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1.
为了研究瓦房店和蒙阴矿区铬铁矿成分与金伯利岩含矿性关系,对2个矿区的铬铁矿进行了系统的采样,利用电子探针波谱技术测定了不同品位含矿岩管金伯利岩中的100个铬铁矿微区化学成分.分析结果表明：不同世代的铬铁矿的化学成分不同,主要差别在铬和铝2个元素上.如果用Cr/（Cr+Al）=Cr'来表示铬铁矿与金伯利岩含矿性的关系,那么金刚石包裹体中铬铁矿的Cr'值为89.75%;富矿岩体中的第一世代铬铁矿Cr'值为89.47%;中等含矿岩体中第一世代铬铁矿Cr'值为86.83%,第二世代铬铁矿Cr'值为82.74%;贫矿的岩体中第三世代铬铁矿Cr'值为68.98%.金伯利岩岩体中含金刚石由富到贫,对应岩石中铬铁矿Cr'值依次变低,具有明显的找矿矿物学特征. 相似文献
2.
山东蒙阴金刚石矿区金伯利岩中的尖晶石族矿物究竟是铬铁矿还是尖晶石一直倍受争议,为了确定山东蒙阴矿区形态复杂的尖晶石族矿物种类,项目组对矿区的尖晶石族矿物进行了系统的采样,利用电子探针对50件尖晶石族矿物MgO、FeO、TiO2、Al2O3、MnO、Cr2O3进行微区化学成分分析,结果显示,山东蒙阴金刚石矿区金伯利岩中尖晶石族矿物A、B端元成分复杂,不存在单纯的铬铁矿或尖晶石矿物种,以化学分子式分类为基础得到的尖晶石族矿物种类主要有:铁镁-铬铁钛、镁铁-铬铁铝钛、铁镁-铬铝铁、镁铁-铬铝铁、铁镁-铬铁钛铝、镁铁-铬铝、铁镁-铬铝7个亚种。山东蒙阴金伯利岩中尖晶石族矿物的主要端元组分为MgAl2O4、MgCr2O4、FeCr2O4,矿物化学成分分析表明,Mg质量分数较高(7.3%~11.8%),其中Fe、Mg离子数比近于1:1,构成富镁的铬铁矿。 相似文献
3.
铬铁矿是金伯利岩型金刚石矿床含矿性重要指示矿物之一.通过对山东蒙阴金刚石矿区无矿、贫矿、中等含矿、富矿金伯利岩岩筒中的铬铁矿红外光谱系统采集,寻找不同金伯利岩岩筒中铬铁矿红外谱图参数特征与金伯利岩含矿性的关系,以达到判断金伯利岩体无矿、贫矿还是富矿的目的.不同含矿性金伯利岩岩筒中50个铬铁矿红外光谱参数特征统计显示：铬铁矿红外光谱A峰吸光度与高频峰吸光度平均比值从无矿、贫矿、中等含矿到富矿金伯利岩岩筒,数据依次为0.71、0.73、0.83~0.93、1.09,显示出明显的找矿指示意义. 相似文献
4.
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
5.
石榴石是山东蒙阴金伯利岩型金刚石矿区的重要指示矿物之一,为了确定山东蒙阴金刚石矿区颜色复杂的石榴石种类,判断矿区石榴石特征与含矿性关系。项目组对矿区不同含矿程度金伯利岩中的石榴石进行了系统采样,测定了50件单晶石榴石微区化学成分和128个石榴石单晶的晶胞参数,测试结果显示：山东蒙阴金伯利岩中石榴石族矿物化学式A3B2[SiO4]3中的A组阳离子由Mg2+、Ca2+和Fe2+组成,二价阳离子主要为Mg2+,Mg2+占据十二面体空腔中心位置达53%～82%左右,Ca2+占据十二面体空腔中心位置小于7%～17%、Fe2+占据十二面体空腔中心位置5%～31%左右。B组阳离子主要由Al3+、Cr3+和Fe3+组成,三价阳离子主要为Al3+,[AlO6]八面体占位达62%～92%左右,[FeO6]和[CrO6]八面体占位小于38%;按50个石榴石不同阳离子占据十二面体空腔和八面体空腔的位置多少,山东蒙阴石榴石可划分为10个亚种。根据山东蒙阴金伯利岩中石榴石成分,计算出石榴石形成压力为6.0～9.0 GPa,推测山东蒙阴矿区金伯利岩中有来自深源的石榴石。128件石榴石晶胞参数统计结果显示：山东蒙阴无矿、贫矿、中等含矿、富矿金伯利岩岩体中紫色石榴石晶胞参数分别为大于1.162 nm、1.159～1.160 nm、1.156～1.160 nm和1.155～1.157 nm之间,从无矿岩体→贫矿岩体→中等含矿岩体→富矿岩体,紫色石榴石晶胞参数值有明显变小的趋势。 相似文献
6.
