Abstract:The Wulagai early Paleozoic gabbroic diorite pluton is outcropped in the East Ujimqin Banner of Inner Mongolia. It is located on the northern margin of the Xing-Meng Orogenic Belt (XMOB) and was previously referred as part of the Erenhot-East Ujimqin Paleozoic magmatic belt. This study reports zircon U-Pb age, elemental and isotopic geochemical data of the pluton, so as to reveal its petrogenesis and implications for the evolution of the XMOB. Zircon U-Pb dating yielded an weighted mean age of 499.6 ±1.2 Ma, indicating that it is the earliest intrusive pluton in Erenhot-East Ujimqin Paleozoic magmatic belt. Geochemically, the Wulagai pluton shows moderate SiO₂ (51.60%~54.28%), high Al₂O₃, depletion of magnesium and iron, and low alkali and potassium, thus belonging to calc alkali rocks. The gabbroic diorites are also enriched in LILE, depleted in HFSE, and exhibit gradual right-oblique chondrite-normalized REE patterns with unconspicuous positive europium anomalies (δEu=1.03~1.34). All the samples display depleted isotopic compositions with the data (⁸⁷Sr/⁸⁶Sr)_i=0.704 5~0.704 7 and εNd(t)=+2.71~+4.17, but the εHf(t) values of zircons (+10.8~+18.7) are much higher relative to the εNd(t) and show a Nd-Hf decoupling feature. Integrated geochemical, geochronological and Sr-Nd-Hf isotopic data suggest that the Wulagai gabbroic diorites were generated by the subduction of Paleo-Asian Ocean along the Sunid-Xilinhot island arc in early Paleozoic, and were formed at the initial stage of the subduction. The rocks originated from a mantle wedge which was mainly modified by the slab-derived melt prior to fluids, and there were also indistinct sedimentary materials in the source. The back-arc extension and opening of Hegenshan Ocean possibly led to the separation of Wulagai pluton from the Sunid-Xilinhot island arc. Along with the closure of Paleo-Asian Ocean, the pluton was ultimately isolated from the subduction zone by Hegenshan ophiolite complex.

Abstract:This paper discusses the petrogenesis of the two-mica granite and its genetic relationship with pegmatite in Jiajika area, west Sichuan Province, by detailed field investigation and laboratory analysis. The whole rock analytical results show that SiO₂ content of two-mica granite is 73.93%~75.06%, and total alkali is 7.90%~8.36% with high concentration of K, suggesting high-K calc-alkaline series; the content of Al₂O₃ is 14.24%~14.77%, and A/CNK=1.14~1.24, implying strong peraluminous S type granite; ΣREE=31.18×10^-6~41.67×10^-6,LREE/HREE=4.15~6.41,δEu=0.46~0.70, and CaO/Na₂O=0.07~0.12(<0.3),indicating that its source might have been pelite with rare content of psammite, and high ratio of Al₂O₃/TiO₂ (133.1~279.8) implies that it is high-pressure-low-temperature post-collision granite. The SiO₂ content of the granite pegmatite is 72.59%~80.91%, the total alkali is 5.26%~10.60%, Al₂O₃ is 11.79%~17.64%, σ=0.74~3.80; A/CNK=0.98~2.38; ΣREE=4.03×10^-6~8.29×10^-6, LREE/HREE=2.61~10.40, and δEu=0.18~0.68. There are considerable differences between two-mica granite and granite pegmatite in the aspect of the content of major and trace elements. And there is close genetic relationship between granite and pegmatite in the area. Magma immiscibility might be the key factor for the formation of (ore-bearing) granite pegmatite. The pegmatite melt riched in volatile components might be separated during the upwelling of granite magma and metasomatized minerals in wall rock to further concentrate rare metal elements during its migration. The difference between two-mica granite and pegmatite might cause the apparent differences in REEs and elements such as Th, Sr, Ti, Y, Rb and Nb. The different characteristics of pathways and environments that the pegmatite melt passed and emplaced might have resulted in element concentration variance in different sites. In comparison with two-mica granite, there existed a certain degree of jumping characteristic during the formation and evolution of the pegmatite in Jiajika area.

