Geology,Geochemistry and Zircon U-Pb Geochronology of Porphyries in the Dabate Mo-Cu Deposit,Western Tianshan,China:Petrogenesis and Tectonic Implications

The Dabate Mo-Cu deposit is a medium-sized porphyry-type deposit in the Sailimu Lake region, western Tianshan, China. We present the geology, geochemistry and zircon U-Pb geochronology of granite porphyries from the Dabate district with the intent to constrain their tectonic setting and petrogenesis. Porphyries in the Dabate district include granite porphyry I（gray white color with large phenocrysts）, granite porphyry II（pink color with small phenocrysts） and quartz porphyry. Granite porphyry II is the Cu and Mo ore-bearing granitoid in the Dabate deposit. LA-ICPMS zircon U-Pb analyses indicate that granite porphyry II was emplaced at 284.2±1.8 Ma. Granite porphyry I and II have similar geochemical features and are both highly fractionated granites：（1） They have high SiO2 content（70.93–80.18 wt% and 72.14–72.64 wt%, respectively）, total alkali（7.58–8.95 wt% and 9.35–9.68 wt%, respectively）, mafic index（0.95–0.98 and 0.93–0.94, respectively） and felsic index（0.79–0.94 and 0.89–0.91, respectively）;（2） They are characterized by pronounced negative Eu anomaly, ＂seagullstyle＂ chondrite-normalized REE patterns and ＂tetrad effect＂ of REE;（3） They are rich in Rb, K, Th, Ta, Zr, Hf, Y and REE, but depleted in Sr, P, Ti and Nb. The magma of granite porphyries in Dabate can be interpreted to have been generated by partial melting of the upper crust due to mantle-derived magma underplating in a post-collisional extensional setting.

Climate change during the last glacial period on the southeast margin of Badain Jaran Desert, Northwest China

Reconstruction of the desert paleoclimate is important to understand the mechanisms that triggered and/or enhanced climate change.Through optically stimulated luminescence(OSL)dating,grain size,magnetic susceptibility,X-ray powder diffraction(XRD)and geochemical indicators,we provide a welldated record of a sedimentary outcrop on the southeast margin of the Bardain Jaran Desert,Northwest China,during the last glacial period.Four Qz-OSL ages are obtained,41.0±3.4 ka,54.7±4.4 ka,59.5±5.0 ka and 66.8±5.8 ka,corresponding to the depths of 35 cm,70 cm,150 cm and 200 cm respectively.Indicators like grain size,clay content,magnetic susceptibility,XRD and geochemical index(e.g.Sr,Ba,Sr/Ca)jointly indicate abrupt climate changes at the depth of 35 cm(age,ca.41.0 ka)and200 cm(age,ca.67 ka).Namely,the 280 cm sedimentary outcrop perfectly records a warm wet climate stage,corresponding to the late Marine Isotope Stages(MIS)4 to the early MIS 3.Besides,there is a trend of grain size increase after around 40ka BP,which is most likely a signal of wind strength change.Our research supports that enhancing Siberian High pressure system during the late MIS 3played a key role in NW East Asia climate evolution.

O,H,and Sr isotope evidence for origin and mixing processes of the Gudui geothermal system,Himalayas,China

