鲁中山区中生代构造活动对现今岩溶地下水赋存规律的控制作用

为了掌握中生代构造运动以来鲁中山区岩溶地下水富集规律,以莱芜盆地为例,通过水文地质调查及数据统计分析、钻探施工、地质露头观测、碳酸盐岩可溶组分分析等方法,对中生代构造活动特征、岩浆活动特征,及其对岩溶地下水赋存规律的控制作用进行研究。结果表明：鲁中山区具有典型盆-山结构水文地质特征,盆地南北两侧水文地质特征不尽相同;区域滑脱构造形成的层间虚脱、空隙、碎裂岩带,使得鲁中山区下寒武统朱砂洞组含水层表现为"似层状"特征;热液混合岩溶作用形成的溶蚀裂隙、洞穴可成为岩溶地下水良好的赋存空间;由中生代滑脱构造及热液岩溶活动形成的岩溶介质环境受同期或后期层间溶蚀裂隙及断层沟通,形成立体的岩溶地下水网络。岩溶地下水沿该网络径流、富集,形成鲁中山区特有的岩溶地下水赋存特征。     

Noble gases dissolved in groundwater in a volcanic aquifer: Helium isotopes in the Kumamoto Plain

This study Investigates a tracing method using dissolved noble gases to survey the groundwater flow in a large groundwater basin. The tracing method is based on measuring the concentrations of noble gases and the ratio of helium isotopes in groundwater samples. Since it is very difficult to detect trace amounts of noble gases and helium with high accuracy in a 15-ml groundwater sample, dissolved gases were extracted and purified, then a high-resolution mass spectrometer was used for measurement and comparison with standard samples. We used this method with samples from a confined aquifer formed by the deposition of pyroclastic flow in the Kumamoto Plain on the west side of Mt. Aso in central Kyushu, Japan. The groundwater basin under the plain is divided into four small basins, based on the helium concentrations and isotope ratios, with two major groundwater flows. One flow is buried by the Aso pyroclastic flow along the old Kase River; the other is along the Tsuboi River Valley. These two groundwater flows were identified from the different helium isotope-ratios. The helium component from the deep mantle is mixed into the groundwater under the Kumamoto Plain. Finally, data on the concentrations and ratios of³He to⁴He in groundwater samples were used to determine the location of faults in the volcanic aquifer.     

The Eaux-Bonnes landslide (Western Pyrenees,France): overview of possible triggering factors with emphasis on the role of groundwater

The purpose of this study is to achieve an understanding of the failure mechanisms which caused the Eaux-Bonnes landslide. The geological investigations carried out on the slope of the landslide showed that the sliding mass was cut by numerous faults. The factors controlling the landslide failure were complex, and it is known that neither earthquakes nor heavy precipitation could have triggered the disruption. The groundwater within the solid rock mass has been surveyed, because significant precipitation events during the 2 years preceding the beginning of the paroxysmal phase of the landslide could have led to an increase in pore water pressure along these fractures, thereby triggering the landslide. In order to achieve a full understanding of the failure mechanism, and to identify the origin of the groundwater, a hydrogeochemical survey was carried out over a period of 1 year. The results reveal the existence of high sulphate concentrations in the groundwater originating in springs located at the bottom of the landslide. The sulphate concentrations are correlated with high calcium concentrations, and clearly indicate the presence of gypsum in the vicinity of the lower reaches of the landslide. The presence of gypsum in this area of the Pyrenees suggests that deep groundwater played a role in triggering the landslide.     

Iron concentrations in selected groundwater samples from the lower Friulian Plain,northeast Italy: importance of salinity

High amounts of iron, up to 14 mg/L, were found in groundwater samples from Marano Lagoon in the Friuli Venezia Giulia Plain (northeast Italy). In order to characterize groundwater hydrochemistry in the area, an investigation has been conducted on 35 wells that were monitored since 2006. Leaching tests were performed (under anaerobic conditions with deionized and saline waters) on two core samples in the area to study the iron release from soils to groundwater. Collected data indicated the main role of salinity in metal leaching and highlighted spatial correspondence between high levels of chloride and iron. To understand the mechanism of groundwater salinization, sulphate/chloride ratio has been investigated and a statistical relation between salinity, pH and iron was found. These data do not show any relation between past activities and high iron groundwater contents. High iron concentrations are diffuse in the whole area and therefore comparable to background values. Consequently, the study states that no remediation plan should have been made for iron concentrations in this area.     

