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1.
Field and laboratory investigations were performed to identify the principal mechanisms of the hydrochemical groundwater evolution
among low mineralised groundwater in the Triassic Bunter sandstone aquifer of the Odenwald low mountain range, central Germany.
Hydrochemical composition comprises low pH, SO4-rich shallow groundwaters issued by springs (Ca-Mg-SO4-type) grading to SO4-poor deep groundwaters with near-neutral pH (Ca-HCO3-type). Batch experiments of the original rock were run to determine primary mineral alteration reactions and the origin of
dissolved ions. Principal experimental reactions comprise the decomposition of anorthite, K-feldspar, biotite and jarosite
as mineral components of the original sandstone rock and the formation of clay minerals of the smectite group (Ca-montmorillonite,
beidellite), and iron hydroxides as secondary minerals. Mobilisation of fluid inclusion in quartz grains contributes to Na
and Cl concentrations in the leachates. The evolution of deep groundwater circulation proceeds by mineral alteration reactions
calculated by the inverse modelling of both primary and secondary minerals to produce low-T mineral phases. The dissolution
of K-feldspar converts Ca-montmorillonite to illite (illitisation). The formation of Na-beidellite correlates with decreasing
concentration of Na in solution. Mineral reactions further proceed to the formation of kaolinite as stable mineral phase.
As indicated by modelled adsorption curves, the decrease of SO4 concentrations during groundwater evolution relates to the adsorption of SO4 on iron hydroxides. The leaching of calcite indicated for individual groundwaters relates to the distribution of loess in
the appropriate catchment areas. 相似文献
2.
Jeremy H. Wei David B. Finkelstein Julie Brigham‐Grette Isla S. Castañeda Norbert Nowaczyk 《Sedimentology》2014,61(6):1793-1811
Marine Isotope Stage 11 has been proposed as an analogue for the present interglacial interval; yet, terrestrial climate records from both this region and time interval are rare. The sediments deposited at Lake El'gygytgyn (67°30′N, 172°5′E) in Far East Russia contain a 3·56 Ma record of climate variability. This study presents a high‐resolution record of sediment colour change from Marine Isotope Stage 8 to 12 (ca 275 to 475 ka) and demonstrates the link between lake catchment processes and climate variability. The hue colour parameter, calculated from data collected via colour reflectance spectroscopy in the visible spectrum (380 to 720 nm), exhibits correspondence with global climate records. Determining the source of sediment colour changes was achieved through detailed mineralogical and sedimentological methods, and linked to colour changes through a series of colour sensitivity tests. Mineralogical data, measured by X‐ray diffraction, reveal fluctuations in concentrations of clay minerals corresponding to colour changes. Further analyses of the clay mineral assemblages show no change in relative clay mineral abundances, yet demonstrate a lake catchment dominated by physical weathering processes. Using measured mineral abundances, reconstructions of sediment colour based on colour reflectance mineral standards link mineral and clay mineral content to overall sediment colour. Colour sensitivity tests demonstrate the ability of iron oxide minerals to stain sediments red. Additionally, colour sensitivity to organic matter content was tested, suggesting that organic content drives variability in the red portion of the spectrum and darkens the overall colour signal. Sediment colour is then ultimately linked to physical weathering of bedrock minerals, with small amounts of chemical weathering producing iron oxides during wet intervals. Fluctuations in the sediment colour reveal a high‐resolution record of wet/dry cycles, and provide new information about wet periods for the Russian Arctic region not yet understood from other lake proxy records. 相似文献
3.
E.C. Gaucher C. Tournassat F.J. Pearson C. Crouzet S. Altmann 《Geochimica et cosmochimica acta》2009,73(21):6470-6487
The chemistry of pore water is an important property of clayrocks being considered as host rocks for long-term storage of radioactive waste. It may be difficult, if not impossible, to obtain water samples for chemical analysis from such rocks because of their low hydraulic conductivity. This paper presents an approach for calculating the pore-water compositions of clayrocks from laboratory-measured properties of core samples, including their leachable Cl and SO4 concentrations and analysed exchangeable cations, and from mineral and cation exchange equilibria based on the formation mineralogy. New core sampling and analysis procedures are presented that reduce or quantify side reactions such as sample oxidation (e.g. pyrite) and soluble mineral dissolution (celestite, SrSO4) that affect measured SO4 concentrations and exchangeable cation distributions. The model considers phase equilibria only with minerals that are observed in the formation including the principal clay phases. The model has been used to calculate the composition of mobile pore water in the Callovo-Oxfordian clayrock and validated against measurements of water chemistry made in an underground research laboratory in that formation. The model reproduces the measured, in situ pore-water composition without any estimated parameters. All required parameters can be obtained from core sample analysis. We highlight the need to consider only those mineral phases which can be shown to be in equilibrium with contacting pore water. The consequence of this is that some conceptual models available in the literature appear not to be appropriate for modelling clayrocks, particularly those considering high temperature and/or high pressure detrital phases as chemical buffers of pore water. The robustness of our model with respect to uncertainties in the log K values of clay phases is also demonstrated. Large uncertainties in log K values for clay minerals have relatively small effects on modelled pore-water compositions. 相似文献
4.
