共查询到20条相似文献，搜索用时 31 毫秒
1.
Using saline tracers to evaluate preferential recharge in fractured rocks,Floyd County,Virginia, USA
Potassium chloride (KCl) and potassium bromide (KBr) tracers were used to explore the role of geologic structure on groundwater recharge and flow at the Fractured Rock Research Site in Floyd County, Virginia, USA. Tracer migration was monitored through soil, saprolite, and fractured crystalline bedrock for a period of 3 months with chemical, physical, and geophysical techniques. The tracers were applied at specific locations on the ground surface to directly test flow pathways in a shallow saprolite and deep fractured-rock aquifer. Tracer monitoring was accomplished with differential electrical resistivity, chemical sampling, and physical monitoring of water levels and spring discharge. KCl, applied at a concentration of 10,000 mg/L, traveled 160 m downgradient through the thrust fault aquifer to a spring outlet in 24 days. KBr, applied at a concentration of 5,000 mg/L, traveled 90 m downgradient through the saprolite aquifer in 19 days. Tracer breakthrough curves indicate diffuse flow through the saprolite aquifer and fracture flow through the crystalline thrust fault aquifer. Monitoring saline tracer migration through soil, saprolite, and fractured rock provided data on groundwater recharge that would not have been available using other traditional hydrologic methods. Travel times and flowpaths observed during this study support preferential groundwater recharge controlled by geologic structure. 相似文献
2.
Christopher S. Heppner John R. Nimmo Gordon J. Folmar William J. Gburek Dennis W. Risser 《Hydrogeology Journal》2007,15(5):915-927
Lysimeter-percolate and well-hydrograph analyses were combined to evaluate recharge for the Masser Recharge Site (central Pennsylvania, USA). In humid regions, aquifer recharge through an unconfined low-porosity fractured-rock aquifer can cause large magnitude water-table fluctuations over short time scales. The unsaturated hydraulic characteristics of the subsurface porous media control the magnitude and timing of these fluctuations. Data from multiple sets of lysimeters at the site show a highly seasonal pattern of percolate and exhibit variability due to both installation factors and hydraulic property heterogeneity. Individual event analysis of well hydrograph data reveals the primary influences on water-table response, namely rainfall depth, rainfall intensity, and initial water-table depth. Spatial and seasonal variability in well response is also evident. A new approach for calculating recharge from continuous water-table elevation records using a master recession curve (MRC) is demonstrated. The recharge estimated by the MRC approach when assuming a constant specific yield is seasonal to a lesser degree than the recharge estimate resulting from the lysimeter analysis. Partial reconciliation of the two recharge estimates is achieved by considering a conceptual model of flow processes in the highly-heterogeneous underlying fractured porous medium. 相似文献
3.
In order to improve understanding of the fate of septic tank or individual sewage disposal system (ISDS) effluent in regolith overlying fractured-rock aquifers, effluent from an ISDS in such a setting was tracked via geophysical, hydrological, and geochemical methods. Under typical precipitation conditions, the effluent entered the fractured bedrock within 5 m of the boundary of the constructed infiltration area. During a period of unusually high spring recharge, the plume migrated between 50 and 100 m within the regolith before infiltrating the fractured bedrock. The chemical signature of the effluent is similar to that required to account for the decline in water quality, suggesting a causative relationship (as estimated from mass-balance models of the surface-water chemistry near the mouth of the basin). The elevated salt content of the effluent during periods of high natural recharge to the infiltration area correlates with elevated salt concentrations in surface and groundwater at the basin scale, suggesting that some of the effluent salt load may be stored in the unsaturated zone during dry periods and flushed during periods of elevated natural recharge. 相似文献
4.