Effects of phosphate mining activity on groundwater quality at Wadi Queh, Red Sea, Egypt

The groundwater in Wadi Queh exists in two main hydrogeological units; fractured Precambrian basement and sedimentary rocks with high contribution for groundwater recharge. To study the impacts of phosphate mining activities on the groundwater quality in the area, three groundwater samples that represent all water wells in the area were collected and analysed for major ions and some heavy metals. In addition, three bulk samples representing the phosphatic sediments collected from upstream and downstream of the drainage basin were collected and analysed to understand the source of groundwater contamination. The total concentrations of dissolved solids suggest that the groundwater in the area grades from fresh to brackish water (961–1,580 mg/l), and is characterized by sodium–calcium–sulphate–chloride and sodium–magnesium–sulphate–chloride chemical types. The results showed high concentrations of the heavy metals in well nos. 1 and 2 in downstream parts compared to well no. 3 in upstream part reflecting their influence by the mining activities.     

An occurrence of marsh gas in deccan traps (Basalt) in central India

During the course of groundwater exploration in the upper catchment of Betwa River basin in Madhya Pradesh, Central India, marsh gas at a depth of 171.33 m below ground level (bgl) has been observed bubbling out of the flowing water. The results of gas analysis reveal the presence of 88% methane and 2.08% helium. Water is of sodium chloride type and possesses a high concentration of fluoride and low concentrations of nitrate and sulphate. Tritium analysis of deep groundwater indicates a value of 2.8 T.U., indicating pre-1953 storage with possible traces of modern contamination, which may have been introduced during well construction. It is believed that an occurrence of marsh gas in Deccan Traps has not been reported earlier.     

四川呷村V HMS矿床：从野外观察到成矿模型

呷村矿床是一个与晚三叠世海相钙碱性酸性火山岩系有关的典型块状硫化物（VHMS）矿床。热水流体系统和贱金属成矿作用发育于义敦岛弧碰撞造山带上的弧间裂谷盆地内,并受其内部的一系列局限盆地及SN向基底断裂－裂缝系统控制。含矿岩系为双峰岩石组合,具火山碎屑岩－矿体－喷气岩“三位一体”特征。硫化物矿床具有“块状矿席＋层控网脉状矿带”式三维结构特征。块状矿席发育多旋回的硫化物－硫酸盐韵律型式,揭示热水流体在海底的幕式排泄以及硫化物－硫酸盐在卤水池内的韵律式化学淀积和滑塌堆积过程。层控网脉状矿带产出于流纹质火山岩系,与上覆的块状矿席平行展布,揭示高渗透性碎屑岩层和多条同级别断层或断裂共同约束海底下部热水流体,并诱导其“弥散式”排泄和侧向流动交代。热水流体的传导冷凝过程导致硫化物沉积、热水流体与冷海水的简单混合导致硅质岩或／重晶石淀积,传导冷凝与海水混合的联合作用导致含硫化物重晶石、硅质岩和红碧玉形成。     

冀东马兰峪背斜南翼与西部倾伏端盖层变形特征及其构造意义

燕山中部冀东遵化、迁西、青龙一带以太古宇深变质结晶岩系为核部的东西向构造形迹长期以来被认为是一个复式背斜构造,近年来又有学者提出它是一个中生代变质核杂岩。这2种不同认识涉及到华北克拉通北部中生代区域大地构造演化和稳定克拉通内部大型基底结晶岩系的剥露机制问题。对马兰峪背斜南翼和西部倾伏端盖层岩系开展的详细构造研究表明,变形总体表现为连续的褶皱变形及伴生的逆冲构造;构造样式表现为基底卷入式的厚皮构造与盖层内部软弱岩系控制的薄皮构造共存的特征;变形机制表现为顺层挤压导致的纵弯弯曲和相关的断裂构造;近南北向的缩短率介于16%～27%之间。盖层岩系中未发现变质核杂岩构造模型所预期的系列高角度正断层。基底与盖层不整合面接触带尽管在后期构造变形过程中曾经发生过局部的差异性滑动,但并不是造成大规模构造剥蚀和地壳柱切失的剥离断层。因此,冀东马兰峪背斜不是中生代的变质核杂岩,而是水平挤压背景下基底结晶岩系与盖层共同卷入纵弯褶皱变形的厚皮式褶皱构造。     

Hydrochemical analysis and evaluation of groundwater quality of a Mio-Plio-Quaternary aquifer system in an arid regions: case of El Hancha, Djebeniana and El Amra regions, Tunisia

