金伯利岩中铬的相态及找矿地球化学信息--以华北地台为例     

隋延辉  戚长谋 《世界地质》2003,22(4):373-375,403

对华北地台金伯利岩地球化学找矿信息提取表明:铬是判别岩体含矿与否的重要指示元素。铬的相态分属尖晶石、镁铝榴石和镁钛铁矿三类矿物族。研究得出,各矿物指示含矿的化学成分标型为:铬尖晶石Cr2O3>53%,Al2O3<11%,MgO<12%,Cr#值大于0 7。镁铝榴石Cr2O3>5%,Al2O3<19%,Cr#值大于0 2。镁钛铁矿Cr2O3>1%,MgO>11%。由于铬尖晶石相对稳定,其化学组成为提取金伯利岩找矿信息的首选对象。  相似文献   

Gold Content of Mantle-Derived Rocks from Eastern China and Its Implications   总被引：2，自引：0，他引：2  

HE Ying  DONG Zhenxin  YUE Kefen  ZHANG Zhanjun  WANG XinKey Laboratory of Continental Dynamics  Ministry of Education  Department of Geology  Northwest University  Xi''an  Shaanxi  E-mail: heying@nwu.edu.cnGeological Museum of Chin  Beijing Department of Chemistry  Northwest University  Xi''an  Shaanxi 《《地质学报》英文版》2003,77(2):212-219

We have analyzed the gold content of 65 samples of mantle-derived xenoliths and their host rocks from eastern China, which is found to be inhomogeneous, falling in the ranges of 1.0×109-8.2×109 (averaging 3.8 ×10-9) and 0.2×10-9-5.3×10-9 (averaging 2.7×10-9) in the mantle-derived xenoliths and the host basalts respectively. Except the samples from Wanquan County of Hebei Province and Anding County of Hainan Province, the gold content is the highest on the margins of the North China platform and decreases spatially towards the north and south, and temporally the samples of the Tertiary have a higher gold content than those of the Quaternary. The gold content of the mantle-derived xenoliths and the host Paleozoic kimberlites is 3.8×10-9-180×109and 0.1×10-9-38.0×10-9 respectively, which are higher than that in the mantle-derived xenoliths in basalt and the host Cenozoic basalts. The mantle-derived xenoliths have a higher gold content than the host rocks, but their relativity is not very clear, su  相似文献   

Sulphide inclusions in diamonds from the Koffiefontein kimberlite, S Africa: constraints on diamond ages and mantle Re–Os systematics     

D.G. Pearson  S.B. Shirey  J.W. Harris  R.W. Carlson 《Earth and Planetary Science Letters》1998,160(3-4):311-326

Re–Os isotope compositions of syngenetic sulphide inclusions in both eclogite suite (E-type) and peridotite suite (P-type) parageneses in diamonds from the Koffiefontein mine, South Africa have been analysed using a technique capable of analysing single inclusion grains, or, in some cases multiple inclusions from the same diamonds. Sulphide inclusion Ni contents broadly correlate with Os abundances in that low-Ni (6.8–8.7% Ni), E-type sulphides have 4.7 to 189 ppb Os whereas the two high-Ni (25%), P-type sulphides have 5986 and 6097 ppb Os. Two P-type sulphides from the same diamond define the first mineral isochron obtained for a single diamond which has an age of 69±30 Ma with chondritic initial ¹⁸⁷Os/¹⁸⁸Os. This indicates that the sulphides, and hence the host diamond, crystallised close to the time of kimberlite emplacement (90 Ma), in the Mesozoic. This is supported by Pb isotopic measurements of a fragment from one of the sulphides, together with the absence of significant Type IaB nitrogen aggregation in the host diamond lattice. E-type sulphide inclusions have radiogenic Os isotopic compositions, ¹⁸⁷Os/¹⁸⁸Os 0.346 to 2.28, and Re–Os model ages from 1.1 to 2.9 Ga. They define an array on a Re–Os isochron diagram that may be interpreted as defining a single period of E-type sulphide growth at 1.05±0.12 Ga, with an elevated initial ¹⁸⁷Os/¹⁸⁸Os. Alternatively, two episodes of sulphide crystallisation, from a chondritic reservoir, may be invoked in the Archaean and in the Proterozoic. The results for both P- and E-type diamonds point to a spectrum of diamond crystallisation ages. High contents of both Re and Os, and the similarity of Re/Os ratios of sulphide inclusions in diamonds to whole rock eclogite and peridotite xenoliths indicate that small amounts of sulphides can dominate the mantle budget of both these elements during melting. Recent addition to the lithospheric mantle of high-Os material similar to that from which the P-type sulphides crystallised may explain the variable, sometimes young Os model ages seen in whole rock xenolith Re–Os data.  相似文献   

俄罗斯雅库特地区拿垦金伯利岩矿区地球化学特征     

王丰玉  С·  В·  格里戈良 《物探与化探》1998,22(6):425-430

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   

Intensive Variables in Kimberlite Magmas, Lac de Gras, Canada and Implications for Diamond Survival   总被引：4，自引：4，他引：4  

