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This paper aims to improve the quality and efficiency of talent cultivation in colleges and universities and effectively analyze and count the number of talents. The cultivation of computer professionals in higher vocational education is taken as the research object. First, a talent cultivation information system for colleges and universities is developed, using deep learning neural networks and data mining algorithms and introducing recurrent neural networks (RNN) and a fusion attention model. With a view to the needs of employment forms and employment data, a diversified talent demand cultivation program is formulated. Based on this, an efficient talent cultivation quality indicator system is established through analyzing talent cultivation data in higher vocational education. Finally, the effectiveness of the system is verified by the performance analysis. The results show an average prediction accuracy for the proposed Attention RNN Word2 algorithm of 80.61%, which is significantly higher than achieved by the latest research algorithm model, and the talent training has a classification accuracy of 82%. This model is not only feasible for categorizing computer professional personnel cultivation but can also accurately reflect problems arising in personnel cultivation, and the results are made obvious by visualization. To sum up, the system reported here can give an intuitive demonstration of the quality of computer professional personnel cultivation in higher vocational education. This research provides a theoretical basis for related research into the cultivation of computer professionals in higher vocational education for application in industry, universities, and research.

This paper discusses the origin and evolution of saline springs in north and central Laos, based on chemical and stable isotopes (δD, δ18O, δ11B, and δ37Cl). All the saline springs in this study are of the Na–Cl geochemical type. The geochemical and water isotope values suggest that the saline springs in this study are mainly derived from meteoric water and/or ice and snow melt from the surrounding mountains and that they also experienced strong evaporation and intense rock–water interactions. The ionic ratios, characteristic coefficients, ternary Ca–SO4–HCO3 phase diagrams, and saturation indices of minerals show that the dissolution of halite, sulfate, and carbonate rocks may be the solute sources for saline springs in this study, whereas the underground brines in the Thakhek potash mining area are geochemically influenced by the dissolution of carnallite and sylvite. The global geothermal δ11B–Cl/B relationship and δ11B values (5.50 to 36.01‰) of saline springs suggest a continental origin of B. This B is most likely derived from marine carbonate rocks and marine evaporates (gypsum and halite) of the late Cretaceous, which is similar to the saline springs of the Nangqen–Qamdo–Simao Salt Basin. The δ37Cl value (−0.12 to +0.79) and the Cl/Br ratio (4076 to 9853) show that dissolution of late cretaceous marine halite layers, atmospheric precipitation, and water–rock interactions between volcanic rocks, mudstones, and sandstone can restrict the δ37Cl values in saline springs. Results from silica geothermometry and multi–mineral equilibrium diagrams indicate that the reservoir temperatures for the saline springs range from 87–137 °C and experience deep circulation. Hydrochemical characteristic coefficients suggest that saline springs in the Muang Say basin may have leached sylvinite and carnallite and that the potash exploration prospect in this area is relatively good.

An experimental study was carried out on the preparation of schoenite from carnallite and thenardite by the double-decomposition method. According to the metastable phase diagram for the qu...

Qarhan Salt Lake (QSL) is the largest potash brine deposit in the continental Qaidam Basin (QB) of western China. The origins of the Qarhan brines, whether from migration of Qaidam mega-paleolakes, paleoriver capture, or mixing of modern river water and Ca-Cl spring water, are controversial. Details about the origin (hydrothermal, diagenetic or both) of the Ca-Cl inflow waters entering QSL in the QB are unclear. Here we show from the strontium (Sr) isotope ratios of river waters, intercrystalline brines, spring waters, halite, gypsum, and Corbicula shells from Qarhan playa, that 87Sr/86Sr increases from Bieletan (western QSL) to Huobuxun (eastern QSL). This trend verifies that river water-spring water mixing has been operating at QSL for the past 50,000 years. Contributions of Ca-Cl inflow waters to the QB have profoundly influenced the brine evolution and mineralogy of salt deposits. Mixing between low Sr2+ concentration, low 87Sr/86Sr value of river waters and high Sr2+ concentration, high 87Sr/86Sr value of Ca-Cl spring inflow waters has produced various intercrystalline brines and salt deposits at QSL. Ca-Cl inflow waters and brines are enriched in Sr2+ and Ca2+ and depleted in Mg2+ and SO42−. These characteristics suggest brine-sedimentary rock (silicate) interactions at burial diagenetic or hydrothermal conditions. Ca-Cl inflow waters and brines have a similar Sr isotopic range as oilfield brines and celestite deposits in the QB, which also suggests a diagenetic-hydrothermal origin. Ca-Cl brines discharge as springs or seeps along fault zones in the QB. They are interpreted to reach the surface of the northern margin of Qarhan playa by topographically driven circulation.