X射线粉晶衍射仪在山东蒙阴金伯利岩蚀变矿物鉴定中的应用 总被引：5，自引：4，他引：1
山东蒙阴金伯利岩组成矿物以蚀变矿物为主,X射线粉晶衍射仪鉴定结果显示无矿金伯利岩矿物组分为方解石、白云石、石英、钙锆钛矿,标志性矿物为白云石和钙锆钛矿;贫矿金伯利岩矿物组分为蛇纹石、方解石、钙铝榴石、磁铁矿和金云母,标志性矿物为钙铝榴石;富矿金伯利岩矿物组分为蛇纹石、方解石、绿泥石、磷灰石、磁铁矿和金云母,标志性矿物为绿泥石和磷灰石。采用X射线粉晶衍射仪鉴定金伯利岩蚀变矿物组合,寻找蚀变矿物组分变化与金伯利岩含矿性的关系,利用标志性的蚀变矿物判断金伯利岩无矿、贫矿还是富矿,是非常有意义的。 相似文献
7.
金伯利岩型金刚石原生矿床含矿性评价是了解金刚石成矿规律和指导区域性找矿的重要依据。华北克拉通是我国重要的金刚石成矿远景区，目前已发现了两个重要的含金刚石金伯利岩岩区（山东蒙阴和辽宁瓦房店）。近年来，对岩区内不同品位金刚石典型矿床的研究表明金伯利岩中的金刚石品位取决于以下两个重要的地质过程：金伯利岩岩浆对金刚石的捕获作用和金伯利岩岩浆对金刚石的熔蚀作用。在华北克拉通下方存在一个金刚石稳定区，温度为950~1200 ℃，压力为4. 4~6. 1 GPa。山东蒙阴和辽宁瓦房店金伯利岩岩浆在上升过程中穿过该区域并捕获其中的金刚石，成为含矿岩浆；而铁岭和鹤县等金伯利岩岩浆在上升过程中不穿过该区域，成为不含矿岩浆。在穿过金刚石稳定区时，富矿的金伯利岩捕获了更多的金刚石以及金刚石的伴生指示矿物（如镁铝榴石，镁铬铁矿）；而贫矿的金伯利岩则相对捕获了少量的金刚石和指示矿物。这些指示矿物往往参加了金刚石的形成过程，有些作为缓冲剂控制了反应（岩浆或熔体）的氧化还原状态，有些则作为反应物或者生成物参与到反应中。部分指示矿物（如镁铝榴石）还进一步地记录了金刚石形成后金伯利岩岩浆对金刚石的交代作用。金伯利岩岩浆温度（T），氧逸度（fO2）和挥发份(H2O和CO2)均会对金刚石的熔蚀作用产生影响，其中氧逸度作用最大，温度次之，而挥发份作用最弱。在华北克拉通，金伯利岩中指示矿物（镁铝榴石、镁铬铁矿）和金伯利岩岩浆特征（温度，氧逸度和挥发份）共同组成了金伯利岩型金刚石原生矿的评价指标。 相似文献
8.
白露山岩体是苏北地区重要的金刚石含矿岩体。通过研究该岩体中的铬铁矿化学成分,探讨其成因及金刚石的含矿性,进一步分析金刚石的成矿潜力。白露山岩体中的铬铁矿具有高Cr、低Al、高Mg的特征,属于镁铬铁矿,是深部地幔橄榄岩结晶而成的,不是岩体本身的结晶产物,可能来源于岩体中的深源捕虏体。铬铁矿的结晶温度为1 253~1 354 ℃,与金刚石的形成温度(1 150~1 400 ℃)相近,二者关系密切。铬铁矿化学成分与山东、辽宁含矿金伯利岩中铬铁矿的化学成分较相似,多数属于S4组和S6组铬铁矿,少数属于S1组和S2组铬铁矿,其中S1组和S2组铬铁矿是含矿岩体的标型矿物。白露山岩体具有良好的金刚石成矿潜力和找矿前景。 相似文献
9.
