海拉尔盆地盐湖及碳酸盐成因

本文根据野外考察和室内分析资料，全面总结了该区盐湖概况、矿物组成、卤水成分及盐元素的物质来源，提出了碱湖的形成和天然碱的成因机理。     

大布苏碱湖的形成演化环境

根据野外现场考察和室内分析研究，首次论述了大布苏碱湖的概况，盐类矿物组合，卤水化学成分和水化学特征，研究了碳酸盐湖的形成条件和演化环境，提出了天然碱，主要是泡碱的形成背景和成碱机理。     

内蒙呼盟地区盐湖资源及其特征

呼伦贝尔盟盐湖众多，主要集中分布于新巴尔虎旗附近、乌尔逊河沿岸和呼伦湖以南三个成盐区．呼盟地区盐湖盐类矿物主要有芒硝、泡碱、石膏和石盐．在矿物组成上，东部和西部有较大差异，东部为芒硝、泡碱和石盐，无石膏沉积，西部则是芒硝、石膏和石盐，无泡碱沉积．盐湖卤水主要由Ｋ＋、Ｎａ＋、Ｃａ_（２＋）、Ｍｇ_（２＋）、Ｃｌ－、ＳＯ_（２－）、ＣＯ_３（２－）和ＨＣＯ_３－组成，并含有一定量的溴、硼、碘等微量元素．呼盟地区盐湖矿物以芒硝为主，天然碱、石膏次之，石盐较少．盐湖矿床以小型为主，埋藏较浅，易于开采，矿层组份简单，易于加工利用．     

腾格里沙漠区盐湖物质成分研究

腾格里沙漠面积广阔 ,区内分布着数十个盐湖 ,盐湖面积大的为十余平方千米 ,小的仅为 0 .0 18km2 。盐湖卤水主要为湖表卤水 ,其矿化度较高 ,大部分盐湖卤水含盐量已达饱和 ,因而进入了自析盐阶段。盐湖卤水化学成分以 Na+ 、K+ 、Cl-、SO4 2 -、HCO3 -、CO3 2 -为主 ,占卤水总含盐量的 99% ,卤水中还有 B2 O3 、L i、I、Br等微量元素。盐湖盐类沉积有碳酸盐类、硫酸盐类和氯化物型盐类、主要盐类矿物为芒硝、钾芒硝、天然碱、泡碱、碳钾钠矾、石盐等。盐湖粘土矿物组合以蒙脱石的普遍存在为特征 ,含有少量的伊利石和水云母。     

海拉尔盆地盐湖中盐矿物初步研究

通过野外科学考察，室内实验研究，本文介绍了该地区盐湖中盐矿物种类及共生组合情况，其中碳钠矾［（Ｎａ６（ＣＯ３）（ＳＯ４）２］又一次在内蒙古天然碱湖中被发现（国内首次发现于昌汗淖和盐海子天然碱湖中）。     

柴达木盆地西部天青石矿区矿物学与元素地球化学特征研究

柴达木盆地天青石资源极为丰富,已发现有大风山、碱山、尖顶山等大型天青石矿床。通过元素分析、元素相关性分析、矿物组合分析等方法与手段,对柴达木盆地天青石矿区矿物特点及元素地球化学特征进行了研究。得到如下结论:大风山矿区以天青石—方解石—镁方解石矿物组合为主,矿物品位均值为59%;碱山矿区以天青石—文石矿物组合为主,矿物品位均值为39.6%;石膏、白云石在各矿区矿物均有分布,且含量较低。石膏与天青石成正相关关系,白云石的存在对天青石成矿来说是不利因素,铁白云石、文石和镁方解石的普遍存在可说明该区矿物成矿温度较高。Sr与S成正相关关系,证明Sr主要以天青石(硫酸锶)形式存在,锶与镁、钙成非线性关系,锶含量高则钙含量低,钙主要赋存在石膏中,而非方解石中。Sr/Ba比值、Sr/Cu比值分析表明该矿区经历过长期干旱的环境,Mg/Ca比值分析表明该区天青石成矿过程中微生物对其成矿作用起到了非常重要的作用。     

