首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 108 毫秒
1.
In this paper we provide a geochemical investigation on 34 groundwater samples in the Mt. Vulture volcanic aquifer representing one of the most important groundwater resources of the southern Italy pumped for drinking and irrigation supply. The present study includes the first data on the abundance and mobility of minor and trace elements and the thermodynamic considerations on water–rock interaction processes in order to evaluate the conditions of alkali basalt weathering by waters enriched in magma-derived CO2. The results highlight the occurrence of two hydrofacies: bicarbonate alkaline-earth and alkaline waters deriving from low-temperature leaching of volcanic rocks of Mt. Vulture, and bicarbonate-sulfate-alkaline waters (high-salinity waters) related to prolonged water circulation in alkali and feldspathoids-rich pyroclastic layers interbedded with clay deposits. The Al-normalized relative mobility (RM) of metals in Vulture's aquifer varies over a wide range (10− 1 < RM < 104), confirming that the basalt weathering is not a congruent and isochemical process. Chemical equilibrium studies show that the bicarbonate alkaline-earth and alkaline waters, having a short interaction with silicate minerals, plot very close to the kaolinite–smectite stability boundary, whereas the high-salinity waters fall in the stability field of smectite and muscovite because of prolonged interaction with alkali and feldspathoids-rich pyroclastic layers. Overall, for the bicarbonate alkaline-earth and alkaline waters, the release of toxic metals in solutions is related to the spatial variation of host-rock geochemistry, the high-salinity waters, collected near urban areas, show values higher than legal limits for Ni and As, likely as a consequence of anthropogenic contribution.  相似文献   

2.
2016～2018年系统采集川西甲基卡稀有金属矿田及周边地表水样品88件,测试分析了样品中Li、Be、Rb、Sr、Zr、Nb、Cs、Hf、Ta九种稀有金属元素含量及八种主要阴阳离子含量。结果表明:甲基卡矿田地表水水化学类型主要为HCO_3-Ca型。甲基卡矿区地表水中Li、Be、Nb、Rb、Cs、Ta等稀有金属元素平均含量明显高于川西河流平均值,Zr、Hf元素含量与川西河流均值相近,Sr含量远低于川西河流均值。经甲基卡矿区地表水稀有金属含量与矿脉分布空间耦合验证,地表水中Li、Rb、Cs、Be元素含量对矿脉的存在有明显的响应特征,其含量分布可以有效地服务于稀有金属矿产勘查,针对甲基卡外围地形高差大、切割深的特点,认为根据水地球化学异常来找矿也不失为一种有效方法,可以尝试运用地表水中稀有金属元素异常来缩小找矿靶区。  相似文献   

3.
Early Paleozoic granitoids of autochthonous and allochthonous facies in the Baikal area (Ol’khon Island, Khamar-Daban Ridge) are in close spatial association with gneisses, migmatites, and plagiogranites and are usually confined to granite–gneiss domes. They are virtually not subjected to magmatic differentiation. Formation of granitoids of the Solzan massif and Sharanur complex lasted 26–28 Myr, which might be considered an indicator of collisional granitoid magmatism. Collisional granitoids of different provinces have a series of indicative features: They are peraluminous and highly potassic and are enriched in crustal elements (Rb, Pb, and Th) but sometimes have low contents of volatiles. In contrast to collisional magmatism, petrogenesis of intraplate granitoids does not depend on the composition and age of the enclosing rocks. The geochemical evolution of intraplate granitoid magmatism in the Baikal area is expressed as an increase in contents of F, Li, Rb, Cs, Sn, Be, Ta, Zr, and Pb and a decrease in contents of Ba, Sr, Zn, Th, and U during the differentiation of multiphase intrusions. The geochemical diversity of these granitoids formed both from crustal and from mantle sources and as a result of the mantle–crust interaction, might be due to the effect of plume on the geologic evolution of intraplate magmatism. The wide range of compositions and geochemical types of igneous rocks (from alkali and subalkalic to rare-metal granitoids) within the Late Paleozoic Baikal magmatism area suggests its high ore potential.  相似文献   