淮南板集煤矿F512断层导水性分析及地面注浆加固 总被引：1，自引：0，他引：1
板集煤矿F512断层落差70m,存在着导通上覆新生界松散层水与下伏太原组岩溶水的威胁,同时,断层带的破碎岩体也将对巷道掘进和支护带来困难。该矿先后施工了3个水文地质钻孔进行抽水和压水试验,根据岩心鉴定成果和岩石RQD值,认为断层带的岩心较为破碎;依据抽水过程中的流量变化、水位降深值和水位恢复值等指标及压水试验中透水率分析,发现该断层的导水性较差,具有弱渗透性。参考相邻矿区的经验,决定对断层破碎岩体采用地面注浆方法进行加固。整个工种注入水泥浆1 600m3,破碎岩体得到了有效加固,巷道掘进顺利通过了F512断层。 相似文献
5.
通过野外构造变形解析得出,江西上饶船坑—铜山一带铜矿床及其相关的侵入岩体主要受中生代推覆构造控制。推覆构造面总体倾向SE,表现为波状起伏。推覆构造外来岩系为中石炭统至上三叠统碳酸盐岩及页岩、泥质粉砂岩,原地岩系为下侏罗统地层。外来岩系变形大多呈同斜褶皱,并伴生不同规模逆冲断层及顺层滑脱构造,局部存在平卧及箱状褶皱; 原地岩系变形亦较强烈。推覆构造表现为自SE向NW的运动。成矿岩体大多呈相互平行的薄层状,岩席侵位于上述推覆体外来岩系顺层滑脱带中。岩石地球化学及同位素年代学分析表明成矿岩体具挤压机制下岩浆弧特征,形成于170 Ma。结合推覆构造卷入的地层、研究区外围德兴一带同类型侵入岩与中生代推覆构造关系的讨论,认为上饶船坑—铜山一带与铜多金属矿相关的中生代石英二长斑岩为受同时代推覆构造变形控制的同构造岩浆岩,可能与中生代古太平洋板块向中国东南大陆俯冲导致岩石圈增厚发生大规模推覆构造,并诱发下地壳重熔岩浆侵位至浅表顺层滑脱空间有关。 相似文献
6.
U. Ring 《International Journal of Earth Sciences》1995,84(4):843-859
Mylonitic structures related to two orogenic events are described from the upper and lower contacts of the Combin zone and the immediately overlying upper Austroalpine Dent Blanche nappe/Mont Mary klippe and the directly underlying lower Austroalpine Etirol-Levaz slice. The first event, Late Eocene in age, commenced during blueschist facies P-T conditions, but pre-dated the peak of subsequent greenschist facies overprint. The second event, Early Oligocene in age, took place during retrograde greenschist facies conditions. Most sense of shear indicators associated with the retrograde mylonites indicate top SE shearing, but subordinate top NW displacing shear sense indicators have also been mapped. Mylonitic top SE shearing appears to be restricted to the Combin zone and its upper and lower contacts. Within the Dent Blanche nappe and Mont Mary klippe and at the base of the Etirol-Levaz slice, structures were observed which developed during blueschist/greenschist facies conditions and are, in conjunction with the P-T-t history of these rocks, inferred to be older. Associated kinematic data indicate a top NW shear sense. Comparable blueschist/greenschist facies shear sense indicators have not been observed in the Combin zone. Nonetheless, the foliation in the Combin zone shows a progressive evolution from blueschist facies to greenschist facies to retrograde greenschist facies conditions. This indicates that the Combin zone and the immediately over- and underlying Austroalpine units shared a common tectono-metamorphic evolution since the Late Eocene. Finite strain data reveal oblate strain fabrics, which are thought to result from a true flattening strain geometry. Flow path modelling reveals a general non-coaxial deformation régime and corroborates significant departures from a simple shear deformation. In the study area, mylonitic top SE shearing in the Combin zone is attributed to Early Oligocene backfolding and backthrusting of the Mischabel phase. Temperature-time curves suggest slight reheating in the Monte Rosa nappe underneath and cooling in the Dent Blanche nappe above the Combin zone, hence confirming a thrust interpretation for this event. The top NW displacing structures are thought to result from Late Eocene emplacement of the Dent Blanche nappe and the Combin zone onto the Middle Pennine Barrhorn series along the Combin fault. As related structures initiated during mildly blueschist facies conditions in the Dent Blanche nappe and the underlying Combin zone and both were emplaced together onto the greenschist facial Barrhorn series, it is concluded that the structures developed as the nappes moved upward relative to the earth's surface. Thus the Combin fault is regarded as a thrust. The geometry of this structure indicates that the Combin fault is an out of sequence thrust that locally cut down section. Hence, top NW out of sequence thrusting caused local thinning of the metamorphic/structural section in association with horizontal shortening. Out of sequence thrusts cutting down section, and back-thrusts, offer the possibility of explaining the pronounced break in the grade of metamorphism across the Combin fault, i.e. the contact between the eclogite facial Zermatt-Saas zone and the overlying lower grade Combin zone, by contractional deformation. 相似文献
7.
