The life and times of Big Bertha: lunar breccia 14321

The lithic units of polymict breccia 14321 (Big Bertha) have been grouped according to composition, texture, degree of metamorphism, and additional criteria based on a systematic study of the interrelationships of all clast-matrix pairs. From this information it has been possible to reconstruct the assembly and metamorphic history of this breccia. The earliest formed fragmental component of 14321 (microbreccia-1) is dominated by KREEP-rich norite, extruded and subsequently brecciated and lithified in an ejecta blanket at approximately 1000°C in the general region of Mare Imbrium after the Serenitatis impact but prior to the Imbrium impact. This early microbreccia component and lesser amounts of mare-type basalt, microgranite, rhyolite glass, anorthosite and olivine microbreccia were assembled at the Apollo 14 site as part of the Fra Mauro ejecta blanket from the Imbrium impact. The resulting microbreccia-3 incorporates all the lithic types above and accretionary lapilli structures (microbreccia-2) in a dark matrix annealed at approximately 700°C. A later impact on the Fra Mauro excavated and mutually abraded microbreccia-3 and a local, 14321-type, basalt which were assembled into polymict breccia 14321. Final placement of 14321 at its sampling location was accomplished during the minor Cone Crater impact event.     

桂岭岩体稀土、微量元素地球化学特征研究

文章运用岩石地球化学方法,对桂岭岩体的构造环境和地球化学特征进行了研究,结果显示：桂岭岩体岩石平均LREE／HREE=7．68,（La／Yb）N-6．77,（La／Sm）N-4．65,（Gd／Yb）N-1．04,平均δEu=0．45〈1,表明轻重稀土轻度分异,轻稀土相对富集,轻稀土内部分馏明显,存在负铕异常;岩体明显亏损Nb、Sr、Ti,显示桂岭岩体的源区可能主要来自地壳,是地壳环境下壳源岩石发生部分熔融的产物;研究表明,桂岭岩体形成于挤压一伸展的大地构造环境。     

Evolution of lunar materials in light of the abundance variation of oxyphile trace elements

Based on the lunar data on lanthanides, U, Th, Ba, and Sr, the partition coefficients for fractional solidification were estimated for these elements. The resultant values suggest the removal of solids with perhaps pyroxenic composition. The partition coefficient for europium can be judged to be normal as divalent europium dominantly present in the melt. When we go back following the trend of fractionation of abundances, we can reach the stage where there is no europium anomaly and where the thorium concentration level is chondritic. It can be imagined that the material corresponding to this stage was the directly original lunar material system. As a possibility, a zone melting is thought to be a possible process for the derivation of that material from chondritic material. The chondrite-normalized lanthanide patterns for silicate materials of two stony-irons appear to provide us with an intriguing clue to this problem.     

General equations for modeling fluid/rock interaction using trace elements and isotopes

General equations for modeling open and closed system fluid/rock interaction using trace elements and isotopes are presented. Taylor's (1977) open system equation for stable isotopes is extended to account for a change in the Δ value between rock and fluid during interaction. It is shown that hydrothermal systems in which fractionation factors vary during fluid/rock interaction will significantly alter the isotopic ratios of rocks compared to equivalent systems with invariant fractionation factors. The equations for modeling trace element exchange are analogous to the stable isotope equations and permit the calculation of fluid/rock ratios using changes in trace element concentrations in the rock. Similarly to stable isotope exchange, the change of the trace element concentration in a rock during infiltration is a function of the trace element concentration in the fluid, the fluid/rock partition coefficient and the fluid/rock ratio rather than simply the concentration of the trace element in the fluid.     

Solar cosmic ray records in lunar rock 64455

Cosmic ray produced ¹⁰Be (half-life = 1.36 × 10⁶ yr), ²⁶Al (7.05 × 10⁵ yr), and ³⁶Cl (3.01 × 10⁵ yr) were measured in a depth profile of 19 carefully-ground samples from the glass-coated lunar surface rock 64455. The solar cosmic ray (SCR) produced ²⁶Al and ³⁶Cl in this rock are present in high concentrations, which in combination with the low observed erosion rate, <0.5 mm/Myr, provide well defined depth profiles characterizing the SCR component of the cosmic rays. In conjunction with new experimentally determined excitation functions, the ³⁶Cl concentrations suggest a softer solar-proton spectral shape than that derived from most previous measurements. The fact that no SCR-produced ¹⁰Be activity could be detected in 64455 is in good agreement with observations in 68815 and also indicates a softer SCR spectrum. Comparison of observed SCR profiles in 64455 with theoretical calculations indicates that the average solar-proton spectrum over the past 2 Myr (based on ²⁶Al) has an exponential rigidity parameter (R₀) of about 90 MV with a proton flux (J) of 73 protons/cm²/s·4π above 10 MeV. Over the last ∼0.5 Myr (based on ³⁶Cl) R₀ is about 70 MV with a flux of ∼196 protons/cm²/s·4π above 10 MeV. These SCR fluxes are consistent with most previous work.     