4.
在伟晶岩锂矿勘查中,为了解决常规物探方法由于矿体与围岩差异不显著、应用效果不佳、化探法对隐伏锂矿效果不明显的问题,以新疆卡鲁安伟晶岩锂矿为研究区,布设了两条总长6 605 m的地气研究剖面,完成了191个测点的国内外首例地气测量勘查伟晶岩锂矿研究工作,每个测点获得Li、Rb、Be、Cs、Nb、Y等39种元素的含量,据此研究了卡鲁安研究区伟晶岩锂矿的地气异常特征。结果表明,在伟晶岩锂矿脉的倾斜方向一侧,均能捕获包含Li、Rb、Be、Cs、Nb、Y等多种元素的显著地气异常;在无矿(化)伟晶岩上方,Rb元素的地气异常幅度会增大,其它元素异常幅度则明显变小,Be不出现地气异常;其它岩性上方,没有地气异常出现。研究证实了地气法对寻找伟晶岩锂矿是准确、有效的,对在伟晶岩锂矿勘查中应用地气法找矿提供了理论参考和技术支持。  相似文献   

5.
Taking a certain rare element-bearing granite-pegmatite in the eastern Qinling Range for example, the author has generaiized in this paper the distribution patterns, characteristic ratios, variations and correlations of major elements (Si, Al, K, Na), characteristic elements (H, F, P, B), minor elements (Ca, Fe, Mg, Mn) and rare elements (Li, Be, Rb, Cs, Nb, Ta) in genetic connection with granite-pegmatites.  相似文献   

6.
Extensive Paleozoic sinter deposits occur at the surface associated with sub-surface quartz veining and epithermal Au mineralisation in the Drummond Basin, Australia. We investigated the trace element composition of the sinter deposits and quartz veins in an attempt to develop a new geochemical exploration guide for geological resources. The Drummond Basin hydrothermal silica deposits are unique in having anomalously enriched incompatible element (Cs, Li, Be, U, Th and REE) concentrations in comparison to hydrothermal quartz veins from various granitic-pegmatitic systems elsewhere. The development of relative Ce deficiencies (Ce/Ce*norm < 1) in silica deposits indicate preferential mobilisation of REE over Ce from source rocks by oxidised hydrothermal fluids, leading to relative Ce enrichment in the source material (e.g., rhyolite intrusions). Sinters and quartz veins and some volcanic source rocks show a conspicuous positive Y anomaly relative to REE. This is interpreted in terms of Y fractionation due to fluorine complexation with REE during hydrothermal activity. The majority of sinter and quartz samples within or near the Au mineralisation zone are more enriched in mobile elements (Cs, Li, Rb and Be) than the silica deposits from areas distal to the mineralised area. Normalised Y–REE patterns of the sinter deposits, quartz veins, and wall rocks provide important information on the physico-chemical environment of epithermal mineral deposition in geothermal systems. Trace element systematics as revealed in the current study, particularly in relation to the alkali element mobility, have significant implications for finding new prospect areas and evaluating the potential of existing prospect areas for epithermal metal deposits and active geothermal fields.  相似文献   

7.
对黑龙江陈家店金矿区内花岗斑岩进行LA-ICP-MS锆石U-Pb定年及元素地球化学研究。测年结果显示,花岗斑岩锆石~(206)Pb/~(238)U加权平均年龄为(227±4)Ma。岩石地球化学特征显示,花岗斑岩具有富Si、富Al、富碱质和低Mg、低Ca的特征;微量元素表现出高场强元素(HFSE)Th、Rb和K明显富集,而大离子亲石元素(LILE)Ba、Sr和Ti明显亏损的特点;稀土元素以明显的轻稀土元素富集重稀土元素相对亏损为特征,轻、重稀土元素分馏程度较强(La/Yb)_N=0.47~4.99,有强烈的Eu负异常(δEu=0.08~0.68)。构造判别图解显示,花岗斑岩具有碰撞后花岗岩特征,形成于碰撞后的构造环境。综合研究认为,矿区花岗斑岩的成因类型为S型花岗岩,其成岩时代为晚三叠世,形成于古亚洲洋闭合后的陆陆碰撞造山环境,地处火山弧形构造带,属于安第斯型大陆边缘。  相似文献   