Abstract:The granitoids in Yunmengshan area, located on the northern margin of the North China Craton, are important for understanding the formation time and mechanism of the tectonic background transition in this area. In this paper, the authors present zircon SHRIMP U-Pb ages and geochemical characteristics of the granitoids in Changyuan pluton, Guanshan pluton and Yunmengshan pluton. The results, in combination with available zircon U-Pb ages, show two magmatic periods in Yunmengshan area:162~151 Ma and 151~141 Ma. Compared with the second period, samples from the first magmatism period are higher in Mg^# but lower in SiO₂, which indicates that they evolved from the mantle source to the crust source during Late Jurassic-Early Cretaceous compression episode, accompanied by crustal thickening, even with some exposed moderately-fractionated granitoids. The transition from compression to extension in the study area lasted for 12 Ma, i.e., from 141 Ma to 129 Ma. The granitoids from Yunmengshan area were formed in a compressional environment before decratonization, and the thickened crust possessed the condition for later delamination.

Abstract:Located on the western margin of the Yangtze Plate, Emeishan Large Igneous Province (ELIP) has experienced multi-episode tectonic movement since Late Permian, and hence the original spatial distribution of the Emeishan basalt has not been fully preserved. This fact leads to the underestimation of the magnitude of ELIP magmatism. Recently, some seismic tomography studies suggest that ELIP was produced by the delamination of lower crust rather than the mantle plume activity, which is based on the absence of high velocity layer in the ELIP crust. According to the linear relationship between P-wave velocity and density and the P-wave velocity of the crust acquired by Ljiang-Qingzhen seismic profile, the authors estimated the crustal densities of the core and periphery zone of inner belt and those of the middle and outer belts of ELIP. The result reveals significant difference of the crustal density structure between the inner belt and the outer zones of ELIP. Compared with the middle belt of ELIP, the density of the upper crust of the inner belt is about 79 kg/m³ higher, and the densities of the upper and the lower parts of lower crust are 68 kg/m³ and 101 kg/m³ higher, respectively. Compared with the outer belt, the density of upper crust of the inner belt is about 92 kg/m³ higher, and the densities of the upper and the lower parts of lower crust are 99 kg/m³ and 126 kg/m³ higher, respectively. The high density of the crust in the core region of the inner belt resulted from the emplacement and accumulation of mafic-ultramafic plutonic rocks. Based on the crustal density structures of different belts, the total volume of (45~120)×10⁴ km³ was estimated for the high density mafic-ultramafic rocks, which were intruded into the core region of the inner belt. Together with the volume of Emeishan basalt, the magnitude of magmatism of ELIP is up to (0.7~1.8)×10⁶ km³. This result favors the mantle plume origin of the ELIP.

Abstract:Subduction is the key geological process that can link the Earth's surface system with deep Earth's interior. It plays a significant role for the study of deep carbon cycle. Carbon in the subducting lithosphere is present in sediments, altered oceanic crust and serpentinite. The evolution of the carbonate-bearing rocks during subduction metamorphism controls the transformation of the carbonate minerals and carbon transport process. In this study, phase equilibria were modeled for the altered oceanic crust to investigate the metamorphic evolution of the carbonate minerals in the metabasalt. The calculated results indicate that the transformation of carbonate minerals are also affected by temperature and iron content in the metabasalt, in addition of the controlling role of pressure. Phase equilibrium modeling demonstrates that carbonates in the subducted oceanic crust may experience calcite/aragonite-dolomite-magnesite transition with increasing pressure, but under HP/UHP conditions, magnesite can be transformed to dolomite with increasing temperature. The iron content in the carbonates is affected by the iron content in the metabasalt, where the iron content in the dolomite and magnesite will increase with the increasing iron content in the metabasalt. When the altered oceanic crust is under water-unsaturated conditions, almost no decarbonation will happen when the oceanic crust subducts to sub-arc depth along either low temperature or high temperature geotherm. However, under water-saturated conditions, almost all of the carbon in the metabasalt will be released when the oceanic crust subducts to sub-arc depth along high temperature or Costa Rica geotherm. The water content in the metabasalt will facilitate the decarbonation reactions.