Tho Gudui geothermal field records the highest temperature at equivalent borehole depths among the lainland hydrothermal systems in China's Mainland.Located about 150 km southeast of Lhasa City,the capital of Tibet,the Gudui geothermal field belongs to the Sangri-Cuona rift belt,also known as the Sangri-Cuona geothermal belt,and is representative of the non-volcanic geothermal systems in the Himalayas.In this study,oxygen-18 and deuterium isotope compositions as well as 87Sr/86Sr ratios of water samples collected from the Gudui geothermal field were characterized to understand the origin and mixing processes of the geothermal fluids at Gudui.Hydrogen and oxygen isotope plots show both,deep and shallow reservoirs in the Gudui geothermal field.Deep geothermal fluids are the mixing product of magmatic and infiltrating snow-melt water.Calculations show that the magma fluid component of the deep geothermal fluids account for about 21.10%-24.04%;magma fluids lay also be a contributing source of lithium.The linear relationship of the 87Sr/86Sr isotopic ratio versus the 1/Sr plot indicates that shallow geothermal fluids form from the mixing of deep geothermal fluids with cold groundwater.Using a binary mixing model with deep geothermal fluid and cold groundwater as two end-members,the nixing ratios of the latter in most surface hot springs samples were calculated to be between 5% and 10%.Combined with basic geological characteristics,hydrogen and oxygen isotope characteristics,strontium concentration,87Sr/(86)Sr ratios,and the binary mixing model,we infer the 6 th-Class Reservoirs Evolution Conceptual Model(6-CRECM) for the Gudui geothermal system.This model represents an idealized summary of the characteristics of the Gudui geothermal field based on our comprehensive understanding of the origin and mixing processes of the geothermal fluid in Gudui.This study may aid in identifying the geothermal and geochemical origin of the Gudui high-temperature hydrothermal systems in remote Tibet of China,whose potential for geothermal development and utilization is enormous and untapped.

Ore-forming age and tectonic setting of the Linjiasandaogou gold deposit in the Liaodong Peninsula,northeast China:constraints from geochronology and geochemistry

The Linjiasandaogou gold deposit is located in the Qingchengzi Orefield,North China Craton,China,and has not attracted many studies.We present geochronological,whole-rock geochemical,and Sr–Nd–Hf isotopic data to constrain the age and tectonic setting of the mineralization.U–Pb dating of zircon from pre-and post-ore dikes indicates the Linjiasandaogou Au deposit formed at ca.227–226 Ma.The granite porphyry(ca.227 Ma)and quartz diorite porphyry(ca.228 Ma),which are slightly older than the mineralization,have(;Sr/;Sr)i-=0.7127–0.7162,εNd(t)=–13.7 to–17.0,andεHf(t)=–14.6 to–16.9,and display enrichment in light rare earth elements and large ion lithophile elements and depletion in high field strength elements.Two lamprophyres(226 and225 Ma),which are slightly younger than the mineralization,have higher(;Sr/;Sr)i(0.7165–0.7216),negativeεNd(t)(–11.2 to–14.3)andεHf(t)(–15.6 to–18.6)values,and are enriched in light rare earth elements but depleted in high field strength elements(Nb and Ta).The geochemical characteristics of the granitoid and lamprophyres indicate a lower crustal and enriched mantle source,respectively.We infer that the Linjiasandaogou Au deposit formed in a postcollisional tectonic setting,following the collision between the North China,Yangtze craton,and Central Asian Orogeny in Triassic.

Zircon U-Pb age of Fengxian acid pyroclastic rocks and its enlightenment to the existence of Pan-African orogeny in the West Qinling Orogenic Belt, China

1.Objective The formation of East Gondwana and its combination with West Gondwana is a result of a series of complex orogenic events,known as Pan-African orogeny.The Northern Qinling Mountain is a microcontinent that formed on the ancient oceanic crust in the northern of Yangtze craton before Neoproterozoic.It is likely that the North Qinling,even the Yangtze craton and its surrounding oceanic crust belong to the ancient Gondwana tectonic domain and be a part of East Gondwana supercontinent(Chen Q,2007).

Hydrogeochemical characteristics of groundwater and pore-water and the paleoenvironmental evolution in the past 3.10 Ma in the Xiong’an New Area,North China

