在迟家店石榴石二辉橄榄岩的橄榄石中发现自然铁及其意义

通过高分辨电子显微镜研究，发现在山东荣成迟家店石榴石二辉橄榄岩的橄榄石中除钛铁矿和磁铁矿出溶物外。还有一种矩形出溶物，长为20μm、宽为5μm．能量损失X射线分光谱(XEDS)分析矩形物的成分为Fe。选区电子衍射花样计算表明该矿物与和JCPDS中的标准矿物自然铁-α和自然铁-γ衍射数据一致。根据自然铁的化学成份推断橄榄石中自然铁-α和自然铁-γ的形成温度范围为490～900℃，压力不超过8．2GPa，并讨论了自然铁与深源地幔流体作用。     

云南六合霓辉正长斑岩中特殊包体岩石的发现及其意义

在六合霓辉正长斑岩中广泛发育的各类包体岩石中,新近发现了三类特殊包体.通过岩相学、岩石化学、电子探针和扫描电镜分析研究表明,纯方解石包晶(体)和含石英的黄玉伟晶岩包体是地幔流体在运移过程中发生去气作用的产物;黑色微晶富铁硅酸盐熔融包体是地幔流体伴随去气作用的分离产物,其主要矿物组成为石英、绿泥石和富铁的柱状和片状硅酸盐矿物,特征矿物有自然铁、磷灰石和锆石;据全岩化学成分和矿物组成特征及结晶状态分析,表明该包体岩石不是常规岩浆作用产物,尤其自然铁的存在进一步证明该微晶熔融包体是还原条件或缺氧环境下的地幔流体物质.通过对特殊包体岩石的研究,为该区不同岩性和地层中的多金属成矿提供了重要的深部过程地球化学背景.     

云南六合霓辉正长斑岩中特殊包体岩石的发现及其意义

在六合霓辉正长斑岩中广泛发育的各类包体岩石中，新近发现了三类特殊包体。通过岩相学、岩石化学、电子探针和扫描电镜分析研究表明，纯方解石包晶（体）和含石英的黄玉伟晶岩包体是地幔流体在运移过程中发生去气作用的产物；黑色微晶富铁硅酸盐熔融包体是地幔流体伴随去气作用的分离产物，其主要矿物组成为石英、绿泥石和富铁的柱状和片状硅酸盐矿物，特征矿物有自然铁、磷灰石和锆石；据全岩化学成分和矿物组成特征及结晶状态分析，表明该包体岩石不是常规岩浆作用产物，尤其自然铁的存在进一步证明该微晶熔融包体是还原条件或缺氧环境下的地幔流体物质。通过对特殊包体岩石的研究，为该区不同岩性和地层中的多金属成矿提供了重要的深部过程地球化学背景。     

铁同位素体系及其在矿床学中的应用

本文报道了世界范围内不同含铁矿物的Fe同位素组成,进一步了解了铁同位素在不同含铁矿物中的基本分布特征;系统总结了铁同位素在不同储库和不同类型矿床中的分布特征,构筑了铁同位素体系的基本框架;结合最新的研究成果,较全面地总结了铁同位素在矿床学领域的应用,得出了铁同位素可以用来示踪流体出溶、流体演化、表生蚀变作用和成矿物质来源的基本认识。在流体出溶过程中,相对于岩体,出溶的流体富集铁的轻同位素;成矿流体体系的演化过程中,矿物的结晶沉淀会导致铁同位素发生分馏,随着Fe(III)矿物的结晶沉淀,流体逐渐富集铁的轻同位素,随着Fe(II)矿物的结晶沉淀,流体逐渐富集铁的重同位素,随着矿物的结晶沉淀,流体的Fe同位素组成随时间发生演化;在成矿后的表生蚀变作用过程,高温蚀变作用形成的产物相对于原矿物富集铁重同位素,低温蚀变作用形成的产物基本保留了原矿物的铁同位素组成;Fe同位素在示踪成矿物质来源具有应用潜力,流体出溶、流体演化等重要成矿作用过程中Fe同位素组成的变化规律是利用Fe同位素示踪Fe来源的关键所在。     

含金石英脉型矿床中自然铁的首次发现及其研究

自然铁是自然界中极为罕见矿物,诺登斯科德(Norden Ski(?)d)最早(1870年)在格陵兰西海岸狄斯哥(Disko)玄武岩中首次发现自然铁。我国迄今未见自然铁的发现和报道.笔者于1985年在小秦岭金矿金硐岔矿区9号含金石英脉第五阶段自然铁——金属硫化物,氧化物矿石中首次发现自然铁.与自然铁共生的矿物有自然铁外壳磁铁矿、微粒(0.1～0.2mm)它形方铅矿、黄铁矿淡棕色闪锌矿、浅色闪锌矿、密黄色闪锌矿、自形八面体磁铁     

贵州安龙戈塘氧化带中自然铝的发现

在贵州省西南部安龙县戈塘乡一带的黄钾铁矾化交代石英岩中,发现了极其罕见的天然矿物——自然铝。 本自然铝主要分布在黄钾铁矾的端点、边缘或充填在空洞中,少数分布在石英颗粒间。自然铝常与自然铜、自然硫等密切伴生,并交代黄钾铁矾。 本文详细介绍了自然铝的物理性质、化学成分及矿物共生组合等。     

