Holocene Yellow Silt Layers and the Paleoclimate Event of 8200 a B.P.in Lop Nur,Xinjiang,NW China

Many yellow silt layers have been identified in the Holocene sediments in the last lake of Lop Nur (playa), Xinjiang, northwestern China. Statistics of drill-hole cores have revealed more than one hundred layers, which exhibit regularity in time sequence. Study has further verified that these yellow silt layers were deposited through eolian processes. The time-frequency distribution diagram shows an obvious peak occurring at about 8200 a B.P., which is consistent with the dry, windy and cold climate event occurring at 8200 a in other places around the world. Therefore, this event is regarded as a response to the global climate change.

Sequence Stratigraphy of the Desert System: A Case Study of the Lower Cretaceous in the Kuqa Basin in Xinjiang, Northwestern China

The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary fades can be identified in this set of arid red beds: mudstones of the plaza and intracontinental sebkha, aeolian sandstones, sandy conglomerates of the intermittent river, conglomerates of the pluvial fan, etc. These types of sedimentary facies constitute a typical desert system. Therefore, the Cretaceous strata in the Kuqa Basin provide a favorable condition for studies of sequence stratigraphic divisions of the desert system. With the rise and fall of the base level of the sedimentary basin, cyclicity is clearly revealed in stratigraphic records, which helps the identification of the third-order sequences. Based on the cyclicity in stratigraphic records, 5 third-order sequences can be found in the strata of the Early Cretaceous in the Kuqa Basin. These sequences comprise a second-order tectonic sequence. The primary feature of these third-order sequences is of an upward-fining sedimentary succession formed by a succession of 'coarse sediments of the alluvial system-fine sediments of the lake system'. The result of this study shows that aeolian sandstones are the best reservoirs of natural gas in the Cretaceous strata in the Kuqa Basin, and that the Kela-2 gas field is the first large gas field dominated by aeolian sandstone reservoirs in China.

Spatio-temporal pattern and changes of evapotranspiration in arid Central Asia and Xinjiang of China

Accurate inversion of land surface evapotranspiration （ET） in arid areas is of great significance for understanding global eco-hydrological process and exploring the spatio-temporal variation and ecological response of water resources. It is also important in the functional evaluation of regional water cycle and water balance, as well as the rational allocation and management of water resources. This study, based on model validation analysis at varied scales in fiwe Central Asian countries and China＇s Xinjiang, developed an appropriate approach for ET inversion in arid lands. The actual ET during growing seasons of the study area was defined, and the changes in water participating in evaporation in regional water cycle were then educed. The results show the simulation error of SEBS （Surface Energy Balance System） model under cloud amount consideration was 1.34% at 30-m spatial scale, 2.75% at 1-km spatial scale and 6,37% at 4-kin spatial scale. ET inversion for 1980-2007 applying SEBS model in the study area indicates： （1） the evaporation depth （May-September） by land types descends in the order of waters （660.24 ram） 〉 cultivated land （464.66 mm） 〉 woodland （388.44 mm） 〉 urbanized land （168.16 mm） 〉 grassland （160.48 mm） 〉 unused land （83.08 mm）; and （2） ET during the 2005 growing season in Xinjiang and Central Asia was 2,168.68x108 m3 （with an evaporation/precipitation ratio of 1.05） and 9,741.03x108 m3 （with an evaporation/precipitation ratio of 1.4）, respectively. The results unveiled the spatio-temporal variation rules of ET process in arid areas, providing a reference for further research on the water cycle and water balance in similar arid regions.

The Ophiolitic Mélanges in Strike-slip Fault Zones in West Junggar,Xinjiang,NW China