The groundwater level has been continuously decreasing due to climate change and long-time overexploitation in the Xiong’an New Area,North China,which caused the enhanced mixing of groundwater in different aquifers and significant changes in regional groundwater chemistry characteristics.In this study,groundwater and sediment pore-water in drilling cores obtained from a 600 m borehole were investigated to evaluate hydrogeochemical processes in shallow and deep aquifers and paleo-environmental evolution in the past ca.3.10 Ma.Results showed that there was no obvious change overall in chemical composition along the direction of groundwater runoff,but different hydrochemical processes occurred in shallow and deep groundwater in the vertical direction.Shallow groundwater(<150 m)in the Xiong’an New Area was characterized by high salinity(TDS>1000 mg/L)and high concentrations of Mn and Fe,while deep groundwater had better water quality with lower salinity.The high TDS values mostly occurred in aquifers with depth<70 m and>500 m below land surface.Water isotopes showed that aquifer pore-water mostly originated from meteoric water under the influence of evaporation,and aquitard pore-water belonged to Paleo meteoric water.In addition,the evolution of the paleoclimate since 3.10 Ma BP was reconstructed,and four climate periods were determined by theδ18O profiles of pore-water and sporopollen records from sediments at different depths.It can be inferred that the Quaternary Pleistocene(0.78‒2.58 Ma BP)was dominated by the cold and dry climate of the glacial period,with three interglacial intervals of warm and humid climate.What’s more,this study demonstrates the possibilities of the applications of pore-water on the hydrogeochemical study and further supports the finding that pore-water could retain the feature of paleo-sedimentary water.

Sedimentary elements,evolutions and controlling factors of the Miocene channel system:a case study of the deep-water Taranaki Basin in New Zealand

Deep-water channel systems are important petroleum reservoirs,and many have been discovered worldwide.Understanding deep-water channel sedimentary elements and evolution is helpful for deep-sea petroleum exploration and development.Based on high-resolution 3D seismic data,the Miocene channel system in the deep-water Taranaki Basin,New Zealand,was analyzed by using seismic interpretation techniques such as interlayer attribute extraction and strata slicing.The channel system was divided into five composite channels(CC-I to CC-V)according to four secondary level channel boundaries,and sedimentary elements such as channels,slump deposits,inner levees,mass transport deposits,and hemipelagic drape deposits were identified in the channel system.The morphological characteristics of several composite channels exhibited stark variances,and the overall morphology of the composite channels changed from relatively straight to highly sinuous to relatively straight.The evolution of the composite channels involved a gradual and repeated process of erosion and filling,and the composite channels could be divided into three evolutionary stages:initial erosion-filling,later erosion-filling(multistage),and channel abandonment.The middle Miocene channel system may have formed as a consequence of combined regional tectonic activity and global climatic change,and its intricate morphological alterations may have been influenced by the channel's ability to self-regulate and gravity flow properties.When studying the sedimentary evolution of a large-scale deep-water channel system in the Taranaki Basin during the Oligocene-Miocene,which transitioned from a passive margin to plate convergence,it can be understood how tectonic activity affected the channel and can also provide a theoretical reference for the evolution of the deepwater channels in areas with similar tectonic conversion environments around the world.

Prediction Model of Coal Reservoir Pressure and its Implication for the Law of Coal Reservoir Depressurization

The main methods of coalbed methane(CBM)development are drainage and depressurization,and a precise prediction of coal reservoir pressure is thus crucial for the evaluation of reservoir potentials and the formulation of reasonable development plans.This work established a new reservoir pressure prediction model based on the material balance equation(MBE)of coal reservoir,which considers the self-regulating effects of coal reservoirs and the dynamic change of equivalent drainage area(EDA).According to the proposed model,the reservoir pressure can be predicted based on reservoir condition data and the actual production data of a single well.Compared with traditional reservoir pressure prediction models which regard EDA as a fixed value,the proposed model can better predict the average pressure of reservoirs.Moreover,orthogonal experiments were designed to evaluate the sensitivity of reservoir parameters on the reservoir pressure prediction results of this proposed model.The results show that the saturation of irreducible water is the most sensitive parameter,followed by Langmuir volume and reservoir porosity,and Langmuir pressure is the least sensitive parameter.In addition,the pressure drop of reservoirs is negatively correlated with the saturation of irreducible water and the Langmuir volume,while it is positively correlated with porosity.This work analyzed the reservoir pressure drop characteristics of the CBM wells in the Shizhuangnan Block of the Qinshui Basin,and the results show that the CBM reservoir depressurization can be divided into three types,i.e.,rapidly drop type,medium-term stability type,and slowly drop type.The drainage features of wells were reasonably interpreted based on the comprehensive analysis of the reservoir depressurization type;the latter was coupled to the corresponding permeability dynamic change characteristics,eventually proving the applicability of the proposed model.

