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1.
Mark Peternell Maria de Fátima Bitencourt Jörn H. Kruhl Christian Stäb 《Journal of South American Earth Sciences》2010,29(3):738-750
In the northeastern Dom Feliciano Belt, Santa Catarina/Brazil, Paleoproterozoic rocks (mainly the Camboriú Complex) and Neoproterozoic granitoids – with the older Itapema Granite and the younger Corre-mar, Rio Pequeno and Serra dos Macacos granites – experienced a deformation history from magmatic to greenschist facies temperatures, under different rheological conditions. The concordance of flat amphibolite facies structures of the Camboriú Complex and magmatic and subsolidus structures in the Itapema Granite indicate the late-tectonic character of the latter. Based on tectonic features, the Corre-mar Granite is interpreted as older than the Rio Pequeno Granite and as related to transcurrent tectonics of the Southern Brazilian Shear Belt.In all granites, microstructures point to widespread magmatic alignment, followed by weak subsolidus and, locally, amphibolite to greenschist facies deformation. Magmatic foliations are progressively weaker in the younger granites. Synmagmatic shear zones in the Rio Pequeno Granite are possibly concentrated at the intrusive contact. The weak solid-state deformation at late-magmatic conditions argues for magmatism within a low-strain zone, which is compatible with the location of the area relative to the Major Gercino and Itajaí shear zones. The amphibolite to greenschist facies deformation structures are attributed to continuous deformation within the same low-strain zone during decreasing temperatures. 相似文献
2.
An appraisal of the 1977–1978 regional reconnaissance geochemical data obtained under the Central Belt Project indicated that the Boundary Range Granite, the Senting Granite, and the Benom Igneous Complex appear to constitute favourable uranium exploration targets. Results of the airborne survey subsequently flown within the Project area in 1980 showed high radiometric responses over these and other granitoids. Recent follow-up of a multi-element geochemical anomaly over the Boundary Range Granite has resulted in the discovery of some uraninite-bearing boulders and an abnormally radioactive ironstained quartz vein containing uranium-bearing rhabdophane and florencite. Yet another potential target appears to be the Main Range Granite. Although not within the Project area, it has the distinction of hosting the first recorded uranium occurrence in Peninsular Malaysia.Contrary to earlier belief, the importance of the continental Mesozoic Tembeling and Gagau Groups as possible uranium hosts has been reduced, judging from the poor airborne radiometric response and the overall low geochemical results. On the other hand the Tertiary basins, not previously accorded attention, should be assessed. 相似文献
3.
The Basement Complex in Western Nigeria in general, and in the Ibadan area in particular, is composed primarily of a banded gneiss in which hornblende-biotite rich bands alternate with quartz-oligoclase rich bands. The banded gneiss, which originated as part of a sedimentary sequence, contains large lenses of granite gneiss and thin intercolated layers of quartzite and amphibolite.Two distinct major structural events can be clearly identified in the early geological history of the Ibadan area. Detailed field studies suggest that the formation of the Ibadan Granite Gneiss, which had yielded an Eburnean Rb-Sr isochron age, was associated with the later of these events. Five phases of dyke or vein formation, two of which pre-date the formation of the Granite Gneiss, have also been identified giving an overall sequence of geological events the first of which may correspond to the beginning of the Liberian orogeny, around 3000 m.y. ago, and the last of which reflects the waning of the Pan-African thermo-tectonic event about 500 m.y. ago. 相似文献
4.