8.
Trace and minor element concentrations in alkali feldspars fromthe layered syenite series in the Klokken gabbro-syenite complex,South Greenland have been measured using an ion microprobe.The technique has high precision, avoids problems of mineralseparation, and has allowed investigation of zoning and theeffects of deuteric alteration. Li, Be, B, Cs and Pb occur at< 1 p.p.m. levels, but Ba, Sr, Rb, Mg, Fe, Ti and P are presentin the 1–7000 p.p.m. range. Provided unaltered strain-controlledcrypto- or microperthitic feldspar is sampled and deutericallycoarsened material is avoided, all of the latter elements exceptMg show systematic variation. This confirms the evidence forin situ fractionation of a single syenitic magma-pulse affordedby major element variation in coexisting mafic minerals, particularlypyroxenes and olivines. The distinction between granular andlaminated syenites in the series is supported by the trace elements,which confirms the view that the granular syenites are a condensedroof-chill series with inverted cryptic variation, while thelaminated syenites are a bottom accumulated sequence. Using mainly experimentally determined partition coefficientsfrom the literature and a simple Rayleigh fractionation modelbased on the variation in Ba, Sr and Rb (elements whose concentrationin the melt is largely controlled by feldspar) we calculategeologically reasonable minimum thicknesses for the entire layeredseries of 1370–3260 m. Ti variation in the feldspars wascontrolled by Fe-Ti oxide fractionation, and Fe contents alsowere controlled by mafic phases. Controls of Mg, and particularlythe irregular P levels, are not clear. Behaviour of Ca, whichis present at < 6000 p.p.m. levels in the feldspars, is qualitativelyexplained in terms of the ternary feldspar phase diagram.  相似文献   

9.
The elements Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr and Ba have been determined by X-ray fluorescence for 65 basaltic and differentiated lavas from Anjouan, while Sc, V, Cr, Co, Ni, Cu, Ga, Rb, Sr, Y, Zr, Nb, Cs, Ba and Hf have been determined by spark-source mass spectrometry for selected lavas from Anjouan and Grande Comore, the most recently formed of the Comores Archipelago. Basaltic lavas studied range through nephelinite, basanite, alkali basalt and hypersthene-normative basalt, while differentiated lavas belong mainly to the trends: alkali basalt - trachyte and basanite - phonolite. The results indicate that during magmatic fractionation behaviour of large-ion elements such as Rb, Sr, Y, Zr, Ba and Nb is controlled by size/charge criteria, resulting in their exclusion from crystallising phases until the late trachytic and phonolitic stages. These elements are clearly fractionated by amphibole, plagioclase and alkali feldspar. Variation of transition elements due to crystal-liquid differentiation is largely in accord with the predictions of crystal field theory. The behaviour of Zn is not readily accounted for. Fractionation of K/Rb, K/Cs and probably Zr/Nb and discrepancies in abundance levels of large-ion elements between the main basaltic types are best accounted for in terms of high-pressure processes and probably also reflect inherent features of source-region geochemistry, coupled with the effects of variable partial melting.  相似文献   