Fracture zone-scale variation of trace elements and stable isotopes in calcite in a crystalline rock setting

With an aim to increase the understanding about the isotopic and chemical heterogeneity of calcites in water-conducting fracture zones with different crystalline wall rock compositions at different depths, we present trace element chemistry, isotopic composition (δ¹⁸O, δ¹³C, ⁸⁷Sr/⁸⁶Sr) and biomarkers of euhedral low-temperature fracture-coating calcite. Paleohydrogeological fluctuations and wall rock influence on the hydrochemistry in the deep groundwater are explored. Samples are from several fracture zone sub-fractures (at −360 to −740 m), retrieved during an extensive core drilling campaign in Sweden.Calcite generally showed fracture zone specific values of δ¹³C, δ¹⁸O and ⁸⁷Sr/⁸⁶Sr, which indicates precipitation from relatively homogeneous fluid (similar to the modern groundwater at the site) at the same event in each fracture zone. δ¹⁸O and δ¹³C in the different fracture zones were consistent with precipitation from waters of different salinity and decreasing organic input with depth, respectively. The latter is also supported by biomarkers showing clear indications of SRB-related organic compounds (e.g. iso- and anteiso-C_17:0-branched fatty acids), except in the deepest zone. In contrast to the isotopes, variation in trace elements within the fracture zones was generally up to several orders of magnitude. Manganese and REE, as oppose to the other metals, were higher in the shallow fracture zones (112–1130 and 44–97 ppm, respectively) than in the deeper (28–272 and 5–11 ppm, respectively), in agreement with the groundwater composition. Although the rock types varied between and within the different fracture zones, this had insignificant influence on the trace element chemistry of the calcites. Co-variation was generally relatively large for many trace elements, with isometric logratio correlation generally better than 0.75, which indicates that their variation in the calcites is due to variation of Ca in the fracture water, but other local factors, especially uptake in co-precipitating minerals (clay minerals, barite, pyrite and zeolites), but also microbial activity and metal speciation may have influenced the metal incorporation into calcite. These detailed studies of fracture calcite are of importance for the understanding of variation in fluid chemistry and trace metal uptake in fracture zones, adding together with hydrochemical studies detailed information optimal for site characterisation.     

Paleohydrogeological events recorded by stable isotopes,fluid inclusions and trace elements in fracture minerals in crystalline rock,Simpevarp area,SE Sweden

Fracture minerals calcite, pyrite, gypsum, barite and quartz, formed during several events have been analysed for δ¹³C, δ¹⁸O, δ³⁴S, ⁸⁷Sr/⁸⁶Sr, trace element chemistry and fluid inclusions in order to gain knowledge of the paleohydrogeological evolution of the Simpevarp area, south-eastern Sweden. This area is dominated by Proterozoic crystalline rocks and is currently being investigated by the Swedish Nuclear Fuel and Waste Management Co. (SKB) in order to find a suitable location for a deep-seated repository for spent nuclear fuel. Knowledge of the paleohydrogeological evolution is essential to understand the stability or evolution of the groundwater system over a time scale relevant to the performance assessment for a spent nuclear fuel repository. The ages of the minerals analysed range from the Proterozoic to possibly the Quaternary. The Proterozoic calcite and pyrite show inorganic and hydrothermal-magmatic stable isotope signatures and were probably formed during a long time period as indicated by the large span in temperatures (c. 200–360 °C) and salinities (0–24 wt.% eq. CaCl₂), obtained from fluid inclusion analyses. The Paleozoic minerals were formed from organically influenced brine-type fluids at temperatures of 80–145 °C. The isotopic results indicate that low temperature calcite and pyrite may have formed during different events ranging in time possibly from the end of the Paleozoic until the Quaternary. Formation conditions ranging from fresh to brackish and saline waters have been distinguished based on calcite crystal morphologies. The combination of δ¹⁸O and crystal morphologies show that the fresh–saline water interface has changed considerably over time, and water similar to the present meteoric water and brackish seawater at the site, have most probably earlier been residing in the bedrock. Organic influence and closed system in situ microbial activity causing disequilibrium are indicated by extremely low δ¹³C (down to −99.7‰), extreme variation in δ³⁴S (−42.5‰ to +60.8‰) and trace element compositions. The frequency of calcite low in δ¹³C and high in Mn, as well as pyrite with biogenically modified δ³⁴S decreases with depth. Strontium isotopes have been useful to separate the different generations and the Sr isotope ratios in the groundwaters have been determined mainly by in situ water–rock interaction processes. The difficulty of separating late Paleozoic calcite from possibly recent calcite, and the fact that these calcites are usually found in the same fracture systems indicate that water conducting structures have been intermittently conductive from the Paleozoic and onwards. The methodology used has been successful in separating the different generations and characterising their formation conditions.     