The cassiterite-sulfide deposits of western Tasmania are spatially and temporally related to Devonian granitoids. The stable isotope and fluid inclusion data of these deposits are best explained by a genetic model in which Sn is leached from the granites by reduced, non-magmatic fluids mixed with late-stage magmatic fluids. These fluids mineralize the overlying dolomite horizons and subjacent faults by a combination of wallrock and boiling induced reactions. The model requires co-incidental release of volatiles and ingress of groundwaters to sustain the leach mechanism. This implies some specific structural/deformational controls on the process and an intimate association between cassiterite-sulfide deposits and volatile-rich granites.The sulfur isotope data show a wide range in values, from about −2 to 20 per mil, and are explained in terms of a near-zero magmatic component and three heavier country-rock sources: the Precambrian Oonah Formation, the Crimson Creek Formation and the Mount Read Volcanics. Following this interpretation, the heavy sulfur isotope values from the Heemskirk Granite (Hajitaheri, 1985) and the Federal-Bassett Fault at Renison (Kitto, 1994) indicate ingress of groundwater into the granites. Salinities of fluid inclusions from the deposits show a restricted range (around 5 to 15 weight percent NaCl equivalent) compared with the range shown by inclusions from alteration zones within the granites (around 5 to 40 weight percent NaCl equivalent). It is suggested that the wide range of salinities in the granites is generated in the critical region of the NaCl---H2O system at temperatures around 400 to 500°C and pressures around 400 to 500 bars. The limited range of salinities in the deposits reflects cooling to sub-critical conditions. Cooling through the critical region promotes homogenization of groundwater and magmatic vapor and brine. Condensation of magmatic volatiles within this zone of mixing maintains acidity and promotes fluid-rock reaction.The geochemistry of the granites underlying the Renison Bell area (Bajwah et al., 1995) is interpreted in terms of two granites. The geological relationships indicate the more mafic phase, the Renison Granite, was intruded by the more fractionated Pine Hill Granite. Fluids from the Pine Hill Granite sericitised and tourmalinized both the Renison Granite and Pine Hill Granite along their mutual contact, generating a broad north-east trending zone of alteration. This contact may have been offset by the Federal-Bassett Fault before the Renison deposit was formed. It is suggested that groundwater flow was essentially constrained within this NW-SE trending structure and subsidiary structures. Magmatic volatiles, emanating from deep within the Pine Hill Granite, acidified the reduced groundwater and promoted leaching of the granite. The siting of the Renison deposit on the margin of the Pine Hill Granite is consistent with a strong up-flow zone on the margin of a cooling pluton. The very constant S-isotope signature in the deposit is consistent with a large-scale homogenization process operating over a sustained period. The very large size of the Renison deposit is accounted for by a long-lived groundwater system maintained by the high heat flow from a fractionated granite. 相似文献
5.
This paper is an analytical presentation of the pattern and persistence of groundwater level fluctuation in humid tropical regoliths. Using the Basement Complex in SW Nigeria as a microcosm of the crystalline rock environments in the humid tropics, the groundwater level fluctuation was monitored in three study areas for a number of consecutive years at the sites of observation wells sunk in thick regoliths. The sample data on saturated zone thickness and depth of water in well were analyzed by rigorous but suitable statistical techniques to identify the groundwater level fluctuation pattern and to asses its persistence. The fluctuation pattern in each study area is optimally described by an empirical equation and is perfectly in consonance with the prevailing rainfall regime. Tests for the persistence of the fluctuation pattern reveal that the groundwater regimes in the regoliths of the study areas are almost identical. by reference to the findings of some other research workers elsewhere in the humid tropics it is inferred, subject to verification from further research, that a generally similar groundwater regime prevails in humid tropical regoliths in low-relief deeply weathered landscapes. 相似文献
6.
The Epupa Metamorphic Complex constitutes the southwestern margin of the Congo Craton and is exposed in a hilly to mountainous terrain of northwestern Namibia, bordering the Kunene River and extending into southern Angola. It consists predominantly of granitoid gneisses which are migmatized over large areas. This migmatization locally led to anatexis and produced crustal-melt granites such as the Otjitanda Granite. We have undertaken reconnaissance geochemical studies and single zircon U–Pb SHRIMP and Pb–Pb evaporation dating of rocks of the Epupa Complex. The granitoid gneisses, migmatites and anatectic melts are similar in composition and constitute a suite of metaluminous to peraluminous, calc-alkaline granitoids, predominantly with volcanic arc geochemical signatures. The zircon protolith ages for the orthogneisses range from 1861 ± 3 to 1758 ± 3 Ma. Anatexis in the migmatitic Epupa gneisses was dated from a melt patch at 1762 ± 4 Ma, and the anatectic Otjitanda Granite has a zircon age of 1757 ± 4 Ma. Migmatization and anatexis therefore occurred almost immediately after granitoid emplacement and date a widespread high-temperature Palaeoproterozoic event at ∼1760 Ma which has not been recorded elswhere in northern Namibia. The Nd isotopic systematics of all dated samples are surprisingly similar and suggest formation of the protolith from a source region that probably separated from the depleted mantle about 2.4–2.0 Ga ago. A major Archaean component in the source area is unlikely. 相似文献
7.
