Discovery of Mass Independent Oxygen Isotopic Compositions in Superscale Nitrate Mineral Deposits from Turpan-Hami Basin,Xinjiang,China and Its Significance

The Turpan-Hami Basin in eastern Xinjiang is one of the driest regions on Earth and a premier environment to form and preserve nitrate.A large nitrate ore field in this basin was found recently.It is estimated there are about 2.5 billion tons of resources of nitrate,and the amount is as much as the Atacama Desert super-scale nitrate deposit in Chile.Nitrate is one of a few minerals with mass-independent fractionation（MIF）,and the oxygen isotope MIF is an effective method to determine the source of nitrate.Theδ^（17）O,δ^（18）O of nitrate were measured by fluorination and thermal decomposition method.The date indicated that this is the first time that oxygen isotope MIF has been located in inland nitrate minerals.The results obtained by two methods are similar,⊿^（17）=δ^（17）O-0.52×δ^（18）O=12‰-17‰.The experiment and observation data proved that oxygen isotope MIF of nitrate are the result of photochemical reactions in the troposphere and stratosphere.Thus, evidence from MIF oxygen isotopic compositions indicate that long term atmospheric deposition of nitrate aerosol particles produced by photochemical reactions is the source of the deposits.

A Comprehensive Appraisal on the Characteristics of Coal-Bed Methane Reservoir in Turpan-Hami Basin

The rich coal-bed methane resources in the Turpan-Hami Basin are mainly located in the Shisanjianfang,Hami,Shanshan,Sha'erhu,Kekeya,Kerjian,Aidinghu inclines and the Dananhu coal-bed methane reservoirs. The big-ger coal-bed reservoirs are sitting at a depth of less than 1500 m. The coalbed methane generation,storage and confin-ing conditions of the Turpan-Hami basin can be indicated by eight key parameters. They are coal-bed thickness,coal rank,missing period,permeability,Langmuir volume,rock covering ability,structural confinement and hydrodynamic sealing environment. These parameters constitute a comprehensive appraisal index system of the coal-bed methane res-ervoir characteristics of the Turpan-Hami basin. In these parameters,the missing period of coal-bed methane is indi-cated by a stratum missing intensity factor. It reflects the relative exposure period of coal series. The results of a fuzzy comprehensive judgment showed that the Shisanjianfang coal-bed methane reservoir has the best prospects for exploita-tion and the Sha'erhu,Shanshan,Hami coal-bed methane reservoirs are next in line.

Oil accumulation related to migration of source kitchens in the Lukeqin structural belt, Turpan-Hami Basin, China

The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the oil accumulation. According to oil geochemical analysis and oil-source correlation, the oil in deep and shallow reservoirs of the Lukeqin Oilfield presents different physical and saturated hydrocarbon mass spectrum characteristics. The Triassic heavy oil is from the northern Upper Permian lacustrine source rocks, and the light oil represented by the Yudong-9 Well is from the northwestern Lower Jurassic coal-measure source rocks. The timing of oil charging was determined by K/Ar isotope dating, reservoir fluid inclusion analysis and the evolution history of different source rocks. In summary, the accumulation process consists of two stages. From the end of Triassic to early Jurassic, the northern Permian source kitchen generated a considerable amount of oil, which was finally degraded to heavy oil, migrated to the south and then accumulated. The northwestern Jurassic coal-measure source kitchen began to generate oil at the end of Cretaceous, while the northern source kitchen could only generate a little hydrocarbon. The heavy oil and the light oil have different source rock locations, migration directions and accumulation times. The migration of hydrocarbon source kitchens affects the distribution of heavy oil and light oil reservoirs at the present time.

Types of Organic Fades and Source Rock Assessment of the Coal-Measure Mudstone in the Turpan-Hami Basin

This paper discusses the enviromental characteristics of carbonaceous mudstone and mudstone (coal-measure mudstone in short) of the Early and Middle Jurassic in the Turpan-Hami basin, which were formed in swamps. Through the organic facies study of the coal-measure mudstone in this area, the authors clarify that the flowing-water swamp is the most advanced organic facies belt. Furthermore, according to the practical materials of coal-measure mudstone in the area and with the evaluation criteria of lacustrine mudstone in the past, the authors have established the integrated symbol systems from the abundance of organic matter and the type of organic matter, which can be used in the source rock evaluation of the coal-measure mudstone.