At the Qarhan Salt Lake (QSL) on the central-eastern Qaidam Basin, northern Tibetan Plateau, Quaternary lacustrine sediments have a thickness of over 3000 m and mainly composed of organic-rich clay and silty clay with some silt halite and halite. In this study, a 102-m-long sediment core (ISL1A) was obtained from the QSL. Combining with AMS 14C and 230Th dating, clay minerals and major-element concentrations of ISL1A were used to reconstruct the weathering process and trend of the QSL since late Pleistocene. The results reveal that the clay mineral from

The relationship between sylvinite (KCl + NaCl) and carnallite (KCl·MgCl 2 ·6H 2 O) is important in potash mines containing carnallite, and especially where sylvinite overlies carnallite. It is generally believed that this reversal of the normal depositional sequence may be caused by dissolution of carnallite. To obtain sylvite (KCl) from carnallite ore in the present study, first carnallite ore dissolution was performed in an aqueous solution at 25 °C, and then the sylvite was separated from halite (NaCl) in the sylvinite by a flotation method. The Br and Rb concentrations in the sylvite derived from the carnallite ore were determined. The results showed that more than 4/5th of the Br and Rb in the carnallite ore transferred to the mother liquor, while the remainder of the Br and Rb was in the sylvinite. The sylvite separated from this sylvinite had purity of 94–96%. In the sylvite derived from carnallite, the Br concentration was obviously lower (by an order of magnitude) than the concentration in primary sylvite from evaporation of MgSO 4 -deficient sea water, and the Rb concentration was twice that in primary sylvite from evaporation of MgSO 4 -deficient sea water. Compared to the Br and Rb concentrations in secondary sylvite from Khorat Plateau, Sergipe, and Prairie evaporites, the concentrations in the sylvite derived from carnallite ore were similar. The redistribution of Br and Rb in the form of secondary sylvite was in a relative stable proportion according to the comparison of Br and Rb. The lower Br and higher Rb concentrations in sylvite derived from carnallite ore could be caused by KCl re-crystallization and redistribution of Br and Rb between the solid and liquid phases. The driving force behind changes in the partition coefficients of Br and Rb is that the dissolution of carnallite is much slower than the nucleation of KCl.

This study presents chlorine isotopic composition of salt deposits recovered in a core from the Qarhan Saline Lake in the Qinghai Province of China. The δ 37 Cl trend has three stages, and they correspond to the upper, middle, and lower salt-bearing groups of the entire evaporite system. The δ 37 Cl values are between −0.22‰ and 0.13‰ with an average value of −0.02‰ in the lower salt-bearing group. It ranges between 0.14‰ and 0.76‰ ( x ¯ = 0.36‰) in the middle salt-bearing group, and varies between −0.35‰ to 0.35‰ ( x ¯ = −0.04‰) in the upper salt-bearing group. This work indicates that stratification of δ 37 Cl values is accompanied by stratigraphic variations in Mg/Cl and K/Cl in halite. We suggest a “evaporation cycles model” and it indicates the potential of Cl isotope as a geochemical tracer in order to understand paleoclimatic conditions during different stages of evaporite deposition.

Drill core (ISL1A) was obtained from the Qarhan Salt Lake in central eastern Qaidam Basin, northeastern Tibetan Plateau (NE TP). Fossil pollen and the lithology of the core sediment were analyzed in conjunction with AMS C-14 and Th-230 dating. The results indicated that Artemisia and Chenopodiaceae dominated the steppe/desert steppe vegetation developed around the lake between 94 and 51.2 ka, corresponding with the organic-rich silty clay deposited in the core sediments. Pediastrum continuously appeared in the core sediments between 94 and 51.2 ka, indicating freshwater to oligohaline conditions of the paleo-Qarhan Lake during the late marine isotope stage (MIS) 5, MIS 4, and early MIS 3. During the 51.2 to 32.5 ka period, Ephedra dominated shrub-desert vegetation expanded in the basin, while, Pediastrum disappeared in the core sediments. The core sediments consisted of interbedded layers of halite silt and clay-rich halite between 51.2 and 32.5 ka, signifying a shift toward drier hydrologic conditions. Thus, the paleo-Qarhan Lake experienced periods of desiccation and shallow water levels. Artemisia and Chenopodiaceae dominated steppe/desert steppe vegetation appeared again from 32.5 to 253 ka, with clay-rich sediments in the core, thereby suggesting an increase of runoff from the lake under relatively wetter climatic conditions. Since 253 ka, however, pollen concentrations declined, corresponding with the amount of halite deposited in the core sediment and, suggesting a cold, dry climatic condition during MIS2. Our findings have important implications for understanding complex regional vegetation and climatic responses to large-scale forcings in the Qaidam Basin. (C) 2015 Elsevier B.V. All rights reserved.