Valeria Murgulov William L. Griffin Suzanne Y. O’Reilly 《Mineralogy and Petrology》2009,95(1-2):17-45
An existing model for the temporal and genetic relationships between the Kidston gold-bearing Breccia Pipe and the nearby Lochaber Ring Dyke Complex has been evaluated using in situ U–Pb and Hf-isotope analyses of zircon grains. The Oak River Granodiorite, the host rock to the Kidston Breccia Pipe, has 1,551?±?6 Ma old zircon cores overgrown by 417.7?±?2.2 Ma rims. The Black Cap Diorite and Lochaber Granite within the Lochaber Ring Dyke Complex have crystallisation ages of 350.7?±?1.3 and 337.9?±?2.6 Ma respectively. The gold-rich Median Dyke within the Kidston Breccia Pipe has a crystallisation age of 335.7?±?4.2 Ma, and thus is temporally related to the Lochaber Granite. However, zircon grains from the Median Dyke have less radiogenic Hf-isotope compositions (? Hf from ?7.8 to ?15.8) than those from the Black Cap Diorite ?Hf?=?0.4 to ?7.2) and the Lochaber Granite (? Hf?=??1.0 to ?7.5), but within the range defined by zircons from the Oak River Granodiorite ? Hf?=??8.0 to ?29.2). The Hf-isotope data thus rule out the proposed fractional crystallisation relationship between the Kidston gold-bearing rocks and the Lochaber Ring Dyke Complex. The Kidston Median Dyke may have been produced by mixing between Lochaber Granite magmas and magmas derived by remelting of the Oak River Granodiorite, which was itself derived from Proterozoic crust. There is no evidence for a juvenile component in the Lochaber Ring Dyke Complex or the Median Dyke. The gold enrichment in the Kidston rocks thus may reflect the multi-stage reworking of the Proterozoic crust, which ultimately produced the Carboniferous felsic magmas. 相似文献
8.
借鉴美国地质调查局在宾夕法尼亚的地下水位预警方法,从统计学的角度,探索了北京平原区地下水预警方法。对监测井多年长期监测资料进行百分位统计分析,把同一时间(月平均、旬平均、日平均)地下水水位(头)标高值的最小值至百分位5、百分位5至百分位10、百分位10至百分位25、百分位25至百分位75范围内的地下水位分别定义为红色、橙色、黄色和蓝色预警,形成地下水位预警判据。根据地下水水位实时监测数据,实时判定监测井代表区域的地下水预警等级,同时修正和完善地下水位预警判据,称之为监测井单点预警,监测井代表的同一层位的区域的集合,构成不同含水层的地下水位区域预警。对北京平原区2009年12月的地下水位预警结果为:潮白河冲洪积扇顶部和中部潜水含水层地下水位为红色预警,前缘为黄色预警,冲洪积平原为蓝色预警区;城区以南地区为红色预警,海淀山后的西北部地区为红色预警,永定河冲积扇和冲积平原大部分地区黄色和蓝色预警,大石河冲洪积扇地区均为蓝色预警;承压水含水层在潮白河冲洪积扇的前缘为红色预警,冲洪积平原为蓝色预警,北运河山前地带均为橙色预警,城区东、东南地区为橙色和黄色预警,少数地区为橙色预警,除上述地区以外,承压水均为蓝色预警。北京市平原区主要地下水开采地区地下水位已经处于历史的较低水位处,特别是潮白河冲积扇中上部地区以及平谷盆地,地下水位几乎全部处于红色预警区。该预警方法原理明确,方法简便,有望在地下水主要开采区推广应用。 相似文献
9.
Mohamed O. Arnous 《Hydrogeology Journal》2016,24(6):1375-1392
Identifying a good site for groundwater exploitation in hard-rock terrains is a challenging task. In Sinai, Egypt, groundwater is the only source of water for local inhabitants. Interpretation of satellite data for delineation of lithological units and weathered zones, and for mapping of lineament density and their trends, provides a valuable aid for the location of groundwater promising areas. Complex deformational histories of the wide range of lithological formations add to the difficulty. Groundwater prospect mapping is a systematic approach that considers the major controlling factors which influence the aquifer and quality of groundwater. The presented study aims to delineate, identify, model and map groundwater potential zones in arid South Sinai using remote sensing data and a geographic information system (GIS) to prepare various hydromorphogeological thematic maps such as maps of slope, drainage density, lithology, landforms, structural lineaments, rainfall intensity and plan curvature. The controlling-factor thematic maps are each allocated a fixed score and weight, computed by using a linear equation approach. Furthermore, each weighted thematic map is statistically computed to yield a groundwater potential zone map of the study area. The groundwater potential zones thus obtained were divided into five categories (very poor, poor, moderate, good and very good) and were validated using the relation between the zone and the spatial distribution of productive wells and of previous geophysical investigations from a literature review. The results show the groundwater potential zones in the study area, and create awareness for better planning and management of groundwater resources. 相似文献
10.