A hydrogeochemical approach has been carried out in the Mio-Plio-Quaternary aquifer system of northern Sfax to investigate the geochemical evolution, the origin of groundwaters and their circulation patterns. The groundwater samples collected from different wells seem to be dominated by sodium chloride type to sulphate chloride type. Detail analysis of chemical data including the thermodynamic calculations was used to assess that the chemical evolution of groundwater is primarily controlled by water–rock interactions. The values of sodium absorption ratio and electrical conductivity of the groundwater were plotted in the US Salinity Laboratory diagram for irrigation water. Most of the water samples in northern Sfax fall in the fields of C4S1, C4S2 and C4S3 indicating very high salinity and medium to high sodium alkalinity hazard. Thus, groundwater quality is ranging between doubtful to unsuitable for irrigation uses under normal condition, and further action for salinity control is required in remediating such problem. Principal component analysis of geochemical data used in conjunction with bivariate diagrams of major elements indicates that groundwater mineralization is mainly controlled by (1) water–rock interaction processes, (2) anthropogenic process in relation with return flow of NO₃-rich irrigation waters and (3) domestic discharges.     

Evaluation of groundwater dynamics and quality in the Najd aquifers located in the Sultanate of Oman

The Najd, Oman, is located in one of the most arid environments in the world. The groundwater in this region is occurring in four different aquifers A to D of the Hadhramaut Group consisting mainly of different types of limestone and dolomite. The quality of the groundwater is dominated by the major ions sodium, calcium, magnesium, sulphate, and chloride, but the hydrochemical character is varying among the four aquifers. Mineralization within the separate aquifers increases along the groundwater flow direction from south to north-northeast up to high saline sodium-chloride water in aquifer D in the northeast area of the Najd. Environmental isotope analyses of hydrogen and oxygen were conducted to monitor the groundwater dynamics and to evaluate the recharge conditions of groundwater into the Najd aquifers. Results suggest an earlier recharge into these aquifers as well as ongoing recharge takes place in the region down to present day. Mixing of modern and submodern waters was detected by water isotopes in aquifer D in the mountain chain (Jabal) area and along the northern side of the mountain range. In addition, δ²H and δ¹⁸O variations suggest that aquifers A, B, and C are assumed to be connected by faults and fractures, and interaction between the aquifers may occur. Low tritium concentrations support the mixing assumption in the recharge area. The knowledge about the groundwater development is an important factor for the sustainable use of water resources in the Dhofar region.     

A temporary sampling technique for investigating groundwater quality near the ground surface

Improved knowledge of processes determining groundwater quality is an important precondition for the solution of various ecological and water management problems. In areas with highly fluctuating groundwater levels, time-limited access, local pollution sources or temporary interactions between surface water and groundwater, a temporary groundwater sampling technique could be of advantage. Furthermore, depth-specific sampling is of high value for investigating groundwater pollution related to seepage or surface water infiltration. A stainless steel core probe has been developed to obtain groundwater samples and to measure the hydraulic head distribution at various defined depths. The sampling technique is applicable only for non-volatile water constituents. An advantage of the core probe is that it can be driven into soil or sediments using ordinary low cost percussion equipment. The probe enables hydraulic head measurements and water sampling over vertical intervals of 0.3 m. Results from field experiments using the stainless steel core probe were in good correspondence with results from groundwater sampling at nearby observation wells. In the upper layer of the aquifer, the intrinsic spatial change in concentrations of sulphate, chloride and other water constituents is a function of distance between observation points and groundwater surface. Results indicate strong effects of a fluctuating groundwater level on groundwater quality at certain depths.     

大兴安岭北部下侏罗统战备村组的建立及其地质意义

大兴安岭北部战备村地区出露一套火山岩,岩石组合主要为一套浅灰色、灰白色流纹质火山碎屑岩、流纹质火山熔岩、碎屑熔岩夹少量火山沉凝灰岩。在1∶5万区域地质填图的基础上,查明该套地层下部呈角度不整合覆盖于晚三叠世二长花岗岩之上,上部被中—上侏罗统塔木兰沟组平行不整合覆盖,锆石U-Pb同位素年龄为178~192Ma,时代为早侏罗世。根据《中国地层指南》关于新建"组"的要求,指定战备村剖面为层型,新建为战备村组。下侏罗统地层单位的建立,对大兴安岭早中生代火山构造岩浆活动的研究及中生代火山岩地层划分对比具有重要地质意义。     

Hydrologic and geologic factors controlling groundwater geochemistry in the Turonian aquifer (southern Tunisia)

Water in the fissured limestone and dolomite of the Turonian aquifer of Tunisia has been investigated using geochemical (major ions) and isotopic (δ¹⁸O, δ²H, ¹⁴C) data. To carry out a characterization of aquifer behaviour, 48 representative samples were collected at the end of the humid season. The evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium, chloride and sulphate contents as a result of leaching of evaporite rock. In the study, three distinct chemical trends in groundwater were identified. The major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories: (1) calcite precipitation, (2) gypsum and halite dissolution, and (3) ion exchange. The stable isotope composition of water samples indicates large-scale interaction between the Continental Intercalaire and the Turonian aquifer and the presence of a young local component which probably enters the system via faults and/or fractures.     

