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1.
Ternary (triangular) diagrams show the compositional variation of three end-members, recalculated to 100%, and represent the projection into two dimensions of three or more components (since an end-member may represent the sum of more than one original component), and hence multiple space. During the present century they have been of particular importance in chemistry, the earth sciences, colour-mixing and the studies of colour that underlie the development of geochemical colour maps. Such concepts can be traced back to Newton's Opticks although he did not use an explicit ternary theory of colour mixing. Development of the trichromatic theory of colour deficiency began with Mariotte in the 17th century and was definitively established by Maxwell in the 1850s. These colour theorems underlie the development in recent years of the colour maps now in widespread use in geochemistry. The progress of regional geochemical mapping in the British Isles has gone hand-in-hand with the development of computer software and hardware. The use of multi-element colour-combined geochemical maps can be traced from early work at Imperial College by Webb and his co-workers (1964–79) to its later application in the British Geological Survey's Geochemical Atlas series (from 1983 onwards). Between 1955 and 1975 the use of ternary diagrams came to be commonly used in studies of mineralogical composition, including economic minerals, petrology, classification, and phase relationships. In igneous petrology, the quartz–alkali-feldspar–plagioclase-feldspathoid double-triangle has achieved increasing international acceptance. We illustrate these applications with examples pertinent to the Northern Highland Caledonides, with particular emphasis on the lamprophyres and associated rocks. Two distinct multivariate trends of variation are shown to be present which may warrant further investigation to elucidate their bearing on Caledonian mineralisation. 相似文献
2.
Dahab stream sediments, southeastern Sinai, Egypt: a potential source of gold, magnetite and zircon 总被引：1，自引：0，他引：1
A. A. Surour A. A. El-Kammar E. H. Arafa H. M. Korany 《Journal of Geochemical Exploration》2003,77(1):25-43
The stream sediments of Dahab area, southeastern Sinai, Egypt, were studied for their content of economic minerals. These sediments are immature as indicated by poor sorting and other mechanical parameters. They are derived from Precambrian basement rocks, which are mostly represented by granitic rocks in addition to lesser amounts of volcanics and gabbros. The mineralogical investigation revealed that these sediments contain considerable amounts of placer gold, Fe–Ti oxides and zircon.The concentrated Fe–Ti oxides comprise homogeneous magnetite and ilmenite in addition to ilmeno-magnetite, hemo-ilmenite and rutile–hematite intergrowths. Isodynamic separation of some raw samples of SIZE=1 mm revealed that up to 15.12% magnetic minerals can be recovered. Zircon shows remarkable variations in morphology, colour, chemistry and provenance. U-poor and U-rich varieties of zircon were discriminated containing UO2 in the ranges of 0.04–1.19 and 3.05–3.68 wt.%, respectively. REE-bearing minerals comprise monazite, allanite and La-cerianite.On mineralogical basis, the present work suggests that Dahab stream sediments represent a promising target for further geochemical exploration for precious metals, especially gold. Fire assay data indicate that placer gold in the studied sediments sometimes reaches 15.34 g/t. Narrow gullies and valleys cutting the basement manifest the development and preservation of gold in this arid environment. Background concentration of gold and variation in lithology suggest multiple source of the metal in the investigated sediments. 相似文献
3.
Estonia may be taken as an example of how cartography has developed in the national languages of the Baltic States. Late in the 17th century the first survey of Estonian and Latvian territories was carried out by the Swedes. Masterpieces of the 18th century and the first half of the 19th century are the Atlas of Livonia by L. A. Mellin and a special map of Livonia by C. G. Rücker. The first maps in Estonian appeared more than one hundred years ago. The short period of independence, 1918–1940, was one of rapid development in cartography, interrupted by occupation of the Baltic States by the USSR. Maps were destroyed or declared secret; use of maps was limited. From the beginning of the 1990s, a rapid renaissance of national cartography began. 相似文献
4.
Forster, A. and Culshaw, M.G., 1990. The use of site investigation data for the preparation of engineering geological maps and reports for use by planners and civil engineers. Eng. Geol., 29: 347–354.
