200 Mt ZnPb ores at mean grades of 10 wt.%Zn and 5 wt.%Pb.The source and mechanism of the regional Zn-Pb mineralization remain controversial despite many investigations that have been conducted.The Wusihe Zn-Pb deposit is a representative large-scale Zn-Pb deposit in the northern SYG,which mainly occurs in the Dengying Formation and yields Zn-Pb resources of^3.7 Mt.In this paper,Zn and S isotopes,and Fe and Cd contents of sphalerite from the Wusihe deposit were investigated in an attempt to constrain the controls on Zn and S isotopic variations,the potential sources of ore-forming components,and the possible mineralization mechanisms.Both theδ66Zn andδ34S values in sphalerite from the Wusihe deposit increase systematically from the bottom to the top of the strata-bound orebodies.Such spatial evolution inδ66Zn andδ34S values of sphalerite can be attributed to isotopic Rayleigh fractionation during sphalerite precipitation with temperature variations.The strong correlations between the Zn-S isotopic compositions and Fe-Cd concentrations in sphalerite suggest that their variations were dominated by a similar mechanism.However,the Rayleigh fractionation mechanism cannot explain the spatial variations of Fe and Cd concentrations of sphalerite in this deposit.It is noted that the bottom and top sphalerites from the strata-bound orebodies document contrasting Zn and S isotopic compositions which correspond to the Zn and S isotopic characteristics of basement rocks and host rocks,respectively.Therefore,the mixing of two-source fluids with distinct Zn-S isotopic signatures was responsible for the spatial variations of Zn-S isotopic compositions of sphalerite from the Wusihe deposit.The fluids from basement rocks are characterized by relatively lighter Zn(~0.2‰)and S(~5‰)isotopic compositions while the fluids from host rocks are marked by relatively heavier Zn(~0.6‰)and S(~15‰)isotopic compositions. | Hongjie Zhang Haifeng Fan Chaoyi Xiao Hanjie Wen Lin Ye Zhilong Huang Jiaxi Zhou Qingjun Guo | 2019 | Acta Geochimica2019，38，5： | 6 |
| 20 | Assessment of pollution levels and human health risk of heavy metals in dust deposited on Yerevan's tree leaves (Armenia)显示文摘The total concentrations of Cd,As,Pb,Cr,Ni,Co,Zn,Cu,Ag,Hg,and Mo were determined in the atmospheric dust of the city of Yerevan by atomic absorption spectrometry(AAnalyst PE 800).Heavy metal pollution levels were evaluated by calculating geo-accumulation(I_(geo)) and summary pollution(Z_c) indices.Potential human health risk was assessed using the United States Environmental Protection agency's human health risk assessment model.The results show that mean contents of all elements tested except Ni and Cr were substantially higher than local geochemical background values.According to the I_(geo),Yerevan territory is strongly-to-extremely polluted by As,Ag,Hg,Mo,and Cd.The Z_c assessment indicated that very high pollution was detected in 36%of samples,high in 32%,average in 12%,and low in 20%.The health risk assessment revealed a noncarcinogenic risk(HI >1) for children at 13 samplings sites and for adults at one sampling site.For children the risk was due to elevated levels of Mo,Cd,Co,and As,while for adults,only Mo.Carcinogenic risk(>1:1,000,000) of As and Cr via ingestion pathway was observed in 25 and 14 samples,respectively.This study,therefore,is the base for further detailed investigations to organize problematic site remediation and risk reduction measures. | N. Maghakyan G. Tepanosyan O. Belyaeva L. Sahakyan A. Saghatelyan | 2017 | Acta Geochimica2017，36，1： | 6 |
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