Volatile and siderophile trace elements in anorthositic rocks from Fiskenaesset. West Greenland: comparison with lunar and meteoritic analogues

Seventeen trace elements (Ag, Au, Bi, Br, Cd, Cs, Ge, Ir, Ni, Rb, Re, Sb, Se, Te, Tl, U, Zn) were analyzed by radiochemical neutron activation and 13 other elements (Ce, Co, Cr, Eu, Fe, Hf, La, Lu, Na, Sc, Sm, Tb, Yb) by instrumental neutron activation in a total of 12 rocks from the layered anorthositic complex at Fiskenaesset, West Greenland and in the plagioclase-rich unbrecciated eucrite, Serra de Magé.Garnet anorthosite 84428, which has an unusually sodic plagioclase, is spectacularly enriched in Cs, K, Rb. Tl and, to a lesser degree, Te. This appears to be the result of later metasomatism and not a reflection of fractionation trends within the anorthositic complex. For the remaining Fiskenaesset rocks, a factor analysis yields 5 principal factors for linear data for 22 elements and 6 factors for data transformed (log, ³√, √) to give approximately normal distributions. Linear correlations are controlled by high values, whereas the logarithmic transform increases the influence of the lowest values. Enrichment of several elements in chromitite 132022 underlies linear Factor 1. Six of these elements Co, Cr, Fe, Ir, Ni, Zn and possibly Re are probably hosted by chromite. In other zones of the intrusion, different fractionation trends may be more important, since in the transformed analysis these elements divide between Factor 1 (Co, Zn, Ni, Fe) and Factor 4 (Ir, Cr and also Au). Linear Factor 2 reflects the strong mutual correlation between Tl, Rb and An, the anorthite content of plagioclase. Transformed Factor 3 emphasizes the anticorrelation of Na and Sm with An. The positive correlations of Cs, U and Ge (linear Factor 3; transformed Factor 2) are largely due to their concentration in later crystallizates, but enrichment in lower zone gabbros of high An content perhaps indicates concentration in minor or accessory cumulate minerals. Flat chondrite-normalized rare earth element patterns in several anorthosites (except for a small positive Eu anomaly) suggests that the Fiskenaesset magma was relatively unfractionated.Factor 4 (linear) and Factor 5 (transformed) reflects the geochemical coherence of Se and Te. The sympathetic enrichment of Sb and Cd in 3 rocks, resulting in Factor 5 (linear) and Factor 6 (transformed) may be due to the lack of a suitable Zn sulfide host for Cd.In 3 rocks of true anorthosite composition, 8 volatile elements show rather constant abundance when normalized to Cl chondrites (mean 4.2 ± 0.4% Cl), possibly suggesting that volatile-rich material was accreted late in the Earth's formation, perhaps after core segregation. These anorthosites are higher than lunar anorthosite 15415 by a factor of 58 ± 9 in volatile elements. Siderophile and chalcophile elements are much more variable in Cl-normalized abundances in both lunar and terrestrial anorthosites, but surprisingly give somewhat similar Earth/Moon abundance ratios.Volatile elements in terrestrial oceanic basalts and lunar mare basalts are not as uniformly abundant as in anorthosites. but nevertheless yield a similar Earth/Moon ratio of 44 ± 8.Volatile elements in Serra de Magé are more abundant than in lunar anorthosites, but lower than in terrestrial equivalents, averaging (3.6 ± 0.8) × 10^?3C1.     