Ronit Nativ 《Environmental Geology》1992,19(1):21-32
The High Plains aquifer in the Southern High Plains (Texas and New Mexico), consisting of Tertiary, Cretaceous, and Triassic formations, has traditionally been considered to be recharged by its uppermost water-bearing unit, the Tertiary Ogallala aquifer. This article provides hydrologic, chemical, and isotopic evidence that in the Southern High Plains: (1) Cretaceous rocks actually contain independent recharge sources; (2) Triassic rocks cannot currently be recharged by the Ogallala aquifer in significant quantities; and (3) in places, both Cretaceous and Triassic aquifers recharge the overlying Ogallala aquifer. On the basis of chemical and isotopic data, playa lakes seem to act as the predominant recharge source of the Ogallala aquifer, suggesting recharge rates greater than 30 mm/yr, as opposed to the much lower rates reported by others. The Cretaceous aquifers are being recharged by cross-formational flow from the Ogallala aquifer but also from overlying Quaternary sands and the underlying Triassic aquifer in eastern New Mexico. Current recharge into the Triassic aquifer may be insignificant. 相似文献
8.
Artificial recharge of groundwater: hydrogeology and engineering 总被引：25，自引：4，他引：25
Herman Bouwer 《Hydrogeology Journal》2002,10(1):121-142
Artificial recharge of groundwater is achieved by putting surface water in basins, furrows, ditches, or other facilities
where it infiltrates into the soil and moves downward to recharge aquifers. Artificial recharge is increasingly used for short-
or long-term underground storage, where it has several advantages over surface storage, and in water reuse. Artificial recharge
requires permeable surface soils. Where these are not available, trenches or shafts in the unsaturated zone can be used, or
water can be directly injected into aquifers through wells. To design a system for artificial recharge of groundwater, infiltration
rates of the soil must be determined and the unsaturated zone between land surface and the aquifer must be checked for adequate
permeability and absence of polluted areas. The aquifer should be sufficiently transmissive to avoid excessive buildup of
groundwater mounds. Knowledge of these conditions requires field investigations and, if no fatal flaws are detected, test
basins to predict system performance. Water-quality issues must be evaluated, especially with respect to formation of clogging
layers on basin bottoms or other infiltration surfaces, and to geochemical reactions in the aquifer. Clogging layers are managed
by desilting or other pretreatment of the water, and by remedial techniques in the infiltration system, such as drying, scraping,
disking, ripping, or other tillage. Recharge wells should be pumped periodically to backwash clogging layers. Electronic supplementary
material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s10040-001-0182-4.
Electronic Publication 相似文献
9.
In a uniform granite gneiss study area in central Zimbabwe, lineaments oriented parallel to the maximum regional compressive stress orientation exhibit the thickest regolith development, while lineaments oriented perpendicular to the maximum compressive stress show the shallowest development of weathered regolith. The principal fracture set orientations were mapped using aerial imagery. The regional stress field, estimated from global stress maps, was used to determine the stresses acting on each principal lineament orientation. Multi-electrode resistivity profiling was carried out across fractures with different orientations to determine their subsurface regolith conditions. The results indicate that the 360 and 060° lineaments, which are sub-parallel to the principal compressive stress orientation (σ1) exhibit maximum development of the regolith, while 130° lineaments perpendicular to σ1 do not exhibit significant regolith development. Since regolith thickness has been positively correlated with groundwater resources, it is suggested that fractures with orientations sub-parallel to the principal compressive stress direction constitute favourable groundwater targets. Knowledge of the regional stress field and fracture set orientations can be used as an effective low cost tool for locating potentially higher yielding boreholes in crystalline rock terrains. 相似文献
10.