Early and Middle JurassicPalaeogeography of the Turpan-Hami Basin

The Turpan-Hami oil basin is well known for its Jurassic oil-prone coal. The palaeogeograpbical units or the Early and Middle Jurassic coal measures iuclude braided chaunel-alluvial plain, meandering channel-alluvial plain, upper delta plain, lower delta plain, subaqueous delta, inter-deltaic bay,lacustrine bay and sballow lake euvironments. The beneficial environments for coal accumulation were tke inter-delta bay and the lower delta plain where intermediate subsidence was maintaiued and there was little input of coarse graiued ediments.

Evolution of groundwater recharge-discharge balance in the Turpan Basin of China during 1959-2021

Groundwater overexploitation is a serious problem in the Turpan Basin,Xinjiang Uygur Autonomous Region of China,causing groundwater level declines and ecological and environmental problems such as the desiccation of karez wells and the shrinkage of lakes.Based on historical groundwater data and field survey data from 1959 to 2021,we comprehensively studied the evolution of groundwater recharge and discharge terms in the Turpan Basin using the groundwater equilibrium method,mathematical statistics,and GIS spatial analysis.The reasons for groundwater overexploitation were also discussed.The results indicated that groundwater recharge increased from 14.58×10^(8)m^(3)in 1959 to 15.69×10^(8)m^(3)in 1980,then continued to decrease to 6.77×10^(8)m^(3)in 2021.Groundwater discharge increased from 14.49×10^(8)m^(3)in 1959 to 16.02×10^(8)m^(3)in 1989,while continued to decrease to 9.97×10^(8)m^(3)in 2021.Since 1980,groundwater recharge-discharge balance has been broken,the decrease rate of groundwater recharge exceeded that of groundwater discharge and groundwater recharge was always lower than groundwater discharge,showing in a negative equilibrium,which caused the continuous decrease in groundwater level in the Turpan Basin.From 1980 to 2002,groundwater overexploitation increased rapidly,peaking from 2003 to 2011 with an average overexploitation rate of 4.79×10^(8)m^(3)/a;then,it slowed slightly from 2012 to 2021,and the cumulative groundwater overexploitation was 99.21×10^(8)m^(3)during 1980-2021.This research can provide a scientific foundation for the restoration and sustainable use of groundwater in the overexploited areas of the Turpan Basin.

The Characteristics and Genesis of the Massive Nitrate Deposits in the Turpan-Hami Basin of Xinjiang,China

Massive nitrate deposits have been discovered in the Turpan-Hami basin in northwestern China.Previously,large ore grade nitrate minerals were thought only to exist in the Atacama Desert in northern Chile.Estimates of the

The World's Largest Soda-Niter Ore Intensive Region Found in the Turpan–Hami Basin

The Xinjiang Geology and Mineral Resources Exploration and Development Bureau have conducted a detailed investigation project of the Xigobi soda-niter deposit in Hami, Xinjiang Province, which was completed at the end of 2011. The project put much emphasis on research of soda-niter mineralization rules, stratum classification, ore-forming

POSITIVE INVERSION STRUCTURE OF THE CENTRAL STRUCTURE BELT IN TURPAN-HAMI BASIN

The central structure belt in Turpan-Hami basin is composed of the Huoyanshan structure and Qiketai structure formed in late Triassic-early Jurassic, and is characterized by extensional tectonics. The thickness of strata in the hanging wall of the growth fault is obviously larger than that in the footwall,and a deposition center was evolved in the Taibei sag where the hanging wall of the fault is located. In late Jurassic the collision between Lhasa block and Eurasia continent resulted in the transformation of the Turpan-Hami basin from an extensional structure into a compressional structure, and consequently in the tectonic inversion of the central structure belt of the Turpan-Hami basin from the extensional normal fault in the earlier stage to the compressive thrust fault in the later stage. The Tertiary collision between the Indian plate and the Eurasian plate occurred around 55Ma, and this Himalayan orogenic event has played a profound role in shaping the Tianshan area, only the effect of the collision to this area was delayed since it culminated here approximately in late Oligocene-early Miocene. The central structure belt was strongly deformed and thrusted above the ground as a result of this tectonic event.