The Sachakou Deposit in West Kunlun of Xinjiang: A Pb-Zn Polymetallic Deposit Associated with Magmatic Metasomatism of Carbonate Rock

Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang （geographical coordinates of E78° 57＇ 54.30＂-78°59＇ 53.63＂, N34° 39＇ 27.50＂-34° 40＇ 57.21＂）. It belongs to the West Kunlun orogenic belt on the northwest edge of the Qinghai-Tibet Plateau and is connected to the Sanjiang orogenic belt to the south （Spurlin et al., 2005）. In recent years, a series of Pb-Zn mineralized spots and deposits have been discovered in this area one after another, which is called the Huoshaoyun ore concentration area. Among them, the Sachakou Pb-Zn deposit has reserves up to140 Mt, which has reached a large scale. However, the study on the genesis of deposits in this area has only just begun. This work studied the genesis ofthis Pb-Zn deposit in order to provide new ideas for the genesis of regional deposits and regional prospecting.

Methods for estimating rotational components of seismic ground motion and their numerical comparisons

Rotational components play an important role in natural earthquake research,engineering seismic investigation,building monitoring,seismic exploration and other fields.Traditional researches mainly focus on three translational components,but less on rotational ones.As the precision of rotational sensing techniques has increased,many scholars have paid more attention to the seismic rotational motions.Because the rotational observations are not very popular before and now,approximately converting the translational components into rotational components is utilized in rotation analysis.Based on numerical six-component seismic data with the finite difference method,we compare three different conversion methods,the travelling-wave,frequency-domain and the difference method,to analyze their characteristics and feasibilities when they are applied to estimate rotational components with translational observations.

Geochemical and Isotopic Techniques Constraints on the Origin,Evolution,and Residence Time of Low-enthalpy Geothermal Water in Western Wugongshan,SE China

Geothermal resources are increasingly gaining attention as a competitive,clean energy source to address the energy crisis and mitigate climate change.The Wugongshan area,situated in the southeast coast geothermal belt of China,is a typical geothermal anomaly and contains abundant medium-and low-temperature geothermal resources.This study employed hydrogeochemical and isotopic techniques to explore the cyclic evolution of geothermal water in the western Wugongshan region,encompassing the recharge origin,water-rock interaction mechanisms,and residence time.The results show that the geothermal water in the western region of Wugongshan is weakly alkaline,with low enthalpy and mineralization levels.The hydrochemistry of geothermal waters is dominated by Na-HCO_(3)and Na-SO_(4),while the hydrochemistry types of cold springs are all Na-HCO_(3).The hydrochemistry types of surface waters and rain waters are NaHCO_(3)or Ca-HCO_(3).The δD and δ^(18)O values reveal that the geothermal waters are recharged by atmospheric precipitation at an altitude between 550.0 and 1218.6 m.Molar ratios of maj or solutes and isotopic compositions of^(87)Sr/^(86)Sr underscore the significant role of silicate weathering,dissolution,and cation exchange in controlling geothermal water chemistry.Additionally,geothermal waters experienced varying degrees of mixing with cold water during their ascent.Theδ^(13)C values suggest that the primary sources of carbon in the geothermal waters were biogenic and organic.Theδ^(34)S value suggests that the sulfates in geothermal water originate from sulfide minerals in the surrounding rock.Age dating using 3H and^(14)C isotopes suggests that geothermal waters have a residence time exceeding 1 kaBP and undergo a long-distance cycling process.

Selection of raw materials and control of trace elements for production of high-quality SG iron

During the production of SG iron, the selection of raw materials and control of chemical composition are most important. From the very early days of SG iron production, the effects of trace elements on graphite form and matrix structure have been studied, and the allowable concentration limits for their detrimental influence has been decreased year by year, during the last fifty years. This paper has reviewed some of the suggested SG iron trace elements in the literature and in several Chinese foundries. It was found that for most SG iron castings, rare earth elements are still required to neutralize the harmful effects of trace elements and improve SG iron quality. It also found that the use of high purity and ultra-high purity base iron melts enabled integrated, safety-critical and complicated SG iron castings of varying thickness, and heavy-section, to be produced successfully. These SG iron castings have surprisingly good structures, and their mechanical and dynamic properties are vastly superior to those specified in current international SG iron standards. Further study is required on the effects of using high purity and ultra-high purity base melts on the structure and properties of SG iron.

