山东蒙阴金刚石的晶体形态和晶面特征   总被引：1，自引：0，他引：1  

王萍  李国昌 《矿产与地质》1999,13(4):253-256

为探讨山东蒙阴金刚石的形成条件,研究了胜利Ⅰ号金伯利岩筒的金刚石晶面及晶形特征,结果认为金刚石的形成温度范围为１０００～１６００℃,压力范围为４０×１０８Ｐａ～５０×１０８Ｐａ。  相似文献   

Static compression of the hydrous magnesium silicate phase D to 30 GPa at room temperature     

D. J. Frost  Y. Fei 《Physics and Chemistry of Minerals》1999,26(5):415-418

Phase D is a dense hydrous magnesium silicate (ideal formula MgSi₂H₂O₆) which contains silicon cations exclusively in octahedral coordination. Measurements of the unit cell parameters of phase D were made to pressures of 30 GPa using a diamond anvil cell and employing synchrotron X-ray diffraction. A neon pressure medium was used. Using a third order Birch-Murnaghan equation of state the isothermal bulk modulus of phase D was determined as 166(±3) GPa with K′ equal to 4.1(±0.3). The compression of phase D is anisotropic with the c-axis twice as compressible as the a-axis. Above 20 GPa, however, the c/a ratio becomes pressure independent. Received: 29 July 1998/ Revised, accepted: 5 August 1998  相似文献   

苏鲁超高压变质带中国大陆科学钻探主孔(CCSD-MH)榴辉岩中发现金刚石   总被引：2，自引：4，他引：2  

张仲明  杨经绥戎合　HU JinZhu　SU JinFu　MAO HoKuang 《岩石学报》2007,23(12):3201-3206

苏鲁榴辉岩中除了早前发现的一粒金刚石外,最近又发现了6粒,它们具有基本相似的外形和大小,但其晶体结构与普通自然界金刚石和人工合成金刚石存在一定差别.金刚石具有异常X-射线衍射峰以及有磁铁矿的包裹体等特征,表明可以排除这些金刚石是人造或被外来样品混染的可能性.金刚石的再发现,证实苏鲁榴辉岩的形成压力可以达到4GPa以上,并且为大别和苏鲁两个超高压变质带的对比提供了一个重要标志.金刚石的异常晶胞参数和X-Ray异常峰的出现有可能与超高压变质作用有关,但需要实验岩石学研究证实.  相似文献   

辽东半岛南部原生金刚石特征     

赵秀英 《国土资源》1988,(1)

辽东半岛南部金刚石在含矿程度不同的金伯利岩岩管中,其主要物理特征和包体成分等是不同的。富矿金伯利岩体中金刚石的特征是颜色种类较多,晶形复杂(以曲面菱形十二面体为主),颗粒粗大,蚀象发育;含包体成分复杂。贫矿金伯利岩体中的金刚石颜色种类少,晶形单一(以平面八面体为主),颗粒细小,蚀象不发育;包体成分简单。高温碱熔试验与热台测定结果表明金刚石晶体形态的演化过程,盆刚石从650℃开始熔解,即八面体晶棱和顶角出现钝化,在温度不断升高时八面体所有晶棱逐渐熔解变为晶面,进而形成曲面菱形十二面体。因此可以推断,金刚石曲面菱形十二面体的初始晶形应是八面体晶形。金刚石包体中的镁铝榴石与金伯利岩中斑晶镁铝榴石的化学成分是一致的,说明二者来自同一岩浆源。  相似文献   

碎岩刀具工作面圆弧化机理及解决途径   总被引：2，自引：0，他引：2       下载免费PDF全文

汪国香  杨凯华 《探矿工程》1998,(1):46-48

通过分析孕镶金刚石刀头碎岩和磨损机理,找出引金刚石刀头工作端面弧化的原因,并提出了克服圆弧化现象的几种方法。  相似文献   

Kinetics of the graphite–diamond transformation in aqueous fluid determined by in-situ X-ray diffractions at high pressures and temperatures     

T.?OkadaEmail author  W.?Utsumi  H.?Kaneko  V.?Turkevich  N.?Hamaya  O.?Shimomura 《Physics and Chemistry of Minerals》2004,31(4):261-268

The graphite-diamond transformation was investigated by in situ time-resolved X-ray diffraction experiments using aqueous fluid containing dissolved MgO as the diamond-forming catalyst under conditions of 6.6–8.9 GPa and 1400–1835 °C. The transformed volume fractions of diamond as a function of time under various pressure-temperature conditions were obtained and analyzed using the JMAK rate equation. Variations in the nucleation and growth processes during diamond formation as a function of pressure and temperature were clarified.  相似文献   

Stratigraphic relations, kimberlite emplacement and lithospheric thermal evolution, Quiricó Basin, Minas Gerais State, Brazil     