金伯利岩中的石榴子石、铬铁矿和铬透辉石是寻找金刚石矿的重要指示矿物,根据这些指示矿物的含量可大致推断金刚石原生矿的存在及含矿性。石榴子石中G10组指示金伯利岩中金刚石的存在,其含量越高,岩体中金刚石品位相对较富。由西峪G10组含量小于常马G10组含量,可推断西峪金刚石品位小于常马金刚石品位,事实证明推断正确;S1、S2、S6组铬铁矿是与金刚石共生的铬铁矿,西峪矿区62粒S6组和1粒S7组铬铁矿与深源捕虏体橄榄岩有关,几乎全部来自金伯利岩,具有重要指示意义;Cr_2O_3≥1.2%的铬透辉石含量越多,金刚石品位越高。通过统计分析,地表铬透辉石中Cr_2O_3≥1.2%含量略大于岩管深部,西峪矿区深部矿体平均品位略低于地表矿体平均品位,说明可通过铬透辉石定性地推断金伯利岩的含矿性。结合CSAMT和钻探等地质工作,在西峪岩管群深部-205m以下找到金刚石原生矿,在外围通过槽探工程发现红旗15-1岩脉,并在选矿样中选获18颗金刚石,充分证明了根据金刚石指示矿物找矿方法定性预测金伯利岩含矿性的有效性和可行性。 相似文献
10.
《矿物岩石地球化学通报》2016,(6)
与金刚石伴生的尖晶石,常作为指示矿物来评价金伯利岩的含矿性。为了解瓦房店30号岩管金伯利岩中尖晶石特征,本文对其进行了细致的形态学观察和电子探针分析。结果表明,尖晶石呈椭圆状-次棱角状,粒径大(500~1000μm),部分被熔蚀成港湾状。尖晶石中Cr_2O_3(最高达66.56%)和MgO(8.88%~16.68%)含量高,Ti含量低(大部分1%),为镁铬铁矿。尖晶石成分变化受Al~(3+)-Cr~(3+)类质同象作用控制。尖晶石为地幔捕掳晶,原地幔岩为橄榄岩。尖晶石成分特征表明30号岩管金伯利岩具有一定地携带金刚石的能力,但与50号岩管和蒙阴常马庄金伯利岩相比,30号岩管金伯利岩金刚石含矿性弱。 相似文献
11.
Conventional diamond exploration seldom searches directly for diamonds in rock and soil samples. Instead, it focuses on the search for indicator minerals like chrome spinel, which can be used to evaluate diamond potential. Chrome spinels are preserved as pristine minerals in the early Paleozoic (∼465 Ma), hydrothermally altered, Group I No. 30 pipe kimberlite that intruded the Neoproterozoic Qingbaikou strata in Wafangdian, North China Craton (NCC). The characteristics of the chrome spinels were investigated by petrographic observation (BSE imaging), quantitative chemical analysis (EPMA), and Raman spectral analysis. The results show that the chrome spinels are mostly sub-rounded with extremely few grains being subhedral, and these spinels are macrocrystic, more than 500 µm in size. The chrome spinels also have compositional zones: the cores are classified as magnesiochromite as they have distinctly chromium-rich (Cr2O3 up to 66.56 wt%) and titanium-poor (TiO2 < 1 wt%) compositions; and the rims are classified as magnetite as they have chromium-poor and iron-rich composition. In the cores of chrome spinels, compositional variations are controlled by Al3+-Cr3+ isomorphism, which results in a strong Raman spectra peak (A1g mode) varying from 690 cm−1 to 702.9 cm−1. In the rims of chrome spinel, compositional variations result in the A1g peak varying from 660 cm−1 to 672 cm−1. The morphology and chemical compositions indicate that the chrome spinels are mantle xenocrysts. The cores of the spinel are remnants of primary mantle xenocrysts that have been resorbed, and the rims were formed during kimberlite magmatism. The compositions of the cores are used to evaluate the diamond potential of this kimberlite through comparison with the compositions of chrome spinels from the Changmazhuang and No. 50 pipe kimberlites in the NCC. In MgO, Al2O3 and TiO2 versus Cr2O3 plots, the chrome spinels from the Changmazhuang and No. 50 pipe kimberlites are mostly located in the diamond stability field. However, only a small proportion of chrome spinels from No. 30 pipe kimberlite have same behavior, which indicates that the diamond potential of the former two kimberlites is greater than that of the No. 30 pipe kimberlite. This is also supported by compositional zones in the spinel grains: there is with an increase in Fe3+ in the rims, which suggests that the chrome spinels experienced highly oxidizing conditions. Oxidizing conditions may have been imparted by fluids/melts that have a great influence on diamond destruction. Here, we suggest that chrome spinel compositions can be a useful tool for identifying the target for diamond potential in the North China Craton. 相似文献
12.