In modern cities hundreds of site investigations have been carried out before the construction of roads, offices, factories and housing estates. The results of these investigations represent a large resource of geological and geotechnical information worth millions of pounds. Much of this information is lost, or is not accessible, because of confidentiality; that which is available will be of variable content and quality. The geographical and stratigraphical distribution will also be uneven. However, maps, and resumés of the engineering behaviour of the geological materials in an area, can be produced to guide planners and to help engineers at the earliest stage of development.
In this paper the authors discuss the use of the data contained in site investigation reports to prepare engineering geological maps and illustrate this by reference to recent applied geological mapping projects carried out by the British Geological Survey. 相似文献
5.
6.
Three periods in the development of geochemical methods for ore prospecting in Bulgaria may be distinguished — initial (1954–1960), middle (1961–1969) and contemporary (since 1970) — which are characterized by successively increasing numbers of samples and improving methods of geochemical data evaluation. Geochemical methods have been recognized as effective, rapid and relatively cheap methods for prospecting for ore deposits (Cu, Pb, Zn, Au, W, Mo, etc.), some nonmetalliferrous raw materials (fluorite, barite, phosphorites) and hydrocarbons. They are used in all stages of exploration at scales from 1:200,000 to 1:200. They have contributed to the elucidation of the ore perspectives in many regions, and a number of new ore bodies and deposits have been discovered.Basic geochemical methods applied to ore prospecting in the country utilize soil and rock to detect secondary and primary aureoles. Stream-sediment surveys, hydrochemical and atmochemical methods are of more restricted use. Samples are analyzed by emission spectrometry, atomic absorption and other methods. A united system of computerized processing of geochemical data has been developed, including automatic drawing of geochemical maps.Interpretation of the data consists in selection of prospective geochemical anomalies and prognostication of the composition, morphology, depth and industrial significance of hidden ore bodies. The main problem in the mathematical processing of data is the presentation of polydimensional results from analyses in the form of generalized quantities — multiplicative or additive geochemical indicator ratios for the type of mineralization, coefficients of zoning, intensity, etc. The geochemical indices for evaluation of the newly found anomalies are derived through studies of the primary geochemical aureoles of typical standard ore deposits.Residual secondary soil aureoles in most cases are well correlated in composition and structure with the ore bodies and primary aureoles which have generated them. Their successful use is related to the landscape-geochemical conditions in the ore regions. Micro- and macro-chemical zoning of ground waters and different concentration of soluble components in different elevation belts are used for evaluation of hydrochemical anomalies. 相似文献
7.
This study utilizes three major data sources: distribution of geological units; density, type, age and distribution of mineral deposits; and elemental analyses from regional geochemical stream sediment surveys to define parameters that ‘characterize’ tectonic terranes in northern British Columbia. A similar approach could be applied anywhere in the Canadian Cordillera.This area, NTS map sheets 104N, 104O and 104P along the British Columbia-Yukon border, forms a transect through allochthonous terranes into North American rocks. These are: the allochthonous island-arc Stikine, oceanic Cache Creek, cataclastic Yukon/Tanana, and island-arc Quensel terranes, the pericratonic Dorsey terrane; the parautochthonous oceanic Sylvester allochthon; and the autochthonous miogeoclinal North American Cassiar terrane. Plutonic rocks of Jurassic-Cretaceous to Tertiary age intrude all terranes.Data sources used in the study are geological base maps and reports, the Ministry of Energy Mines and Petroleum Resources' mineral deposit database (MINFILE) and analytical data from the National Regional Geochemical Survey stream sediment and water sampling program.Geological maps were compiled from various sources and plotted to act as bases for geochemical and mineral deposit overlays for analysis and interpretation.Geochemical samples were separated into background and anomalous populations and compared according to their source terranes. We found that mean concentrations from background sample populations for some elements are statistically distinctive for different terranes. Unfortunately, elemental correlation coefficients for the terranes are similar so cannot be used to characterize each terrane.Data on mineral deposits and occurrences were compiled from minfile and other sources. Particular attention was paid to deposits with histories of production or significant reported reserves. Deposits were sorted by type and commodity to produce synoptic metallogenic maps.The combined data from geological, geochemical and mineral deposit databases form a strong tool for interpreting and predicting patterns of mineralization. 相似文献
8.