George Read  Herman Grutter  Stewart Winter  Nigel Luckman  Frank Gaunt  Fernando Thomsen   《Lithos》2004,77(1-4):803-818

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Phonon density of states in iron at high pressures and high temperatures     

G. ?ShenEmail author  W. ?Sturhahn  E. E. ?Alph  J. ?Zhao  T. S. ?Tollenner  V. B. ?Prakapenka  Y. ?Meng  H.-R. ?Mao 《Physics and Chemistry of Minerals》2004,31(6):353-359

The phonon density of states (DOS) in iron has been measured in situ by nuclear resonance inelastic X-ray scattering (NRIXS) at high pressures and high temperatures in a resistively heated diamond anvil cell. The DOS data provide a variety of thermodynamic and elastic parameters essential for characterizing iron at depth in the Earth interior, such as average sound velocity, Debye temperature, atomic mean square displacement, average kinetic energy, vibrational entropy and specific heat. The NRIXS data were collected at 6, 20, and 29 GPa and at temperatures up to 920 K. Temperatures were directly determined from the measured spectra by the ratio of intensities of the phonon creation/annihilation side bands that are determined only by the Boltzmann factor. The change of the DOS caused by the structural transition from -Fe to -Fe is small and not resolvable within the experimental precision. However, the phonon energies in -Fe are clearly shifted to lower values with respect to - and -Fe. The temperature dependence of derived thermodynamic parameters is presented and compared with those obtained by Debyes model. The Debye temperatures that best describe the data decrease slightly with increasing temperature.  相似文献   

Kimberlite-hosted diamond deposits of southern Africa: A review   总被引：4，自引：0，他引：4  

Matthew Field  Johann Stiefenhofer  Jock Robey  Stephan Kurszlaukis 《Ore Geology Reviews》2008,34(1-2):33

Following the discovery of diamonds in river deposits in central South Africa in the mid nineteenth century, it was at Kimberley where the volcanic origin of diamonds was first recognized. These volcanic rocks, that were named “kimberlite”, were to become the corner stone of the economic and industrial development of southern Africa. Following the discoveries at Kimberley, even more valuable deposits were discovered in South Africa and Botswana in particular, but also in Lesotho, Swaziland and Zimbabwe.A century of study of kimberlites, and the diamonds and other mantle-derived rocks they contain, has furthered the understanding of the processes that occurred within the sub-continental lithosphere and in particular the formation of diamonds. The formation of kimberlite-hosted diamond deposits is a long-lived and complex series of processes that first involved the growth of diamonds in the mantle, and later their removal and transport to the earth's surface by kimberlite magmas. Dating of inclusions in diamonds showed that diamond growth occurred several times over geological time. Many diamonds are of Archaean age and many of these are peridotitic in character, but suites of younger Proterozoic diamonds have also been recognized in various southern African mines. These younger ages correspond with ages of major tectono-thermal events that are recognized in crustal rocks of the sub-continent. Most of these diamonds had eclogitic, websteritic or lherzolitic protoliths.In southern Africa, kimberlite eruptions occurred as discrete events several times during the geological record, including the Early and Middle Proterozoic, the Cambrian, the Permian, the Jurassic and the Cretaceous. Apart from the Early Proterozoic (Kuruman) kimberlites, all of the other events have produced deposits that have been mined. It should however be noted that only about 1% of the kimberlites that have been discovered have been successfully exploited.In this paper, 34 kimberlite mines are reviewed with regard to their geology, mantle xenolith, xenocryst and diamond characteristics and production statistics. These mines vary greatly in size, grade and diamond-value, as well as in the proportions and types of mantle mineral suites that they contain. They include some of the world's richest mines, such as Jwaneng in Botswana, to mines that are both small and marginal, such as the Frank Smith Mine in South Africa. They include large diatremes such as Orapa and small dykes such as those mined at Bellsbank, Swartruggens and near Theunissen. These mines are all located on the Archaean Kalahari Craton, and it is apparent that the craton and its associated sub-continental lithosphere played an important role in providing the right environment for diamond growth and for the formation of the kimberlite magmas that were to transport them to the surface.  相似文献   

流体包裹体压力计研究之二:高温高压下碳氢化合物的拉曼光谱   总被引：1，自引：0，他引：1  

乔二伟  郑海飞  徐备 《岩石学报》2008,24(9):1981-1986

在温度23～315℃、压力高达近2000MPa下用金刚石压腔下研究了正庚烷、环己烷及其混合物的拉曼光谱特征。结果表明：环己烷和正庚烷混合,只是改变了环己烷及正庚烷的平均C-H伸缩振动的拉曼位移,但是并不影响其P-△^-vp关系式。另外,经过数据拟合,得到了平均C-H伸缩振动的拉曼位移与压力的关系为：P=78．21（△^-vp）＋71．56。该公式可以用来作为流体包裹体尤其是油气包裹体的压力计。  相似文献