Abstract:The volcanogenic claystone in the Permian-Triassic boundary plays a significant role in understanding the volcanism and provenance in Yangtze Plate, which is widely distributed in South China. This paper reports zircon U-Pb ages determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) along with Hf isotopes, whole-rock elemental and X-ray diffraction for the samples of claystone in the lower Feixianguan Formation along Cilinbao section. The microscopic characteristics, X-ray diffraction and major elements analysis show that the claystone contains illites and small amounts of calcite and quartz. The detrital zircon age data exhibit a wide range, varying from 2 615 Ma to 246 Ma and concentrated on 2 615~2 383, 1 868~1 328, 1 186~778 and 430~246 Ma, with a~250 Ma peak value. Combined with the in-situ zircon Hf isotope, the authors detected that the zircon characteristics are similar to those in Qinling Mountain, Permian-Triassic boundary sections in South China and Emeishan large igneous province. Indeed, geochemical compositions of the claystone are characterized by relative enrichment of Zr, Hf, Th, Cr, Co and Ti, similar to features around Permian-Triassic boundary sections in South China and Emeishan basalt. Combined with tectonic setting of the end of Permian and detrital zircons, the authors hold that the claystone around the Permian-Trassic boundary along the Cilinbao section at Majiaoba was derived from Qinling Mountain, Longmenshan Islands, volcanism and Emeishan large igneous province.

Abstract:The Sonid Left Banner area, located in the southeast of the Central Asian Orogenic Belt and north of the Suolun suture zone, develops a characteristic volcanic-sedimentary rock series of the Lower Devonian Obootinghundi Formation. The strata are mainly composed of andesite, tuffaceous sandstone, sandstone and siltstone as well as pyroclastic rock. The rock has poor roundness and shows near-source sedimentary characteristics. The results of geochemical analysis show that the sandstone has medium SiO₂ and K₂O content, high Na₂O content, and low Fe₂O₃ and MgO content. Trace elements show right-inclined feature on the spider map, and the content and change trend are similar to those of the upper crust; rare earth element distribution characteristics display LREE-enrichment but HREE-depletion. The average (La/Yb)_N is 6.44, and the Eu anomaly is obvious (Eu/Eu^* average 0.72). Combined with regional analysis, the authors hold that the sandstone was formed on the active continental margin and the continental island arc. The source rocks are mainly metamite with minor andesite, and it is inferred that the Early Devonian paleo-Asian ocean was still in a tectonic setting of northward subduction. The source of the Obootinghundi Formation should mainly be the upper crust felsic rock series of the Uliastai area in the north.

Abstract:Abundant lithium-rich clay rocks are explored in the USA, Chili and some other countries. This kind of clay rocks is mainly altered from volcanic ash. The mung bean rocks are hydrolyzed from the sedimentary volcanic ash and are widely distributed in southwest China. To find out whether the mung bean rocks are rich in lithium, the authors studied the mung bean rocks in Tongliang, Chongqing. The test of X-ray fluorescence spectrometer and ICP-MASS shows that the lithium is relatively rich. The content of lithium is 663×10^-6(Li₂O 0.14%) much higher than the cutoff grade of solid and open mining salt mine (0.06%). The total amount of rare earth can reach 500×10^-6, close to the cutoff grade of ion-absorbing type rare earth ore. The result of X-ray diffraction analysis shows that the major ingredients include quartz, feldspar and clay minerals comprising illite and montmorillonite mixed layer and a little illite. The Li concentration of two samples whose clay minerals are pure illite and montmorillonite mixed layer is higher than that of the other samples. Combined with the characteristics of clay rocks and lithium, the authors infer that the lithium exist in ion state and is absorbed by the clay rocks. If the lithium can be comprehensively used, the value of the mung bean rocks will be enhanced greatly.