In order to better understand chlorine isotopic variations during brine evolution, experiments were designed to determine the changes in the chlorine isotope composition (δ37Cl value) during evaporations of solutions containing NaCl, KCl and MgCl2⋅6H2O at 28 ± 2 °C. Three evaporation experiments were conducted in a clean environment. The precipitate and brine samples were collected during the evaporation, and the chlorine isotopic ratios of the samples were determined using an improved thermal ionisation mass spectrometry procedure based on Cs2Cl+ ion measurement. The results are as follows: the mean fractionation factors of the three solutions are αNa = 1.00055, αK = 1.00025, and αMg = 1.00012, respectively, where αNa, αK and αMg are the fractionation factors between salts (NaCl, KCl and MgCl2⋅6H2O) and saturated solutions. The results showed that the δ37Cl values of precipitate and coexisting brine samples decrease during the precipitation of single chloride minerals. The residual brine was a 35Cl reservoir for different single chloride solutions. New chlorine isotopic evolution curve during seawater evaporation were also calculated. The results indicated that during the primary precipitation stage of halite, δ37Cl decreased continuously, and the most important thing is that this trend continues during the final stages when Mg–salts begin to precipitate.

Late Pleistocene paleoclimatic variability on the northeastern Qinghai–Tibetan Plateau (NE QTP) was reconstructed using a chronology based on AMS 14 C and 230 Th dating results and a stable oxygen isotopic record. These are derived from lake carbonates in a 102-m-long Qarhan sediment core (ISL1A) collected from the eastern Qaidam Basin. Previous research indicates that the d 18 O values of lacustrine carbonates are mainly controlled by the isotopic composition of lake water, which in turn is a function of regional P/E balance and the proportion of precipitation that is monsoon-derived on the NE QTP. Modern isotopic observations indicate that the d 18 O values of lake carbonates in hyper-arid Qaidam Basin are more positive during the warm and wet period. Due to strong evaporation and continental effect in this basin, the positive d 18 O values in the arid region indicate drier climatic conditions. Based on this interpretation and

The palaeoshorelines of a lake are the direct geomorphic evidences to reflect past water levels and record information on palaeoclimatic changes. Previous research indicates that the timing and forcing mechanisms of climatic change on the northeastern Qinghai-Tibetan Plateau (NE QTP) are still controversial. Here, we report quartz optically stimulated luminescence (OSL) ages for beach deposits and accelerator mass spectrometry (AMS) 14C age for plant remains, shoreline features and geomorphic exposures that contribute to a reconstruction of the lake-level history of Hurleg Lake on the NE QTP. The results imply that (1) three high lake levels are dated to 6.8–6.4, 5.0–4.7 and 2.2–1.4 kyr, corresponding to relatively wet and stable climate from pollen records of sediment core in this lake during mid–late Holocene; (2) the highest lake-level period occurred at 5.0–4.7 kyr, which is almost synchronous with the highest effective moisture phase from synthesized lake records influenced by the Westerlies and (3) no beach deposits around Hurleg Lake and lower lacustrine deposits in Toson Lake were found during early Holocene, suggesting lower lake level of Hurleg Lake in this period. These results might imply that the Westerlies and local topography rather than Asian summer monsoon dominate the moisture availability in this region during the Holocene.