甘肃省花牛山幅（K46E017023）1：50 000矿产地质图是根据《矿产地质调查技术要求（1：50 000）》和行业的统一标准及要求,在充分利用1：200 000、1：50 000等区域地质调查工作成果资料的基础上,采用数字填图系统进行野外地质专项填图,并应用室内与室外填编图相结合的方法完成的。本图对南华系-震旦系洗肠井群、寒武系西双鹰山组、奥陶系花牛山群的建造类型进行了重新划分,把图幅内侵入岩时代归纳为晚奥陶世—早志留世、泥盆纪、晚三叠世等3期,建立了岩浆岩的演化序列。本数据库包含12个地层单位和3期岩浆岩资料,数据量约为3.77 MB。这些数据充分反映了1：50 000矿产地质调查示范性成果,对该区矿产资源研究、能源勘探等具参考意义。 相似文献
5.
Y. R. Kulkarni S. J. Sangode D. C. Meshram S. K. Patil Yatindra Dutt 《Journal of the Geological Society of India》2014,83(4):376-384
Mineral magnetic analysis including thermo-magnetic studies and clay mineralogy on bed load and floodplain sediments from the Godavari river indicate distinct mineral assemblages. The floodplain sediments up to the delta region are characterised by unimodal ferrimagnetic mineralogy marked by the presence of maghemite and single domain magnetites derived from Deccan basalts. On the other hand the bed loads show varied magnetic mineral assemblages depicting greater local mixing from the non-basaltic bedrock province. The temperature dependent magnetic susceptibility and clay mineralogy of the floodplain samples show titanomagnetites (Fe3O4-Fe2TiO4), maghemite (χ LF-Fe2O3) and smectite that are characteristic of the Deccan Volcanic Province (DVP). Presence of this ferrimagnetically dominant unimodal assemblage up to the delta region and probably into the Bay of Bengal off the Godavari river is attributed to extensive chemical weathering of the basalt. The quantitative approach of mineral magnetism, therefore, can be used to study the paleomonsoon variability and its relation to Deccan basalt weathering from the Godavari-Bengal fan system. 相似文献
6.
用盐酸对高岭石和蒙脱石进行酸活化改性,再对酸活化后的蒙脱石进行羟基铝柱撑改性,然后采用X射线衍射仪对改性前后的矿物结构进行表征,并在此基础上,采用Hammett指示剂法,以正丁胺-环己烷滴定在H0为+4. 8～-5. 6酸强度范围的固体表面酸上,测出各粘土在不同酸强度下的酸量,拟合得到其酸强度分布曲线,最后以异丙苯裂解转化为模型考察了各粘土固体酸的催化性能。实验结果表明,高岭石和蒙脱石经酸活化后虽然可以提高异丙苯转化率,但是催化稳定性却有所降低;蒙脱石经过羟基铝柱撑改性后不仅大幅度提高了异丙苯转化率,而且还提高了催化稳定性。 相似文献
7.