The geochemistry of trace elements in geothermal fluids,Iceland

Trace element geochemistry was studied in geothermal fluids in Iceland. The major and trace element compositions of hot springs, sub-boiling, and two-phase (liquid and vapor) wells from 10 geothermal areas were used to reconstruct the fluid composition in the aquifers at depth. Aquifer fluid temperatures ranged from 4 to 300 °C, pH values between 4.5 and 9.3, and fluids typically contained total dissolved solids <1000 ppm, except in geothermal areas that have seawater and seawater-meteoric water mixtures. Trace alkali elements Li, Rb and Cs are among the most mobile elements in aquifer fluids, with concentrations in the range of <1 ppb to 3.49 ppm Li, <0.01 to 57 ppb Cs, and <1 ppb to 3.77 ppm Rb. Their chemistry is thought to be dominated by rock leaching and partitioning into Na- and K-containing major alteration minerals. Arsenic, Sb, Mo and W are typically present in concentrations in the range of 1–100 ppb. They are relatively mobile, yet Mo may be limited by molybdenite solubility. The alkaline earth elements Ba and Sr are quite immobile with concentrations in the range of <0.1–10 ppb Ba and <1–100 ppb Sr in the dilute fluids, but up to 5.9 ppm Ba and 8.2 ppm Sr in saline fluids. These elements show a systematic relationship with Ca, possibly due to substitution for Ca in Ca-containing major alteration minerals like calcite, epidote and anhydrite. Incorporation into major Ca-minerals may also be important for Mn. Many metals including Fe, Cr, Ni, Zn, Cu, Co, Pb and Ag have low mobility and concentrations, typically <1 ppb for Ag, Cd, Co, Cr, Cu, Ni, and Pb, <10 ppb for Zn and < 100 ppb for Fe, although for some metals higher concentrations are associated with saline fluids. Based on the metals assessed, saturation is approached with respect to many sulfide minerals and in some cases oxide minerals but Cu, Ni and Pb minerals are slightly but systematically undersaturated, and Ag phases significantly undersaturated. Evaluation of mineral-fluid equilibria for these metals is problematic due to their low concentrations, problems associated with assessing the aqueous species distribution by thermodynamic calculations, and uncertainties concerning the exact minerals possibly involved in such reactions. Reaction path calculations, poor comparison of concentrations measured in the samples collected at the wellhead and published downhole data as well as boiling, cooling and mass precipitation calculations suggest removal of many metals due to changes upon depressurization boiling and conductive cooling of the aquifer fluids as they ascend in wells. These results imply that processes such as mass precipitation upon fluid ascent may be highly important and emphasize the importance of considering mass movement in geothermal systems.     

Concentration and association of minor and trace elements in Mukah coal from Sarawak, Malaysia, with emphasis on the potentially hazardous trace elements

The ash yield and concentrations of twenty-four minor and trace elements, including twelve potentially hazardous trace elements were determined in Mukah coal from Sarawak, Malaysia. Comparisons made to the Clarke values show that Mukah coal is depleted in Ag, Ba, Be, Cd, Co, Mn, Ni, Se, U, and V. On the other hand, it is enriched in As, Cr, Cu, Pb, Sb, Th, and Zn. Among the trace elements studied, V and Ba are associated predominantly with the clay minerals. Manganese, Cr, Cu, Th, and Ni are mostly bound within the aluminosilicate, sulphide and/or carbonate minerals in varying proportions, though a portion of these elements are also organically bound. Arsenic, Pb and Sb are mostly organically bound, though some of these elements are also associated with the sulphide minerals. Zinc is associated with both the organic and inorganic contents of the coal. Among the potentially hazardous trace elements, Be, Cd, Co, Mn, Ni, Se, and U may be of little or no health and environmental concerns, whereas As, Cr, Pb, Sb and Th require further examination for their potential health and environmental concerns. Of particular concern are the elements As, Pb and Sb, which are mostly organically bound and hence cannot be removed by physical cleaning technologies. They escape during coal combustion, either released as vapours to the atmosphere or are adsorbed onto the fine fly ash particles.     