The age framework of Qarhan Salt Lake in arid western China is still controversial due in part to (1) age discrepancy between conventional 14C and 230Th dating results, and (2) no AMS 14C ages of organic carbon from drilling cores in Qarhan Salt Lake were reported until now. In order to discuss these chronological problems, upper 54.50 m lacustrine sediments from a drilling core (ISL1A) recovered from Qarhan Salt Lake were dated based on 230Th and AMS 14C dating techniques. Results show that (1) AMS 14C ages of total organic carbon (TOC) from 4.65 to 30.29 m are almost in stratigraphic order and consistent with 230Th ages of halite in the corresponding layers; (2) AMS 14C ages of TOC from 30.29 to 54.50 m are younger with increasing depth. This phenomenon was also found in Shell Bar in the study area, suggesting that AMS 14C ages from upper 30.29 m are more reliable while those from lower 24.21 m in ISL1A may be underestimated; (3) 230Th ages of halite from lower 24 m lacustrine sediments are obviously older than AMS 14C ages of TOC in the corresponding layers, which results into different age framework of salt lake sediments in Qarhan Salt Lake; (4) if extrapolating these reliable AMS 14C ages in ISL1A, similar age framework with 230Th ages in this core confirms that 230Th ages are much close to the true ages of these sediments, which suggests that the forming timing of the bottom salt layer is ~50 ka.

The procedures of sample preparation for isotopic determination of boron in clay sediments is very cumbersome, by far, there haven’t been relevant reports on that. In order to establish an effective method for sample preparation, a series of experiments were carried out. In this paper, boron in clay sediments was extracted with HCl solution and purified by two-step ion exchange method. Extracted HCl solution should be adjusted to alkalescency before passing through the Amberlite IRA 743 resin column due to the fact that Amberlite IRA 743 resin absorbs boron only from alkalescent solution. However, a mass of hydroxides of Al and Fe will be precipitated when the extracted HCl solution becomes alkalescent. Hydroxides of Al and Fe have a strong adsorption capacity for boron, which can cause boron isotope fractionation. To treat precipitated hydroxides of Al and Fe, four procedures, namely direct ion exchange (DRIE), decationizing ion exchange (DCIE), once sedimentation ion exchange (OSIE) and repeated sedimentation ion exchange (RSIE) were used and assessed. The influences of the four procedures on separation and extraction and isotopic composition of boron in experimental solutions and clay sediments were also discussed. According to the results, the DRIE, DCIE and OSIE are improper. The result of sample determination indicates that when extracting boron via RSIE, with the increase of precipitation times, there’s an obvious decrease in boron content in the precipitated hydroxides while a sharp increase in recovery of boron and it is favorable for weakening the influence of boron isotope fractionation. But the process of RSIE is time consuming and it may introduce boron. It needs further research to establish a more effective sample preparation method for isotopic determination of boron in clay sediments.

The evaporites on the Khorat Plateau comprise one of the largest potash deposits in the world, and their origin has long been a controversial problem. Based on boron isotope measurements from borate as a good indicator to distinguish marine and nonmarine evaporites, the borates of potash layers were identified and the results were used to indicate the source of evaporites in the study area as representative of the whole Khorat Plateau. The results show that the main borates include boracite and hilgardite. The boracites occur as crystals and ooids with minor amounts of hilgardite aggregates. The range of δ11B values is from +21.30‰ to +32.94‰ (averaging +29.74‰) and falls in the range of marine borates. The δ11B values in the potash layer are seemingly variable because of the influence of fluvial influx when salts were precipitating. Although the composition of seawater has possibly been modified, the evidence from boron isotopic composition implies that the evaporites in the study area or in the whole Khorat Plateau are marine deposits.

Palaeoshorelines, highstand lacustrine sediments and lakeshore terraces are preserved around saline lakes in the arid Qaidam Basin. Previous research indicates that the chronology of a mega-paleolake in the Qaidam Basin during the late Pleisotocene is controversial. Here we report quartz optically stimulated luminescence (OSL) age estimates of highstand lacustrine sediments, shoreline features and geomorphic exposures that contribute to a revision of the lake level history of Gahai and Toson lakes in the north-eastern Qaidam Basin, on the northeastern Qinghai- Tibetan Plateau (QTP) margin. The results imply that: (i) high lake levels at Gahai and Toson lakes based on quartz OSL dating occurred at 85-72, 63-55, 31, 5.4 and 0.9-0.7 ka, probably corresponding to periods of warm and wet climate; (ii) periods of high lake levels are almost synchronous with other lakes on the QTP (e.g. Qinghai and Namco lakes), with the highest late Pleistocene levels occurring during Marine Oxygen Isotope Stage 5; and (iii) highstand phases on the QTP are out of phase with those of low-latitude lakes in the southern hemisphere, possibly driven by solar insolation variability in the low-latitude region. Copyright # 2011 John Wiley & Sons, Ltd.