J. Escuder Viruete M. Joubert P. Urien R. Friedman D. Weis T. Ullrich A. Prez-Estaún 《Lithos》2008,104(1-4):378-404
We present new regional petrologic, geochemical, Sr–Nd isotopic, and U–Pb geochronological data on the Turonian–Campanian mafic igneous rocks of Central Hispaniola that provide important clues on the development of the Caribbean island-arc. Central Hispaniola is made up of three main tectonic blocks—Jicomé, Jarabacoa and Bonao—that include four broad geochemical groups of Late Cretaceous mafic igneous rocks: group I, tholeiitic to calc-alkaline basalts and andesites; group II, low-Ti high-Mg andesites and basalts; group III, tholeiitic basalts and gabbros/dolerites; and group IV, tholeiitic to transitional and alkalic basalts. These igneous rocks show significant differences in time and space, from arc-like to non-arc-like characteristics, suggesting that they were derived from different mantle sources. We interpret these groups as the record of Caribbean arc-rifting and back-arc basin development in the Late Cretaceous. The> 90 Ma group I volcanic rocks and associated cumulate complexes preserved in the Jicomé and Jarabacoa blocks represent the Albian to Cenomanian Caribbean island-arc material. The arc rift stage magmatism in these blocks took place during the deposition of the Restauración Formation from the Turonian–Coniacian transition (~ 90 Ma) to Santonian/Lower Campanian, particularly in its lower part with extrusion at 90–88 Ma of group II low-Ti, high-Mg andesites/basalts. During this time or slightly afterwards adakitic rhyolites erupted in the Jarabacoa block. Group III tholeiitic lavas represent the initiation of Coniacian–Lower Campanian back-arc spreading. In the Bonao block, this stage is represented by back-arc basin-like basalts, gabbros and dolerite/diorite dykes intruded into the Loma Caribe peridotite, as well as the Peralvillo Sur Formation basalts, capped by tuffs, shales and Campanian cherts. This dismembered ophiolitic stratigraphy indicates that the Bonao block is a fragment of an ensimatic back-arc basin. In the Jicomé and Jarabacoa blocks, the mainly Campanian group IV basalts of the Peña Blanca, Siete Cabezas and Pelona–Pico Duarte Formation, represent the subsequent stage of back-arc spreading and off-axis non-arc-like magmatism, caused by migration of the arc toward the northeast. These basalts have geochemical affinities with the mantle domain influenced by the Caribbean plume, suggesting that mantle was flowing toward the NE, beneath the extended Caribbean island-arc, in response to rollback of the subducting proto-Caribbean slab. 相似文献
9.
Neil Alderman 《Geoforum》1996,27(4):461-477
The role of innovation in influencing business performance and survival is widely accepted, but there is only limited evidence identifying any direct relationships between them. This paper uses data from a cohort study of mature British mechanical engineering establishments to investigate locational, technological and other characteristics of establishments surviving during two time periods: 1981–1986 and 1987–1992. The study is concerned with all causes of non-survival, whether attributable to business failure or to corporate decision-making. The analysis makes use of a mix of bivariate and multivariate techniques to assess influences on the survival or non-survival of the establishments. The results support previous research concerning the role of such factors as establishment size and industry sector, but contradict conventional wisdom concerning such factors as age, suggesting in particular that the relationship between age and survival applies to new start-ups, but not to mature establishments. Some evidence for locational variation in closure rates, particularly during the most recent recession, is presented. The role of technological innovation is found to be equivocal. The effects of process innovation appear to be limited, but there are suggestions that investment in research and development and design-related technologies have been related to the survival prospects of the establishments in the cohort in recent years. Some of the shortcomings of the measures of innovation available and the approach adopted are discussed. 相似文献
10.
