Salt-Lake Basin Bedrock Weathered Crust Gas Reservoir in the Altun Mountains Front of the Qaidam Basin,Western China

The bedrock weathered crust in front of the Altun Mountains in the Qaidam Basin,western China,is different from others because this is a salt-lake basin,where saline water fluid infiltrates and is deposited in the overlying strata.A large amount of gypsum infills the bedrock weathered crust,and this has changed the pore structure.Using core observation,polarized light microscopy,electron probe,physical property analysis and field emission scanning electron microscopy experiments,the characteristics of the weathered bedrock have been studied.There are cracks and a small number of dissolved pores in the interior of the weathered crust.Matrix micropores are widely developed,especially the various matrix cracks formed by tectonics and weathering,as well as the stress characteristics of small dissolved pores,and physical properties such as porosity and permeability.This‘dual structure’developed in the bedrock is important for guiding the exploration of the lake basin bedrock for natural gas.

Column leaching process of rare earth and aluminum from weathered crust elution-deposited rare earth ore with ammonium salts

In order to better understand the leaching process of rare earth （RE） and aluminum （Al） from the weathered crust elutiondepositedRE ore, the mass transfer of RE and Al in column leaching was investigated using the chromatographic plate theory. Theresults show that a higher initial ammonium concentration in a certain range can enhance the mass transfer process. pH of leachingagent in the range of 2 to 8 almost has no effect on the mass transfer efficiency of RE, but plays a positive role in the mass transferefficiency of Al under strong acidic condition （pH〈4）. There is an optimum flow rate that makes the highest mass transfer efficiency.The optimum leaching condition of RE is the leaching agent pH of 4？8, ammonium concentration of 0.4 mol/L and flow rate of0.5 mL/min. The mass transfer efficiencies of RE and Al both follow the order： （NH4）2SO4〈NH4Cl〈NH4NO3, implying thecomplexing ability of anion.

Exploration of playa surface crusts in Qehan Lake, China through field investigation and wind tunnel experiments

Globally,many lakes are drying up,leaving exposed lakebeds where wind erosion releases dust and sand rich in salt and harmful heavy metals into the atmosphere.Therefore,understanding the characteristics and spatial distribution of playa surface crusts is important to recognize the manifestation of salt dust storms.The objective of this study was to explore the playa surface crust types as well as their spatial distribution and evolution of Qehan Lake in Inner Mongolia Autonomous Region,China to understand the salt dust release potential of different types of playa surface crusts.Various crust characteristics were investigated by field sampling in Qehan Lake,and playa surface crusts were further divided into five types:vegetated areas,salt crusts,clay flats,curly crusts,and margins.It should be noted that curly crusts were distributed in clay flats and covered only a small area in Qehan Lake.The spatial distribution characteristics of playa surface crust types were obtained by supervised classification of remote sensing images,and the salt dust release potential of crusts was explored by the wind tunnel experiments.The field investigation of Qehan Lake revealed that playa surface crust types had a circum-lake band distribution from the inside to the outside of this lake,which were successively vegetated areas,clay flats,salt crusts,and margins.The spatial distribution patterns of playa surface crust types were mainly controlled by the hydrodynamics of the playa,soil texture,and groundwater.There was a significant negative correlation between crust thickness and electrical conductivity.The results of the wind tunnel experiments showed that the initial threshold of friction wind velocity for the salt dust release was higher in clay flats(0.7–0.8 m/s)than in salt crusts(0.5–0.6 m/s).Moreover,the particle leap impact processes occurring under natural conditions may reduce this threshold value.Salinity was the main factor controlling the difference in the initial threshold of friction wind velocity for the salt dust release of clay flats and salt crusts.This study provides a scientific reference for understanding how salt dust is released from a lakebed,which may be used for ecological restoration of dry salt lakes.