Qarhan playa is located in the eastern-central Qaidam Basin in the northeastern Qinghai-Tibetan Plateau. As a lake-depocenter since the Pleistocene and surrounded by Gobi and yardang fields, it might have deposited abundant aeolian materials. Distinguishing its aeolian signature from lacustrine sediments is important for understanding the landform processes and environmental changes, which is the focus of the current study. Based on major-elements analysis, microtextures of quartz grains, and features of grain-size frequency curves and other grain-size parameters, we demonstrate the existence of aeolian component in the lacustrine sequences of a 102 m core (ISL1A). Grain-size distribution curve statistics on 60 samples from two extreme palaeoclimate environments (hyperarid and humid), as well as multi-proxies records comparison, indicate that the mode at about 40 μm represents the aeolian component and the 10–70 μm fraction of grain-size is a valid proxy of East Asian winter monsoon, and that the 70–650 μm fraction represents the intensity of dust storms. The erosive lacustrine sediments in the western Qaidam Basin and the alluvial/fluvial fans in nearby piedmont are probably important sources for these aeolian materials. The similarities of major-element data for samples from the Qaidam Basin (both lacustrine and loess), Qinghai Lake (loess), and the Chinese Loess Plateau (loess) indicate that the Qaidam Basin is a dust source for the loess in Qinghai Lake and the Chinese Loess Plateau.

Brine from the saline Qarhan Lake was evaporated at 28±2°C in a clean environment. Two groups of experiments were conducted; one with complete separation of precipitate and brine at different stages of evaporation, and the other with continuous precipitation during the evaporation. Seventy-nine precipitate and brine samples were collected during the experiments, and the δ 37Cl values were determined using an improved thermal ionization mass spectrometry procedure for precise measurement of chlorine isotopes based on Cs2Cl+ ions. Based on the concentrations of Na+, K+, and Mg2+, evaporation was divided into three main precipitation stages as follows: halite dominant, carnallite dominant, and bischofite dominant. The δ 37Clsolid and δ 37Clliquid values of the precipitate and coexisting brine samples at different stages showed the following characteristics. The precipitates were enriched with 37Cl relative to the coexisting brine samples, and the δ 37Cl of both the precipitate and brine samples decreased gradually during evaporation. The fractionation factors (α h) between halite and brine were the highest, followed by that (α c) between carnallite and brine, and then that (α b) between bischofite and brine. The α c and α b values of less than one, which indicate the precipitate is enriched in 35Cl, were found when the evaporation process entered a new stage. However, the δ 37Cl values of carnallite, bischofite, and the coexisting brine samples decreased during evaporation. The residual brine is a 35Cl reservoir. The experimental phenomena were consistent with the δ 37Cl values in saline deposits in the literature. δ 37Cl can be used as an indicator of brine evaporation processes, which is important in the exploration of sylvinite deposits.

Late Pleistocene paleoclimatic history on northeastern Qinghai–Tibetan Plateau (QTP) has been reconstructed mainly from lake sediments; however, data regarding dry–wet climate changes reported in this region are still not clear and controversial. Based on shoreline features and highstand lacustrine sediments around lakes on the QTP, high lake level histories in this paper were summarized and compared with paleoclimatic records from lake sediments, ice core and glaciation evolution surrounding mountains on the NE QTP during late Pleistocene. The results indicate that periods of high lake level occurred at MIS 5, MIS 3 and early-middle Holocene and most likely corresponding to warm and wet climate periods, while periods of low lake level existed in intervening intervals, corresponding to cold and dry climate periods, which most likely coincide with glacial advances surrounding high mountains. With an exception, no wide glacial advance in study area was found during MIS 3, possibly suggesting that effective moisture is lower than that in the other region of NE QTP in this period.