The West Junggar region of western China,located in the far eastern end of the Kazakhstan orocline,occupies the junction of the Siberia,Tarim and Kazakhstan blocks,which is crucial for palinspastic reconstruction of the CAOB.The principal rock assemblages in West Junggar include Paleozoic ophiolitic mélanges and a thick,undeformed Upper Devonian–Lower Carboniferous sedimentary succession as the boundary of the mélanges,both of which are intruded by sub-circular Upper Carboniferous granitoid plutons and intermediate-basic-mafic dykes.On the basis of the sedimentary structures like cross bedding and convolute bedding and the geochronology data,the Upper Devonian–Lower Carboniferous sedimentary successions were identified as the Tailegula,Baogutu,and Xibeikulasi formations from the bottom up,which is an apparent shallowing-upwards ocean basin fill succession,from radiolarian cherts through 2000 meters of flysch to a more neritic Baogutu Formation to a fluvial Xibeikulasi Formation.At the bottom of the Tailegula Formation there is a peperite-bearing unit:a succession of extrusive mafic rock,mainly basaltic lava,with interbeds or blocks of sedimentary rocks including carbonate,radiolarian chert,calcareous siltstone and minor fine-grained tuffaceous sandstone.Peperites in the Tailegula are thickest and best developed as the type section.Four types of peperites were identified based on of the volcanic clast shapes and sediment-matrix properties in Tailegula:(1)arbonatesediment-hosted fluidal peperites,(2)sandstone-hosted fluidal peperites,(3)tuff-hosted mixed fluidal and blocky peperites and(4)carbonate-sediment-hosted blocky peperites.Zircon LA-ICP-MS U-Pb dating of a tuff lens enclosed by lava showed that the peperites formed in the Late Devonian(ca.364 Ma).The widespread peperitebearing succession in the Tailegula Formation is of variablethickness at different sites in West Junggar,such as the Tailegula,Baijiantan,Kalaxiuka,Saertuohai,Dagun,west of the Akebastaw granite and Shinaizha areas.The peperite-bearing unit is generally undeformed in contrast to the highly deformed slices of ophiolite,and is continuously distributed as a stratigraphic section regionally on either side of the Darbut and Baijiantan ophiolitic belts.It can be taken as a mark layer to demonstrate the existence of a shallow remnant ocean basin from the end of Devonian in West Junggar,which is an important component of oceanic crust in the remnant ocean basin.Peperite,underlying Devonian or earlier oceanic crust developed in the spreading process of the ocean basin,and overlying Carboniferous remnant ocean basin-fill succession constitute the complete evolution sequence of the remnant ocean basin.The Darbut and Baijiantan ophiolitic belts should not be interpreted as significant plate boundaries and represent the underlying ocean crust uplifted along tectonic lineaments within a continuous shallow remnant ocean basin.The Baijiantan and Darbut ophiolites are both steep fault zones(>70°)of serpentinite mélange,in contact on either side with regionally distributed and undeformed Upper Devonian–Lower Carboniferous ocean-floor peperitic basalts and overlying sedimentary successions.Ultramafic rocks is serpentinized and foliated to form the matrix of mélange.Some small blocks of peridotite are mylonitic and strongly foliated.Blocks of gabbro generally underwent prehnitization,epidotization and chloritization and many are metasomatized to rodingite.Pods of medium to fine grained amphibolites are encased in serpentinite and display relict gabbroic textures and amphibolite-facies assemblages.The Baijiantan ophiolitic mélange also includes amphibolite brecciasconsistingofcentimeter-sizedmylonitic amphibolite clasts embedded within a serpentinite matrix.Basalt lavas cropping out in the Baijiantan ophiolitic mélange are of two types:type 1 and type 2 lavas.The type1 lavas occur within the fault zones as small blocks withinthe matrix of ultramafic rocks,tectonically juxtaposed against other rocks.The type 2 basalt lava came from the peperite-bearing unit.Besides the ultramafic rocks,gabbros,and basalt lavas,the other supracrustal rocks in the ophiolitic mélange include sandstone,chert,tuff,and very rare limestone.Sandstones predominate and most of them are tuffaceous;their characteristics are consistent with the sandstones from surrounding Lower Carboniferous sedimentary formations.Sandstone blocks within the mélanges also have detrital zircon age distributions(300-400 Ma)and characteristics similar to surrounding Carboniferous sediments.The rock assemblages in the mélanges indicate the ophiolitic mélanges consist of locally derived rocks,in contrast to conventional ophiolitic mélanges.The ophiolitic mélanges show classic structural features of strike-slip shearing regimes,including subhorizontal slickenside lineations(<20°),consistent steeply dipping foliation(>75°)in the matrix,and elongated shapes of blocks aligned parallel to the shear zone.Consistent shear-sense indicators including slip-fiber lineations,Riedel shears,asymmetric blocks,shear band cleavages and veins indicate a horizontal sinistral sense of movement.The occurrence of the amphibolite and ultramafic mylonite in the mélanges probably record early,deep-seated strike slip,indicating that the fault zones extended downward through the oceanic crust.The amphibolite-facies metamorphism then was superimposed by brittle deformation at a shallow level to form fault breccias during the mélange formation.So the ophiolitic mélanges originated from crustal-scale sinistral strike-slip fault zones,not as major plate boundaries or subduction-suture zones.The youngest units of the mélanges are the deformed blocks of Lower Carboniferous basin-fill sedimentary rocks,indicating that the ultimate formation of the mélanges was after deposition of the Lower Carboniferous strata(detrital zircon age modes:320-330 Ma),but before the age of the intruding granite and the dike cutting the mélanges(~310 Ma).Based on above discussions and taking into consideration of the previous studies,a tectonic evolution scenario is proposed for the Devonian to Carboniferous in the West Junggar region.In the middle Devonian or earlier(>390Ma),a paleo-ocean basin existed,stretching across North Xinjiang from Darbut-Baijiantan area in West Junggar to the Kalamaili area in East Junggar.This basin was most likelyaback-arcbasinrelatedtothe Boshchekule–Chengiz–Yemaquan arc.Subduction ended in thepaleo-oceanbasinrepresentedbythe Hongguleleng-Kujibai-Armantai ophiolite belt by late Devonian(375-360 Ma),leading to slab break-off and upwelling of asthenosphere under the remnant ocean basin,which induced The OIB-like basalts in West Junggar.The oceanic basin started to receive sufficient sediment deposition into which OIB-like basalts flows could bulldoze to form the regional distributed peperites(~360 Ma).A little later,in the early Carboniferous(~340 Ma),continent-continent collision took place between the Junggar block and the Yemaquan arc,and Kalamaili ophiolite obduction occurred in the eastern part of Junggar block.The remnant ocean basin was preserved in the western part of the Junggar Block.Accompanying the relative motion between Junggar block and ocean basin in West Junggar during collision,a series of NW trending sinistral strike-slip faults were triggered and activated parallel to the western boundary of the Junggar block.During the late stage of the Early Carboniferous(~320 Ma),the remnant ocean basin was almost filled with sediments.The collision between the Yili and Junggar blocks at the beginning of the late Carboniferous reactivated the strike-slip faults,which disrupted the oceanic crust and basin-fill successions and caused diapirs of serpentinite to form the Baijiantan and Darbut ophiolitic mélanges.The emplacement of Upper Carboniferous(~310 Ma)stitching A-type granitoid plutons indicates the evolutionary history of the remnant ocean basin and strike-slip fault zone ophiolitic mélanges terminated by that time.