Water Absorption Capcapability and Moisture Content Seasonal Changing of Salt-Crust in Lop Nur Dry Lake

The Lop Nur dry salt lake,Xinjiang province,is charactered by typical physiognomy salt-crust,located in39.6-41.3N.latitude and 89.6-91.4E.longitude.The thickness of salt-crust is about from 20 cm to 100 cm,and

Influence of Climate and Tectonics on the Crystallization of Carnallite and Related Salts in the Congolese Atlantic Basin during the Lower Cretaceous, Republic of Congo

Lithological, petrographic, and morphoscopic studies were conducted on cuttings and cores from three boreholes drilled in the Loemé salt, Kanga site, Republic of the Congo, to determine 1) the preferential conditions for crystallization of carnallite and associated salts and 2) to reconstruct paleoenvironmental and paleoclimatic conditions at the time of sedimentation. Sequential analysis of logs, sedimentary structures, carnallitite facies and associated salts concluded to the existence of a potassic carnallitite lagoon basin with low water cover, on a very wide and extensive plateau, affected by coastal waves and swells resulting from successive collapses. This basin evolved in two phases: confined and then open. The regular stratifications of halite, the rhythmicity of the halite-carnallitite elementary sequences are characteristic of salts that precipitated in relatively stable brines. These salts are therefore tectonosedimentary. The brecciated facies of the carnallitites sometimes associated with tachyhydrite result from the evolution of these deposits into salt crusts reworked by the surges into subaquatic allochemical gravelly cords under water. These crusts mark stages of partial and complete drying of the basin in a very hot and arid climate. Prolonged exposure of halite brines as well as their homogenization by surges accelerated evaporation and their abrupt evolution into carnallite brines obstructing the fossilization of sylvite. The precipitation of tachyhydrite marks the final stage of the successive complete drying of the basin.

盐结皮土壤形成发育过程影响下的能量平衡动态变化

地表能量平衡是地气交互作用的关键环节,探究不同下垫面的地表能量平衡特征对了解地表的热量传输具有重要意义。然而,目前对于能量平衡在盐结皮土壤形成过程下的变化特征的研究未见报道,主要难点在于缺少盐结皮形成过程中土壤表面反照率的计算方法,严重影响了盐渍化土壤热量传输的精确定量描述。因此,利用模拟试验结合能量平衡模型,应用反照率计算方法,定量分析了盐结皮土壤形成发育过程下能量平衡的动态变化特征。结果表明:(1)Logistic增长模型可以很好地拟合盐结皮在土壤表面的形成发育过程(R2=0.99)。(2)在持续照射条件下(1000 W·m^(-2),16 d),随着盐结皮的持续发育,盐结皮土壤的反照率比对照高出0.15~0.41,从而显著降低了土壤对热量的吸收,导致盐结皮土壤表面温度比对照降低了16℃。(3)盐结皮土壤的净辐射、感热通量、潜热通量和土壤热通量在反照率和表面温度影响下分别比对照减少了47.9%、52.4%、46.8%和47.4%,显著影响了土壤的剖面温度。研究结果对进一步探讨盐结皮影响下的土壤水热传输过程具有重要的科学价值。

风化壳淋积型稀土矿中主要矿物对NH_(4)^(+)的吸附行为和机理研究

为了高效洗脱风化壳淋积型稀土矿残留铵盐,研究了风化壳淋积型稀土矿中主要粘土矿物(蒙脱土、埃洛石、伊利石、高岭土)、石英、云母、长石对NH_(4)^(+)的吸附行为和机理。结果表明,蒙脱土、埃洛石、伊利石、高岭土、石英、云母、长石及稀土矿对NH_(4)^(+)的吸附属于单分子层吸附,符合Langmuir等温吸附模型,对NH_(4)^(+)的最大吸附量分别为4.1 mg·g^(-1)、1.5 mg·g^(-1)、0.9 mg·g^(-1)、0.3 mg·g^(-1)、0.1 mg·g^(-1)、0.1 mg·g^(-1)、0.2 mg·g^(-1)、3.4 mg·g^(-1);粘土矿物对NH_(4)^(+)的吸附亲和力大小顺序为:蒙脱土>埃洛石>伊利石>高岭土;石英、云母、长石对NH_(4)^(+)的吸附是一个快速吸附过程,在50 min内可达到吸附平衡;蒙脱土、埃洛石、伊利石、高岭土、石英、云母、长石对NH_(4)^(+)吸附的最佳pH值分别为8、6、7、6、7、5、5。

甲酸铵复配铵盐浸取风化壳淋积型稀土矿渗透性研究

风化壳淋积型稀土矿的渗透性对稀土浸取效率具有重要影响,为了更好地了解浸矿过程中浸取剂的渗透规律,分别探讨了硫酸铵、氯化铵和硝酸铵复配甲酸铵作为浸取剂浸取稀土时,矿石初始含水率、装矿高度及压差对风化壳淋积型稀土矿渗透性的影响。结果表明,3种复配铵盐在矿石中的渗透速度均随着初始含水率的增加、装矿高度的减小和压差的增大而增大,其中硝酸铵复配甲酸铵作为浸取剂时浸取液在矿体中的渗透速度最快且达到稳定渗流的时间最短。

