Recharge processes limit the resource elements of Qarhan Salt Lake in western China and analogues in the evaporite basins

The Qarhan Salt Lake(QSL)in western China is K-Sr-Li-B-Br-Rb multi-resource coexisting Quaternary brine deposits.Significant research efforts have been directed to the origin of K-Li resources and evolutionary history of the QSL.However,the study on the different sources,recharge processes,and differential distribution patterns for these resource elements in brine deposits is still inadequate.Therefore,we measured Li-B concentrations and H-O-Sr-B isotopic compositions of different waters(river,spring,and brine)from the QSL,combined with the reported K-Sr contents and multiple isotopes of waters,to discuss the recharge,source of K-Sr-Li-B and their spatial distributions,by analogy with other evaporite basins in the world.The results show that:(1)the K-Li-B-Sr elemental concentrations of brines and their spatial distribution in the QSL are diverse;(2)high K and Sr values are distributed in Dabuxun and Qarhan sections,respectively,which are controlled by Ca-Cl springs in the northern QSL;on the contrary,Li and B values are enriched in the Bieletan section and are charged by thermal springs in the Kunlun Mountains;(3)the formation and evolution of Ca-Cl and thermal springs constrain fundamentally on the recharge processes of K-Sr and Li-B elements in the terminal salt lakes of the Qaidam Basin(QB);(4)some analogues of recharge processes limit the resource elements of the QSL and other salt lakes(Da Qaidam,Lop Nur,Zhabuye,Atacama,and Guayatayoc)in the world provides a reference for the resource exploration in deep formation waters in the evaporite basins.

Grain-size characteristics of linear dunes on the northern margin of Qarhan Salt Lake, northwestern China

In order to clarify the formation mechanism of linear dunes on the northern margin of Qarhan Salt Lake, northwestern China, we analyzed the grain-size and sorting parameters of the dune and interdune sands. The surface sands （0-30 ram） from the dune base to the crest of both flanks and interdune corridors were sampled along transects from upwind to downwind through the dune field. The results indicated that the grain-size distribution differed at different positions between and within the dunes. The frequency curve for dune sands mainly showed a bimodal distribution, while the interdune sediments showed a trimodal distribution. The grain size distribution of the linear dunes showed a finer crest pattern, i.e. the crests were composed of sands that were generally finer, better sorted than those of base sands. In addition, at the dune field scale, the dune crest sands were tending to become much finer but sorting became worse along the downwind transects. However, the grain-size parameters of sediments in the interdune corridors showed no clear pattern. The results demonstrated that the grain size and sorting parameters exhibited a systematic change not only at the individual scale but also at the dune field scale. Our results quantitatively estimate the limited role of cohesive sediments on the formation of linear dune under unidirectional wind regime. More attention should be paid to a long-term wind regime observation, internal sedimentary structures and their formation ages.

Evaluation of boron isotopes in halite as an indicator of the salinity of Qarhan paleolake water in the eastern Qaidam Basin, western China

In this study, nineteen brine samples from the Qarhan Salt Lake(QSL) in western China were collected and analyzed for boron(B) and chlorine(Cl) concentrations, total dissolved solids(TDS), pH values and stable B isotopic compositions. The B concentrations and δ^(11) B values of brines in the QSL range from 51.6 mg/L to138.4 mg/L, and from +9.32& to +13.08&, respectively. By comparison of B concentrations and TDS of brines in QSL with evaporation paths of brackish water, we found that B enrichment of brines primarily results from strong evaporation and concentration of Qarhan lake water. Combining with comparisons of B concentrations, TDS, p H values and δ^(11) B values of brines, previously elemental ratios(K/Cl, Mg/Cl, Ca/Cl, B/Cl) and δ^(11) B values of halite from a sediment core(ISL1 A), we observe good correlations between B concentrations and TDS, TDS and pH values, pH and δ^(11) B values of brines, which demonstrate that higher B concentrations and more positive δ^(11) B values of halite indicate higher salinity of the Qarhan paleolake water as well as drier paleoclimatic conditions. Based on this interpretation of the δ^(11) B values of halite in core ISL1 A, higher salinity of the Qarhan paleolake occurred during two intervals, around 46-34 ka and26-9 ka, which are almost coincident with the upper and lower halite-dominated salt layers in core ISL1 A,drier climate phases documented from the δ^(18) O record of carbonate in core ISL1 A and the paleomoisture record in monsoonal central Asia, and a higher solar insolation at 30°N. These results demonstrate that the δ^(11) B values of halite in the arid Qaidam Basin could be regarded as a new proxy for reconstructing the salinity record of paleolake water as well as paleoclimate conditions.