Hydrogeochemistry of the Saloum (Senegal) superficial coastal aquifer

Seawater has entered and concentrated in the Saloum hydrologic system up to 100 km upstream, contaminating both the surface water and the superficial 'Continental terminal' (CT) groundwater resources, and large proportions of cultivated lands. In the areas affected by saltwater contamination, chloride concentrations as high as 3,195 mg/l have been measured in the groundwater samples collected from wells located in the vicinity of the Saloum River, making the water inadequate for drinking water purposes. This paper presents the results of a study designed to characterise the current extent of the saline groundwater and the mechanism of saline surface water body/fresh groundwater mixing in relation to the groundwater flow trends. It also describes the groundwater chemical and isotopic composition and geochemical processes controlling the chemical patterns. Four major water types occur in the study area, namely Na-rich saline groundwater, Ca-Na-rich saline groundwater, Na-dominant fresh groundwater and Ca-dominant fresh groundwater. A hydrogeochemical zonation of the aquifer, based on the presence of different water families and on the groundwater flow, led to the identification of the main processes controlling the groundwater chemistry. Cation exchange reactions on the kaolinite clay mineral, calcite dissolution in the eastern zone where calcite minerals have been identified, reverse cation exchange reactions in the saline-contaminated band along the Saloum River and, to a lesser extent, a gypsum dissolution are the predominant processes. Results of i¹⁸O and iD analysis in 15 groundwater samples compared with the local meteoric line indicate that the groundwater has been affected by evaporation, and the groundwater is isotopically lighter as the depth of water table increases. In this study, i¹⁸O data were used in conjunction with chloride data to identify the source of high chloride. Results show a departure of the contaminated water samples from the seawater mixing line, which indicates that other processes rather than mixing between modern seawater and native groundwater alone increase the chloride concentrations.     

漳州盆地水热系统氚同位素研究

本文依据26个天然水样品的氚同位素测试数据,分析了漳州盆地地下热水及其它天然水的氚值特征及其形成条件;利用“活塞模型”方法计算了漳州盆地地下水和地下热水的年龄;为弄清全盆地地下水的补给、迳流和排泄的总体格局和揭示地下热水的成因提供了依据。     

Salinity mapping of coastal groundwater aquifers using hydrogeochemical and geophysical methods: a case study from north Kelantan,Malaysia

Integrated hydrogeochemical and geophysical methods were used to study the salinity of groundwater aquifers along the coastal area of north Kelantan. For the hydrogeochemical investigation, analysis of major ion contents of the groundwater was conducted, and other chemical parameters such as pH and total dissolved solids were also determined. For the geophysical study, both geoelectrical resistivity soundings and reflection seismic surveys were conducted to determine the characteristics of the subsurface and groundwater contained within the aquifers. The pH values range from 6.2 to 6.8, indicating that the groundwater in the study area is slightly acidic. Low content of chloride suggests that the groundwater in the first aquifer is fresh, with an average concentration of about 15.8 mg/l and high geoelectrical resistivity (>45 ohm m). On the other hand, the groundwater in the second aquifer is brackish, with chloride concentration ranging from 500 mg/l to 3,600 mg/l and very low geoelectrical resistivity (<45 ohm m) as well as high concentration of total dissolved solids (>1,000 mg/l). The groundwater in the third aquifer is fresh, with chloride concentrations generally ranging from 2 mg/l to 210 mg/l and geoelectrical resistivity of greater than 45 ohm m. Fresh and saltwater interface in the first aquifer is generally located directly in the area of the coast, but, for the second aquifer, both hydrogeochemical and geoelectrical resistivity results indicate that the fresh water and saltwater interface is located as far as 6 km from the beach. The considerable chloride ion content initially suggests that the salinity of the groundwater in the second aquifer is probably caused by the intrusion of seawater. However, continuous monitoring of the chloride content of the second aquifer indicated no significant changes with time, from which it can be inferred that the salinity of the groundwater is not affected by seasonal seawater intrusion. Schoeller diagrams illustrate that sulphate concentrations of the groundwater of the second aquifer are relatively low compared to those of the recent seawater. Therefore, this result suggests that the brackish water in the second aquifer is probably from ancient seawater that was trapped within the sediments for a long period of time, rather than due to direct seawater intrusion.     