FEDORTCHOUK  YANA; CANIL  DANTE 《Journal of Petrology》2004,45(9):1725-1745

Crystallization temperatures (T) and oxygen fugacities (fO₂)of kimberlite magma are estimated from oxides included in olivinephenocrysts from the Leslie, Aaron, Grizzly and Torrie kimberlitepipes in the central Slave Province, Canada. Crystallizationtemperatures recorded by olivine–chromite pairs at anassumed pressure of 1·0 GPa are 1030–1170°C± 50°C, with a mean of  相似文献   

在我国发现的自然碳化钨   总被引：1，自引：0，他引：1  

张建洪  杨国杰  李朝晖 《矿物学报》1986,(4)

作者重点研究了产于我国山东金伯利岩岩筒和岩脉中的自然碳化钨。矿物呈黑色、钢灰色,细粒集合体,粒径0.5—4μ。俄歇微探计分析W:C=1:1,X射线粉晶衍射强线值为2.501(9),1.874(10),1.290(8),1.233(8),1.148(8),1.015(9)。六方晶系,晶胞参数a=2.903,c=2.835,单位晶胞中含有一个分子的WC。  相似文献   

Integration of Structural,Gravity, and Magnetic Data Using the Weights of Evidence Method as a Tool for Kimberlite Exploration in the Buffalo Head Hills,Northern Central Alberta,Canada     

Paganelli  F.  Richards  J. P.  Grunsky  E. C. 《Natural Resources Research》2002,11(3):219-236

In the Buffalo Head Hills area a weights of evidence statistical approach was used to determine the spatial relationship of NNE-, NE-, NW-, and ENE-trending lineaments to known kimberlite locations. This method outlined different degrees of spatial correlation between and lineaments, with higher correlations defined for the NNE, NE, and ENE lineament data sets. A weights of evidence model then was constructed using the structural lineament maps, the Buffalo High and Buffalo Utikuma terrane boundary, Bouguer gravity data, and magnetic characteristics of the Buffalo High and Buffalo Utikuma terranes. The model reveals maximum favorability for kimberlite exploration along the Buffalo High and Utikuma terrane boundary in correspondence with NNE-trending lineaments and their intersections with NE and ENE lineaments. The relationship of the kimberlite occurrences along the Buffalo High-Buffalo Utikuma terrane boundary and structural lineaments seems to favor an hypothesis of kimberlite emplacement through a major zone of weakness in the basement, here characterized by the boundary between the Buffalo High and Buffalo Utikumaterranes.  相似文献   

镁铝榴石中的结构水的研究   总被引：2，自引：0，他引：2  

王五一  郭立鹤  王阿莲  张安棣 《岩石矿物学杂志》1992,11(1):61-69

通过对34个取自金伯利岩管中的粗晶镁铝榴石及碱性玄武岩中镁铝榴石巨晶样品的红外光谱分析发现,金伯利岩中部分镁铝榴石粗晶含有结构水,但不同颗粒之间含量差异很大,含量较高者约0.07wt%,而所研究的碱性玄武岩中的镁铝榴石不含结构水。分析发现,结构水在同一样品内分布基本均匀。在红外光谱3800—3500cm~(-1)波长范围内,分别记录到三峰谱和单峰谱两种类型,其中位于3570cm~(-1)±的吸收峰峰位明显受镁铝榴石结构中八配位阳离子(Mg~(2+)、Fe~(2+))影响,而六配位阳离子(Cr~(3+)、Al~(3+))的影响不明显。结构水在镁铝榴石晶格中的存在形式是多样的。  相似文献   

镁铝榴石的形成温度及其结构水成因探讨     

王五一 《岩石矿物学杂志》1992,11(4):366-374

在红外光谱有关镁铝榴石中微量结构水的研究基础上,运用质子探针分析方法系统研究了辽宁50号金伯利岩管中粗晶镁铝榴石Ni、Zn、Ga、Sr、Y、Zr、Pb等微量元素的含量。根据镁铝榴石中微量元素Ni含量地质温度计,计算该岩管中镁铝榴石粗晶的形成温度,对比研究了不同含矿性的金伯利岩中粗晶镁铝榴石形成温度范围的异同,并探讨了该方法运用于金刚石找矿勘查的可能性;讨论了含结构水镁铝榴石的形成温度范围及其意义,并结合其它微量元素分析资料,探讨了镁铝榴石中微量结构水与地幔交代作用之间的成因联系。  相似文献   

鲁西金伯利岩勘查中电法勘探的应用效果分析     

潘玉玲  戴昭明  李平 《地质科技情报》1993,(Z1)

以在已知金伯利岩管上直流电阻率法视电阻率异常和低频电磁法虚分量异常特征分析为例,论证了电法勘探在金伯利岩勘查中的效果,并指出扩大电法勘探应用的有效途径。  相似文献