Sequence Stratigraphy and Paleogeography of the Early and Early Middle Jurassic Coal Measures in the Turpan-Hami Basin,Northwestern China

This paper analyses the sequence stratigraphy and palaeogeography of the Early and early Middle Jurassic coal measures in the Turpan-Hami Basin, northwestern China.The controls of the palaeogeography and sequence stratigraphy on the coal accumulation in this basin have been discussed.The results show that the coal measures were formed in a fluvial-delta-lacustrine sedimentary system,and a total of 4 third-order sequences were developed,

Provenance Variability of the Triassic Strata in the TurpanHami Basin: Detrital Zircon Record of Indosinian Tectonic Reactivation in the Eastern Tianshan

The Triassic strata in the Turpan-Hami Basin potentially chronicled the missing sedimentary record of Indosinian tectonic evolution in the Eastern Tianshan.In this study,we conducted detrital zircon U-Pb geochronological analyses on subsurface Triassic samples collected from the Turpan-Hami Basin to unravel sedimentary response of Indosinian tectonic reactivation and its geodynamics.The detrital zircon age spectra of the Triassic samples are quite different,reflecting significant provenance variability.The zircon grains in the Lower Triassic sample were mainly from the Central Tianshan,while the Jueluotag acted as a minor provenance.By contrast,the Late Paleozoic rocks in Jueluotag act as the main provenance for the Middle-Upper Triassic samples,while the Central Tianshan acted as a minor provenance.Furthermore,zircon grains in the Middle Triassic sample were mainly from the Permian rocks in Jueluotag,while Indosinian strike-slipdriven rapid exhumation brought deeper Carboniferous rocks of Jueluotag as an important age population for the Upper Triassic sample.The inter-sample variability of age spectra of the Triassic samples provides sedimentary evidence for Indosinian tectonic reactivation in the Eastern Tianshan and its periphery,which could be attributed to differential exhumation of different sources driven by coeval strike-slip tectonics along deep faults.The Indosinian tectonic behavior in the Eastern Tianshan,which is characterized by partial melting of the pre-thickened crust and strike-slip deformation,acted as a far-field respond to the coeval continental accretion occurring along the southern Eurasian margin.Additionally,our new detrital zircon data,together with previously published data in the Turpan-Hami Basin,demonstrate that there are significant changes in source-to-sink system from the Permian to the Triassic,suggesting that the Permian-Triassic unconformity in the Eastern Tianshan and its periphery was generated by Late Permian-Early Triassic tectonic contraction and inversion rather than an increasingly arid climate.

MESOZOIC-CENOZOIC INVERSION OF THE TURPAN-HAMI BASIN, NORTHWEST CHINA

The Turpan-Hami basin, rich in coal and petroleum, is a superimposed basin of three types basins in different tectonic environments. This coal, oil and gas basin has undergone a complex tectonic-sedimentary evolution, in which two important stages were the negative inversion from a foredeep to a extensional basin during Early Mesozoic and the positive inversion to a thrust foreland basin in Late MesozoicEarly Cenozoic. The early normal faults residues are recognized with the addition of tectonic-sedimentary analysis to confirm the basin extension during Jurassic time and its tectonic inversion subsequently.