Pattern analysis of a linear dune field on the northern margin of Qarhan Salt Lake,northwestern China

In terms of formation mechanisms of linear dunes,there are open arguments for their widespread distribution and multi-morphological diversities.In order to clarify the formation mechanism of linear dunes of Qarhan Salt Lake,we used pattern analysis method to analyze the statistical characteristics and spatial variation of their pattern parameters.Except at the west-northwest margin,the pattern parameters showed regular spatial variation from the up-middle part towards the downwind end of the dune field.Based on the cumulative probability plots for inter-crest spacing and crest length,we divided the linear dunes into three groups,which corresponding to the three evolution stages of these dunes.The first group comprises erosional relics,with shorter crests,smaller inter-crest spacing and more random dune orientation.The second group comprises dunes whose sand supply is just sufficient to maintain stability and these dunes are approaching the net erosion stage.The crest length and inter-crest spacing of these dunes are much larger than those of the first group,and dune orientation is closer to the resultant drift direction （RDD） .The last group comprises linear dunes that are still undergoing vertical accretion and longitudinal elongation,which follows the RDD of the modern wind regime.The presence of regular spatial variation of pattern parameters and a similar geometry with the vegetated linear dunes suggest that deposition and erosion coexist in the development and evolution of linear dunes of Qarhan Salt Lake,i.e.deposition predominates at the downwind end of linear dunes in the vertical accretion and longitudinal elongation stage,whereas erosion mainly occurs at the upwind end of linear dunes in the degradation stage.Therefore,the formation mechanism of linear dunes in Qarhan Salt Lake can be reasonably explained by the combination of depositional and erosional theories.

The Formation of the Qarhan Saline Lakes as Viewed in the Light of Neotectonic Movement

Investigations on stratigraphy, geomorphology and neotectonic movement in the Eastern Kunlun Moun-tains show that there existed a series of ancient lakes, including some saline lakes. in the studied region about30,000 years ago, They were distributed south of the middle Kunlun fault. from the middle-upper reaches of thepresent Narin Gol River in the west to the Alag Lake-Tosou Lake in the east. Of these the ancient Narin GolLake and Kunlun Lake were mainly recharged by the hot water related to valcanos. so the B, Li and K con-tents are relatively high. The neotectonic movement that commenced at 30.000 a B.P. caused the river system in the EasternKunlun Mountains to invade southwards. as a result the ancient lake water was captured to recharge theQarhan area. Therefore, the hot springs related to recent volcanism and faulting on the southern bank of theupper reaches of the Narin Gol River became an important source of saline materials for the Qarhan Lake.

STABLE ISOTOPES DISTRIBUTION IN CORE Ck6 AND VARIATIONS OF PALEOCLIMATE OVER QARHAN LAKE REGION IN QAIDAN BASIN, CHINA

Depositing ages of sediment in Core Ck6 of Qarhan Lake were dertermined by 14C, 230Th and geomagnetic polarity methods. Results of analyses of stable isotopes composition in carbonate and organic matter were used to set up a model of fluctuating paleoclimate (since 750 ka B. P.) consisting of 11 warm and humid stages and 10 dry and cold stages.

Aeolian component records in lacustrine sediments and its atmospheric circulation significance for evolution of Qarhan salt lake,NE Qinghai-Tibetan Plateau

1 Introduction The Qarhan Playa of Qaidam Basin is located at the northeastern QinghaiTibetan Plateau(QTP),in which thick lacustrine and evaporate sediments deposited since the late Pleistocene(Chen et al.,1985,1986).As surrounded by capacious Gobi and yardang fields and suffered strong westerly-northwesterly wind,abundant aeolian materials were trapped in these sediment sequences in the

Variation of soil physical-chemical characteristics in salt-affected soil in the Qarhan Salt Lake,Qaidam Basin