Electron probe microanalysis and microscopy is a widely used modern analytical technique primarily for quantifying chemical compositions of solid materials and for mapping or imaging elemental distributions or surface morphology of samples at micrometer or nanometer-scale. This technique uses an electromagnetic lens-focused electron beam, generated from an electron gun, to bombard a sample. When the electron beam interacts with the sample, signals such as secondary electron, backscattered electron and characteristic X-ray are generated from the interaction volume. These signals are then examined by detectors to acquire chemical and imaging information of the sample. A unique part of an electron probe is that it is equipped with multiple WDS spectrometers of X-ray and each spectrometer with multiple diffracting crystals in order to analyze multiple elements simultaneously. An electron probe is capable of analyzing almost all elements (from Be to U) with a spatial resolution at or below micrometer scale and a detection limit down to a few ppm.Mineral inclusions in chromite from the Wafangdian kimberlite, Liaoning Province, China were used to demonstrate the applications of electron probe microanalysis and microscopy technique in characterizing minerals associated with ore deposits, specifically, in this paper, minerals associated with diamond deposit. Chemical analysis and SE and BSE imaging show that mineral inclusions in chromite include anhydrous silicates, hydrous silicates, carbonates, and sulfides, occurring as discrete or single mineral inclusions or composite multiple mineral inclusions. The chromite–olivine pair poses a serious problem in analysis of Cr in olivine using electron probe. Secondary fluorescence of Cr in chromite by Fe in olivine drastically increases the apparent Cr2O3 content of an olivine inclusion in a chromite. From the chemical compositions obtained using electron probe, formation temperatures and pressures of chromite and its mineral inclusions calculated using applicable geothermobarometers are from 46 kbar and 980 °C to 53 kbar and 1130 °C, which are within the stability field of diamond, thus Cr-rich chromite is a useful indication mineral for exploration of kimberlite and diamond deposit. A composite inclusion in chromite composed of silicate and carbonate minerals has a bulk composition of 33.2 wt.% SiO2, 2.5 wt.% Al2O3, 22.0 wt.% MgO, 7.5 wt.% CaO, 2.5 wt.% BaO, 0.8 wt.% K2O, 25.5 wt.% CO2, and 0.8 wt.% H2O, similar to the chemical composition of the Wafangdian kimberlite, suggesting that it is trapped kimberlitic magma. 相似文献
13.
金刚石矿是辽宁省的重要矿产之一,辽宁瓦房店地区已探明的原生金刚石矿资源/储量占中国金刚石资源量的一半以上。通过开展三维建模工作,对该区金伯利岩管的形态、深部找矿方向等提出了一些新的认识。研究认为,三维模型可以更好地展示金伯利岩型金刚石矿体的空间展布形态,并可为勘查工作提出指导性意见。 相似文献
14.
Mica kimberlite and alkali picrite were identified in the northwestern Urik-Iya Graben of the eastern Sayan region. Typomorphism
of Cr-diopside and high-Cr (up to 55.22 wt % Cr2O3) spinel from kimberlite of the Bushkanai dike indicate that the melt was generated in the mantle, composed of spinel peridotite.
The high content of Cr-spinel (45–55 wt % Cr2O3) microlites in the groundmass of kimberlite and small amounts of ulvospinel and titanomagnetite in the absence of perovskite
testifies to the diamond potential of this kimberlite. Picroilmenite, manganoilmenite with an anomalously high MnO content
(11.37–17.78 wt %), and barium titanate with (wt %) 62.21 TiO2, 0.61 Cr2O3, 15.89 FeO, 4.05 MnO, 1.71 CaO, and 11.13 BaO close in composition to a new mineral species from the Murun pluton were identified
in the groundmass for the first time. Kimberlite from the Bushkanai dike belongs to the Zolotitsa low-Ti geochemical type
of kimberlites derived from the slightly enriched lithospheric mantle EM1. The distribution of trace elements, including REE,
in picrite from the same dike corresponds to the slightly depleted asthenospheric mantle. Different mantle sources of kimberlite
and picrite from the same dike indicate that these rocks are related to independent melts rather than to products of fractionation
of a common parental alkaline ultramafic magma. 相似文献
15.
辽南瓦房店地区袁家沟金刚石原生矿找矿前景分析 总被引：1，自引：0，他引：1
通过对瓦房店袁家沟地区地质特征、遥感影像特征、物探异常特征、化探异常特征和重砂金伯利岩副矿物特征的综合分析,发现上述特征与头道沟矿区十分相似.特别值得关注的是近期辽宁省第六地质大队首次提出的金伯利岩墙成矿概念,打破了传统的金刚石岩管成矿的说法,对金刚石的成因、赋存规律有了新的认识,扩大了隐伏矿的找矿空间.通过总结袁家沟地区成矿规律,分析找矿前景,认为在袁家沟地区有望实现金刚石原生矿找矿突破,并具有找寻隐伏矿的巨大潜力. 相似文献
16.