河南省罗山县陡坡花岗斑岩型钼矿床地质特征及成因探讨

陡坡钼矿床是一新发现的中型钼矿床,该矿床赋存于早白垩世灵山超单元岩体与围岩的接触带内侧,矿化类型主要为细脉浸染状。矿床中金属矿物主要为黄铜矿、辉钼矿、方铅矿、闪锌矿、黄铁矿、磁铁矿、赤铁矿,次为磁黄铁矿、斑铜矿等。灵山超单元花岗岩岩石类型属高硅富碱钙碱性(偏碱性)系列,SiO2含量72～77%,K2O+Na2O总量大于7.9%,K2O/Na2O大于1。矿床的围岩蚀变叠加组合主要为硅化——钾长石化——黄铁矿化组合、硅化——绿泥石化——黄铁矿化组合。该矿床属中高温热液斑岩型钼矿床,结合岩浆岩特征,成矿作用于与岩体关系密切,并可能受幔源岩浆混合作用的影响。     

柴达木盆地西部天青石矿区矿物学与元素地球化学特征研究

柴达木盆地天青石资源量极为丰富,已发现有大风山、碱山、尖顶山等大型天青石矿床。本文通过元素分析、元素相关性分析、矿物组合分析等方法与手段,对柴达木盆地天青石矿区矿物特点及元素地球化学特征进行了研究。得到结论如下：大风山矿区以天青石-方解石-镁方解石矿物组合为主,矿物品位均值为59%,碱山矿区以天青石-文石矿物组合为主,矿物品位均值为39.6%,石膏、白云石在各矿区矿物均有分布,且含量较低。石膏与天青石成正相关关系,白云石的存在对天青石成矿来说是不利因素,铁白云石、文石和镁方解石的普遍存在可说明该区矿物成矿温度较高。Sr与S成正相关关系,证明Sr主要以天青石（硫酸锶）形式存在,锶与镁、钙成非线性关系,锶含量高则钙含量低,钙主要赋存在石膏中,而非方解石中。Sr/Ba比值、Sr/Cu比值分析表明该矿区经历过长期干旱的环境,Mg /Ca比值分析表明该区天青石成矿过程中微生物对其成矿作用起到了非常重要的作用。     

贵州从江污牙钨矿地质特征及矿床成因浅析

本文论述含钨矿体的地质特征、矿床成因、矿物组合及指示矿物产出状态,总结了含钨矿的岩石矿化富集规律。     

柴达木盆地碱山深钻的硼同位素地球化学特征

沉积物硼(B)同位素组成可以反映其地质成因及经历的地质过程,因此在许多领域的研究中都有较为广泛的应用。通过对位于柴达木盆地碱山背斜顶部的SG-1b钻孔沉积物(7.3～1.6 Ma)水溶组分的B同位素研究,发现钻孔沉积物B含量在38.55～172.3μg/g之间,平均含量为87.6μg/g;δ~(11)B值的变化范围在3.61‰～16.26‰之间,平均值为10.65‰,B含量与δ~(11)B值具有一定的正相关关系。进一步分析表明,受到碱山背斜构造隆升以及晚新生代以来气候干旱化的影响,柴西古湖逐渐咸化萎缩,沉积环境以及碳酸盐含量、粘土矿物含量及其矿物组合等也在发生变化,B含量和δ~(11)B值自钻孔底部向上的逐步增加以及后期的急剧增加,与水溶离子含量以及矿物和粒度等的变化一致,这说明柴达木盆地晚中新世以来湖泊沉积物的B含量和δ~(11)B值可以很好地反映研究区气候和湖水的演化过程,共同指示了研究区自7.3 Ma以来气候的持续干旱化和湖水盐度的逐步增加,以及3.3Ma以来干旱化和湖水浓缩过程的加剧。     

