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F. J. Dahlkamp 《Mineralium Deposita》1978,13(1):83-104
A listing of the recognized types of uranium mineralization shows nineteen determinable types out of which only six can be classified as of economic significance at present: Oligomictic quartz pebble conglomerates, sandstone types, calcretes, intra-intrusive types, hydrothermal veins, veinlike types. The different types can be genetically related to prevalent geological environments, i. e. 1. the primary uranium occurrences formed by endogenic processes, 2. the secondary derived from the primary by subsequent exogenic processes, 3. the tertiary occurrences are assumed to be formed by endogenic metamorphic processes, however, little is known about the behaviour of the uranium during the metamorphosis and thereby the metallogenesis of this tertiary uranium generation is still vague. A metallotectonic-geochronologic correlation of the uranium deposits shows that a distinct affinity of the uranium exists to certain geologic epochs: to the Upper Archean — Lower Proterozoic, to the Hercynian and in a less established stage: to the Upper Proterozoic. 相似文献
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《International Geology Review》2012,54(6):978-983
Sulfide deposits are believed to be convergent, that is, similar in composition, structure, and geologic location, but different in genesis. The three chief genetic classifications of sulfide deposits are: 1) sedimentary - exhalational, 2) subvolcanic exhalational - hydrothermal, and 3) plutonic hydrothermal. The first two groups are very closely related,frequently forming almost simultaneously with the same stage of volcanic activity in spilite-keratophyre rocks of eugeosynclines. They are associated with the derivatives of basaltic magmas. The plutonic hydrothermal sulfide deposits are associated with porphyry series of rocks in the marginal zones of geosynclines, generated by a granitoid magma.—E. K. Russell. 相似文献
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Except for the fringing reef, the limestones of Christmas Island in the Indian Ocean are of Late Eocene (Tertiary “b") and Early Miocene (Tertiary “e” to “f") age. The Upper Eocene limestone is an algal limestone containing Discocyclina, Nummulites, and Heterostegina. The Lower Miocene limestone is an algal limestone containing in its lower part species of Lepidocyclina (Eulepidina) followed by Miogypsinoides dehaarti. Miogypsinoides dehaarti extends into the zone of Flosculinella bontangensis. No rocks younger than Burdigalian were identified other than on the fringing reef which contains an assemblage of Pliocene‐Pleistocene Foraminifera. 相似文献
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通过对太阳系起源的研究,笔者指出,超大型金刚石矿床、磷矿床、油气田和油页岩矿床,都与碳质球粒陨石星子有成因联系。碳质球粒陨石星子被吸积于原始地球上地幔表层,形成原始富碳区。当地壳形成后,富碳区的岩石圈没有被软流层的对流作用均匀化,并在155—250km深度范围内,碳质聚合成金刚石。随着金伯利岩和钾镁煌斑岩岩浆侵位,金刚石被带入地壳上部形成金刚石矿床。在富碳区,除金刚石矿床外,还形成了超基性岩-碱性岩-碳酸岩富磷杂岩体及超大型,大型磷灰石矿床。富磷杂岩体为超人型磷块岩矿床的形成提供了成矿物质,也为成油生物群的繁殖提供了矿物养料,从而为形成超大型油气、油页岩矿床创造了物质条件。碳质球粒陨石中的有机质在高温条件下合成油气,被封存于大陆岩石圈上地幔部分,在构造条件有利时进入储油构造,促进了超大型油气田的形成。超大型矿床的存在,是岩石圈成矿物质横向不均匀性的反映。 相似文献
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Australian uranium ores are often composed of complex mineral assemblages. Differences in ore compositions and textures are seen between deposits as well as within a single deposit, which can host a range of ore types. Such a wide variety of uranium ores make it impossible for a single extraction or treatment process to be developed that will accommodate all of the ores. From a mineralogical perspective, key issues confronting the Australian uranium mining industry include: the prevalence of low grade ores; a lack of detailed chemical and mineralogical information (uranium speciation, texture, grainsize) for the various ore deposit types; and the presence of refractory uranium-bearing minerals and highly acid-consuming gangue minerals. This paper reviews some of the main controls on uranium geometallurgy by linking concepts relating to ore genesis and the resulting ore mineralogy, with the processing behaviour of specific Australian uranium ore types. Emphasis is placed on the value of detailed ore mineralogical analysis and the insight this provides into the factors of importance when considering uranium extraction. 相似文献
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Zeolites are present in altered pyroclastic rocks at many localities in Greece, and large deposits of potential economic interest are present in three areas: (1) the Evros region of the province of Thrace in the north-eastern part of the Greek mainland; (2) the islands of Kimolos and Poliegos in the western Aegean; and (3) the island of Samos in the eastern Aegean Sea. The deposits in Thrace are of Eocene-Oligocene age and are rich in heulandite and/or clinoptilolite. Those of Kimolos and Poliegos are mainly Quaternary and are rich in mordenite. Those of Samos are Miocene, and are rich in clinoptilolite and/or analcime. The deposits in Thrace are believed to have formed in an open hydrological system by the action of meteoric water, and those of the western Aegean islands in a similar way but under conditions of high heat flow, whereas the deposits in Samos were formed in a saline-alkaline lake. 相似文献
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Basanta K. Sahu 《Mineralium Deposita》1982,17(1):99-105