Biodegradation of Tetrachlorothylene Using Methanol as Co-metabolic Substrate

Objective To investigate the biodegradation of tetrachloroethylene （PCE） using methanol as electron donor by acclimated anaerobic sludge. Methods HP-6890 gas chromatograph （GC）, together with HP-7694 autosarnpler, was used to analyze the concentration of PCE and intermediates. Results PCE could be decholrinated reductively to DCE via TCE, and probably further to VC and ethylene. The degradation of PCE and TCE conformed to first-order reaction kinetics. The reaction rate constants were 0.8991 d^-1 and 0.068 d^-1, respectively, and the corresponding half-life were 0.77 d and 10.19 d, respectively. TCE production rate constant was 0.1333 d^-1, showing that PCE was degraded more rapidly than TCE. Conclusion Methanol is an electron donor suitable for PCE degradation and the cometabolic electron donors are not limiting factors for PCE degradation.

Rock-forming mechanism of Fenghuangshan rockbody in Tongling area

Based on the detailed geological investigation and record of galleries and drill holes, a new idea has beenadvanced that granodiorite is earlier than quartz monzodiorite porphyry. Both of them are products of two differentmagmatic intrusive activities. The analysis results of trace elements show that the Sr content is beyond any othercrustal rock and the Th content is beyond that of Ta. The whole-rock analysis indicates that rockbody is rich in CaOand poor in K2O. In the composition of Pb istope of rockbody, the ratio of 207Pb to 204Pb is less than 15.60. Allthese show that the magma mainly comes from the upper mantle. Ti,Zr,Cr,Nb trace elements and the relation be-tween the Gardini index(τ) and the Rittmann index(σ) indicate that the rockbodies are formed in the orogenic beltand island arc tectonic setting. The summation (∑REE) and the characteristic value (m (La)/m (Yb)) of the rareearth elements show that the original rock is alkalic basalt. The analysis of the characteristic values of REE and thequantitative modeling calculation indicate that the rock-forming process is dominated by mixed crystallization. Ac-cording to the analysis on the rock-forming order, magmatic source, tectonic setting and rock-forming process, com-bined with the achievements of regional rock-controlling structures and division of sublayer of crust, it is believedthat Fenghuangshan rock body derives from the deep-seated alkalic basalt magma. The rock-forming process has un-dertaken sialic and calcareous assimilation and contamination of two different degrees. The rock-forming model be-longs to the typical assimilation and fractional cryatalization mechanism.

Coupling mechanism of mineralization and hydrocarbon-forming in hydrothermal convection system: An example from Longtoushan Sn-polymetal deposit, Dachang

Longtoushan Sn-polymetal deposit is a large-scale deposit of high-tenor. The ore-bodies occur in reef limestone of middle Devonian. There is much anthraxolite in reef limestone and ore-bodies. The anthraxolite is the postmature result of oil-gas' thermal metamorphism. The close relationship of anthraxolite and Sn-polymetal deposit reveals the space-time relation between oil-gas evolution and Sn-polymetal mineralization. Sulfur isotope of Longtoushan deposit is close to oil's sulfur in Devonian, which indicates obvious relationship between the sulfur's source of deposit and oil-gas' activity. The forming of Longtoushan deposit relates to exhalative-sedimentary mineralization in Devonian. Because of the favorable hydrocarbon-forming condition of Longtoushan reef and surrounding basin facies' black shale and peat, coupling of ore-formation and hydrocarbon-forming occurs in seabed's hydrothermal convection. The distributing of ore-forming elements indicates the presence of hydrothermal convection system. The thermal fluid containing organic matters conduces to Sn-polymetal elements' activation and transfer, and provides catalyzing condition to the transforming from SO42- to S2-. The erosion action of brine containing organic acid to reef limestone induces the growing of crannies and karst's caverns, which provides advantageous space to Sn-polymetal mineralization. The heat source of mineralization provides thermocatalysis condition to hydrocarbon-forming. When the circulatory fluid containing oil-gas enters the high-temperature region(＞150 ℃ ), the oil-gas is decomposed and anthraxolite comes into being.