Chromian Spinels in Listwaenite and Related Rocks in the Sartohay Ophiolitic Mélange, Xinjiang, NW China

Listwaenite,carbonate-talc schist,and serpentinite of Sartohay ophioliticmélange,Xinjiang,northwestern China,contain variably altered chromian spinels.During the hydrothermal alteration from serpentinite to listwaenite

Geochemical characteristics and geological significance of picritic rocks in Permian Tiaohu Formation from Santanghu Basin, Xinjiang, NW China

1 Introduction Santanghu Basin is located between the Armantai and Karamaili suture zone,at the junction of the Siberia,Kazakhstan and Tarim plates(Chen and Jahn,2004;Xiao et al.,2008).As an important part of the Central Asian

Trace Element Geochemistry of the Baishiquan and Pobei Intrusions,Xinjiang,NW China:Petrogenisis Implications

The Baishiquan and Pobei Early Permian mafic-ultramafic intrusions were emplaced into Proterozoic metamorphic rocks in the Central Tianshan and the Beishan Fold Belt,northern Xinjiang,NW China.The Baishiquan intrusion comprises mainly gabbro,and mela-gabbro sills occur within and along the margins of the gabbro body.In the Pobei intrusion,two distinct gabbroic packages,a lower gabbro and the main gabbro,are intruded and overlain by small cumulate wehrlite bodies.

Xinjiang to Become China's Largest Natural Gas Producer

With the opening of the Kela No. 2 gas field in the Tarim basin in China’s northwest Xinjiang Uygur Autonomous Region on Dec. 1, Xinjiang will produce 10 billion cubic meters of natural gas next year, becoming the country’s largest gas producer, according to an official with the China National Petroleum Corporation.

Feature: Friendship, Unity Prevail Despite Violence in China’s Xinjiang

Rizgan took an hourlong bus ride to downtown Ummqi to . donate blood for those injured in Sunday＇s deadly riot. ＂I＇m furious at the brutal killings and hope to help those innocent people with my own blood＂ said the Uygur woman in her 50s.