V. P. Afanasiev O. V. Snegirev N. S. Tychkov N. P. Pokhilenko 《Doklady Earth Sciences》2013,448(1):103-105
The dissolution stability of garnets from kimberlite has been studied in new experiments in which etching in HF simulated natural chemical weathering. The experiments lasted 42 days and included weight loss monitoring and analysis of chemistry and parageneses of the output grains. The etched garnets of Cr2O3-rich parageneses became corroded less strongly. The greater chemical resistance of Cr-rich pyropes is consistent with the behavior of bulk Cr2O3 observed in a natural garnet assemblage from a weathered placer derived from the Mir kimberlite. Chemical weathering being the principal control of the assemblage composition, the placer assemblages with uncorroded pyropes may be compositionally proximal to their counterparts in the kimberlite. 相似文献
17.
Within the ‘glimmerite’ nodules occurring within kimberlite pipes we recognize the MARID suite consisting of varying proportions of mica, amphibole, rutile, ilmenite and diopside. Banding of some specimens is interpreted as cumulate layering. All specimens were deformed either before incorporation into the host kimberlite or during intrusion. Compared with minerals in peridotite xenoliths, the MARID ones are lower in Al2O3 and Cr2O3, but richer in total iron. The MARID micas, amphiboles, diopsides, ilmenites and probably rutiles contain substantial Fe2O3 indicative of oxidizing conditions. The amphibole is potassic richterite. Micas of the megacryst suite in kimberlite have less total iron and Fe2O3 than micas of the MARID suite. We suggest that the rocks of the MARID suite crystallized under oxidizing conditions from a magma, chemically similar to kimberlite, within the higher parts of the upper mantle: the presence of amphibole restricts the depth to less than ~ 100 km. A xenolith containing olivine and orthopyroxene as well as minerals similar to but not the same compositionally as MARID-types is interpreted as a metasomite, possibly representing wall-rock of a magma body from which MARID-suite rocks crystallized. 相似文献
18.
V. Ya. Gor’kovets N. S. Rudashevskii V. N. Rudashevskii M. G. Popov A. V. Antonov 《Doklady Earth Sciences》2013,450(1):475-478
The mineralogy of a new lamproitic diatreme 200–250 m in diameter and 3 ga in area is studied in detail. The chemical and 3-D mineralogical analysis identify the diatreme rocks as strongly altered olivine lamproites with a large volume (50–60%) of xenoliths of strongly altered spinel (garnet) lherzolites and harzburgites-dunites. Numerous grains-xenocrysts of indicator minerals of diamond have been extracted from the heavy concentrates (the weight of the initial product is 742 g and the size is 100–500 μm) as a result of hydroseparation: (1) subcalcium (CaOav. 2.6 wt %) high-Cr (Cr2O3 av. 5.3 wt %) pyrope (50 grains); (2) chrome diopside (7 and 8 mol % of kosmochlor and jadeite components, respectively, >40 grains); (3) high-Cr chromite (Cr2O3 > 62 wt %); and (4) picroilmenite (MgO 12–13.8 wt %) and Cr-rutile (Cr2O3 1.1 wt %). Xenocrysts prove the mantle endogene (the level of garnet lherzolites) source of the magmatic center of lamproites and forecast the diamond potential of the new diatreme in the Kostomuksha ore district. 相似文献
19.
D. I. Rezvukhin V. G. Malkovets I. S. Sharygin D. V. Kuzmin K. D. Litasov A. A. Gibsher N. P. Pokhilenko N. V. Sobolev 《Doklady Earth Sciences》2016,466(2):173-176
The results of study of rutile inclusions in pyrope from the Internatsionalnaya kimberlite pipe are presented. Rutile is characterized by unusually high contents of impurities (up to 25 wt %). The presence of Cr2O3 (up to 9.75 wt %) and Nb2O5 (up to 15.57 wt %) are most typical. Rutile inclusions often occur in assemblage with Ti-rich oxides: picroilmenite and crichtonite group minerals. The Cr-pyropes with inclusions of rutile, picroilmenite, and crichtonite group minerals were formed in the lithospheric mantle beneath the Mirnyi field during their joint crystallization from melts enriched in Fe, Ti, and other incompatible elements as a result of metasomatic enrichment of the depleted lithospheric mantle. 相似文献