辽宁丹东五龙金矿矿化类型及其构造控制机理 总被引：7，自引：1，他引：7
位于辽宁丹东地区的五龙金矿受ＮＥ向剪切系统控制．在剪切带发展演化过程中，于不同阶段形成不同类型的金矿化。在早期韧性剪切带上升剥蚀阶段出现的ＮＥ向脆－韧性线状剪切带，控制同剪切带型金矿；叠加在韧性剪切带之上的ＮＮＥ向一级断裂控制破碎带蚀变岩型金矿的形成和分布；沿ＳＮ向和ＮＷ向的二级断裂构造控制含金石英脉型金矿。 相似文献
11.
神府矿区活鸡兔矿井烧变岩水文地质特征 总被引：5，自引：1，他引：4
烧变岩是活鸡兔矿井的顶板充水含水层,直接威胁着矿井的生产安全。烧变岩分布广泛,裂隙发育程度在垂向上规律明显:下剧—中强—上弱。其富水性除受构造、地形和地貌的控制外,还决定于是否接受其他含水层的补给。烧变岩水水质良好,符合国家饮用水标准,供排结合是矿井水综合利用的有效方法。 相似文献
12.
13.
塔里木盆地西南缘山前带逆冲推覆构造特征 总被引：14，自引：0，他引：14
塔里木盆地西南缘山前带是西昆仑逆冲推覆构造在前陆形成的冲断带,主要由断层相关褶皱、双重构造、叠瓦状构造、三角带等构造组成。通过地表构造剖面、地震与非震资料的综合解释与研究,结合平衡剖面的正演方法,对该冲断带进行了几何学、运动学与动力学研究,对冲断带断层的扩展方式以及冲断时代进行了讨论。研究认为塔西南逆冲推覆构造具有"南北分带、东西分段以及垂向结构变异"的特点。自南向北分为逆冲推覆的根带、中带、锋带和反冲断裂带,由西向东可以划分为帕米尔弧形构造段、齐姆根弧形构造段、甫沙-克里阳三角带构造段与和田南逆冲推覆体构造段。冲断带在垂向结构上由三套区域性滑脱层划分为浅构造层次的外来系统断坡背斜、中构造层次的准原地系统双重构造、三角带构造以及深构造层次的原地系统弱变形带三层结构。冲断席内断层的扩展方式为前展式,而不同冲断席间则为后展式模式。冲断带自中新世中期开始形成,中新世末发生位移推覆,上新世—早更新世定型,中更新世—全新世隆升均衡调整。 相似文献
14.
郯庐断裂带北段构造特征及构造演化序列 总被引：10，自引：3，他引：7
根据大量野外地质调查和盆地地震资料分析,认为郯庐断裂北段在中-新生代发生多期不同性质的活动,形成各具特色的构造变形现象。密山县知一镇敦密断裂韧性剪切带具有左旋走滑特征,其中黑云母~(40)Ar/~(36)Ar-~(39)Ar/~(36)Ar等时线年龄为161±3Ma,是郯庐断裂带被利用发生第二期左旋走滑运动并向北扩展到中国东北-俄罗斯远东地区的产物。四平市叶赫乡佳伊断裂带中负花状断裂形成于早白垩世早中期,是郯庐断裂北段在早白垩世遭受左旋走滑-拉张作用的典型代表。四平市石岭镇佳伊断裂大型走滑-逆冲断褶带、桦甸县敦密断裂"逆地堑"、沈阳-哈尔滨逆冲断裂形成于晚白垩世嫩江运动-晚白垩世末期,这一时期脆性右旋走滑-逆冲事件规模大,影响范围广,导致整个郯庐断裂北段遭受到强烈改造。佳伊断裂带和敦密断裂带中古近纪盆地在横剖面上呈不对称地堑,并且不对称地堑沿断裂带走向发生断、超方向左右变位,是郯庐断裂带北段在古近纪时受右旋走滑、伸展双重机制控制的产物。根据郯庐断裂带北段中-新生代不同地质时期变形特征,建立了郯庐断裂北段构造演化序列。即郯庐断裂北段构造演化分为左旋韧性剪切(J_2末期)、左旋张扭(K_1早中期)、右旋压扭(K_2晚期-末期)、右旋走滑断陷(E)和构造反转(E_3末期)五个阶段。其演化历史主要受控于环太平洋构造域的构造作用。 相似文献
15.