M.L. Lehtonen J.S. Marmo A.J. Nissinen B.S. Johanson L.K. Pakkanen 《Journal of Geochemical Exploration》2005,87(1):19-43
Diamondiferous kimberlites occur in eastern Finland, in the areas of Kaavi–Kuopio and Kuhmo. Active diamond exploration has been ongoing in the country for over two decades, but the Karelian craton still remains under explored given its size and potential. In order to develop techniques that can be applied to diamond exploration in glaciated terrains, the Geological Survey of Finland (GTK) carried out a detailed heavy mineral and geochemical survey of Quaternary till in 2001–2003 around two of the known kimberlitic bodies in Finland, Pipe 7 in Kaavi and Dyke 16 in Kuhmo. The mineralogical and geochemical signatures of these two kimberlites were studied in the basal till deposited down-ice from the targets. The kimberlites were selected to represent two different types in terms of shape, size, age and petrology, as well as showing contrasting country rocks and Quaternary deposits. Till samples up to 60 kg in weight were taken by excavator and by drill rig. Kimberlitic indicator mineral grains (0.25–1.0 mm) were concentrated using a GTK modified 3″Knelson Concentrator. Fine fractions (< 0.063 mm) of selected samples were analyzed by XRF and ICP-MS. The indicator grains down-ice from Pipe 7 form a well-defined fan in the basal till that can be followed for at least 2 km with a maximum concentration at 1.2 km distance from the pipe. Another kimberlitic body discovered during the study 300 m down-ice from Pipe 7 demonstrates that there are in fact at least two superimposed indicator fans. The results do not rule out the possibility of even more undiscovered kimberlitic sources in the area. In contrast, the indicator dispersal trail from Dyke 16 is shorter (1 km) and less well-defined than that at Kaavi, mainly due to the lower indicator content in the kimberlite itself and subsequently in till, as well as a large population of background chromites in till. The latter population is likely having been derived from the Archean Näätäniemi serpentinite massif and the associated ultramafic metavolcanics of the Kuhmo greenstone belt, located ca. 30 km up-ice from the sampling area. The indicator maximum at Seitaperä dyke swarm occurs immediately down-ice from the kimberlite, after which the concentration drops rapidly. Results of this study contribute to the overall understanding of the Quaternary history of the Kaavi and Kuhmo areas, and more importantly, provide key information to diamond exploration in these particular regions and also elsewhere in glaciated terrains. 相似文献
11.
12.
《International Geology Review》2012,54(12):1593-1610
The geology of the Central Kamchatka ore zone, with particular reference to the petrology on chemical composition of the rock units, is the first part of this two-part paper. Although the paper is not clearly divided into two parts, the second and major section deals with the chemistry, alteration, and chemical alteration which has occurred as the result of hydrothermal alteration. The author has illustrated the changes in chemical composition by the use of "Input-output" variation diagrams. The paper illustrates the development of hydrothermally altered rocks in the Central Kamchatka ore zone, both horizontally and vertically, and is proffered as an aid to mineral exploration in that area. The relationship of mineral facies and a combination of mineral facies to ore mineralization is also discussed.--M. A. Klugman. 相似文献
13.
Software for presentation of geochemical data on maps has been integrated into a user-friendly package, ALKEMIA, at the Geological Survey of Finland (GSF). ALKEMIA contains procedures for generating dot maps, colour surface maps, shaded relief maps, and vector images, and for interpolating and smoothing irregularly gridded data. Combining dots and colour surfaces provides a means of visually integrating up to three variables on a map, revealing the spatial relationships between them. The methods employed are described in detail, particularly the moving weighted median, which has been widely used at the GSF for interpolating and smoothing geochemical and other numerical data. Several geochemical and oncological atlases and series of maps have been produced with these methods. 相似文献
14.