表生作用条件下硼酸盐矿床的形成问题

沉积硼酸盐矿床在自然界分布相当广泛 ,主要见于南、北美和我国青藏高原的盐湖中、美国和土耳其某些第三纪沉积盆地中 ,以及欧洲某些古代海相盐矿床中。为了研究其形成问题 ,从 70年代开始 ,我们利用青藏高原盐湖卤水和泉水进行了许多模拟实验工作。从 40～ 5 0个样品中获得了大量钠硼酸盐、纳钙硼酸盐、镁硼酸盐和含氯化镁的镁硼酸盐复盐。这对于阐明表生作用条件下硼酸盐矿床的形成是非常重要的。实验和研究结果证明 :1)与地热和火山活动有关的水体是硼酸盐矿床形成的物质来源 ;2 )硼酸盐矿床可形成于Ｎａ、Ｋ、Ｍｇ//Ｃｌ、ＳＯ4 ·Ｈ2 Ｏ和Ｎａ、Ｋ//Ｃｌ、ＳＯ4 、ＨＣＯ3、ＣＯ3·Ｈ2 Ｏ不同水盐平衡体系的不同富硼水体中 (盐度 :1 2 7～ 41 4% ,Ｂ2 Ｏ3含量 :0 0 5～ 2 97% ) ;3 )硼酸盐矿床通常形成于稳定平衡条件下 ,而不是介稳平衡条件下 (蒸发过程中 ) ;4)低温条件有利于硼酸盐自水体中析出 ;5 )硼酸盐矿床的形成与水体的化学类型、ｐＨ值和硼含量有密切关系 ;6)我们实验中所获的硼酸盐反映了天然硼酸盐矿床形成的原始条件。不仅揭示了大陆盐湖硼酸盐矿床的形成 ,也揭示了古代海相盐矿床硼酸盐的成因。     

Diatoms from the Shelton Mastodon Site

A fairly diverse and abundant diatom flora is associated with remains of Mammut americanum at the Shelton Mastodon Site in northern Oakland County, Michigan. The most abundant elements of this flora are species commonly recorded from late-glacial deposits in North America and Europe. The nearest modern analogues of this flora are assemblages deposited in small lakes in the high arctic and present day periglacial environments. Based on the diatoms present, the most probable depositional habitat was the margin of a moderately alkaline (pH>7.0) and moderately productive pond which existed under arctic conditions.     

The sensitivity of East African rift lakes to climate fluctuations

Sequences of paleo-shorelines and the deposits of rift lakes are used to reconstruct past climate changes in East Africa. These recorders of hydrological changes in the Rift Valley indicate extreme lake-level variations on the order of tens to hundreds of meters during the last 20,000 years. Lake-balance and climate modeling results, on the other hand, suggest relatively moderate changes in the precipitation-evaporation balance during that time interval. What could cause such a disparity? We investigated the physical characteristics and hydrology of lake basins to resolve this difference. Nine closed-basin lakes, Ziway-Shalla, Awassa, Turkana, Suguta, Baringo-Bogoria, Nakuru-Elmenteita, Naivasha, Magadi-Natron, Manyara, and open-basin Lake Victoria in the eastern branch of the East African Rift System (EARS) were used for this study. We created a classification scheme of lake response to climate based on empirical measures of topography (hypsometric integral) and climate (aridity index). With reference to early Holocene lake levels, we found that lakes in the crest of the Ethiopian and Kenyan domes were most sensitive to recording regional climatic shifts. Their hypsometric values fall between 0.23–0.29, in a graben-shaped basin, and their aridity index is above unity (humid). Of the ten lakes, three lakes in the EARS are sensitive lakes: Naivasha (HI = 0.23, AI = 1.20) in the Kenya Rift, Awassa (HI = 0.23, AI = 1.03) and Ziway-Shalla (HI = 0.23, AI = 1.33) in the Main Ethiopian Rift (Main Ethiopian Rift). Two lakes have the graben shape, but lower aridity indices, and thus Lakes Suguta (HI = 0.29, AI = 0.43) and Nakuru-Elmenteita (HI = 0.30, AI = 0.85) are most sensitive to local climate changes. Though relatively shallow and slightly alkaline today, they fluctuated by four to ten times the modern water depth during the last 20,000 years. Five of the study lakes are pan-shaped and experienced lower magnitudes of lake level change during the same time period. Understanding the sensitivity of these lakes is critical in establishing the timing or synchronicity of regional-scale events or trends and predicting future hydrological variations in the wake of global climate changes.     