We use a data set of 86 surface pollen samples from moss polsters and surface soils from northeastern Qinghai-Tibetan Plateau to explore the relationship between modern pollen assemblages and contemporary vegetation patterns. The samples span seven main vegetation zones from east to west: mountain forest, alpine shrub, alpine meadow, temperate steppe, steppe desert, shrub/semi-shrub desert and desert. Principal components analysis (PCA) was used to determine the relationships between modern pollen, vegetation, and regional climatic gradients. The results show that the major vegetation communities occurring today in the northeastern Qinghai-Tibetan Plateau can be clearly differentiated by their modern pollen assemblages. The representation of surface pollen varies with genera and species. For instance, relative to Betula, a low representation of Picea and Cupressaceae was found in the forest zone: Artemisia. Chenopodiaceae and Ephedraceae had high representation values, while Cyperaceae, and Nitraria showed values in the middle range, and Poaceae, Asteraceae, Tamarixaceae, Calligonum, Polygonaceae, Ranunculaceae, Fabaceae, Scrophulariaceae and Primulaceae had low representation values. Rosaceae have low representation values in the sampling sites in alpine shrub community where the dominant plant species are Potentilla fruticosa and Potentilla glabra. PCA results indicated a high correlation between the modern pollen assemblages and mean annual precipitations (MAP) and July temperature (T(july)). The Artemisia/Chenopodiaceae (A/C) ratio is sensitive to variations in MAP in this region and is a useful tool for qualitative and semi-quantitative palaeoclimate reconstruction on the northeastern Qinghai-Tibetan Plateau. (C) 2010 Elsevier B.V. All rights reserved. We use a data set of 86 surface pollen samples from moss polsters and surface soils from northeastern Qinghai-Tibetan Plateau to explore the relationship between modern pollen assemblages and contemporary vegetation patterns. The samples span seven main vegetation zones from east to west: mountain forest, alpine shrub, alpine meadow, temperate steppe, steppe desert, shrub/semi-shrub desert and desert. Principal components analysis (PCA) was used to determine the relationships between modern pollen, vegetation, and regional climatic gradients. The results show that the major vegetation communities occurring today in the northeastern Qinghai-Tibetan Plateau can be clearly differentiated by their modern pollen assemblages. The representation of surface pollen varies with genera and species. For instance, relative to Betula, a low representation of Picea and Cupressaceae was found in the forest zone: Artemisia. Chenopodiaceae and Ephedraceae had high representation values, while Cyperaceae, and Nitraria showed values in the middle range, and Poaceae, Asteraceae, Tamarixaceae, Calligonum, Polygonaceae, Ranunculaceae, Fabaceae, Scrophulariaceae and Primulaceae had low representation values. Rosaceae have low representation values in the sampling sites in alpine shrub community where the dominant plant species are Potentilla fruticosa and Potentilla glabra. PCA results indicated a high correlation between the modern pollen assemblages and mean annual precipitations (MAP) and July temperature (T(july)). The Artemisia/Chenopodiaceae (A/C) ratio is sensitive to variations in MAP in this region and is a useful tool for qualitative and semi-quantitative palaeoclimate reconstruction on the northeastern Qinghai-Tibetan Plateau. (C) 2010 Elsevier B.V. All rights reserved.

Surveys and exploration for oil and gas have revealed many oil-field brines in the Tertiary strata of the western Qaidam Basin, China. The source and formation of these brines are unclear. Brine samples collected from petroleum wells in the oilfield area were analyzed for their general chemical composition and for hydrogen, oxygen, strontium and helium isotopes in order to trace their origin, formation, and resource distribution. Results show that the concentrations of resources such as K, B, Sr, Br and Li are unusually enriched in oil-field brines and have excellent potential for development and utilization in future. The geology, H, O, Sr and He isotopic composition, the chemical composition, and the geophysical measurements all show that the tertiary oil-field brines predominantly originated from the deep mixture of formation water and magmatic residual fluids in the western Qaidam Basin. The tectonic geology, intense and frequent magmatic-hydrothermal activity as well as high 3He/4He ratio indicate that the magmatic fluids possibly originate from the upper mantle-derived magmatic fluids. Thus, according to our interpretation of the formation and evolution of the oilfield brine, this source is adequate for the volume and composition to be explored and utilized latterly.

65 soil samples from north-eastern Tibetan Plateau,northwest China(94.17°E～102.37°E,35.72 °N～38.05°N),were analyzed for pollen content.The pollen belong to six main vegetation types:forest,alpine shrubs,alpine meadows,temperate steppes,steppe deserts,shrub and semi-shrub deserts.The aim of this study is to provide new data on the modern pollen rain in the semi-arid to arid areas of northwest China.These data were interpreted by using diagrams of pollen percentages and numerical analyses.Our result shows that the present major vegetation communities in Qinghai area can be well defined by their pollen assemblages.Artemisia/Chenopodiaceae(A/C)ratio is sensitive to mean annual precipitation (MAP).It decreases from the alpine shrub and alpine meadow zone,through the temperate steppe,to the shrub and semi-shrub desert zone.Detrended correspondence analyses indicate that pollen assemblages have obvious relationship with the mean annual precipitation(MAP)and the July mean annual temperature (July Temp).This study also provides the theoretical basis for quantitative reconstructions of palaeoclimate and palaeovegetation based on fossil pollen spectra from the lacustrine sediments of the Qinghai Lake and Qaidam basin.

