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在对岩筒实例分析的基础上,确立了次火山岩筒的存在,并探讨了次火山岩筒与火山岩筒之间在特征与成因上的差别。在对山东胜利1号大小金伯利岩筒的特征进行分析后认为,该岩筒并非前人所述的火山岩筒(通道),而具次火山岩筒的特征。  相似文献
2.
Medium-scale magnetotelluric sounding conducted within the Malaya Botuobiya (Yakutian diamondiferous province) and Zimnii Bereg (Archangelsk diamondiferous province) kimberlite regions revealed the main features of their geoelectric sections. These features have a genetic relation to the processes of kimberlite formation. All of the known kimberlite pipes of the two regions are located within the outlines of the revealed conducting geoelectric heterogeneities. The presence of such heterogeneities can be regarded as a possible deep criterion for distinguishing promising areas for kimberlite exploration. Original Russian Text ? E.V. Pospeeva, 2008, published in Tikhookeanskaya Geologiya, 2008, Vol. 2, No. 3, pp. 18–32.  相似文献
3.
Since 1998, BHP Billiton has mined diamonds at the Ekati Diamond Mine™ near Lac de Gras in the Northwest Territories of Canada. Current operations are based on mining multiple pipes by the open-pit method, but as some pits deepen, converting to underground mining is being considered.

As a test of underground mining methods and to provide access to the lower elevations of the Panda and Koala pipes, the Koala North pipe is being developed for underground mining. Initially, the top 40 m of the pipe were mined as an open pit to provide grade information and a prepared surface for the transition to underground mining. Currently, Koala North is being developed as an open-benching, mechanized, trackless operation. Although the method was successfully used at several De Beers diamond operations in South Africa, it has never been tested in an Arctic environment.

This case study describes basic geology, mining method layout and ongoing geological and geotechnical investigation. From the beginning of underground development, geotechnical daily routines have been fully integrated within the technical services department, which supports the operation. Geotechnical, geological and structural information obtained from underground mapping and core logging is compiled, processed, reviewed and analyzed on site by the geotechnical staff. Conclusions and recommendations are implemented as part of the operations in a timely manner. This ongoing “live” process enables the operators to make the most efficient use of resources both for ground support and excavations as well as to address safety issues, which are the top priority.  相似文献

4.
The Peninsular India hosts extensive record of Mesoproterozoic, and Neoproterozoic successions in several mobile belts, and cratonic basins. The successions provide excellent opportunities for chronostratigraphic classification, in tune with the chronometric classification adopted by IUGS for inter-regional correlation on a global scale. Major tectono-thermal events at 1000–950 Ma in the mobile belts, correlatable with the Grenville orogeny may be considered as the datum for Meso-Neoproterozoic classification in India. Principles of chronostratigraphic classification, however, can not be applied yet to the cratonic successions of India because of inadequate radiometric data, paucity of biostratigraphic studies, and lack of regionally correlatable stratigraphic or palaeoclimatic datum. The kimberlite magmatism which affected the Peninsular India on a continental scale at about 1100 Ma, holds the key to the identification of Neoproterozoic successions of the cratonic basins. Thus, the stratigraphically confined diamond-bearing conglomerates and/or the tuffs associated with kimberlites, may be considered as the datum to define the base of the Neoproterozoic, fixed at about 1000 Ma. Accordingly, the Rewa, and Bhander Groups in the Vindhyan basin, the Kurnool Group in the Cuddapah basin, the Jagdalpur Formation in the Indravati basin, and the Sullavai Group in the Pranhita-Godavari basin are taken to represent the Neoproterozoic successions in the Peninsular India. The Chattisgarh Group in the central India, the lower part of the Marwar Supergroup in western Rajasthan, the Badami Group in the Kaladgi basin, and the Bhima Group are the other “possible Neoproterozoics” in the Peninsula.The closing phase of the Mesoproterozoic in all these basins are characterised by stable shelf lithologic associations attesting to high crustal stability. The Neoproterozoic basins, by contrast, mark a new phase of rifting, and extension, and the basin fills exhibit signatures of initial instability which evolved with time into a more stable platformal condition. A major episode of sea level rise has been recorded in most of the basins. The riftogenic origin, and evolution of the basins are comparable with the history of Neoproterozoic basins of Australia though there is no unequivocal record of glaciation in the Indian formations.  相似文献
5.
通过对俄罗斯雅库特地区拿垦金伯利岩矿区的水系沉积物,土壤,钻孔岩心进行不同规模的地球化学测量,根据区内圆形构造及金伯利岩指示元素Cr,Co,Sr,Zr,Y的分布特征圈出金伯利岩指示元素次生晕异常,证实了地球化学方法寻找深层隐伏金伯利岩管的可行性。  相似文献
6.
根据1:2.5万航磁资料,分析和总结了辽南已知金伯利岩矿田区的区域磁场特征,同时对该区区域地质构造状况作了相应的对比解释;以本区两大典型金伯利岩管kb42和kb50为例,阐述了本区表露型金伯利岩管的航磁及地磁异常分布特征、岩管产出状态与磁异常的对应关系;通过kb3-2隐伏金伯利岩体的航磁及地磁异常反映,阐述了隐伏金伯利岩体的低缓磁异常特征,并进一步证实了高精度磁测工作的有效性。  相似文献
7.
首次在Mir金伯利岩筒中的锆石中发现了烃类包裹体。利用低温荧光光谱仪测定出烃类包裹体的成分为萘和菲的同系物,芘,1,12-苯并芘等;其成分与Udachnaya岩筒中的橄榄石内的烃类和Mir岩筒中的石榴石中的烃类的成分相近。测定出锆石的δ^13C值为-21.83‰--33.54‰,与用榴辉岩共生组合中最轻的金刚石测出的同位素δ^13C值范围相符。文中引述了有关有机物来源的讨论及多环芳烃(PAH)由缩聚作用形成的论述。伴生矿物中相当数量的PAH的存在证明在形成金刚石及其伴生矿物的情况下,若有相当浓度的自由氢存在则可能发生缩聚作用。这些缩聚作用中碳的来源显然与形成金刚石时碳的来源是相同的(即液态的CH4,CO及CO2)。  相似文献
8.
The morphological and spectral-optical properties of diamond crystals from placers in North Timan rivers have been studied with IR-spectroscopy and cathode luminescence methods. As a result, correlation between external characteristics of diamonds (size and degree of mechanical damage) and number of optically active centers has been revealed. The habit and the type of distribution of structural defects in diamond crystals studied are comparable with those in diamonds from the Archangelsk Region and North Timan’s placers. Based on the obtained data, origin issues and possible primary sources of diamonds from North Timan’s placers are discussed. Original Russian Text ? G.K. Khachatryan, M.B. Kopchikov, V.K. Garanin, M.V. Chukichev, N.N. Golovin, 2009, published in Vestnik Moskovskogo Universiteta. Geologiya, 2009, No. 2, pp. 39–47.  相似文献
9.
金刚石母岩可以是榴辉岩、辉石岩、橄榄岩等多种岩石,它们与金刚石都是在地幔深处形成的,并上侵最终固结于地壳中。母岩中的金刚石等矿物在地壳中又发生准稳定生长。地壳中金伯利岩和钾镁煌斑岩岩浆作用对金刚石母岩侵入体进行改造,使原生金刚石发生破碎、溶解、再生长等一系列变化,并形成巨晶、劣质金刚石和黑金刚石等新类型,这些现象不是在金刚石母岩形成之初发生的。  相似文献
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