Stable carbon and hydrogen isotopic characteristics of natural gas from Taibei sag, Turpan-Hami Basin, NW China

Turpan-Hami Basin is a major petroliferous basin in China. To date the natural gas exploration is concentrated in the Taibei sag. The origin and source of natural gas in the Taibei sag has long been controversial. To further investigate the origin and source of the natural gas in the Taibei sag, combined with previous studies and the local geological backgrounds, this study collected 23 gas samples from the Baka, Qiuling, Shanshan and Wenmi oil fields in the Taibei sag and analyzed the sample composition, stable carbon and hydrogen isotopes of all the gas samples. The results show that, gases from the four oil fields in the Taibei sag are dominated by hydrocarbon gas and belong to wet gas. Methane accounts for 65.84% to 97.94%, the content of heavy hydrocarbon (C2-5) can be up to 34.98%, while the content of nonhydrocarbon (CO2, N2) is trace. The δ13C1 value is –44.9‰ to –40.4‰,δ13C2 is –28.2‰ to –24.9‰,δ13C3 is –27.1‰ to –18.0‰ and δ13C4 is –26.7‰ to –22.1;while the variation of δD1 is not significant from –272‰ to –252‰,δD2 is –236‰ to –200‰ and δD3 is –222‰ to –174‰. Methane and its homologues (C2-5) are characterized by normal stable carbon and hydrogen isotopic distribution pattern, i.e., with the increase of carbon number, methane and its homologues become more and more enriched in 13C or D (δ13C1<δ13C2<δ13C3<δ13C4<δ13C5,δD1<δD2<δD3), which is consistent with the carbon and hydrogen isotopic features of typical thermogenic gas. All these results show that the natural gases in the four oil fields are coal-derived gas with low maturity (Ro averaged at 0.7%), and are sourced from the Middle-Lower Jurassic coal measure. The hydrogen isotopic data of natural gas are affected by both thermal maturity and the water medium of the environment where source rocks are formed. The hydrogen isotopic data indicate that the source rocks are formed in terrestrial limnetic facies with freshwater. Natural gases from Well Ba23 and Well Ke19 experienced biodegradation in the late stage.

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins,NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin,the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin,the geochemical characteristics of the marine（Tarim Basin）,saline lacustrine（Qaidam Basin）,and swamp（Turpan Basin） oils were investigated.The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene,and relatively high abundance of triaromatic hydrocarbons including phenanthrene,dibenzothiophene and fluorene.In contrast,the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study.The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils.Aromatic parameters based on the isomer distributions of dimethylnaphthalenes（DMN）,trimethylnaphthalenes（TMN）,tetramethylnaphthalenes（TeMN） and methylphenanthrenes（MP）,i.e.,1,2,5-trimethylnaphthalene（TMN）/1,3,6-TMN ratio,1,2,7-TMN/1,3,7TMN ratio,（2,6-＋2,7-）-dimethylnaphthalenes（DMN）/1,6-DMN ratio,1,3,7-TMN/（1,2,5-＋1,3,7-）TMN,1,3,6,7-TeMN/（1,3,6,7-＋1,2,5,6-＋1,2,3,5-）-TeMN ratio and MP index,may reflect the diversity of organic source input,thermal maturity and depositional environments.In addition,the dibenzothiophenes（DBTs）/fluorenes（Fs） and dibenzofurans（DBFs）/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine,saline lacustrine,and swamp depositional environments,and for oil-oil correlations.

Groundwater hydrochemistry and isotope geochemistry in the Turpan Basin, northwestern China