基于点要轴理论的环渤海地区旅游空间结构研究

环渤海地区共157座城市,约占全国城市的四分之一,陆地面积112万平方公里,约占全国国土面积13.31%,总人口2.6亿,占全国总人口22.2%。全区交通便利,人均收入水平高,旅游资源丰富,类型多样,是集山、泉、林、岛、江、河、湖、海为一体的自然景观和古代文明与现代艺术相结合的人文景观构成的旅游大区。点轴系统理论对旅游区域开发研究具有十分重要的指导意义,以环渤海地区为研究对象,使用旅游区位熵和城市流,从理论上分析并归纳了环渤海地区概况,并据此确定了环渤海地区四个等级的重要发展节点,二个等级的旅游发展轴线以及三大旅游区,构建了环渤海地区“点—线—面”的区域旅游空间结构体系,合理的空间结构可以促进全区发展,带动环渤海地区各市旅游业繁荣。     

Structure of river valleys on the Lena-Katanga Plateau

Exploration data for different-order river crossings on the Lena-Katanga Plateau (northern Irkutsk oblast) were used to identify, according to the occurrence conditions of bedrocks, weathering crusts and alluvial deposits, three types of structure of river valley bottoms. In the geological evolution history of loose deposits in the valleys, six stages were determined, which occurred mostly during the Holocene. Karst lakes evolved into existence along tectonic fault lines in the river valleys at that time period which complicated their structure.     

Hydrochemical regime of saline lakes in the Southeastern Transbaikalia

Results from hydrochemical investigations into macrocomponent composition of some of the lakes in the Southeastern Transbaikalia are presented. The region's saline lakes, as a rule, are soda-chloride or chloride-soda lakes according to their chemical composition. The lakes hydrochemistry is determined by a combination of evaporative concentration of salt composition, intra-water body hydrobiological processes, especially by the production of organic matter and reduction of sulfates as well as by hydrogenic sedimentation.     

Late Holocene history of the floodplain lakes of the Cauca River, Colombia

We conducted a paleolimnological investigation of late Holocene deposits on a distal, constrained floodplain of the Cauca River, northern Colombia, i.e. the La Caimana sedimentary succession. The record starts sometime between 4,500 and 4,000 cal yr BP, when the first high-energy fluvial events inundated an ancient soil surface. From that time until about 3,260 cal yr BP, a stable and probably seasonal flooding regime was established on the floodplain. From ~3,260 to ~2,800 cal yr BP, ephemeral and shallow swamps developed on the floodplain. Their formation and duration depended on their connection with the Cauca River. From ~2,800 to ~2,400 cal yr BP, fluvial influence became more dominant, establishing a semi-permanent connection between the river and the floodplain. From ~2,400 to 1,400 cal yr BP, episodic formation of ephemeral swamps occurred. During this stage, floodplain lakes displayed high salinity and nutrient concentrations, and possibly alkaline conditions as a consequence of reduced water volume when the connection with the river was reduced or lost completely. A change in the hydrological regime occurred from ~1,400 to ~850 cal yr BP, when high-energy fluvial events were punctuated by periods of reduced flooding that enabled soil formation. Generally, connection with the Cauca River resulted in lake waters with low salinity and nutrient concentration, whereas loss of connection with the river led to lakes with greater salinity and nutrient content. Paleocurrent analyses indicate that flows came predominantly from the Cauca River, suggesting the lakes were formed by the impoundment of La Caimana Creek. The sedimentary succession of La Caimana offers a unique, high-resolution record of the evolution and dynamics of an ancient floodplain of the Cauca River and its aquatic ecosystems.     

Chironomidae (Diptera) remains in surficial lake sediments from the Canadian Cordillera: analysis of the fauna across an altitudinal gradient

The altitudinal distribution of Chironomidae (Diptera) in the southern Canadian Cordillera was analyzed by means of head capsules preserved in surficial sediments of 30 lakes. Taxa characteristic of late-glacial deposits of southern, coastal British Columbia are extant at high elevations, particularly in the Rocky Mountains, and in large, deep, low-elevation lakes. Many chironomid taxa common at low elevations in the southern Canadian Cordillera were not found in alpine and upper subalpine lakes. These faunal differences are probably climatically related. The differences in fauna between high and low-elevation lakes parallel differences between arctic and temperate lakes.