J. M. Eiler J. W. Valley C. M. Graham L. P. Baumgartner 《Contributions to Mineralogy and Petrology》1995,118(4):365-378
Retrograde interdiffusion is widely proposed as the dominant factor in producing the stable isotopic fractionation among minerals
in slowly cooled igneous and metamorphic rocks. Mineral zonation consistent with interdiffusion of stable isotopes has never
been directly observed, however, leaving doubt as to the mechanism responsible for the bulk-mineral isotopic compositions
commonly measured. Ion microprobe analyses of oxygen isotope ratios in magnetite were combined with conventional bulk mineral
analyses and diffusion modeling to document the relationship between mineral zonation and the mechanism of retrogression inferred
from bulk mineral data. Two samples of magnetitebearing, quartzo-feldspathic Lyon Mountain gneiss from the Adirondack mountains,
N.Y. were studied in detail. Conventional stable isotope analysis of both samples indicates that isotope thermometers are
discordant and were reset by as much as 200°C from the estimated peak temperature of 750°C. The relative order of apparent
temperatures recorded by various thermometers differs between the two samples, however, with T
qtz-fsp≫T
mt-qtz and T
mt-fsp in one sample and T
qtz-fsp<T
mt-qtz and T
mt-fsp in the other. Diffusion modeling using the Fast Grain Boundary model shows that the former pattern of apparent temperatures
is consistent with closed system interdiffusion during cooling, whereas the latter is not. The modeling predicts that 0.5
mm diameter magnetite grains common to this rock type will contain isotopic zonation of 1‰ (rims lower in δ18O than cores), and that the cores of smaller (0.1 mm) grains will be similarly lower than to the cores of large (0.5 mm) grains.
Ion microprobe analysis reveals that the zoning patterns of magnetite grains from the first sample contain clear core to rim
zonation in multiple grains (Δcore-rim=1.1±0.4‰) and predicted grain-size vs core composition variations, consistent with
diffusion-controlled resetting of bulk mineral fractionations. In contrast, the second sample shows irregular inter-and intra-granular
variations over an 8‰ range, consistent with open system alteration. These results provide direct documentation of the importance
of interdiffusion in affecting stable isotope distributions in slowly cooled rocks. The correlations of bulk-mineral resetting
with zonation show that bulk mineral data, when interpreted with detailed modeling, can be used to determinate what processes
controlling retrogression. 相似文献
8.
Mineral prospectivity mapping is a classification process because in a given study area, a specific region is classified as either a prospective or non-prospective area. The cost of false negative errors differs from the cost of false positive errors because false positive errors lead to wasting much more financial and material resources, whereas false negative errors result in the loss of mineral deposits. Traditional machine learning algorithms using for mapping mineral prospectivity are aimed to minimize classification errors and ignore the cost-sensitive effects. In this study, the effects of misclassification costs on mapping mineral prospectivity are explored. The cost-sensitive neural network (CSNN) for minimizing misclassification costs is applied to map Fe polymetallic prospectivity in China’s southwestern Fujian metalorganic belt (SFMB). A CSNN with a different cost ratio ranging from 1:10 to 10:1 was used to represent various misclassification costs. The cross-validation results indicated a lower misclassification cost compared to traditional neural networks through a threshold-moving based CSNN. The CSNN’s predictive results were compared to those of a traditional neural network, and the results demonstrate that the CSNN method is useful for mapping mineral prospectivity. The targets can be used to further explore undiscovered deposits in the study area. 相似文献
9.
《矿床地质》是中国报道矿产资源最新研究成果的代表性刊物，同时也是汇集矿床学领域重要研究进展及成果的学术交流平台，对其载文热点追踪及期刊量化评价有助于梳理国内矿床学领域的研究进展，探究未来发展趋势，并为学科相关研究人员提供借鉴和参考。文章基于文献计量学研究、借助大数据和机器学习等手段，分析了1982~2022年《矿床地质》刊载论文的内容与信息，揭示矿床学40年的研究热点及主题演化情况，并通过与国际同领域知名期刊的对比，系统性地总结和讨论其展现的研究领域的进展和发展趋势。该刊主要聚焦于地球科学领域，热点关键词主要包括：流体包裹体、成矿作用、矿床成因、成矿流体和地质特征等。历年刊文可归纳为5个研究主题，包括区域成矿规律、成矿背景与构造环境、成矿流体和矿化特征、成岩成矿年龄和岩浆热液成矿作用以及元素富集成矿。热门地区主要是内蒙古、新疆和西藏等中西部省区。未来矿床学研究将会更加注重新技术和新方法的宏观和微观应用、多学科交叉融合对矿床成因机制和成矿规律的揭示，以及矿产勘查的综合指导等方面。 相似文献
10.
A new borate mineral has been found in a sample from Larderello, mixed with larderellite and lesser amounts of sassolite. The mineral is never well crystallized, but it constantly appears as very small, clear and colourless grains; its refractive indices are: =1.422, =1.435, =1.480. Single-crystal X-ray photographs show that the mineral is orthorombic with cell dimensions: =11.10 Å, b=11.18 Å, c=9.08 Å. X-ray powder diffraction and partial chemical analyses carried out on the whole sample (it being impossible to separate a sufficient quantity of pure material) confirm the foregoing data, according to which the mineral may be considered as the natural equivalent of the synthetic compound KB5O8 · 4H2O. It is likely that it originated from the reaction between potassium-bearing hot solutions and primary deposits of larderellite. It is named for the Tuscan naturalist Giorgio Santi.This new mineral has been approved by the Commission on New Minerals and New Mineral Names of the International Mineralogical Association.This research was supported by Consiglio Nazionale delle Ricerche, Roma. 相似文献
11.