Soil salinization has adverse effects on the soil physical-chemical characteristics.However,little is known about the changes in soil salt ion concentrations and other soil physical-chemical characteristics within the Qarhan Salt Lake and at different soil depths in the surrounding areas.Here,we selected five sampling sites(S1,S2,S3,S4,and S5)alongside the Qarhan Salt Lake and in the Xidatan segment of the Kunlun Mountains to investigate the relationship among soil salt ion concentrations,soil physical-chemical characteristics,and environmental variables in April 2019.The results indicated that most sites had strongly saline and very strongly saline conditions.The main salt ions present in the soil were Na^(+),K^(+),and Cl^(-).Soil nutrients and soil microbial biomass(SMB)were significantly affected by the salinity(P<0.05).Moreover,soil salt ions(Na^(+),K^(+),Ca2+,Mg^(2+),Cl^(-),CO_(3)^(2-),SO_(4)^(2-),and HCO_(3)^(-))were positively correlated with electrical conductivity(EC)and soil water content(SWC),but negatively related to altitude and soil depth.Unlike soil salt ions,soil nutrients and SMB were positively correlated with altitude,but negatively related to EC and SWC.Moreover,soil nutrients and SMB were negatively correlated with soil salt ions.In conclusion,soil nutrients and SMB were mainly influenced by salinity,and were related to altitude,soil depth,and SWC in the areas from the Qarhan Salt Lake to the Xidatan segment.These results imply that the soil quality(mainly evaluated by soil physical-chemical characteristics)is mainly influenced by soil salt ions in the areas surrounding the Qarhan Salt Lake.Our results provide an accurate prediction of how the soil salt ions,soil nutrients,and SMB respond to the changes along a salt gradient.The underlying mechanisms controlling the soil salt ion distribution,soil nutrients,and SMB in an extremely arid desert climate playa should be studied in greater detail in the future.

Boron Isotopic Composition of Halite from 46-m-long Sediment Core in the Qarhan Salt Lake,Western China

Previous studies have investigated the boron isotopic composition of salt lake brines in the Qaidam Basin,western China.However,the research on boron isotopic composition of halite is very limited due to halite’s low

不同时间尺度下气象-水文要素变化对察尔汗盐湖盐田蒸发作用的影响

目前对察尔汗盐湖蒸发量的研究主要集中在气象-水文因素与卤水蒸发量定量关系,缺乏在不同时间尺度下盐湖蒸发量的驱动因素动态变化研究。利用2020年11月5日—2023年5月1日察尔汗盐湖盐田的空气温度、露点温度、风速、相对湿度、总辐射日累计以及盐田的蒸发量、水温、水位等监测数据,结合获取的察尔汗盐湖补给河流格尔木河流量等水文资料,采用相关性分析、多元回归模型等方法探讨了不同时间尺度下盐田蒸发作用与气象-水文因素之间的关系。研究表明,不同盐田的水温、水位、淡水蒸发量变化保持一致,卤水蒸发量变化与盐田密度有关。随着时间尺度的增大,蒸发量与气象要素之间的相关性增强。察尔汗盐田蒸发量在逐小时与逐月尺度主要受到环境温度的影响,日尺度下主要受到太阳辐射的影响。在极端天气作用下河流水文与盐湖微气象因子呈同步变化,对蒸发量的影响具有滞后性。这一研究结果可为盐田生产工艺优化提供理论指导。

基于DPSR模型的察尔汗盐湖环境承载力评价

青海察尔汗盐湖是目前我国最大的钾盐、镁盐和锂盐生产基地,也是世界特大型盐湖矿床之一,钾资源储量占全国的87.6%,镁资源储量居世界第二位(Li Ruiqin et al.,2021;刘婷玥等,2021)。察尔汗盐湖近年来开发强度不断增加,平衡好开发利用与环境之间的关系非常重要,对察尔汗盐湖环境承载力进行遥感评价,可以为盐湖开发和环境保护治理提供技术依据,对盐湖的持续监测及盐矿的后续开采具有重要意义。

青海省察尔汗盐湖区卤水中十二烷基吗啉的分布特征及变化规律

青海省察尔汗盐湖区钾肥生产目前主要使用的反浮选药剂是十二烷基吗啉(DMP),但目前对于察尔汗盐湖区卤水中DMP的浓度及分布特征尚不清楚。采集了察尔汗盐湖区33个采样点的卤水样(其中部分为淡水样),采用甲基橙分光光度法对水样中DMP浓度进行定量检测,分析湖区DMP浓度及分布特征。研究结果表明:(1)察尔汗盐湖区DMP浓度的空间分布呈现整体较低、部分地区出现高值的特征。(2)在湖区所采的不同类型水样中,DMP浓度呈现生产线卤水>盐田卤水>盐湖卤水>淡水≈采卤渠卤水的分布特征,质量浓度介于0.06~18.90 mg/L,平均值为2.16 mg/L。(3)卤水中DMP浓度受pH、电导率、Na^(+)、K^(+)、Mg^(2+)变化影响。