Mustafa A. Eissa James M. Thomas Ronald L. Hershey Maher I. Dawoud Greg Pohll Kamal A. Dahab Mohamed A. Gomaa Ashraf R. Shabana 《Environmental Earth Sciences》2014,71(4):1855-1869
The Wadi Watir delta in the Wadi Watir watershed is a tourist area in the arid southeastern part of the Sinai Peninsula, Egypt, where development and growth of the community on the delta are constrained by the amount of groundwater that can be withdrawn sustainably. To effectively manage groundwater resources in the Wadi Watir delta, the origin of groundwater recharge, groundwater age, and changes in groundwater chemistry in the watershed needs to be understood. Mineral identification, rock chemistry, water chemistry, and the isotopes of hydrogen, oxygen, and carbon in groundwater were used to identify the sources, mixing, and ages of groundwater in the watershed and the chemical evolution of groundwater as it flows from the upland areas in the watershed to the developed areas at the Wadi Watir delta. Groundwater in the Wadi Watir watershed is primarily from recent recharge while groundwater salinity is controlled by mixing of chemically different waters and dissolution of minerals and salts in the aquifers. The El Shiekh Attia and Wadi El Ain areas in the upper Wadi Watir watershed have different recharge sources, either from recharge from other areas or from different storm events. The downgradient Main Channel area receives groundwater flow primarily from the El Shiekh Attia area. Groundwater in the Main Channel area is the primary source of groundwater supplying the aquifers of the Wadi Watir delta. 相似文献
11.
Groundwater-level fluctuations at a large scale have a significant effect on the preservation and restoration of vegetation. This study determined suitable groundwater depth within which natural vegetation grows well, and analysed the effect of groundwater regulation on vegetation restoration in Tianjin City, northern China. Normal and lognormal distributions were used to fit the curve of the relation between vegetation and groundwater depth. The groundwater depth range corresponding to the higher frequency of vegetation distribution was regarded as the ‘suitable water depth’ range for vegetation growth. The suitable groundwater depth for shrub growth was 3–5 m and for grass growth 1–3 m. A groundwater flow model predicted the future changes of groundwater depths in the vegetation distribution area under the condition that the current levels of groundwater extraction are maintained. The results showed that there is potential for the extraction of groundwater in shrubland areas, but for grassland areas the water-table elevation showed a downward trend, meaning that water shortages in some areas may be more severe in the future. Finally, based on the current groundwater extraction regime, two regulation schemes were developed: (1) for shrubland, groundwater extraction was reduced by 10% in the ecological water deficit areas, and extraction was increased by 10% in the ecological water surplus and suitable areas, and (2) for grassland, groundwater recharge was increased by the restoration of the wetland areas. In conclusion, the groundwater depths in most of the area would be more suitable for vegetation growth under the regulation schemes. 相似文献
12.
In Ghana, 68% of the population live in rural communities, which are scattered and remote. Groundwater is the most feasible source of potable water supply for most of these dispersed and remote settlements. To meet the present and future challenges of population expansion vis-à-vis the observed declining rainfall in most parts of Africa including Ghana, it is necessary to assess, efficiently manage, and utilize the groundwater resources. The objective of this paper is therefore to describe the hydrogeologic framework and analyze borehole yields as part of the groundwater-resources assessment of Ghana. The hydrogeologic units are broadly categorized as: (1) the Basement Complex (crystalline rocks), which underlies about 54% of the country; (2) the Voltaian System, which underlies about 45%; and (3) the Cenozoic, Mesozoic, and Paleozoic sedimentary strata (Coastal Provinces), which underlie the remaining 1% of the country. The Basement Complex and the Coastal Provinces have higher groundwater potential than the Voltaian System. This is particularly significant, because the Basement Complex and the Coastal Provinces underlie the most densely populated areas of the country and can hence be tapped for human use. The average borehole yields of the Basement Complex, the Coastal Provinces and the Voltaian System range from 2.7–12.7, 3.9–15.6, and 6.2–8.5?m3/h, respectively. 相似文献
13.