Mineral deposits are characterized by certain continuity of assay values, thickness and top and bottom surfaces of ore zones etc., which are amenable to stochastic modelling with respect to spatial coordinates. The French School (Matheron, 1963) introduced rather difficult terminology of semi-variogram, kriging etc. for quantitative assessment of reserves and average grade of mining property under the assumption of second-order stationarity of first differenced (d=1) data. A more general, powerful and well-known time-domain (spatial) stochastic models (ARIMA (p, d, q); based on Box and Jenkins, 1970, 1976; Anderson, 1976) are introduced herein which include Matheron Model (d=1) as a special case. 相似文献
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A multivariate statistical technique (principal component analysis) has been used to investigate the granulometric features of 414 samples of pyroclastic rocks: 216 samples were collected from areas of recent and active volcanism in Central and Southern Italy; data for the remaining 198 samples were obtained from the literature and relate to products from Somma-Vesuvio, Mount St Helens and the Japanese volcanic arc. The analysis offers an improved means of discriminating pyroclastic deposits using their grain-size characteristics. 相似文献
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Many nickel deposits are known in Brazil, accounting for about 350 · 106 tons of ore with an average of 1.5% Ni. All are of the lateritic type. These deposits are scattered throughout the country, being rarer in the Northeastern Region and in the South, below 25 °S latitude. They are mainly associated with mafic-ultramafic massifs of large dimensions and ultramafic alkaline complexes, and occur in climatic regions of contrasting seasons. The weathering profile developed over the fresh rock consists, from bottom to top, of the following horizons: altered rock, coarse saprolite, argillaceous saprolite, ferruginous saprolite and lateritic overburden. The thickness of each horizon varies from one deposit to another, the whole profile generally exceeding 20 m. The saprolitic horizons with inherited minerals (serpentine, chlorite) or neoformed minerals (smectites) constitute the silicated nickel ore and are thicker were climatic conditions are drier; the ferruginous upper horizons made up of iron oxide-hydroxides are more developed in more humid regions. In Brazil, the silicated ore generally prevails over the oxidized ore. The main Ni-bearing minerals are serpentine, smectite, garnierite and goethite. The lateritic nickel deposits of Brazil may be correlated with two erosion surfaces, corresponding to the Sul Americano (Lower Tertiary) and Velhas (Upper Tertiary) levelling cycles. The degree of dismantling of the higher and more ancient surface and the consequent development of the Velhas Surface control the position of the nickel accumulation in the landscape. Thus, the deposits may be found either in the lowlands or in the highlands, where they are always covered by a silcrete layer. The alteration profiles in the Brazilian lateritic nickel deposits are broadly similar to those described elsewhere in the world. However, they present two characteristic features: the silicated ore prevails over the oxidized ore, and a silicified layer covers the profies developed on the highlands. 相似文献
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A plot of median grain size against quartile deviation (after Buller and McManus) can be used to distinguish mudflow deposits. A characteristic envelope for poorly sorted streamflow deposits is also defined. Unlike most other sediment transport mechanisms, mudflows appear to deposit sediments with sorting independent of median grain size. 相似文献
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中国浅成低温热液金矿床 总被引：2，自引：0，他引：2
浅成低温热液金矿床在中国传统上称为陆相火山岩型金矿床,主要发现在中国东部,后来在北疆地区也有新的发现.根据产出的大地构造背景,它们集中分布在3个带,并分属于3个成矿时期.它们包括:(1)新生代台湾东部岛弧带;(2)晚古生代北疆岛弧带;(3)中生代沿中朝克拉通北界的大陆边缘带;(4)中生代中国东南沿海地区的大陆边缘带.绝大多数矿床是低硫化型的,只有3个是高硫化型的,另有1个是与碱性岩系有关的Au-Te型矿床.除了中国最大的金矿床金瓜石矿床外,迄今为止中国大陆上的浅成低温热液金矿床总的来说只有较小的经济重要性.在中国东部发现的浅成低温热液金矿床的总储量,与区内广泛分布的中生代陆相火山岩十分巨大的体积极不相称.较古老的成矿年龄,中国东部的中生代和北疆的晚古生代,是中国大陆浅成低温热液金矿床的一个鲜明的特点.根据中国的成矿条件和保存条件的分析,以及与美国西部和俄国东部的对比,提出了中国浅成低温热液金矿床成矿潜力的一个初步评估.北疆可能有较大的寻找浅成低温热液金矿床的潜在重要性. 相似文献
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Petroleum potential of Baikal deposits 总被引：1，自引：0，他引：1
A.E. Kontorovich V.A. Kashirtsev V.I. Moskvin L.M. Burshtein T.I. Zemskaya E.A. Kostyreva G.V. Kalmychkov O.M. Khlystov 《Russian Geology and Geophysics》2007,48(12):1046-1053
We analyzed oils, gases, and bitumens of bottom sediments from natural shows on the southeastern shore of Lake Baikal, in the mouth of the Stvolovaya River near Capes Tolstyi and Gorevoi Utes. Based on a set of geological data, we have established that: (1) the lake oils underwent biodegradation to a variable degree: “Fresh” nondegraded paraffin oil floats up near Cape Gorevoi Utes; in the mouth of the Stvolovaya River and near Cape Tolstyi, aromatic-naphthene oil lacks n-alkanes, monomethyl alkanes, and acyclic isoprenoids; (2) Cenozoic oil originated from the organic matter of fresh-water basins with significant amounts of higher land plant remains, including angiosperm plants (oleanane), which suggests the lake or delta genesis of oil source formations of Cretaceous and younger ages. Judging from the carbon isotope composition (average δ13C = −43.84‰), methane from the bottom sediments near Cape Gorevoi Utes is catagenetic. The initial in-place resources in the Baikal sedimentary basins are estimated by the volumetric-statistical method at 500 mln tons of equivalent hydrocarbons. 相似文献
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《International Geology Review》2012,54(3):518-525
Commercial uranium deposits and those likely to become commercial in the near future are genetically classified as magmatic, hydrothermal, exogenous, metasedimentary, and deposits of questionable origin. A brief discussion of each type is included. — C.E. Sears. 相似文献