Many Countries Say Xinjiang Riot China’s Internal Affair

Many countries around the world said the July 5 riot in northwest China is an internal affair of the country, and the Chinese government is handling the incident properly.

A Cross-sectional Survey Assessing Carriage of Streptococcus pneumoniae in a Healthy Population in Xinjiang Uygur Autonomous Region of China

The carriage rate and serotype distribution of Streptococcus pneumoniae（S.pneumoniae）in a healthy population in China remains unclear.In this study,we collected the oropharyngeal swabs from513 individuals in Xinjiang,China.Real-time PCR targeting the lytA gene and 12 serotypes were assessed to identify S.pneumoniae carriage.

The Economic Development of Xinjiang after the Founding of New China

Before the founding of the People＇s Republic of China, the economy of Xinjiang was a natural economy, with farming and livestock breeding as the mainstay. Industry was underdeveloped, and there were no railways or up-to-the- mark factories or mines. Famines were frequent in some areas, and the people were impoverished. Xinjiang was peacefully liberated on September 25, 1949.

Dynamic Variability in Daily Temperature Extremes and Their Relationships with Large-scale Atmospheric Circulation During 1960–2015 in Xinjiang, China

Climate changes are likely to increase the risk of numerous extreme weather events throughout the world.The objectives of this study were to investigate and analyze the temporal-spatial variability patterns of temperature extremes based on daily maximum(TX)and minimum temperature(TN)data collected from 49 meteorological stations in Xinjiang of China during 1960–2015.These temperature data were also used to assess the impacts of altitude on the temperature extremes.Additionally,possible teleconnections with the large-scale circulation pattern(the El Nino-Southern Oscillation,ENSO and Arctic Oscillation,AO)were investigated.Results showed that all percentile indices had trends consistent with warming in most parts of Xinjiang during 1960–2015,but the warming was more pronounced for indices derived from TN compared to those from TX.The minimum TN and maximum TX increased at rates of 0.16℃/10 yr and 0.59℃/10 yr,respectively during 1960–2015.Accordingly,the diurnal temperature range showed a significant decreasing trend of–0.23℃/10 yr for the whole study area.The frequency of the annual average of the warm events showed significant increasing trends while that of the cold events presented decreasing trends.Over the same period,the number of frost days showed a statistically significant decreasing trend of–3.37 d/10 yr.The number of the summer days and the growing season showed significant increasing trends at rates of 1.96 and 2.74 d/10 yr,respectively.The abrupt change year of each index was from the 1980 s to the 1990 s,showing that this periodic interval was a transitional phase between cold and warm climate change.Significant correlations of temperature extremes and elevation included the trends of tropical nights,growing season frequency,and cold spell duration indicator.This result also indicated the clear and complex local influence on climatic extremes.In addition,the relationship between each index of the temperature extremes with large-scale atmospheric circulation(ENSO and AO)demonstrated that the influence of ENSO on each index of the temperature extremes was greater than that of the AO in Xinjiang.

HPV Infection among Uygur Women in a Rural Area of Hetian Prefecture,Xinjiang Uygur Autonomous Region, China

It is not clear how HPV infection is prevalent among Uygur women in Xinjiang Uygur Autonomous Region, China and whether the distribution of HPV infection is related with cervical intraepithelial neoplasia （CIN） incidence among them. A study including 883 Uygur women were conducted from 2006 to 2007 in Hetian Prefecture, Xinjiang Uygur Autonomous Region, China.

Ore-Forming Mechanism of the Asikaerte Granitic Pegmagtite Beryllium Deposit in Xinjiang, China

Objective Granitic pegmatite has great significance for studying magmatic-hydrothermal evolution, which is the main formation mechanism of rare metal deposits. Conventionally, granitic pegmatite rare metal deposits are regarded as crystallization from H20-saturated granite magma that formed in the late fractional crystallization of granitic magma. However, some scholars recently believed that the liquid immiscibility of granitic magma promoted the formation of pegmatite deposits. The Asikaerte beryllium deposit in Xinjiang, China, bearing metallogenic belts from lower granite belt to upper pegmatite belt, could benefit us to understand the formation of pegmatite through analyzing fluid and melt inclusions data.