Martin Mazurek 《Contributions to Mineralogy and Petrology》1992,109(4):494-510
Metapelites that have undergone variable degrees of migmatization were encountered in two deep boreholes in Northern Switzerland. Microtextures and calculated phase diagrams yield three successive stages of metamorphism, consistent with one P-T loop: (1) Amphibolite-grade metamorphism (biotite-sillimanite-garnetoligoclase-quartz-ilmenite), P-T conditions are estimated at 4.5–6.5 kbars/550–650 °C. (2) Anatectic migmatization melting reactions. Leucosomes do not represent pure crystallized melt but rather a mixture of melt, cordierite and K-feldspar grown at the expense of biotite and sillimanite. (3) Retrograde hydration, recorded by the growth of large amounts of muscovite at the expense of cordierite and K-feldspar, P-T conditions are estimated at <2.5 kbars/ <600 °C. Oxygen isotope measurements were obtained for whole-rocks and eight mineral species. Isotopic equilibrium among three or even four minerals grown during stage 1 can be demonstrated. Calculated isotopic temperatures are consistent with phase petrology. Migmatization did not re-equilibrate the isotopic composition of the pre-existing quartz grown in stage 1 even over distances as little as 10 cm. High 18O in migmatitic quartz is best explained by disequilibrium melting in coexistence with an infiltrating, isotopically heavy fluid. Lack of equilibration of oxygen isotopes between different quartz generations suggests that mineralogical and geochemical changes were rapid relative to diffusion rates. A meteoric-hydrothermal alteration at 300–400 °C, probably genetically linked to the intrusion of Variscan granites, strongly affected the rocks. Quartz did not exchange isotopes with hydrothermal fluids except in segregations where it is recrystallized. The 18O values of micas, feldspars and cordierite are often very low and fractionations with quartz very large, which reflects significant hydrothermal effects that were previously detected in the Black Forest by other workers. 相似文献
15.
Analysis of geochemical maps and their legends permits the proposal of several ways of improving their information content. Firstly, coherent and comparable classification of the objects to be presented must be developed. This classification should be based on strictly defined quantitative geochemical features of the objects; natural associations, anomalous elements, rocks, ore deposits and ore-bearing areas. Secondly, the most informative features of objects must be selected and uniquely displayed with a standard set of symbols. These symbols must be clear, readily understood and logically connected. The third requirement is that maps must be prepared in accordance with the tasks they are intended to deal with, must be optimally scaled, and display only appropriate information.One possible way of meeting the above-mentioned requirements, is proposed in a system of geochemical discrimination and related map presentation methods. The latter involves black hachures for the geological base, and directed colour lines and other features of colour hachures to characterize geochemical associations. Ore deposits may be characterized on the basis of eight most meaningful features encoded in one complex hieroglyph-like symbol constructed from easily understood and memorable components. This type of construction facilitates the computerized analysis of maps and makes them far more useful for prognosis, genetic reconstruction and resource evaluation. 相似文献
16.
华南钦杭结合带燕山期岩浆活动异常活跃,且具有较明显的成矿专属性。近年来微区测试技术日益成熟,积累了大量锆石微量数据。通过全体数据挖掘的思维方法,对前人发表的数据进行了进一步数据挖掘,利用锆石稀土元素对岩体成矿潜力进行判别,探讨有效的找矿地球化学标志。利用Python语言编程,对采用的13种稀土元素及元素比值进行穷举式组合,获得了4095个二元图解及121485个三元图解,并设计筛选算法,自动筛选出能有效区分锆石母岩成矿类型的图解。结果表明,锆石稀土元素含量及比值图解对不同成矿类型岩体的区分程度各异:与Ce、Eu有关的地球化学指标可以较清晰地对斑岩铜矿和钨锡(锡)矿床进行判别,这可能与岩体的氧逸度和含水量有关。此外,还挖掘出一些新的元素组合图解,如Dy/Lu-Er/Lu、Gd/Dy-Er/Yb等,可以有效区分岩体成矿类型,其隐含的地球化学机制尚待进一步解释。地球化学数据挖掘结果可以作为找矿标志使用,为华南燕山期岩浆-热液矿床研究及找矿勘查提供了科学依据,也是大数据技术在矿床学方面应用研究的积极探索。 相似文献
17.
Lu-Hf同位素体系及其岩石学应用 总被引：120，自引：174，他引：120
Lu-Hf是近几年来发展极为迅速的一门同位素定年和地球化学示踪技术。本文对这一同位素体系的发展历史、岩石学应用和存在的问题进行了全面的评述,对目前常见的样品溶解、质谱测定和激光剥蚀技术进行了全面介绍。虽然Lu-Hf同位素的发展历史可划分为TIMS、hot-SIMS、MC-ICPMS三个阶段,但MC-ICPMS仪器的出现,使Hf同位素发展速度明显加快。在介绍了Lu-Hf同位素的基本地球化学行为和基本原理之后,本文对这一同位素体系在岩石学上的应用作了全面的介绍,内容包括含石榴石和磷灰石岩石的同位素定年、早期大陆地壳形成与演化、不同端元地幔的性质及成因、岩浆作用过程的Hf同位素鉴别、区域地球动力学演化、变质作用过程中的Hf同位素变化等。最后对Lu的衰变常数、测定标准(JMC475溶液和固体锆石/斜锆石标准)的Hf同位素组成及Hf同位素的封闭温度等问题进行了讨论。 相似文献
18.