10.
The mineralogy and geochemistry of the waste rocks distributed at Taojiang Mn-ore deposit, central Hunan province, China, were studied using X-ray powder diffraction (XRD), electron microprobe analysis (EMPA) fitted with energy dispersive spectrometer (EDS) and inductively coupled plasma mass spectrum (atomic emission spectra) ICP-MS (AES), with the aim of predicting the environmental impacts of weathering of the waste rocks. The mineralogical results from microscope observation and XRD and EMPA studies show that the waste rock is composed of black shale and minor Mn carbonates. The oxidation of sulfide minerals such as galena, pyrite and chalcopyrite is accompanied by decomposition of Mn carbonates and K-feldspar during exposure to atmospheric O2. The geochemical characteristics of major, rare earth elements (REE) and trace elements of the waste rocks also show that the waste rock can be divided into black shale and Mn carbonate, and both of them are currently under chemical weathering. The major alkalies and alkaline elements (Ca, Mg, Na, K, Rb, Sr and Cs) and major elements (Fe, S and P) and heavy metals (Sc, V, Cr, Th, U, Sn, Co, Ni, Cu, Zn, Pb, Mo, Cd, Sb, an Tl) are being released during weathering. The mobility of alkalis and alkaline elements Ca, Mg, Na, K, Rb, Sr and Cs is controlled by decomposition of Mn carbonates. The dispersion of Cr, Sc and Th (U) might be related to weathering of K-feldspar, and the release of the heavy metals Co, Ni, Cu, Zn, Pb, Mo, Cd Sb and Tl is dominated by the breaking of sulfide minerals. The REE of the waste rocks and surrounding soils and the spidery distribution patterns of heavy metals in the waste rocks, the surrounding soils and the surface waters show that weathering of the waste rocks and bedrock might be the sources of heavy metal contamination for the surrounding soils and surface water system for the mining area. This is predicted by the mass-balance calculation by using Zr as an immobile element. Therefore, it is urgently necessary take measures to treat the waste rocks distributed throughout the area for the local environmental protection.  相似文献   

11.
Geochemical exploration by stream sediment sampling using bulk leach extractable gold (BLEG) technique and applying concentration-number (C-N) fractal model, factor analysis (FA), and geochemical mineralization probability index (GMPI) resulted in the recognition of new Au occurrences around the Sukari gold mine in the central Eastern Desert of Egypt. The geochemical data of 128 stream sediment samples collected from the study area was used for delineating the geochemical anomalies and characterizing the dispersion trains of ore and associated elements (Au, Ag, As, Sb, Cu, Pb, Zn, Mo). Statistical analysis of the geochemical data applying the C-N fractal modeling enabled us to identify significant anomaly and background populations of the investigated elements and to construct reliable geochemical anomaly maps. Factor analysis using centered log-ratios (CLR), to address the problem of closed compositional data, revealed significant element associations for mineralization (Au, As, Mo, Zn, Ba), country rock compositions (Rb, Li, Be, Sn, Bi for granite, and Co, Cr, Ni for mafic rocks), and element mobility (e.g. Sb, Zr, and Ag). Weak and moderate Au anomalies that cannot be detected by factor score maps can be delineated clearly by using the C-N fractal method and GMPI distribution map. Our study revealed that Ag, As, and Sb are the main pathfinder elements for gold mineralization in arid to semiarid regions exemplified by the Sukari gold district. Silver can be used as a “direct” pathfinder, whereas As and Sb are “indirect” pathfinders for Au in such regions. The spatial distribution of Au and Ag anomalies indicate that gold mineralization in the Sukari district is structurally controlled. However, the spatial distribution of Cu, Pb, Zn, and Mo is controlled by mineralogical and lithological factors and is not related to any significant base metal deposits.  相似文献   

12.
The water quality of the Vacacaí River was assessed at different sites in the period between winter 2005 and autumn 2006. All samples were analyzed for 52 elements (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Li, Be, Mg, Al, Ca, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, In, Cs, Ba, Tl, Pb, Bi, U, Na, K, Hg, B, Mo, Sn, Te, Ti), temperature, pH, ammonia, and alkalinity levels. Water from the Vacacaí River ranged from slightly acidic to alkaline. No difference was observed in the chemical composition at different sites of the Vacacaí River. Levels of Ba, Ca, Sr and Mg increase in the dry seasons and reach their highest concentrations in autumn; Be and U decrease in the dry season and reach their highest concentration in spring. Al, Fe, Cr, Ni, Th, U Mn, Ca and Mg are highly positively related, indicating a common origin. Se and Cu are probably from anthropogenic source, from the rice crops of the margins of the river. Waterborne Al and Fe levels were above the desirable level for drinking water at all sites during all seasons. These results demonstrate the need for constant monitoring of water parameters, which is crucial to ensure water quality for the population of this region.  相似文献   