Sedimentary environments of organic matter from Middle Permian source rocks in northern Xinjiang, China

A systematic analysis of the inorganic and organic geochemistry of Middle Permian source rocks comprising carbonate rocks and mudstones was carried out, with samples collected from the outcrop and bore of the Junggar, Turpan and Ili basins in northern Xinjiang. This study confirmed that sedimentary parameters for an ancient water body, such as inorganic geochemistry and paleosalinity, have a close relation to the organic matter of source rocks. It is also disclosed that phytane predominance in the source rocks is mainly due to a reducing environment. Biomarkers, such as gammacerane and β-carotene, in the samples reflect a specific salinity in the sedimentary environments. Sedimentary zones with a strong reducing environment are more likely to produce deposits of primary organic matter, which will be buried and preserved contemporarily. Consequently, the source rocks are generally high in organic content and better in organic type than ordinary ones, and vice versa.

The Petrology and Geochemistry of Listwaenite in the Sartohay Ophiolitic Melange of West Junggar, Xinjiang, China

The west Junggar,located in the eastern part of Balkash-Junggar tectonic province,is a major component of the core of the Central Asian metallogenic region.This area is characterized by occurrences of ophiolitic mélanges,such as the Sartohay ophiolitic mélange in the NE and the Tangbale ophiolitic mélange in the west.As a hydrothermal alteration product of serpentinite in the Sartohay ophiolitic mélange,listwaenite lenses are gold-mineralized and crop out on surface in the ophiolitic mélange via weathering of exhumated hanging wall of fault zone.Listwaenite is mainly composed of magnesite,quartz,dolomite,and trace amounts of mariposite,chromian spinel,talc and sulfide.A vertical thermal gradient model for the hydrothermal alteration shows that serpentinite would first be transformed to talc schist,then into listwaenite as the ophiolite slices continued to rise along shear zone,with XCO2,oxygen and sulfur fugacity increase and temperature decrease.Both serpentine and magnetite were progressively destroyed during the transformation from serpentinite to talc schist,andcompletely vanished in listwaenite,while mariposite generated in weakly deformed to mylonitized listwaenite.Concentrations of most trace elements including high field strength elements and metallogenic elements,increasing from undeformed,through weakly deformed,to mylonitized listwaenite,show a positive correlation with deformation degree and content of apatite,rutile,monazite,zircon and sulfide in listwaenite.The shear zone served as pathways for percolation and accumulation of fluid and trace elements during the metasomatism from serpentinite to listwaenite.Compared to undeformed listwaenite,mylonitized listwaenite will be more favorable to be fractured and brecciated due to more intense shearing,which caused strong metasomatic reaction and then induced trace element-bearing mylonitized listwaenite.

Gravity and magnetic field characteristics and regional ore prospecting of the Yili ancient continent, West Tianshan, Xinjiang Uygur Autonomous Region, China

Gold,iron,copper,lead-zinc and other mineral exploration in West Tianshan,Xinjiang Uygur Autonomous Region,has made remarkable progress in recent years.However,due to the dispute on the tectonic division of West Tianshan,the ore-controlling factors and the regional metallogenic laws are controversial.The authors analyze regional gravity data and notice that the high-value region corresponds to the Yili ancient continent,thus the southeastern boundary of the Yili ancient continent is delineated.Comparative analysis of gravity,aeromagnetic and geologic data reveals that the Tulasu basin,where some medium to large epithermal gold deposits locate,lies above the Yili ancient continent;the Yili Carboniferous-Permian rift extends in E-W direction,numbers of copper deposits have been found in the mid-west section of the rift which lies above the Yili ancient continent,whereas few copper deposits have been discovered in the east section which is outside the Yili ancient continent.Accordingly,the Yili ancient continent may be rich in gold,copper and other metal elements;the metal-bearing hydrothermal solution moves up with the activity of magmatism,and deposits in the favorable places(the Tulasu basin and the Yili Carboniferous-Permian rift),forming numerous small and medium gold,copper deposits,as well as some large and super-large gold deposits.Therefore,the tectonic-magmatic hydrothermal zone above the Yili ancient continent should be the prospective area for epithermal gold and copper polymetallic deposits.

Aquatic beetle species and their distributions in Xinjiang, China

The species of aquatic beetles and their distributions in lotic and lentic habitats were investigated during July to August of 2005 and 2006 in Xinjiang Uygur Autonomous Region, China. A total of 66 species belonging to 7 beetle families （Dytiscidae, Gyrinidae, Haliplidae, Helophoridae, Noteridae, Hydraenidae, Hydrophilidae） are recorded, of which 16 are new records of aquatic beetles for China.