The application of variations in the earth's gravity in groundwater exploration on a regional scale, especially in sedimentary
basins, metamorphic terrains, valley fills, and for buried alluvial channels, is well established. However, its use in hard
crystalline rocks is little known. In granite, for example, the upper weathered layer is a potential primary aquifer, and
the underlying fractured rock can form a secondary aquifer. Fracturing and weathering increases the porosity of a rock, thereby
reducing the bulk density. Changes in gravity anomalies of 0.1–0.7 mGal for granites, due to weathering or variations in lithology,
can be detected.
To test the use of gravity as a groundwater exploration tool for crystalline rocks, a gravity survey of the peninsular shield
granites underlying Osmania University Campus, Hyderabad, India, was undertaken. At the site, gravity anomalies reflect variations
in the lithology and in the thickness of weathered zones. These anomalies also define the position of intrusives and lineaments.
Areas of more deeply weathered granite that contain wells of higher groundwater yield are represented by negative gravity
values. In the weathered zone, well yield has an inverse relation to the magnitudes of residual gravity. The study confirms
the feasibility of gravity as a tool for groundwater exploration in crystalline rocks.
Electronic Publication 相似文献
16.
综合利用马坑矿区积累的水位、水温资料,结合前期对矿区水文地质条件的认识,查明了矿区岩溶水在疏干条件下的补给的变化特征。矿区岩溶含水层以石炭系船山组至二叠系栖霞组灰岩为主,大气降水为其主要补给来源。矿区开采过程中由于矿山采石场开采灰岩造成的溶洞出露地表、采空塌陷裂隙、第四系扰动及沟谷堵塞等使大气降水入渗补给量增大;断层破碎带使分布于灰岩含水层上部的二叠系文笔山组泥质砂岩地层具有了良好的含水性及导水性,致使其上部加福组砂岩裂隙水通过小娘坑断层及F3断层等破碎带补给岩溶水;溪马河河水沿河床与F1断层交汇段渗漏补给岩溶水;深部花岗岩低温热水也沿F1及F10断层破碎带进入矿坑。 相似文献
17.
甘肃小西弓金矿地质特征及成因探讨 总被引：1，自引：0，他引：1
根据小西弓金矿矿体产出特点与规律，认为金矿化受韧性剪切带，老地层，后期脆性断裂等多重因素控制，前长城系西尖山群第四岩组的二云片岩，绢云石英片岩是成矿的主要物质来源和直接的赋矿围岩，华力西期的钾长花岗岩和二长花岗岩是成矿的热动力来源，区域性杨圈沟-西尖山-华窑山大断裂和小西弓-乌龙泉韧性剪切带具有切割深，活动时间长的特点，是成矿的导矿构造，发育于小西弓-乌龙泉韧性剪切带之上的3条次级韧性剪切带和叠加其上的脆性断裂提供了流体运移的通道和容矿空间，矿床属与韧性剪切带有关的中低温热液多因复成蚀变岩型金矿。 相似文献
18.
Recovery scenarios for deep over-exploited aquifers with limited recharge: methodology and application to an aquifer in Belgium 总被引：2，自引：0，他引：2
Recharge of deep-seated aquifers must be provided through leakage from overlying geological formations and can be very limited.