13.
《Applied Geochemistry》1997,12(5):593-605
The impact of sediment type on stream water geochemistry was studied in a catchment in Finland affected by sulphidic fine-grained sediments. Stream water samples for general characterisation of water quality (pH, electrical conductivity) were taken at the basin outlet during various hydrological conditions, while samples for detailed geochemical analysis were collected at 119 sites in the catchment on one single occasion during high-water flow in autumn. The occurrence of sulphidic fine sediments was estimated based on data from an airborne electromagnetic survey carried out by the Geological Survey of Finland.Growing-symbol maps, which were prepared for each of the studied variables in water, and statistical calculations including factor analysis and Spearman correlations show that the concentrations of Al, Ga, U and Tl, all the lanthanides and several alkali and alkaline earth metals (K, Mg, Na, Li, Ca, Rb, Sr), transition metals (Cd, Co, Cu, Zn, Sc, Mn, Ni, Y, Hf) and non-metals (S, Br, I, Si) increase in water when the proportion of the catchment cover of sulphidic fine sediments increases. It is therefore argued that these elements are released and mobilised in considerable amounts by the oxidation and subsequent acidification and weathering of this type of sediment. Other elements are either slightly depleted in streams in areas of sulphidic fine sediments (V, Nb, Pb, Zr), have a distribution unrelated to sediment type (Fe, Cr, Cs, Mo), or are only weakly impacted by the occurrence of sulphidic sediments in the catchment (As, Ti, Ba). It is argued that these elements are not leached extensively from the oxidising sulphidic sediments, and that their distributions at least partly may be controlled by the contents of dissolved humic material and/or suspended organic and inorganic phases in the water.  相似文献   

14.
朱鑫祥  刘琰 《岩矿测试》2021,(2):296-305
雪宝顶矿床位于四川省的松潘甘孜造山带中,以出产大颗粒含W-Sn-Be-F-P的矿物而闻名,前人对该矿床已经开展了大量的研究,但缺乏对粗粒矿物的主次痕量元素研究。本次研究采用X射线荧光光谱(XRF)、电子探针(EMPA)和电感耦合等离子体质谱(ICP-MS)技术对矿床中各矿物的主次痕量元素进行测试分析。结果显示,雪宝顶矿床中的绿柱石、白钨矿、锡石、白云母、萤石、磷灰石、电气石,除富含W、Sn、Be、Na、K、Ca等主要成矿元素外,还富集Li、Rb、Cs等碱金属元素和F、B、P等挥发份。其中,雪宝顶绿柱石中富含Li(3484~4243μg/g)、Rb(39.3~71.1μg/g)、Cs(2955~3526μg/g);白云母中Li、Rb和Cs元素含量分别高达4243μg/g、72.3μg/g和3526μg/g;磷灰石中除主量元素P外,F(4.48%~5.21%)含量相对较高;电气石中的B含量高达30990~32880μg/g。雪宝顶矿床中的花岗岩岩体W、Sn、Be、Li、Rb、Cs、F、B、P等元素相对富集,但CaO含量(0.46%~0.82%)相对较低。其中Li、F、B、P等元素对成矿元素在成矿流体内的富集起到了极大的促进作用。矿区内大理岩是一种富Ca的方解石大理岩,为成矿提供了大量的Ca元素,有利于粗粒矿物的大规模沉淀。因此,粗粒矿物中的W、Sn、Be、Li、Rb、Cs、F、B、P等元素主要来源于原始岩浆流体,大理岩地层为粗粒矿物提供了大量的Ca元素。  相似文献   