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13.
Franziska Nehring Stephen F. Foley Pentti Hölttä 《Contributions to Mineralogy and Petrology》2010,159(4):493-519
Analyses of trace elements in the mineral phases of granulites provide important information about the trace element distribution
in the lower crust. Since granulites are often considered residues of partial melting processes, trace element characteristics
of their mineral phases may record mineral/melt equilibria thus giving an opportunity to understand the nature and composition
of melts in the lower continental crust. This study provides an extensive set of mineral trace element data obtained by LA-ICP-MS
analyses of mafic and intermediate granulites from Central Finland. Mass balance calculations using the analytical data indicate
a pronounced contribution of the accessory minerals apatite for the REE and ilmenite for the HFSE. Coherent mineral/mineral
ratios between samples point to a close approach to equilibrium except for minerals intergrown with garnet porphyroblasts.
Mineral trace element data were used for the formulation of a set of D
mineral/melt partition coefficients that is applicable for trace element modelling under lower crustal conditions. D
mineral/melt were derived by the application of predictive models and using observed constant mineral/mineral ratios. The comparison of
the calculated D
mineral/melt with experimental data as well as the relationship between mineral trace element contents and a leucosome with a composition
close to an equilibrium melt provides additional constraints on mineral/melt partitioning. The D values derived in this study are broadly similar to magmatic partition coefficients for intermediate melt compositions. They
provide a first coherent set of D values for Sc, V, Cr and Ni between clinopyroxene, amphibole, garnet, orthopyroxene, ilmenite and melt. In addition, they
emphasize the strong impact that ilmenite exerts on the distribution of Nb and Ta. 相似文献
14.
凹凸棒黏土是具有层链状结构的含水富镁铝硅酸盐矿物,矿床成因不同导致凹凸棒黏土中微量元素的组成存在差异,其中Be、Cr、Ni、As、Cd、Sb、Hg、Pb会对健康和环境产生不利影响,而V、Mn、Co、Cu、Zn、Mo、Sn、Ba作为凹凸棒黏土的重要微量元素影响其性能和应用范围,因此,对凹凸棒黏土中微量元素进行精准分析可为... 相似文献
15.
《Applied Geochemistry》2006,21(2):289-304
Mineral springs from Daylesford, Australia discharge at ambient temperatures, have high CO2 contents, and effervesce naturally. Mineral waters have high HCO3 and Na concentrations (up to 4110 and 750 mg/L, respectively) and CO2 concentrations of 620–2520 mg/L. Calcium and Mg concentrations are 61–250 and 44–215 mg/L, respectively, and Si, Sr, Ba, and Li are the most abundant minor and trace elements. The high PCO2 of these waters promotes mineral dissolution, while maintaining low pH values, and geochemical modelling indicates that the CO2-rich mineral water must have interacted with both sediments and basalts. Amorphous silica concentrations and silica geothermometry indicate that these waters are unlikely to have been heated above ambient temperatures and therefore reflect shallow circulation on the order of several hundreds of metres. Variations in minor and trace element composition from closely adjacent spring discharges indicate that groundwater flows within relatively isolated fracture networks. The chemical consistency of individual spring discharges over at least 20 a indicates that flow within these fracture networks has remained isolated over long periods. The mineral water resource is at risk from mixing with potentially contaminated surface water and shallow groundwater in the discharge areas. Increased δ2H values and Cl concentrations, and lower Na concentrations indicate those springs that are most at risk from surface contamination and overpumping. Elevated NO3 concentrations in a few springs indicate that these springs have already been contaminated during discharge. 相似文献
16.
Joyce K. FROST 《Geostandards and Geoanalytical Research》1991,15(1):43-50
Data for as many as 31 elements were determined by instrumental thermal neutron activation analysis for nine European Council for Mutual Economic Assistance (CMEA) rock and ore standards. The National Bureau of Standards plastic clay 98 and the University of Gent fired clay FCG were also analyzed. Synthetic, multielement standards were used and USGS rock standards provided reference samples. Correction factors for uranium fission products on cerium and molybdenum, and also for less commonly encountered spectral interferences, such as those due to the 213 ppm tantalum in granitoid 2B, were evaluated. 相似文献
17.