Spectrochemical determination of trace elements in the U.S.G.S. silicate rock standards

Spectrographic determinations for twenty trace elements in the six new U.S.G.S. silicate rock standards along with the rock standards G-1, W-1, SR-1, GR and BR are given. Most of the results represent the average of triplicate determinations on each of five splits of the portions of the standards available to the authors. Thus, the preferred values represent, in most cases, the average of fifteen replicate determinations.     

Heat-producing elements in the lunar mantle: Insights from ion microprobe analyses of lunar pyroclastic glasses

We provide new estimates for the abundance of heat-producing elements in the lunar mantle by using SIMS techniques to measure the concentrations of thorium and samarium in lunar pyroclastic glasses. Lunar pyroclastic glasses are utilized in this study because they represent quenched products of near-primary melts from the lunar mantle and as such, they provide compositional information about the mantle itself. Thorium and samarium were measured because: (1) Th is not significantly fractionated from Sm during partial melting of the pyroclastic glass source regions, which are dominated by olivine and pyroxene. Therefore, the Th/Sm ratios that we measure in the pyroclastic glasses reflect the Th/Sm ratio of the pyroclastic glass source regions. (2) Strong correlations between Th, U, and K on the Moon allow us to use measured Th concentrations to estimate the concentrations of U and K in the pyroclastic glasses. (3) Th, Sm, U, and K are radioactive elements and as such, their concentrations can be used to investigate heat production in the lunar mantle.The results from this study show that the lunar mantle is heterogeneous with respect to heat-producing elements and that there is evidence for mixing of a KREEP component into the source regions of some of the pyroclastic glasses. Because the source regions for many of the glasses are deep (?400 km), we propose that a KREEP component was transported to the deep lunar mantle. KREEP enriched sources produce 138% more heat than sources that do not contain KREEP and therefore, could have provided a source of heat for extended periods of nearside basaltic magmatism. Data from this study, in conjunction with models for the fractional crystallization of a lunar magma ocean, are used to show that the average lunar mantle contains 0.15 ppm Th, 0.54 ppm Sm, 0.039 ppm U, and 212 ppm K. This is a greater enrichment in radiogenic elements than some earlier estimates, suggesting a more prolonged impact of radiogenic heat on nearside basaltic volcanism.     

Activities of trace elements in silicate melts

A theoretical model has been developed which describes the amphoteric character of oxides in silicate melts. This has been used to account for the increased stability of the higher oxidation states of altervalent trace elements in silicate melts with increasing basicity and to derive a general expression for the estimation of trace element activities in silicate melts.     

Minor and trace elements in HF-soluble zircons

Electron probe analysis of a group of HF-soluble zircons from porphyroids of the Thuringian Forest, Germany, established yttrium, phosphorus, and iron to be the significant minor constituents. It is believed that these elements render the zircon structure HF-soluble. The Y content varies from about 6500–48000 ppm=0.83–6.10% Y₂O₃; the P concentrations range from a low of about 790 to a maximum of 4000 ppm=0.18–0.92% P₂O₅; the Fe content varies from about 400–15000 ppm=0.06–2.10% Fe₂O₃. Although both Y and P are distributed throughout each given grain, they are sometimes mutually enriched in growth zones. These zones are also resolved in reflected light micrographs and the electron images.     

Fertiliser characterisation: Major,trace and rare earth elements

In recent years, there has been increasing concern regarding the chemical impact of agricultural activities on the environment so it is necessary to identify contaminants, and/or characterise the sources of contamination. In this study, a comprehensive chemical characterisation of 27 fertilisers of different types used in Spain has been conducted; major, minor and trace elements were determined, including rare earth elements. Results show that compound fertilisers used for fertigation or foliar application have low content of heavy metals, whereas fertilisers used for basal and top dressing have the highest content of both REE and other heavy metals. REE patterns of fertilisers have been determined in order for them to be used as tracers of fertilisers in future environmental studies. Furthermore in this work REE patterns of fertilisers are used as tracers of the source of phosphate in compound fertilisers, distinguishing between phosphorite and carbonatite derived fertilisers. Fertilisers from carbonatites have higher contents of REE, Sr, Ba and Th whereas fertilisers from phosphorites have higher contents of metals of environmental concern, such as Cd, U and As; and the sum of the heavy metals is higher. Some of the analysed fertilisers have Cd concentrations that exceed maximum values established in some countries and can be expected to produce long-term soil accumulation. Furthermore, other elements such as U, As and Cr are 10–50 times higher in concentration than those of Cd, but there is no legislation regarding them, therefore it is necessary to regulate fertiliser compositions in order to achieve environmental protection of soils and waters.     