盐结皮厚度对土壤水盐分布特征的影响

土壤盐结皮对干旱区土壤演化和生态水文过程具有重要影响,目前的研究对于盐结皮土壤的水盐分布特征涉及较少,并且未考虑盐结皮厚度的影响,导致研究结果存在较大差异。因此,通过室内模拟试验,设置4种初始盐分浓度(0 g·L^(-1)、10 g·L^(-1)、150 g·L^(-1)和250 g·L^(-1))以获取不同盐结皮厚度(4.5 mm、6.6 mm和7.3 mm),采用部分重复逐步退出的方法对比分析土壤剖面水盐的动态变化。结果表明:(1)对比无盐处理,含盐处理盐结皮越厚,土壤剖面含水量越大,含盐量变化幅度越小。(2)试验结束时,4.5 mm厚度盐结皮土壤含水量分布特征和无盐处理相似,6.6 mm和7.3 mm厚度盐结皮土壤剖面含水量显著大于无盐处理(P<0.05)。(3)试验结束时4.5 mm、6.6 mm和7.3 mm厚度盐结皮土壤剖面最小含盐量相比初始含盐量分别减小了90.5%、46.3%和32.1%。研究结果验证了盐结皮厚度会对土壤水盐分布产生较大影响,因此建议未来对于盐结皮土壤水盐分布特征的相关研究需综合考虑盐结皮厚度的影响。

Na_(2)SO_(4)盐结皮对风沙土水分蒸发的影响

干旱区盐结皮对土壤水分蒸发有着重要影响,但Na_(2)SO_(4)盐结皮研究不足.利用风沙土进行盐水土柱蒸发试验,观测并分析了盐结皮的形态以及盐晶体的变化情况,结果表明:1)当Na_(2)SO_(4)盐水土柱表面结皮形成后降低了风沙土水分的蒸发速率,从而使盐水土柱的土壤水分平均蒸发速率比纯水土柱降低了14.30%;2)土壤内部有盐结晶形成也会降低土壤水分蒸发,蒸发期间盐水土柱土壤水分蒸发速率比纯水土柱降低了19.34%;3)当盐结皮由无水Na_(2)SO_(4)或Na_(2)SO_(4)·10H_(2)O潮解为一层液膜时,会短暂促进土壤水分蒸发,盐水土柱的土壤水分蒸发速率比纯水土柱提高了48.44%;4)Na_(2)SO_(4)表面结皮和内部结晶均会有效降低含盐风沙土水分的蒸发速率,延缓含盐土壤内部水分蒸发损失速率,而盐结皮的潮解则会加剧土壤水分的蒸发,不利于土壤的水分保持.

罗布泊现代盐壳地貌特征与成因初步研究

罗布泊在最后的干涸过程中形成了现代盐壳地貌,其基本类型包括:平坦状盐壳、龟裂状盐壳、微丘状盐壳,其中龟裂状盐壳又可分出多边形构造盐壳、复式多边形构造盐壳和蜂窝状盐壳等。不同的地貌类型是盐壳演变中的特殊阶段,在环境因子的综合影响下,沿着平坦状盐壳-龟裂状盐壳-微丘状盐壳-平坦状盐壳的顺序进行演化。现代盐壳在较短时间形成,不同类型盐壳的物质组成有极大的相似性。