Environmental risks of shale gas exploitation and solutions for clean shale gas production in China

Shale gas is a relatively clean-burning fossil fuel,produced by hydraulic fracturing.This technology may be harmful to the environment;therefore,environmentally friendly methods to extract shale gas have attracted considerable attention from researchers.Unlike previous studies,this study is a comprehensive investigation that uses systematic analyses and detailed field data.The environmental challenges associated with shale gas extraction,as well as measures to mitigate environmental impacts from the source to end point are detailed,using data and experience from China’s shale gas production sites.Environmental concerns are among the biggest challenges in practice,mainly including seasonal water shortages,requisition of primary farmland,leakage of drilling fluid and infiltration of flowback fluid,oil-based drill cuttings getting buried underground,and induced seismicity.China’s shale gas companies have attempted to improve methods,as well as invent new materials and devices to implement cleaner processes for the sake of protecting the environment.Through more than 10-year summary,China’s clean production model for shale gas focuses on source pollution prevention,process control,and end treatment,which yield significant results in terms of resource as well as environmental protection,and can have practical implications for shale gas production in other countries,that can be duplicated elsewhere.

GA-BP Air Quality Evaluation Method Based on Fuzzy Theory

With the rapid development of China’s economy,the scale of the city has been continuously expanding,industrial enterprises have been increasing,the discharge of multiple pollutants has reached the top of the world,and the environmental problems become more and more serious.The air pollution problem is particularly prominent.Air quality has become a daily concern for people.In order to control air pollution,it is necessary to grasp the air quality situation in an all-round way.It is necessary to evaluate air quality.Accurate results of air quality evaluation can help people know more about air quality.In this paper,refers to previous research results and different evaluation methods,combined with artificial neural network,fuzzy theory,genetic algorithm,GA-BP hybrid algorithm based on fuzzy theory is proposed to evaluate air quality.At the same time,for the problem that the two-grade standard of air quality annual evaluation is not suitable for practical application,the four-grade standard for annual air quality evaluation has been proposed,and its practicality has been verified through experiments.By setting contrast experiments and comparing the air quality evaluation model based on standard BP algorithm,it is proved that the fuzzy GA-BP evaluation model is better than the standard BP model,both in efficiency and accuracy.

Bright Prospect Ahead for Petrochemical Industry

China’s petrochemical industry will show better performance in the year of 2010, Feng Shili, deputy secretary general with the China Petroleum and Chemical Industry Association (CPCIA), recently told China’s

Evidence for the Late Pliocene Aridification in the Eastern Tarim Basin,Northwest China

INTRODUCTION The vast arid regions in mid-latitude Asia(MLA)are among the most prominent landscapes on Earth’s surface and have been thought to provide a key source of global atmospheric dust(Hovan et al.,1989).Over the past decades,research on aridification of MLA have made tremendous progress and pointed large-scale aridity has prevailed in this region since the Late Pliocene despite long-term stepwise drying(Fang et al.,2020;Liu et al.,2014).However,direct sedimentary records for the late Pliocene aridification is still lack,hindering our understanding of regional comparison and the behind drive mechanism.The Tarim Basin in northwest China is one of the driest and largest inland basins and is considered as an ideal candidate for aridity records of MLA(Sun et al.,2013).Although considerable studies of environmental variations have been conducted(Liu et al.,2020;Zheng et al.,2015),a comprehensive picture of climatic change of the basin during the Late Pliocene is still unavailable,due to fragmentary sedimentary records,especially in the eastern Tarim Basin.In this contribution,we report the Late Pliocene lacustrine sediments found in Lop Nur of the east of Tarim Basin.The occurrence of abundant magnesite,their related crystal morphology and C-O isotopic signature suggested a typical brackish or even saline lake environment and arid climatic condition in eastern Tarim Basin during this interval.