Chemistry of major and minor elements, 87Sr/86Sr, δD, δ18O and δ34S of brines were measured from Tertiary strata and Quaternary salt lakes in the western Qaidam Basin. The water chemistry data show that all oilfield brines are CaCl2 type. They were enriched in Ca2+, B3+, Li+, Sr2+, Br−, and were depleted in Mg2+, SO42−, which indicated that these brines had the characteristics of deeply circulated water. The relationship between δD and δ18O shows that all data of these brines decline towards the Global Meteoric Water Line (GWL) and Qaidam Meteoric Water Line (QWL), and that the intersection between oilfield brines and Meteoric Water Lines was close to the local spring and fresh water in the piedmont in the western Qaidam Basin. The results suggest that oilfield brines has initially originated from meteoric water, and then might be affected by water-rock metamorphose, because most oilfield brines distribute in the range of metamorphosing water. The 87Sr/86Sr values of most oilfield brines range from 0.71121 to 0.71194, and was less than that in salt lake water (>0.712), but close to that of halite in the study area. These imply that salt dissolution occurred in the process of migration. In addition, all oilfield brines have obviously much positive δ34S values (ranging from 26.46‰ to 54.57‰) than that of salt lake brines, which was caused by bacterial sulfate reduction resulting in positive shift of δ34S value and depleteed SO42− in oilfield brines. Combined with water chemical data and δD, δ18O, 87Sr/86Sr, δ34S values, we concluded that oilfield brines mainly originate from the deeply circulated meteoric waters, and then are affected by salt dissolution, water-rock metamorphose, sulfate reduction and dolomitization during the process of migration. These processes alter the chemical compositions of oilfield brines and accumulate rich elements (such as B, Li, Sr, Br, K and so on) for sustainable utilization of salt lake resources in the Qaidam Basin.

Since 2006, we have conducted a geological exploration of the Khammuane area in southeastern Laos. Several thick sequences of potash deposits containing sylvite and carnallite were discovered from drilling Paleocene strata of the Thangon Formation (E1 tg). To constrain the origin of the brine that formed thick sequences of salt mineral deposits, we measured the strontium and boron isotope composition of some salt minerals in the potash deposit. Boron isotope composition of halite- and potash-associated minerals in the Khammuane potash deposit varied from 19.91% to 31.01‰, which differs significantly from continental evaporates (−6.83‰–−5.79‰) but is very close to that of salts precipitated from evapo-concentrated seawater (10‰–36‰). The 87Sr/86Sr ratios (0.707542 to 0.709461) of salts were also close to the values of Paleocene seawater (0.70772 to 0.707830). The content of Br− (0.01%–0.25%) and Br×103/Cl ratios (0.10–0.52) of halite were >10 times higher than that of common continental salts. These characteristics indicate clearly that the Laos potash deposits were deposited from seawater. The small variation in boron and strontium isotopes in all salt sedimentary sequences (gypsum-halite-potash-halite) also suggests that the recharge source should be stable and the effects of other continental water mixing are negligible. Large-scale potash deposits are commonly precipitated from seawater. Hence, the results of recent regional drilling work and geochemical research suggest extensive potash resources could occur in the Thangon Formation of southeastern Laos.

The large-scale geomorphology of the Huang He (Yellow River) headwaters, centered around the Bayan Har Shan (5267 m asl) in the northeastern part of the Tibetan Plateau, is dominated by an uplifted ...

Three well-dated Sabina Przewalskii ring-width chronologies from Dulan, China, have been used to reconstruct annual precipitation (from prior July to current June) variations on the northeast Tibetan Plateau since 850 AD. The reconstructions account of the instrumentally recorded precipitation variance are: 54.7% for the period of 1385–2000AD; 50.5% for 1099–1384AD and 45.7% for 850–1098AD. On the millenary scale, the precipitation variation over this region displays “W” shape, which has three peaks and two valleys. The precipitation is low during 1571–1879 AD, and high during 1880–2000 AD. 1900–2000 AD is the century with the highest precipitation over the northeast Tibetan Plateau in the last 1000 years, and 1962–2000 is the period with the highest precipitation, and the highest variability of precipitation as well in the last 1000 years. The reconstructed series also reveals that the variability of annual precipitation is large when the precipitation is more, and contrarily, variability is small when the precipitation is low. With the temperature increasing obviously in the 20th century, the precipitation in the study region significantly increased too, the variability of precipitation became larger, and drought and flooding occurred more frequently.