不同盐结皮光谱特征及其盐渍化信息预测研究

盐碱地是我国重要的后备耕地资源,为及时、准确获取土壤盐渍化信息,以宁夏银北地区不同盐结皮土壤为研究对象,运用土壤学和地统计学方法,以土壤野外原位光谱数据和室内盐分指标测定数据为基本信息源,系统分析不同盐结皮光谱特征,确定对结皮层pH值、电导率(EC)和盐分离子含量最敏感的土壤光谱反射率转换形式、波段和光谱盐分指数,进而建立并验证基于敏感盐分指数的盐分指标预测模型。结果表明:研究区白碱结皮光谱反射率在450～1 050 nm波段最高,马尿碱结皮次之,黑油碱结皮最低。通过野外光谱反射率可以将研究区主要盐结皮类型进行分类。反射率平滑后再经过一阶微分、倒数对数一阶微分、连续统去除和连续统去除一阶微分转换后,最大相关系数比只作平滑处理的反射率显著增大。与pH值、EC和CO2-3、Mg2+含量相关性最强的转换方式是连续统去除一阶微分,与SO2-4、Ca2+、K+含量相关性最强的转换方式是倒数对数一阶微分,与HCO-3、Cl-、Na+含量相关性最强的转换方式是一阶微分。整体上连续统去除一阶微分与各盐分指标的相关性最强。整体来看,盐分敏感区域在蓝光450、470、485 nm附近,绿光501、575 nm附近,红光680 nm附近和近红外多个波段。与各盐分指标相关性最强的盐分指数分别为:pH值为盐分指数S1,Cl-、K+含量为盐分指数SI3,SO2-4、Mg2+含量为盐分指数S2,EC和HCO-3、Na+含量为盐分指数S3,CO2-3、Ca2+含量为盐结皮指数SCI。除CO2-3含量外,利用敏感盐分指数可以准确预测土壤结皮层pH值、EC和其他盐分离子含量,其中对Na+含量的拟合度最大。该研究可为银北地区不同盐结皮土壤分类及盐渍化信息的准确预测提供科学依据。

新疆罗布泊环状盐壳的特征与成因

通过实地测量、物质成分分析和卫星像片判读，得出关于罗布泊东湖环状盐壳特征与成因的部分新结论：在东湖耳轮状区域内，地表物质组成以石盐为主，特别是氯化物占优势，碎屑矿物中主要为石英；“大耳朵”形态的形成受原湖心岛和湖岸地形所控制；“大耳朵”形态盐壳形成于20世纪60年代初期的4—5年之内；卫星像片上的“耳轮环线”是盐壳形成过程中的年、季韵律构造线：环状盐壳色调深浅变化取决于卤水层埋深、盐壳含沙量及地表粗糙度的变化。

极端干旱区咸水滴灌林地盐结皮对土壤蒸发的影响

由于长期使用高矿化度咸水滴灌,土壤盐结皮在塔里木沙漠公路防护林带内广泛发育,它会对林带土壤蒸发过程产生重要影响。采用田间取样分析和微型蒸发器(MLS)人工控制试验相结合,分别研究了一个灌溉周期内盐结皮影响下林间裸地和防护林带内的土壤蒸发过程。结果表明,土壤水分蒸发量自表层向下层逐渐减少,且有盐结皮的土壤蒸发量小于无盐结皮土壤;土壤日蒸发量随着含水量的降低而逐渐减小,有盐结皮土壤前期高于对照,而后期低于对照;土壤累积蒸发量随着时间的变化逐渐增大,但增加量逐渐减小,有盐结皮土壤累积蒸发量小于对照;盐结皮对土壤蒸发的抑制效率随着时间的变化而不断降低,但裸地的降低速度高于林地;盐结皮抑制土壤水分蒸发的效果明显。

塔中奥陶系优质储集层特征及断裂控制作用

塔中北坡上奥陶统礁滩体和下奥陶统鹰山组风化壳为两套优质储集层,早期分别受台地边缘高能相带和早奥陶世风化壳的控制,后期受到断裂活动的整体改造。综合研究认为,塔中北坡奥陶系储集层的类型和分布规律均与断裂活动有关。塔中奥陶系两套优质储集层受3期重要断裂运动的控制:早奥陶世末的区域拉张奠定了塔中I号坡折带形成的基础,促进了下奥陶统鹰山组风化壳岩溶储集层的形成及随后上奥陶统礁滩体的沉积;奥陶纪末的大规模挤压运动促使塔中北坡发育盐相关构造(沿中寒武统的膏盐层产生滑脱与盐拱),断裂同时改造礁滩体和风化壳储集层;志留纪末的走滑断裂活动对奥陶系储集层的改造有限,却控制着喜马拉雅期塔中奥陶系气侵的部位。