内蒙古克什克腾旗双山子银铅锌矿地质特征及成因

双山子区位于乌兰浩特-巴林右旗铜多金属成矿带的南西端,目前共发现有5条银铅锌盲矿体.区内银铅锌矿体主要受早期北东东向断裂构造所控制,铅锌矿（化）体具有集中分布于火山碎屑角砾岩内及其边部的特征,矿床属于岩浆热液型矿床成因.区内呈北东东向以不规则状出现的物探激电异常、中低视电阻率异常与△T磁异常及较高浓度Ag、Cu、Pb、Zn、As等元素的土壤异常分布区,是本区重要的找矿信息和标志.     

大别山北麓上天梯-皇城山一带中生代火山岩成矿系列研究

以往对赋存于大别山北坡中生代火山岩中的上天梯非金属矿带和皇城山银矿带分割开来进行地质评价和研究,且厘定出各自的火山岩地层层序。据近年研究成果,上天梯-皇城山一带的火山碎屑岩为同源二次熔结凝灰岩喷发产物,形成于火山柱体喷发塌落机制,乃是相应喷发的不同产物。因而,由火山岩浆活动所形成的金属矿床与非金属矿床不仅与岩相、构造有密切联系,而且与岩浆热液活动机理亦密切相关。本文便是从火山岩喷发相入手,结合火山矿床特征,把与上天梯-皇城山一带中生代火山岩相有关的已知金属、非金属矿床划分为与母山潜火山侵入活动有关、与皇城山浅成火山热液活动有关、和与杨家湾侵出活动有关的三个成矿系列,并对各成矿系列的典型矿床特征进行了详细论述。     

Investigation of discharge-area groundwaters for recharge source characterization on different scales: the case of Jinan in northern China

Discharge-area groundwater in Jinan, a typical karst region in northern China, was investigated by studying both the hydrological and chemical processes evolving from the recharge in mountainous terrains to the karst-spring outflows in the metropolitan area. Large-scale exploitation of karst groundwater has led to a disturbing trend in the ever-decreasing spring outflow rates and groundwater level. There is insufficient information about the Jinan karst aquifers, which provide the main water sources to meet human demand and to sustain spring outflow. The coupling of hydrological and chemical processes quantifies the flow system through aqueous chemistry characterization of the water sources. This approach is used to study the groundwater flow discharges in different locations and geological settings. The potentiometric data indicated limited vertical connectivity between distinct hydrogeological units and alteration of the recharge regime by the faults and by artificial exploitation. Shallow groundwater primarily belongs to the local flow system, with high nitrate concentration and enriched stable isotopic contents. Thermal groundwater has high concentrations of chloride and total dissolved solids, derived from a regional flow system with the highest recharge altitudes and long residence time. Non-thermal karst water may be attributed to the intermediate flow system, with uniform HCO₃–Ca(Mg) facies and low nitrate concentration. This work highlighted discharge as a fingerprint of groundwater flow conditions and provides a better insight into the hydrogeological system.     

Hydrochemical characteristics of groundwater in the Kingston Basin,Kingston, Jamaica

The Kingston Basin in Jamaica is an important hydrologic basin in terms of both domestic and industrial sector. The Kingston hydrologic basin covers an area of approximately 258 km² of which 111 km² underlain by an alluvium aquifer, 34 km² by a limestone aquifer and the remainder underlain by low permeability rocks with insignificant groundwater resources. Rapid development in recent years has led to an increased demand for water, which is increasingly being fulfilled by groundwater abstraction. A detailed knowledge of the water quality can enhance understanding of the hydrochemical system, promoting sustainable development and effective management of groundwater resources. To achieve this, a hydrochemical investigation was carried out in the Kingston Basin. Results showed that the water is Na–Ca–Cl–HCO₃ and Na–Ca–HCO₃ type with higher concentrations of nitrate, sodium and chloride as the leading causes of contamination in most of the wells. High concentrations of nitrate correlate with wells from areas of high population density and could be attributed to anthropogenic causes, mainly involving improper sewage treatment methodologies or leaking sewer lines. Jamaica, owing to its island nature, has the continuous problem of saline water intrusion, and this is reflected in the higher levels of chloride, sodium and conductivity in the water samples collected from the wells. The wells studied show higher concentrations of chloride ranging from around 10.2 mg/l in wells located approximately (4931.45 m) from the coast to around 234 mg/l in the well located near to the coast. The conductivity values also closely correlate with the chloride levels found in the wells.