基于系统动力学的察尔汗盐湖钾盐资源承载状态预断评估

针对察尔汗盐湖钾盐开采规模不断扩大引发的资源可持续问题,构建了钾盐资源承载率指标,基于系统动力学搭建了察尔汗盐湖钾盐资源可持续利用系统仿真模型;利用所建模型,对2020—2040年间察尔汗盐湖钾盐资源承载状态进行预测评估;模拟预测了5种开发情景下盐湖水资源与氯化钾资源承载状态的变化情况。研究结果表明:受柴达木盆地气候变暖趋势影响,未来察尔汗盐湖钾盐资源承载率将由2022年的2.3降低至2040年的1.2;通过降低开采强度与提高技术水平等方法可以有效缓解钾盐资源承载率过高的情况,同时需要通过合理制定生产计划与提高技术水平研发等手段以确保氯化钾资源长期稳定供应。

中国含盐盆地卤水溴元素分布与物源

中国含盐盆地赋存丰富的盐湖卤水和深部卤水资源,卤水中富集溴(Br)元素,具有潜在的开发利用价值。Br作为盐湖卤水中重要的资源元素,目前对其分布规律和物质来源的系统对比研究鲜有报道。本文以柴达木盆地察尔汗盐湖四个区段晶间卤水为研究对象,分析整个湖区Br元素分布规律和物质来源,对比中国不同含盐盆地卤水Br资源变化和物源联系,并总结不同卤水开发利用价值。结果表明:①察尔汗盐湖Br含量呈东高西低特征且不同区段差异明显;②别勒滩和达布逊区段卤水低Br受河流补给并经蒸发富集,而察尔汗和霍布逊区段高Br受北部断裂带上涌富Ca泉水补给;③中国含盐盆地(柴达木盆地、库车盆地、江汉盆地、吉泰盆地)大部分深部卤水高Br值主要受水-岩反应、沉积物及有机质中Br的解吸获得;④盐湖晶间卤水虽远不及深部卤水Br含量高,但其优点在于便于开发、综合利用率高,尤其浓缩卤水及老卤中的Br含量可预见性的高于工业开采品位,是当下和今后值得关注的资源。

察尔汗盐湖畔土壤中元素含量特征研究

文章采用电感耦合等离子体发射光谱法(ICP-OES)、等离子体质谱法(ICP-MS)和容量法,对察尔汗盐湖湖畔某处100~500 m的13种元素进行了含量测定分析。结果表明,在11~20号元素中Na、Cl和S元素,在距盐湖200 m处质量分数达到最高值,Si、Ca、Al、K和Mg元素,在200m处质量分数达到最低值,P、Se、Rb、Sr和Ba元素受盐湖距离的影响不大。

察尔汗盐湖察尔汗区段西部固体钾矿溶采效果研究

察尔汗盐湖察尔汗区段固体钾矿具有品位低、矿体不连续、资源储量较大等特点,不能使用常规采矿方法直接开采,为钾矿的开采和利用造成诸多困难。对察尔汗盐湖察尔汗区段西部大规模水溶开采前(2013年)和开采后(2021年)典型钻孔固体钾矿变化特征进行分析,结果表明:固体钾矿的溶解率在34.40%~99.98%,平均溶解率为80.55%,且垂向上固体KCl品位越高,溶采过程中的溶解率越高,含量降低幅度就越大;长时间的浸泡可以使固体KCl品位在0.1%~0.2%的钾盐也被溶解;固体镁盐品位较以往有所下降,而固体石盐品位较以往有所上升。对察尔汗区段西部典型钻孔固体钾矿品位、厚度及卤水组分变化特征进行研究,为固体钾矿的溶采效果评价提供了科学依据,整体而言,水溶开采在大部分区域的开采中具有良好效果,但水力坡度大、卤渠阻隔、水力联系弱等因素对开采造成的影响,仍需进一步研究。