Carrick M Eggleston Andrew G Stack Kevin M Rosso Angela M Bice 《Geochemical transactions》2004,5(2):33
The reactivity of a mineral surface is determined by the variety and population of different types of surface sites (e.g.,
step, kink, adatom, and defect sites). The concept of "adsorbed nutrient" has been built into crystal growth theories, and
many other studies of mineral surface reactivity appeal to ill-defined "active sites." Despite their theoretical importance,
there has been little direct experimental or analytical investigation of the structure and properties of such species. Here,
we use ex-situ and in-situ scanning tunneling microcopy (STM) combined with calculated images based on a resonant tunneling model to show that observed
nonperiodic protrusions and depressions on the hematite (001) surface can be explained as Fe in an adsorbed or adatom state
occupying sites different from those that result from simple termination of the bulk mineral. The number of such sites varies
with sample preparation history, consistent with their removal from the surface in low pH solutions. 相似文献
18.
H. W. van der Marel 《Contributions to Mineralogy and Petrology》1964,9(5):462-480
A scheme is presented for the identification and classification of chlorite and related minerals in sediments which is mainly based on X-ray characteristics of the orginal sample and the sample heated at 350°C and treated with K+ and with glycerol. Examples are given. It is emphasized that additional data about clay mineral genesis, electron microscopy, infrared spectroscopy and chemical analyses are needed for the ordening of a certain mineral in the proposed scheme. Many names of minerals so far found to occur in the clay separate of sediments proved to be synonymous (52 of a total of 88) and thus should be abandoned. They only give confusion and needlessly increase the many difficulties which already exist in the identification, classification and quantitative determination of this complicated group of minerals of about 36 well defined specimens which may be found in sediments. 相似文献
19.
A total of about 1100 well-distributed samples of suspended matter in surface waters off the length of eastern Asia are available. From these samples, 180 were selected for detailed examination of the non-combustible fraction using optical and electron microscopy along with computer methods of particle measurement and counting. The results showed that, generally, all major components of the suspended matter are most abundant in the nearshore belt (combustible fraction, mineral grains of silt size, skeletal debris, and clay minerals), the result of mechanical transport of detrital sediment and chemical transport of nutrients from the land. Mineral grains of silt size average about 2%, skeletal debris plus clay minerals—23%, and combustible organic matter—75% of total sample weights, but the last two categories vary over a wide range depending upon geographical positions of the samples. Most evident is an oceanward decrease in percentage and concentration of the total noncombustible fraction and an oceanward increase in median diameter of the mineral grains. 相似文献
20.
As the two important components of shale, organic matter(OM) and clay minerals are usually thought to strongly influence the hydrocarbon generation, enrichment and exploitation. The evolution process of OM and clay minerals as well as their interrelationship over a wide range of thermal maturities are not completely clear. Taking Yanchang(T_3y), Longmaxi(S_1l) and Niutitang(?_1n) shales as examples, we have studied the microstructure characteristics of OM and clay minerals in shales with different thermal maturities. The effects of clay minerals and OM on pores were reinforced through sedimentation experiments. Using a combination of field emission scanning electron microscopy(FESEM) and low-pressure N_2 adsorption, we investigated the microstructure differences among the three shales. The results showed that both OM and clay minerals have strong effects on pores, and small mesopore(2–20 nm) is the dominant pore component for all three samples. However, the differences between the three samples are embodied in the distribution of pore size and the location. For the T_3y shale, clay minerals are loosely arranged and develop large amounts of pores, and fine OM grains often fill in intergranular minerals or fractures. Widespread OM pores distribute irregularly in S_1l shale, and most of the pores are elliptical and nondirectional. The ?_1n shale is characterized by the preferred orientational OM-clay aggregates, and lots of pores in the composites are in the mesopore range, suggesting that over maturity lead to the collapse and compaction of pores under huge pressure of strata. The results of the current research imply that with increasing thermal maturity, OM pores are absent at low maturity(T_3y), are maximized at high maturity(S_1l) and are destroyed or compacted at over-mature stage(?_1n). Meanwhile, clay minerals have gone through mineral transformation and orientational evolution. The interaction of the two processes makes a significant difference to the microstructure evolution of OM and clay minerals in shale, and the findings provide scientific foundation in better understanding diagenetic evolution and hydrocarbon generation of shale. 相似文献