14.
Five suites of rocks collected from the Precambrian basement in the NE Bayuda Desert of central northern Sudan give late Proterozoic whole-rock isochron ages. The Abu Harik Complex, thought by some previous workers to be an older basement, gives an age of 898 ± 51 Ma. Upper amphibolite-facies metasediments give a metamorphic age of 761 ± 22 Ma. The supposedly younger greenschist-facies El Koro Volcanic Series were erupted 800 ± 83 Ma ago. These are chemically similar to the volcanics which unconformably overlie the Sol Hamed ophiolite in the Red Sea Hills of NE Sudan and to some modern island are volcanics. The metasediments were intruded 678 ± 43 Ma ago by the Diefallab Granite, which is itself deformed. The younger, weakly-deformed Amaki Series, with a basal conglomerate containing basement clasts overlain by purple grits, is probably equivalent to the molasse-type Hammamat Group of the Eastern Desert of Egypt which was deposited between 616 and 596 Ma ago. Finally, the post-tectonic Shallal Granite, with within-plate geochemistry, was intruded 549 ± 12 Ma ago. Geochemical data suggest that the Abu Harik Complex, the El Koro Volcanic Series and the Diefallab Granite are arc-related magmatic rocks. They were intruded into, or thrust onto, shallow-water, shelf sediments during subduction and then collision, between c. 900 and 550 Ma. The data presented here give no support to previous views that the high-grade metasediments were metamorphosed prior to the late Proterozoic events, that they unconformably overlie a still older, perhaps Archaean, basement or that they are unconformably overlain by younger late Proterozoic low-grade volcanics. The Precambrian rocks along the E side of the Bayuda Desert must now all be assigned to the late Proterozoic and the boundary between this late Proterozoic fold belt and an older craton, known to crop out at Jebel Uweinat, must lie farther to the W. 相似文献
15.
青木关岩溶槽谷地下水水源地固有脆弱性评价 总被引：2，自引：1，他引：1
岩溶地下水脆弱性评价是基于保护岩溶含水层从而有效地管理和利用地下水提出的有效方法和手段。我国西南岩溶区大多数地区缺少应有的地下水保护带,地下水比较容易受到污染。通过采用改进的斯洛文尼亚模式,考虑四个因子:覆盖层(O)、径流特征(C)、降雨条件(P)、岩溶发育程度(K),对重庆市青木关岩溶槽谷地下水水源地的固有脆弱性进行了定量评价。结果表明:流域范围内12.6%为高脆弱性地区;43%为中等脆弱性;44.4%为低脆弱性区域。消水洞及周边100m和消水河及其两边10m,以及岩溶管道发育地区为高脆弱性区。大部分岩溶区为中等脆弱性区。砂岩地区为低脆弱性地区。评价结果与实际吻合。该评价结果为各级决策部门合理规划利用和保护地下水资源提供简单明了的科学依据。该方法对于川东岩溶槽谷地区脆弱性评价有推广价值。 相似文献
16.
地下水是海原盆地唯一的供水水源,近年来部分地区地下水溶解性总固体(TDS)增高,引起了有关部门和水文地质工作者的高度关注。通过分析69组地下水样品的水化学和氢氧稳定同位素数据,对地下水补给来源和咸化的水文地球化学过程进行了研究。结果表明:地下水TDS值198.2~6 436.4 mg/L,沿着地下水流向,咸化程度增加,水化学类型从基岩区的HCO3—Ca·Mg型演化至滞留—排泄区的SO4·Cl—Na·Mg型。地下水补给来源主要为大气降雨和基岩裂隙水侧向径流,补给源—对地下水咸化贡献较小。溶滤作用具空间差异,基岩区和补给区以碳酸盐、硅酸盐风化为主,径流区和滞留—排泄区则为蒸发岩风化,硫酸盐是地下水中阳离子的主要来源。补给水、溶滤和蒸发对第四系地下水TDS的贡献比率分别为4.8%~81.2%、11.9% ~85.9%、1.7%~29.5%,溶滤作用是控制海原盆地地下水咸化的首要因素。当地有关部门应加大对基岩泉水的综合利用,同时注意控制海原县和西安镇等地区地下水开采量,防止地下水进一步咸化。另外,在微咸水分布区可引进地下水去除硫酸盐技术,提高微咸水利用程度。 相似文献
17.