Climate in northeast Qinghai-Tibetan Plateau is characterised by the alternation of summer and winter monsoon circulation, which is generated by thermodynamic and kinetic effects of the immense plateau. The Plateau Monsoon system during the recent geological past has been investigated through a 44-m loess-paleosol section and a 17-m well to obtain the Plateau Monsoon climate changes during the last glacial-interglacial cycle. Thermoluminescence (TL) and optically stimulated luminescence (OSL) methods, as well as field observations and stratigraphic correlation, are used to date the deposit. Magnetic susceptibility (MS), frequency-dependent magnetic susceptibility (FMS), and calcium carbonate content, which are regarded as proxy indicators of strength of the Plateau Summer Monsoon (PSM), are measured. Measurement of grain size distribution, which is regarded as a proxy index of strength of the Plateau Winter Monsoon (PWM), is also carried out. The results show that changes of the unique Plateau Monsoon system during the past 130 kyr are associated with the glacial and interglacial alternations in the Northern Hemisphere. The PSM was unusually strengthened during a period matching the marine oxygen isotope stage 5e (OIS 5e), but it was weak during the OIS 5a and OIS 5c, and was close to that of the OIS 3. The PWM was significantly depressed during OIS 3, and was as weak as that in the Holocene. The PWM and PSM circulations were not always coupled during the last glacial cycle. Changes of the Plateau Monsoon system did not always parallel the SE Asian monsoon, although linkage between them existed to some extent. There are millennial-scale variations in the Plateau Monsoon system, but this is not further discussed in this paper. © 2004 Elsevier B.V. All rights reserved.

The Qaidam Basin is one of the main areas where the desert of the Qinghai-Xizang Plateau is distributed. According to the environment records and the age of stratigraphy in Xiaxitai section in southeast part of Qaidam Basin, this paper reached the following conclusions: the desert development, formation of the cold-dry climate, evolution of natural environment and their reverse changes occurred frequently since the late glacial. In eolian sand deposits, the Younger Dryas event clearly appeared, which manifesed a dry-cold climatic period. Now there are two different opinions about the climatic effect of Younger Dryas. According to the predecessors’ research and the field work of the authors, it is considered that the Younger Dryas event not only exists in different climatic zones of China, but also manifests the unitary dry-cold climatic effect.

This paper adopt the Shannon entropy algorithm to search the optimal wavelet packet from bottom to up, and decompose the original image and watermark respectively with wavelet packet, and finally embed the watermark data into the selected basis of wavelet packet of the original image. The experiments against attack show that the watermark created by the algorithm is invisible, and image quality have been well preserved, and strong robustness have been shown at same time.

This paper introduces the technology that dynamically and automatically embedding watermark into digital pictures in ASP.NET web site without changing the original website code, and meanwhile gives the primary code which implements the function. The technology proposed in this paper is an efficient, cheap and feasible solution.

Archeological research over the past several years has started to provide evidence relevant to understanding both the timing of and processes responsible for human colonization of the Tibetan Plateau. This harsh, high-elevation environment is known to exact a heavy demographic toll on recent migrants, and such costs likely erected a substantial biogeographic barrier to initial human colonization. This chapter presents a series of simple metapopulation models that link processes of colonization to mutually exclusive archeological predictions. Current archeological evidence from the northern Tibetan Plateau suggests that seasonal forays into high elevation settings were “adaptive radiations” coincident with the appearance of both Early (ca. 30 ka) and Late Upper Paleolithic (ca. 15 ka) adaptations in low-elevation source areas around the Plateau. More permanent occupation of the Plateau probably did not begin before ca. 8200 ka and may have been driven by “competitive exclusion” of Late Upper Paleolithic foragers from low-elevation environments by emerging settled agricultural groups. The appearance of specialized epi-Paleolithic blade and bladelet technologies on the high Plateau, after 8200 ka, may indicate “directional selection” impacting these new full-time residents. An adaptive radiation of agriculturalists into the mid-elevations of the Plateau, this time leading to year-round occupation, is again seen after 6000 Cal yr BP. The short chronology presented here contradicts genetic-based models suggesting that human populations may have been resident on the Tibetan Plateau for as long as 30,000 years. If the short chronology withstands further empirical scrutiny, it suggests either that initial colonists were genetically predisposed to the rapid accumulation of mutations leading to successful physiological adaptation, or that high-elevation selective pressures are much more severe than usually conceived.