Abstract:The Dalaku'an mafic-ultramafic complex is located in the Late Paleozoic Karamilan arc zone, which is the southern active zone of the East Kunlun, and consists of lherzolite, wehrlite, olivine websterite, clinopyroxenite, plagioclase-bearing pyroxenite and grabbro. The olivine in the wehrlite and olivine websterite belongs to chrysolite with the Fo value ranging from 84.55 to 89.08, and the content of MnO and NiO ranging from 0.13% to 0.29% and 0.09% to 0.28%, respectively. The clinopyroxene belongs to diopside and augite with the content of MgO, FeO, CaO ranging from 15.12% to 16.98%, 3.84% to 5.34%, 21.10% to 22.95%, respectively. The mineral compositions of the Dalaku'an rock mass are different from those of the mafic-ultramafic cumulates from ophiolites, indicating that the Dalaku'an rock mass isn't a component of ophiolite but a continental intrusion. The mineral compositions of clinopyroxenes indicate that the parent magma belongs to the tholeiite series, which was formed in the continental margin rift during the subduction. There exist favorable conditions for the Cu-Ni sulfide deposit, as shown by the type of the intrusion, mineral chemistry and tectonic setting.

Abstract:The Tawenchahanxi Fe-polymetallic deposit is a medium-sized deposit newly discovered in Qimantag area of Qinghai Province. In this area the orebody and metallogenic rock body are both covered by Quaternary eolian sandstone. By using LA-ICP-MS zircon U-Pb isotope dating, the authors obtained the petrogenetic age of the granite diorite porphyry (236.0±2.3 Ma.) which is the main ore-forming rock mass in the ore deposit. The result is close to the age of Tawenchahanxi deposit. It might have been formed at the collision-post collision conversion stage of Late Paleozoic to Early Mesozoic tectono-magmatic cycle associated with the crustal thickening setting. On the basis of chronological, petrologic and geochemical studies, the authors have revealed that the granodiorite porphyry is a peraluminous, high K calc-alkaline series granite, which is enriched in LREE and HFSE and depleted in HREE and LILE, with medium negative Eu anomalies. The granodiorite porphyry belongs to the I-type and crust-mantle magma mixing source, related to regional large-scale mantle magma underplating and crust-mantle magma mixing. The Tawenchahanxi Fe-polymetallic deposit is a typical skarn deposit, which is mainly distributed in the contact zone between granodiorite porphyry and Qimantag Group carbonatite. There are two type of orebodies (metasomatic iron-oxide orebody and veinlet sulfide polymetallic orebody) in the ore deposit, and the evolution of the ore-forming fluid can be divided into skarn stage, retrograde alteration stage and sulfide-quartz stage.

Abstract:The passivation treatments are widely used for treating tailings which contain heavy metals with the purpose of preventing the production of acid mine drainage(AMD)from the sources. Therefore, it is very important to find an inexpensive passivator which causes little harm to the environment. In this paper, the authors used H₂O₂(pH=4)as an oxidant to oxidize the pyrite so as to discuss the passivation effect of bone char on the oxidation and release of heavy metals from pyrite. The results showed that the bone char had a strong neutralization capability, and the addition of bone char(different contents of 0.5 g, 2.5 g, 5 g) resulted in pH increase in the solutions, which were 8.93, 10.01 and 10.42, respectively. The presence of bone char decreased the release of Pb, Zn and Cd, but the release of As increased when the bone char was over 2.5 g. The infrared spectroscopy (FTIR)showed that the characteristic peaks at 420, 563, 603, 1 044, 1 091 cm^-1 belong to vibration of PO₄^3- produced by the dissolution of the bone char. XRD analysis suggested that the secondary mineral phases on the surface of the pyrite were graftonite and phosphogartrellite, which played an important role in heavy metals immobilization. As a passivating agent, bone char is most suitable for treating pyrite tailings which contain heavy metals.