Geological controls on soil parent material geochemistry along a northern Manitoba–North Dakota transect 总被引：1，自引：1，他引：0
As a pilot study for mapping the geochemistry of North American soils, samples were collected along two continental transects extending east–west from Virginia to California, and north–south from northern Manitoba to the US–Mexican border and subjected to geochemical and mineralogical analyses. For the northern Manitoba–North Dakota segment of the north–south transect, X-ray diffraction analysis and bivariate relations indicate that geochemical properties of soil parent materials may be interpreted in terms of minerals derived from Shield and clastic sedimentary bedrock, and carbonate sedimentary bedrock terranes. The elements Cu, Zn, Ni, Cr and Ti occur primarily in silicate minerals decomposed by aqua regia, likely phyllosilicates, that preferentially concentrate in clay-sized fractions; Cr and Ti also occur in minerals decomposed only by stronger acid. Physical glacial processes affecting the distribution and concentration of carbonate minerals are significant controls on the variation of trace metal background concentrations. 相似文献
19.
A. O. Ogunkunle 《GeoJournal》1993,30(4):397-402
Samples were taken at 0–15 cm, 15–30 cm and 60–90 cm at 15 m interval from the crest to the valley bottom of two toposequences, one on quartzite schist and the other on banded gneiss within the same microclimate. Variations in pH, colour, (hue, value and chroma) particle size fractions, gravimetric moisture, gravel and CEC were examined. Soil pH was the least variable (cv = 3–5%) irrespective of depth or toposequence. The highly variable properties were silt (cv = 34–106%), CEC (cv = 22–101%), moisture (cv = 33–67%), clay (cv = 30–66%) and colour chroma (cv = 26–62%). Some of the properties (eg subsoil clay) show distinct regions while many properties show no discernible pattern along the toposequence (eg coarse sand). The quartz schist toposequence showed higher variation than the banded gneiss. The two toposequences were more similar near the soil surface (0–30cm) than in the subsoil (60–90cm). Clustering of points by property values along the toposequence and using the clusters that are common to the highest number of soil properties produced 3–4, and 4 homogeneous regions at 0–30cm and 60–90cm respectively along the toposequences. 相似文献
20.
The petrographic and geochemical composition of coal wastes exposed to fire in the minestone dump of Piekary Ślą1skie town (Upper Silesia, Poland) was investigated using samples collected at various distances from a recent fire site. The question as to whether geochemical biomarker maturity parameters could be applied to assess thermal changes in organic matter caused by waste dump fires, was examined using the data obtained. Geochemical parameters were correlated with observed petrographic changes in the organic matter caused by oxidation and heating. Petrographic analyses included the determination of maceral group contents (vitrinite, liptinite and inertinite), mineral matter and coke contents, and reflectance measurements on organic matter. All results were supported by proximate and ultimate analyses. Geochemical analysis included ultrasonic solvent extraction of bitumen followed by gas chromatography–mass spectrometry (GC–MS) of the extracts. In petrographic terms, the influence of heating was seen in reflectance variations and as oxidation rims, cracks, pores and coke development. Some zoned oxidation rims may be interpreted as re-heating episodes. In terms of chemical fingerprints, less thermally-stable compounds such as lighter n-alkanes, cyclic isoprenoids, methyl- and dimethylnaphthalenes, methyphenanthrenes and five-ring polycyclic aromatic hydrocarbons were destroyed or evaporated in the most fire-affected material. The presence/absence of particular compound groups was used to assess heating temperatures. Biomarker parameters of thermal maturity were used to assess alterations in organic matter around the waste dump fires, especially those indices and ratios with higher maturity ranges, e.g. (3-methylbiphenyl + 4-methylbiphenyl)/dibenzofurane and Σdimethylbiphenyls/Σmethyldibenzofuranes. 相似文献