Although hydraulic characteristics of these aquifers may be favorable for extensive exploitation, the renewability of the
groundwater resource may be very restricted and only significant on long time scales. Over-exploitation of such aquifers leads
to steadily declining piezometric levels and water balancing and steady state conditions are not to be expected on the short
term. Recovery of such systems is very difficult, also because of the socio-economic dependencies of the water resource and
the long time it requires to replenish the system. Management plans for restoration should be based on the transient hydrodynamical
behaviour. A recovery plan should be developed based on results of a groundwater flow model. In a first step must be simulated
how long it will take for the aquifer system to fully recover by natural recharge. As this will most often be a very long
time it can be cancelled out as a realistic scenario. An alternative objective is to be formulated which could be achieved
in the near future on a time scale of years or decades. Using model simulations, reduction schemes of exploitation rates shall
be quantified that will allow to reach these defined goals, such as raising piezometric levels above the top of the aquifer
itself or above the top of the overlying geological unit. The methodology is illustrated with an example of a deep hard rock
aquifer in Belgium where piezometric levels have dropped below the top. The objective here was to raise the levels again above
the top within the next 50 years. However, this is not accomplished by balancing aquifer recharge and discharge, but is reached
by a lateral redistribution of the water over the aquifer extent. A full recovery of this aquifer would require at least a
century with only a very limited amount of exploitation. 相似文献
19.
用地面露头、地震和CEMP(连续电磁剖面法)勘探资料揭示的库车坳陷-南天山盆山过渡带构造变形特征难以用经典的“A型俯冲”冲断褶皱楔变形模型来解释,因而文中提出一种“分层变形、垂向叠置”的“非俯冲”收缩构造解释模型。所谓分层变形是指受古近系膏盐岩层和侏罗系含煤地层等软弱岩层分隔,不同深度的岩层发育不同的收缩变形样式;所谓垂向叠置是指不同层次的强变形带在垂向上叠置,不存在区域性大位移的拆离断层。位于盐岩层之上的新生界以滑脱褶皱变形为主,而盐下层的中生界沉积层及盆地基底则以收缩断裂变形为主。浅部的滑脱褶皱表现出紧闭背斜和宽缓向斜组合,背斜具有不对称形态,其核部在古近系盐岩层或侏罗系含煤地层中滑脱,可在陡翼发育破冲断层或缓翼发育顺层滑脱逆冲断层。深层断裂变形以向山脉倾斜的高角度基底卷入逆冲断层为主干断层,断层上盘形成冲断隆起,次级断层相对较少,下盘则发育一系列同向倾斜的次级逆冲断层构成楔状叠瓦冲断构造。深层断层向上延伸在古近系盐岩层中尖灭,部分次级断层向下延伸并在侏罗系含煤地层中或盆地基底面滑脱,但是主干逆冲断层高角度切入基底,向上则对应于浅层背斜的核部。基底卷入的高角度主干逆冲断层可能利用了先存正断层发生反转位移,并成为控制局部构造变形的主要构造要素。天山上升引起的垂直剪切作用是导致库车坳陷-南天山盆山过渡带发育高角度逆冲断层或促成先存正断层的反转的可能原因。 相似文献
20.
石泉羊坪湾金矿床韧性剪切带特征及找矿标志 总被引：1，自引：0，他引：1
羊坪湾金矿位于巴山弧形断裂东侧，矿区总体构造为-呈NW走向的紧闭褶皱，金矿体受北西向展布的脆-韧性剪切带控制，剪切带内窗棂褶皱、小褶曲、微褶皱劈理、节理构造及片理化带相当普遍，特别是金矿化蚀变带内及近旁更为发育；另外，岩石的显微组构也反映强烈的揉皱构造、岩石裂隙、碎裂结构、碎斑结构等，这些对金元素赋存有利；早期形成金的矿源层，在韧性剪切作用下，使金元素被激活并发生迁移，在软硬岩层的接触面附近或断裂处聚集形成金矿体；金矿化与褐铁矿化、纤维状黄铁矿、细粒黄铁矿化和石英脉关系密切；进而总结了该区8条找矿标志。 相似文献