15.
城市环境地球化学研究综述   总被引：20，自引：0，他引：20  
近年来地球科学越来越多地面向城市,城市环境受到人类活动的广泛影响,自然及人类活动引起的城市地球化学问题日益受到人们的重视。城市环境地球化学是应用地球化学的原理和方法研究城市生态环境问题,主要研究城市土壤、沉积物、尘埃、地表水、地下水、生物、空气等介质中化学元素及同位素的分布、演化、环境作用及健康效应,重点解决城市地球化学环境质量变化的原理及由此产生的生态环境效应及人体健康效应。城市环境地球化学的主要研究对象是传统工业城市、典型矿业城市及国际化的大都市。在城市地球化学概念出现之后短短的10余年时间内,很多国家开展了城市环境地球化学调查和研究工作,取得了重要的成果和进展,并发展成为环境地球化学与城市环境的重要方向,但仍存在着一定的问题,需要深入研究。目前,城市环境系统的地球化学填图、城市地球化学与环境污染研究、城市地球化学与生态风险研究、城市地球化学与人体健康研究、城市地球化学系统的调控与环境规划等领域是国际城市环境地球化学的热点和前沿。  相似文献   

16.
This study reports the results of thirteen rare-earth elements in thirty geochemical reference samples. Three alkali (K, Rb, Cs) and two alkaline earth (Sr, Ba) elements were also determined in eighteen reference samples. The analytical procedure involved is based on spiked samples and later measurement of the rare-earth elements by high-performance liquid chromatography and the alkalies and alkaline earths by thermo-quartz mass spectrometric isotope dilution (THQ-MSID). Whenever possible, the results are compared with literature values.  相似文献   

17.
Numerous natural and anthropogenic processes in a watershed produce the geochemical composition of a river, which can be altered over time by snowmelt and rainfall events and by built infrastructure (i.e., dams and diversions). Trace element concentrations coupled with isotopic ratios offer valuable insights to disentangle the effects of these processes on water quality. In this study, we measured a suite of 40+ trace and major elements (including As, Cd, Ce, Cr, Cs, Fe, La, Li, Mo, Pb, Rb, Sb, Se, Sr, Ti, Tl, U, and Zn), Sr isotopes (87Sr/86Sr), and stable isotopes of H and O (δD and δ18O) to investigate natural and anthropogenic processes impacting the Provo River in northern Utah, USA. The river starts as a pristine mountain stream and passes through agricultural and urban areas, with two major reservoirs and several major diversions to and from the river. We sampled the entire 120 km length of the Provo River at 13 locations from the Uinta Mountains to Utah Valley, as well as two important tributaries, across the range of hydrologic conditions from low flow to snowmelt runoff during the 2013 water year. We also sampled the furthest downstream site in the Utah Valley urban area during a major flood event. Trace element concentrations indicate that a variety of factors potentially influence Provo River chemistry, including inputs from weathering of carbonate/siliciclastic rocks (Sr) and black shales (Se and U), geothermal groundwater (As, Cs, Li, and Rb), soil erosion during snowmelt runoff (Ce, Cr, Fe, La, Pb, and Ti), legacy mining operations (Mo, Sb, and Tl), and urban runoff (Cr, Pb, and Zn). Although specific elements overlap between different groups, the combination of different elements together with isotopic measurements and streamflow observations may act as diagnostic tools to identify sources. 87Sr/86Sr ratios indicate a strong influence of siliciclastic bedrock in the headwaters with values exceeding 0.714 and carbonate bedrock in the lower reaches of the river with values approaching 0.709. δD and δ18O changed little throughout the year in the Provo River, suggesting that the river is primarily fed by snowmelt during spring runoff and snowmelt-fed groundwater during baseflow. Based on nonmetric multidimensional scaling (NMS) water chemistry was unique across the upper, middle, and lower portions of the river, with high temporal variability above the first reservoir but minimal temporal variability below the reservoir. Thus, the results show that dams alter water chemistry by allowing for settling of particle-associated elements and also by homogenizing inflows throughout the year to minimize dilution during snowmelt runoff. Taken together, trace element concentrations and isotopic measurements can be used to evaluate the complex geochemical patterns of rivers and their variability in space and time. These measurements are critical for identifying natural and anthropogenic impacts on river systems.  相似文献   