The Turpan Basin is located in the arid zone of northwestern China and is a typical closed inland basin surrounded by high mountains. It is one of the most arid regions in the world and, as a result, the groundwater in this area is very important for both domestic and agricultural uses. In the present study, the relationships of major elements（K＋, Na＋, Ca2＋, Mg2＋, HCO3-, SO42- and Cl-） and environmental isotopes（δ18O, δ2H and T） in groundwater were analyzed to investigate the evolution of the regional hydrochemistry within the Turpan Basin. The hydrochemistry results demonstrate that groundwater with high total dissolved solids（TDS） concentration is dominated by sodium chloride（Na-Cl） and sodium sulfate（Na-SO4） type water, whereas that with low TDS concentration（typically from near mountain areas） is dominated by calcium bicarbonate（Ca-HCO3） type water. The evolution of groundwater hydrochemistry within the Turpan Basin is a result of calcium carbonate precipitation, evaporation concentration, cation exchange and dissolution of evaporites（i.e. halite, mirabilite and gypsum）. Furthermore, evaporite dissolution associated with irrigation practice plays a key role in the groundwater salinization, especially in the central part of the basin. Environmental isotopes reveal that the groundwater is recharged by precipitation in the mountain areas and fast vertical infiltration of irrigation return flow. In the southern sub-basin the shallow groundwater and the deep groundwater is separated at a depth of about 40 m, with substantial differences in terms of hydrochemical and isotopic characteristics. The results are useful for decision making related to sustainable water resource utilization in the Turpan Basin and other regions in northwestern China.

Geochemical Evidence for Coal and Carbonaceous Mudstone as the Possible Major Oil Source Rock in the Jurassic Turpan Basin, Northwest China

Petroleum geologists have debated whether the hydrocarbons from Jurassic coal measures are derived from the coals, carbonaceous mudstones or coal-measure mudstones in the Turpan Basin. Based on the geochemistry analysis of the 20 crude oils and 40 source rocks from the Turpan Basin, some data have been obtained as follows： carbon preference index and methylphenanthrene index of the Jurassic oils are 1.16-1.45 and 0.28-0.80, and the ααα C29 sterane 20S/（20S＋20R） and C29 sterane ββ/（ββ＋αα） are 0.44-0.51 and 0.4-0.54 respectively, which show the normal maturity of oils; the vitrinite reflectance of the source rocks from the Xishanyao to Badaowan Formations range from 0.47% to 0.97%, which indicate immature to mature thermal evolutionary stage and sufficient conditions for generating mass mature oil. The effect of hydrocarbon expulsion should be considered when studying the source of coal-derived oil by using Biomarkers. Biomarkers in the Jurassic oils from the basin are similar to those in the coals and carbonaceous mudstones, with a strong predominant content of pristane, relatively high ratio of C15 /C16 sesquiterpenoids （1）, a relatively high content of low carbon number tricyclic terpanes and C 24 tetracyclic terpane, little gammacerane and C 29 Ts detected, an absolute predominant content of C29 sterane and a relatively high content of diasterane. However, the opposite characteristics are shown in mudstones, with an approximately equal content of pristane and phytane, relatively low ratio of C15 /C16 sesquiterpenoids （1）, a relatively high content of high carbon number tricyclic terpanes and a low content of C 24 tetracyclic terpane, peaks of gammacerane and C29 Ts detected obviously and an increasing C27 sterane content. All of these characteristics identify the coals and carbonaceous mudstones as the possible major oil source rocks in this area, and they were formed in the stronger oxidizing environment with shallower water than mudstones.

THE UTILIZATION OF WATER RESOURCE AND THE OASIS ECONOMIC DEVELOPMENT IN ARID LAND—A CASE STUDY OF TURPAN BASIN

Turpan Basin is a unique geographic region in China. The topography of the Basin is closed and the climate is extremely dry. The shortage of water resource has been restricting the existence and development of the oasis in Turpan Basin. This paper briefly analyzes the characteristics of the basin's water resources, and expounds the processes of their utilization and regional development. It points out that the exploration of water resource is close to the limit and the utilization of water resource is unreasonable. So it is nonrealistic to follow the traditional exploration pattern. According to the transforming pattern between runoff and groundwater in the basin, an overall planning of the utilization of the water resource is advanced. Based on the relation between the maintenance of Aydingkol Lake and the existence of the oasis, the amount of water resource used must be controlled in order to guarantee the existence of the lake. The orientation of the utilization of water resource is to improve the management level of water resource, and to apply advanced water saving technology. Building up an economic system which can effectively use water resource is the orientation of the oasis sustainable economic development.