以地下水污染调查数据、地下水监测数据和遥感数据为基础,分析了1998年以来（1998—2019年）兰州不同区域地下水环境变化趋势,探讨了土地利用变化、污染源排放、地下水开采等城市发展要素对地下水的影响。结果表明：1998年以来兰州市地下水环境变化的主要特征是水质恶化、水位上升。溶解性总固体、总硬度、硝酸根、氟等典型水化学指标在大部分地区呈稳定上升趋势,局部地下水中硝酸根比重增加,出现了硝酸型地下水。污染负荷增加是水质恶化的重要驱动因素,且恶化指标与城市主体功能存在直接关系,城关区是主要的居住、商业区,水质恶化的典型指标为硝酸盐;西固区是化工、冶炼等重工业集中区,地下水污染程度最重,反映工业污染的氟化物上升显著;七里河区、安宁区是商业、居住及轻工业的综合分布区,矿化度、总硬度、硝酸根等指标都有不同程度上升,但升幅不大。西固及三滩地区地下水位上升较为明显,其他城区相对稳定,城市不透水界面阻碍了降雨、灌溉等地表垂直入渗,使地下水位年内波动趋于平缓;水源地开采量减少、沿河工程建设以及地下管网渗漏等因素导致地下水补径排条件发生变化,不仅引起城区地下水位上升,还能够增强污染物淋滤和地下水蒸发浓缩,对水化学环境造成一定影响。 相似文献
18.
河北平原京津以南深层地下水资源形成规律的研究 总被引：1，自引：0，他引：1
本文应用同位素技术，结合含水岩组水文地质结构特征的分析及地下水动力方法的年龄计算，揭示了河北平原京津以南地区深层地下水的形成规律，得出深 地下水资源补给能力及承受开采能力很低的结论，这为今后深 地下不资源的合理开发利用提供了重要依据。 相似文献
19.
A. K. Dwivedi Abhinav Kumar A. K. Chaturvedi 《Journal of the Geological Society of India》2016,88(2):159-172
This research aims at integrating remote sensing data and field studies to prospect for uranium mineralisation in the Palaeoproterozoic Mahakoshal Group of rocks in the Son valley area, Central India. In present work, a revised geological map of Mahakoshal Fold Belt (MFB) bounded by Son-Narmada north fault (SNNF) and Son-Narmada south fault (SNSF) along Chorhut-Sidhi-Chitrangi sector falling in Sidhi, Rewa and Shahdol districts of Madhya Pradesh has been prepared based on interpretation of digitally enhanced satellite images. The satellite image interpretation is supported by limited field works, radioelemental measurements (eU, eTh and % K) of in-situ rocks by four channel Portable Gamma Ray Spectrometer (PGRS) and existing published geological maps of Geological Survey of India. In search for mineral potential areas, accurate and up-to-date geological maps are essential as it represent the most basic information for carrying out further exploration activities. However, available geological maps of MFB and sedimentary formations ofVindhayan Supergroup along SNNF and Chhotanagpur Granite Gneissic Complex (CGGC) and Gondwana Supergroup along SNSF available in public domain are discontinuous and multi-scaled. 相似文献
20.
为了揭示黄土高原山地-沟壑区黄土地下水水化学特征及成因,对六盘山东西两侧山区及其西部典型黄土高原山地-沟壑区进行了多次实地考察,合理选择采样点,采集了浅层地下水监测水样。对采集的样品水化学数据进行了分析,结果表明:六盘山地区浅层地下水以低TDS重碳酸盐型为主,径流途径较短,循环条件较好,保持了较好的天然淡水资源状态;而在山地-沟壑区水化学类型则复杂多样,TDS平均值达1 870mg/L,淡水资源相对匮乏。结合各类水化学图可以看出,浅层地下水和地表水的离子来源优势机制以岩石风化为主,并且在山地-沟壑区受到不同程度蒸发作用控制。通过分析地下水中的离子浓度比以及锶元素,发现六盘山区主要为补给区和径流区,山地-沟壑区则是补给区、径流区和径流滞缓区,黄土地下水可能有来自六盘山岩溶水的补给。氟离子浓度和硬度超标是影响区域内水质的最主要因素,在受蒸发作用影响较大的地区尤为突出。黄土高原地下水资源的分布状况和质量参差不齐,保护好区域内较好的淡水资源并且按照地下水分布规律进行合理的开发与宏观调控,是缓解黄土高原水资源问题的关键。 相似文献