华北克拉通东北部新太古代晚期岩浆作用和地壳增生:锆石U-Pb-Hf同位素、微量元素和地球化学制约

辽西-辽南地区新太古代花岗质岩石的锆石LA-ICP-MS U-Pb年代学和微量元素及全岩地球化学和锆石Hf同位素研究为探讨华北克拉通东北部前寒武纪地壳生长和演化提供了制约。结果表明,辽西地区钓鱼台二长花岗岩和辽南地区城子坦片麻状石英闪长岩、安波花岗质片麻岩中锆石均发育岩浆生长环带,结合相对高的Th/U比值(0.24~1.75)和锆石稀土元素特征,暗示它们均为岩浆锆石。定年结果显示,钓鱼台二长花岗岩、城子坦片麻状石英闪长岩和安波花岗质片麻岩的原岩分别形成于2519±9Ma、2505±10Ma和2519±11Ma,即它们均形成于新太古代晚期。辽西-辽南地区新太古代花岗质岩石均具有高SiO2(61.85%~73.38%)、低MgO(0.36%~2.83%)、富Na2O+K2O(7.64%~10.86%)的特征,为准铝质-弱过铝质的高钾钙碱性系列岩石;富集轻稀土元素和大离子亲石元素,亏损重稀土元素和高场强元素,发育弱的Eu负异常和Sr、P、Ti的亏损。岩浆锆石均具有正的εHf(t)值,介于0.4~5.9之间,tDM1变化于2595~2798Ma之间,峰值年龄为2740Ma,与华北克拉通最重要的一次地壳增生事件相一致。辽西-辽南地区新太古代花岗质岩石形成于板块俯冲的弧构造环境下新增生下地壳物质的部分熔融。     

A lunar rock of deep crustal origin: sample 76535

Lunar sample 76535 is a coarse-grained troctolitic granulite exhibiting a texture indicative of long annealing times. It is composed of homogeneous crystals of plagioclase (58 per cent, An₉₆), olivine (37 per cent, Fo₈₈) and bronzite (4 per cent, En₈₆).Chromian spinel-bronzite-diopside (Wo₄₆En₅₀Fs₄) symplectic intergrowths commonly occur along olivine-plagioclase boundaries and as tiny inclusions within olivine grains. These symplectites apparently formed by a reaction of the type:

$\text{OI + An + Chromite → Opx + Cpx + Al-Mg-chromite}$

. The reaction is related to the experimentally determined reaction

$\text{OI + An = Opx + Cpx + Sp}$

of Kushiro and Yoder (1966). The enstatite content of the diopside coexisting with the bronzite indicates equilibration at about 1000°C. Thermodynamic calculations for 1000°C indicate that the symplectites formed at a minimum pressure of about 0.6 kb. Low alumina contents of the pyroxenes indicate equilibration near this minimum pressure.Clusters of the same assemblage found in the symplectic intergrowths, but containing accessory metal, troilite, Ca-phosphates, baddeleyite, plagioclase and/or K-feldspar occur sporadically throughout the rock. These apparent late stage products crystallized in the low temperature-high pressure region discussed above.Phase relations of co-existing metal phases indicate that the rock cooled at a few tens of degrees/my, corresponding to depths of 10–20 km below the lunar surface, in agreement with the above pressure estimate.We infer that 76535 represents an original cumulate deposited at a depth between about 10 and 30 km. The last liquid crystallized in the relatively high pressure-low temperature field opx + cpx + Al-Mg-chromite. Cooling was extremely slow and accompanied by extensive chemical and textural re-equilibration. Reaction to form the symplectites occurred during the late stages of re-equilibration.     

福建马坑矿区水化学微量组分的指示作用

通过对区域地质背景调查分析、现场取样和室内测试,研究了马坑矿区地下水水化学特征,确定不同类型地下水的特征鉴别离子,分析地下水中微量元素含量异常原因所在,并通过研究地下水中稀土元素的水文地球化学特征,判断矿区地下水径流交替的强弱和稀土元素富集特征,为判别矿坑主要涌水水源提供确切依据。