Abstract:In order to evaluate the toxicity of the airborne particles in Beijing during the pollution process, the authors collected the PM₁₀(particulate matter with aerodynamic diameters of less than 10 μm) in the urban area of Beijing in 2016 and analyzed the oxidative capacity of the particles by plasmid scission assay. The results indicated that the oxidative capacity of PM₁₀ during the haze was higher than that after haze, and both were higher than that before the haze. In addition, the damage rate of supercoiled DNA by the samples increased with increasing experimental dose levels. The TD₂₀ values of the PM samples before, during, and after the haze displayed a descending order of before haze (788.01 μg/mL) > after haze (470.40 μg/mL) > during haze (55.78 μg/mL), which indicated a descending order of the PM oxidative capacity of during haze>after haze>before haze. The TI value during haze was higher than that after haze, both were higher than that before haze, suggesting that the PM₁₀ during haze was more harmful to human health.

Abstract:In order to explore the effect of extracellular metabolites of psychrophilic bacteria in Huanglong water on the travertine deposition rate and deposition products, the authors started with the Huanglong travertine water isolated advantage of indigenous psychrophilic bacteria, and took its landmark extracellular metabolites D-glucose and D-ribose as the object of study. The effects of two kinds of monosaccharide components on the deposition of travertine were investigated and, by means of X-ray diffraction (XRD), scanning electron microscope (SEM), infrared absorption spectroscopy (FT-IR) analysis, the types of calcium carbonate crystal morphology and structural composition were characterized. The results are as follows:D-glucose could promote the deposition of calcite-type calcium carbonate at low temperature and accelerate the deposition rate. The deposition products of low concentration (20 mg/L, 40 mg/L) were all calcite calcium carbonate and had a certain effect on their morphology; high concentrations (80 mg/L and 160 mg/L) could induce the synthesis of small amounts of aragonite calcium carbonate. D-ribose could promote the deposition of calcium carbonate at low temperature and accelerate the deposition rate. Unlike D-glucose, D-ribose could only synthesize calcite-type calcium carbonate, but it was an inhibitory effect on the growth of calcite crystal face, and its inhibitory effect was obvious with increasing concentration. The results can provide a theoretical basis for the exploration of Huanglong travertine.

Abstract:In this study, the effects of pH and temperature on adsorption and polymerization of glycine on anatase surface were investigated, respectively. The adsorption and polymerization capability of semiconductor minerals toward amino acid and the relevant mechanism were discussed. The results showed that the maximum adsorption capacity of glycine on anatase surface was obtained at pH=6.0. Under weak acid conditions, glycine was adsorbed by bonding the carboxyl group with functional groups or atoms on the anatase surface. Anatase catalyzed glycine polymerization in the range of 80~120℃ to form DKP, Gly₂, Gly₃ and other oligopeptides, suggesting that the catalytic polymerization products were controlled by temperature. The surface of anatase could provide active sites for the adsorption and condensation of glycine, and could further catalyze the polymerization of glycine when the enough energy (i.e., heating) was given.

Abstract:The Shanbo Stone has long been one of the varieties in larderite. Its exquisite texture and delicate feature make it popular, and the "Peanut Cake" has important significance for its identification and classification. In this paper, the authors investigated the Shanbo Stone and its "Peanut Cake" through detection and experimental analysis. The detection results by optical microscope and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS), laser Raman spectroscopy (LR), Infrared spectrometer(IR) and electron microprobe analysis (EPMA) show that a large number of microcrystalline anatases are the main factors influencing the white "Peanut Cake", and the main impurities in the red "Peanut Cake" are iron minerals, which form disseminated red patches later. Quartz is distributed in some white "Peanut Cake", and pyrophyllite is also observed in part of white "Peanut Cake". Besides, the complete crystal anatase dispersed in Shanbo stone constitutes a visible gold like reflective point.