混合铵盐浸出风化壳淋积型稀土矿中稀土的研究

采用氯化铵和硝酸铵配成的混合铵盐作浸出剂,用柱浸模拟风化壳淋积型稀土矿的浸出过程,考察混合铵盐浸出剂的配比、浓度、液固比、pH和流速等对稀土浸出率的影响。结果表明,这种类型的浸出剂对该稀土矿有较高的稀土浸出率,且能较好地抑制黏土矿物的膨胀,最优工艺条件为:NH4Cl和NH4NO3的质量比8∶2、浸出剂质量浓度10g/L、浸出液pH=4.0、液固比2∶1、流速0.5mL/min,在此条件下稀土浸出率为96.29%,黏土矿物的线膨胀率为2.738%。

复合铵盐浸出风化壳淋积型稀土矿的研究

采用复合铵盐作浸出剂浸出风化壳淋积型稀土矿中的稀土。考察浸出剂的配比、浓度、液固比、流速、pH等因素对稀土浸出率的影响。结果表明,NH4Cl、NH4NO3、(NH4)2SO4质量比为4∶5∶6的复合铵盐浸出剂为最佳组合;液固比越大、流速越慢,浸出率越高;当浸出剂浓度为10g/L、pH=3.5时浸出效果最好。

罗布泊干盐湖表层盐壳含水率季节性变化及吸水特征研究

根据罗布泊遥感影像图,在干盐湖区域选择"黑纹"和"白纹"观测区为典型研究对象,对其表层盐壳含水率、地下水位埋深、气象参量的动态变化进行了1年多的系统观测,结果发现两个观测区的表层盐壳的季节含水率存在一定的差异,其吸附水含水率均大于结晶水含水率,两观测区的吸附水含水率差异在1%左右,但黑纹观测区盐壳结晶水含水率是白纹观测区的3倍以上;黑纹观测区的地下水水位埋深相对稳定,表层盐壳的吸附水变化与地下水水位变化无明显的直接关系。另在高湿度、不同温度的野外环境和室内模拟环境下开展的盐壳吸水能力实验都发现,黑纹观测区盐壳的吸水能力明显强于白纹观测区,甚至达到10倍以上的差异,分析表明这和表层盐壳盐类矿物成分(如硫酸镁)的差异性密切相关。

基于决策树方法的罗布泊“大耳朵”干盐湖区盐壳分类研究

本研究在野外综合考察基础上结合试验分析数据及遥感影像上提供的信息建立了罗布泊"大耳朵"干盐湖区盐壳分类体系,采用决策树方法对ETM+遥感影像进行分类,经过混淆矩阵检验,分类总精度达到86.3%,Kappa系数为0.8420。结果表明,罗布泊"大耳朵"干盐湖区不同盐壳类型在空间上呈环状分布与"耳轮"影像特征大致吻合;影像上同一条带的盐壳表现出相间分布的特点;相似形状的盐壳受地表湿度影响在遥感影像上呈现不同色调。

柴达木盆地三湖坳陷盐壳遮挡型生物气成藏模式

柴达木盆地三湖坳陷广泛发育第四系生物气藏,已建成目前我国最大的生物气生产基地,但近年来,该区的生物气勘探遇到了“地震真假异常识别、微幅度构造落实、岩性圈闭识别刻画”等诸多难题,成为制约其勘探突破的瓶颈。为此,开展了生物气成藏模式研究,在分析精细构造解释成果的基础上,结合室内实验探讨了盐壳的封盖能力、分布范围、形成时间及成因,提出了盐壳遮挡型生物气成藏模式,并结合烃源、储层等条件,预测了盐壳遮挡型生物气藏的勘探前景。研究结果表明:①三湖坳陷第四系为滨浅湖相砂泥岩互层,烃源岩及储集条件优越,纵向上形成多套生储盖组合,生物气具有持续运移、聚集、散失、再聚集的动态成藏特征;②三湖坳陷受喜马拉雅运动的影响,气候变化频繁,形成古湖水盐度分带,南部河流注入端形成淡水区,北部形成卤水区,受蒸发作用的影响,北部潜水不断咸化,在陵间断层东段形成一套分布面积广、厚度稳定、封盖能力强的盐壳;③凹陷中心湖相泥岩生成生物气通过横向及纵向运移至陵间断裂带,遇盐壳有效遮挡聚集成藏。结论认为,三湖坳陷发育优质的烃源岩和储层、强封闭性的有效遮挡层——盐壳,形成良好的生储盖时空配置关系,可形成盐壳遮挡型生物气藏,天然气资源规模大、勘探前景广阔。