18.
Through a systematic observation of water level and temperature, and a comprehensive analysis of the data on major/trace elements, nitrite, hydrogen-oxygen isotopes, the conclusion has been drawn that there are two relatively independent groundwater systems （cool water and hot water）, and the geochemical indicators of hot/cool waters are described. The cool water system is relatively enriched in Ca^2＋, Mg^2＋ and HCO3^-. Its TDS is relatively low, about 1400-1800 mg/L. The hot water system is relatively enriched in K^＋, Na^＋, Cl^- and SO4^2-. Its TDS is relatively high, about 2200-2300 mg/L. The cool water system is enriched in Ba, Ga, Cd, and the hot water system is enriched in B, Ti, Cr, Ni, Cu, Mo, Rb, and Cs, relatively. Especially, the contents of Rb and Cs in the hot water system are more than five times as high as those in the cool water system. The NO3^- contents of cool water discharged from the gold mine are relatively high, and those of hot water are extremely low. The 8D and 8-80 values follow an increasing order of surface water〉mine cool water〉mine hot water. The cool water comes mainly from the lateral supply of phreatic water, while the hot water comes mainly from the vertical supply of deeply circulating structure-fracture water. The ratio of cool water over hot water was estimated to be about 1：1 by a water quality model..  相似文献   

19.
关键金属是全球高科技产业不可或缺的战略性资源,其富集机制和成矿作用是目前国际矿床学研究的热点之一。我们对喜马拉雅带吉隆和亚东地区淡色花岗岩开展系统的地球化学研究,发现侵入到藏南拆离系的淡色花岗岩含有较高的Sn、Cs、Tl、Be、W、B、Li和Bi。全岩元素地球化学分析表明,这些淡色花岗岩具有如下特征：（1）富集关键金属元素;（2）为原始岩浆经历斜长石、锆石、独居石、磷灰石、云母分离结晶作用后的残余熔体;（3）关键元素的富集和矿化与花岗岩高度分离结晶作用密切相关。随着分异程度的增强,岩浆变为富挥发分的高SiO2体系,关键金属元素在残余熔体中富集,并且最后可能形成具有工业价值的矿床。由于地球化学特征的相似性,Cs和Tl呈类质同象替代钾、铷进入云母中。富集关键金属元素的花岗岩在时间上和空间上属于与藏南拆离系相关的同构造侵位花岗岩,藏南拆离系的活动促使了原始岩浆的广泛分离结晶作用,以及后期的关键金属元素（如Rb、Cs和Tl）的富集。  相似文献   

20.
Chemical analyses and crystallographic and some optical data have been obtained for 28 samples of beryl from Bahia State, Brazil. The larger range of variability in the chemical composition is shown by Mg, Fe and Li. Sodium is the more diffuse alkali element. Potassium is always very limited. Calcium appears in noticeable amounts only in three samples. The Ti, Cr, Rb, and Cs elements were also tested. The samples studied here can be defined as sodium-potassium beryls with low alkali content. Unit cell parameters show the following ranges: a=9.210–9.245 and c=9.190–9.220 Å. From a statistical analysis of these data it may be seen that: an increase of Fe and (Fe+Mn+Mg) percentage has a positive correlation with a, but no influence on c, which in turn has a close positive correlation with Li and is negatively correlated with Be. Less negative correlations also exist between the pairs {Be, Li}, {a,Al}, {Al, Fe} and {Al, (Fe+Mn+Mg)}. A positive correlation also exists between sodium and the parameter a.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号