多源遥感融合技术在古湖岸识别中的应用——以察尔汗盐湖为例

多源遥感融合技术在识别被侵蚀或被覆盖的古湖岸线方面具有独特的优势。察尔汗盐湖为我国最大的第四纪液体钾盐矿床,识别该盐湖晚更新世以来的多级古湖岸及其湖面变化过程,对于保障我国的钾肥安全具有重要的意义。本研究以合成孔径雷达(SAR)哨兵一号数据(Sentinel-1A)为数据源,应用IHS融合、PC融合、GS融合和HSV融合4种融合方法对高分辨率多光谱哨兵二号数据(Sentinel-2B)在察尔汗盐湖区域进行了融合实验,并对融合结果进行精度评价;选取信息熵、互信息、平均梯度、空间频率、标准差、相关系数、差异相关性总和以及视觉保真度8种客观评价指标对融合结果进行了计算与分析。利用野外实测古湖岸的遗迹高程结合数字高程数据(DEM)对岸线进行模拟,并生成地形剖面图,来恢复晚更新世以来察尔汗盐湖古湖岸动态变化。结果表明,融合方法中的HSV算法是最适合应用于察尔汗盐湖古湖岸线的提取,对恢复晚更新世以来被侵蚀和覆盖的三级古湖岸线地貌具有较好的效果。

察尔汗钻孔介形类记录及其对察尔汗古湖晚更新世高湖面的指示

察尔汗盐湖作为柴达木盆地第四纪的沉积中心,沉积了巨厚的第四系湖相沉积,其演化历史研究对于揭示柴达木盆地及青藏高原北部第四纪古气候、古环境演变历史具有重要意义。本文在AMS^(14)C测年的基础上,以察尔汗盐湖晚更新世钻孔(ZK53630-1)岩芯中介形类微体化石为研究对象,通过系统的采样和室内分析,共识别出7属10种。基于分类学研究,识别出2个介形类组合(自下而上):Ilyocypris biplicata-Limnocythere inopinata和Ilyocypris bradyi-Ilyocypris sebeiensis。介形类及其伴生化石均显示察尔汗古湖在距今34~28 ka期间的晚更新世晚期(MIS 3a)主体为淡水—微咸水湖泊,气候温暖湿润,与现今极端干旱的盐湖环境截然不同。

察尔汗盐湖别勒滩区段固态锂的赋存状态与分布特征

察尔汗盐湖别勒滩区段赋存大量具有开发潜力的固态锂资源,但目前对固态锂的赋存状态和分布特征研究较少。文章利用水溶法、稀酸溶法和全岩溶解法3种方法对该区4个钻孔的15件岩芯样品进行主微量元素分析。研究结果显示,水溶法的w(Li)(Li溶出量,余同)为23.37×10-6~85.98×10-6,稀酸溶法的w(Li)为47.77×10-6~139.58×10-6,全岩溶解法w(Li)为49.47×10-6~151.64×10-6。以同一样品全岩溶解所得的w(Li)为100%,水溶法、稀酸溶法的w(Li)平均值分别为56.44%和92.83%。结合矿物薄片鉴定、扫描电镜分析和X射线衍射的鉴定结果,岩芯样品中的矿物主要是石盐、杂卤石、光卤石、石英、绿泥石、钠长石、硬石膏、白云石、伊利石、菱镁矿和方解石等,推测固态锂大部分赋存于易溶盐类矿物,其余赋存于不易溶的碳酸盐、硫酸盐和硅酸盐等矿物中。根据4个钻孔岩芯样品的Li溶出量来看,察尔汗盐湖别勒滩区段固体钾盐层中固态锂的分布特征是由西向东逐渐递减,与别勒滩区段卤水Li含量在空间上的规律性相同,说明别勒滩区段固态锂的含量可能受到卤水中Li浓度的影响。

柴达木盆地别勒滩杂卤石矿床特征及其沉积环境研究

别勒滩是青海察尔汗盐湖固体钾矿的主要分布区段,也是企业固转液开采和生产钾盐的主要矿区,该区段分布着大面积的杂卤石矿(K_(2)Ca_(2)Mg[SO_(4)]_(4)2H_(2)O)。文章利用2022年察尔汗盐湖储量核查项目获得的岩芯样品和钻孔资料,通过系统的分析测试,开展别勒滩杂卤石成矿特征及沉积环境研究。文章首次查明别勒滩区段杂卤石矿床分布面积超过150 km^(2),平均厚度0.8 m,w(K_(2)SO_(4))平均大于5%,计算获得K_(2)SO_(4)资源量2089.79×10^(4) t。研究认为,别勒滩杂卤石形成于钾石盐、光卤石析出阶段的高浓缩盐湖相沉积环境,周期性淡化带入的大量Ca^(2+)和SO^(2-)_(4)与卤水中含量较高的K^(+)、Mg^(2+)离子反应形成了杂卤石矿层。别勒滩杂卤石矿层具有较好渗透性和给水能力,适合选用固液转化的方式进行开采。但考虑到杂卤石溶解效率远低于钾石盐和光卤石,因此短期内杂卤石开发价值有限。