The first dinosaur tracksite from Xinjiang, NW China (Middle Jurassic Sanjianfang Formation, Turpan Basin)──a preliminary report

A new dinosaur tracksite was discovered in a steeply inclined sandstone layer of the Middle Jurassic Sanjianfang Formation in the Shanshan area of the Turpan Basin. The site is the first record of dinosaur footprints from Xinjiang Province in northwestern China. More than 150 tridactyl theropod dinosaur footprints are preserved as positive hyporeliefs on the lower bedding plane of a fine-grained sandstone body. Most of the footprints are isolated and appear to be randomly distributed. Some show well defined phalangeal pads, heels and rarely indistinct impressions of the distal part of the metatarsus. Two distinct morphotypes are present: a larger type with relatively broad pads shows similarities to Changpeipus and Megalosauripus, and a slightly smaller, slender and gracile type which is similar to Grallator, Eubrontes and Anchisauripus. In both morphotypes, digit III is the longest with a length between 11.4 and 33.6 cm. A single imprint shows prominent scratches, probably formed during slipping of the track maker.

Analysis on Hydrological Regimes of the Medium and Small Rivers in Hami of Xinjiang——Take Toudaogou Basin as an Example

[ Objective] The research aimed to analyze hydrological regimes of the medium and small rivers in Hami of Xinjiang. [ Method] According to actual observation data at Toudaogou hydrological station during 1956 -2010, climate, runoff, flood, sediment and water quality in the basin were analyzed. [ Result] Runoff in Toudaogou River was mainly from bedrock fissure water and rainfall, and depended on temperature and precipi- tation in the catchment zone. Runoff in Toudaogou River had very big change during the year. Runoff in whole year mainly concentrated during April -June, which occupied 57.9% of annual runoff. Flood in Toudaogou basin was divided into spring and summer flood from time, and snowmelt and rainstorm flood from type. Sediment load was related to terrain, gradient, runoff, precipitation, flood and process. Suspended sediment load at Toudaogou hydrological station had close relationship with the annual maximum flow capacity of flood peak, and related coefficient was 0.917. [ Conclusion] Hydrological regime in Toudaogou basin basically represented corresponding hydrological information of rivers without glacier water supply in Hami even whole western arid zone of China. The research could provide theoretical basis for scientifically using water resources of the medium and small rivers in the zone.

基于PLUS-InVEST模型吐哈盆地陆地生态系统碳储量时空变化及多情景模拟

土地覆盖变化能够改变区域碳储存能力,从而引起全球气候变化。研究土地覆盖变化对碳储量的影响,预测未来不同土地覆盖情景下的碳储量,对实现区域“碳中和”战略目标具有重要意义,然而目前针对中国西部生态脆弱区的研究仍有待探究。以新疆吐哈盆地为研究区,基于土地覆盖产品数据,结合PLUS模型和InVEST模型,探讨了土地覆盖变化与区域碳储量的时空变化关系,预测和评估了2025、2030年可持续发展情景,维持现状发展情景,经济优先发展情景下土地覆盖和碳储量的时空动态特征。结果表明:(1)近20 a来,吐哈盆地耕地和裸土地面积增加最大,其次是建设用地,而草地表现出最大的减少趋势,草地转为耕地和建设用地是最主要的转移类型。(2)2000、2010年和2020年吐哈盆地平均碳储量分别为26.01 t·hm~(-2)、25.68 t·hm~(-2)、25.73 t·hm~(-2),呈现出先降低后增加的趋势,平均碳储量累计减少了0.28 t·hm~(-2),其中土壤有机质碳储量占比最高,约占总碳储量的94%,裸土地、草地贡献了最多的碳储量。(3)2030年3种情景下,森林、灌木林、湿地几乎无明显变化,裸土地呈现出减少的趋势,而建设用地呈现增加的趋势。(4)到2030年可持续发展情景下吐哈盆地总碳储量较2020年增加了0.18×10~6t,维持现状发展情景和经济优先发展情景下分别减少了0.30×10~6t、1.01×10~6t,经济优先发展情景下碳储量损失最大。研究结果可为吐哈盆地土地利用优化以及制定生态系统可持续发展措施提供依据。