幔源岩与自然金

根根文献报道,近年来在一些地区的幔源岩中不断发现自然金如: 1.在我国西藏红区幔源超镁铁岩中除常量矿物橄榄石、辉石、铬尖晶石和少量矿物铁铝—镁铝榴石、碳硅石、锆石、刚玉、碳铬矿等矿物之外,还发现了自然金。 2.在取自印度洋断裂下部幔源超镁铁岩的碎块中找到了20粒与硫化物共生的自然金,粒度为～0.05mm,他形晶(片状、树枝状、变形虫状)。自然金的直接围岩为蛇纹石     

南秦岭泥盆系典型金矿床高盐度流体脑其深源特征

对赋存于南秦岭泥盆系浅变质碎屑岩中的陕西太白金矿到八卦庙金矿主成矿阶段的石英和含铁白云石中的流体包裹体进行研究,发现局部富含高盐度、含子矿物的流体包裹体,通过光学显微镜,电子探针（ＥＰＭＡ）,扫描电镜／能谱（ＳＥＭ／ＥＤＳ）发现子矿物主要为黄铁矿,铁白云石、石盐、毒砂及一些成分复杂的子矿物,认为矿床成矿流体具复杂的物理化学条件,不同于一般的热液金矿床,结合矿床形成的大地构造位置分析,主成矿阶段矿物     

南越大陆架基岩中油,气藏的热液成因

在南越大陆架结晶基底的断层附近发现了油饱和花岗岩、这些花岗岩具有特征的热液交代作用和淋滤晕矿物共生组合。自然银、重晶石、含锌、铜和铁的氯化物的存在表明，矿化流体为深部成因。这些热蚀变花岗岩是一种可能的新型油，气储集层，这将会大为拓宽油，气勘探的领域。     

地幔流体的交代作用——来自碱性正长岩及其深源岩石包体的证据

滇西玉龙县小桥头硅化霓辉正长斑岩中,含有较多镁铁-超镁铁质深源包体岩石。经岩相学和电子探针及扫描电镜分析发现,伴随交代蚀变,寄主岩和各类镁铁-超镁铁质包体岩石中,普遍发育沿粒间和矿物晶体裂隙或解理纹贯入或穿插的黑色不透明物质,主要由微晶硅酸盐矿物和磁铁矿组成。本文研究认为,硅酸盐矿物与磁铁矿在背散射电子图像中表现为熔离特征,这种在透光显微镜下呈黑色不透明的微晶固体,是引发交代蚀变、具熔浆流体特点和超临界流体性质的地幔流体交代作用的一种微观表现。     

The Fazenda Largo off-craton kimberlites of Piauí State, Brazil

In the late 1990s, the Fazenda Largo kimberlite cluster was discovered in the Piauí State of Brazil. As with earlier known kimberlites in this area – Redondão, Santa Filomena-Bom Jesus (Gilbues) and Picos – this cluster is located within the Palaeozoic Parnaiba Sedimentary Basin that separates the São Francisco and the Amazonian Precambrian cratons. Locations of kimberlites are controlled by the ‘Transbrasiliano Lineament’. The Fazenda Largo kimberlites are intensely weathered, almost completely altered rocks with a fine-grained clastic structure, and contain variable amounts of terrigene admixture (quartz sand). These rocks represent near-surface volcano-sedimentary deposits of the crater parts of kimberlite pipes. By petrographic, mineralogical and chemical features, the Fazenda Largo kimberlites are similar to average kimberlite. The composition of the deep-seated material in the Fazenda Largo kimberlites is quite diverse: among mantle microxenoliths are amphibolitised pyrope peridotites, garnetised spinel peridotites, ilmenite peridotites, chromian spinel + chromian diopside + pyrope intergrowths, and large xenoliths of pyrope dunite. High-pressure minerals are predominantly of the ultramafic suite, Cr-association minerals (purplish-red and violet pyrope, chromian spinel, chromian diopside, Cr-pargasite and orthopyroxene). The Ti-association minerals of the ultramafic suite (picroilmenite and orange pyrope), as well as rare grains of orange pyrope-almandine of the eclogite association, are subordinate. Kimberlites from all four pipes contain rare grains of G10 pyrope of the diamond association, but chromian spinel of the diamond association was not encountered. By their tectonic position, by geochemical characteristics, and by the composition of kimberlite indicator minerals, the Fazenda Largo kimberlites, like the others of such type, are unlikely to be economic.     

Clinopyroxenes in Kimberlites of China

The author studied the grain size, shape, colour, altered coat, mineral species, chemical composition,end- member components and infrared spectra of clinopyroxenes occurring as megacryst, macrocryst andgroundmass minerals, intergrowths with pyrope and ilmenite and minerals in deep-seated xenoliths and inclu-sions in diamonds in kimberlites of China. The clinopyroxenes under study were compared with megacrystclinopyroxenes in basalts and minerals in their deep-seated xenoliths and clinopyroxenes in lamproites andminettes. The coexisting clinopyroxene-pyrope pair was studied. Besides the author also studied the origin ofclinopyroxenes in kimberlites, P-T conditions for their formation and their reflected tectonic environments ofthe kimberlite formation. He suggests that this mineral is an indicator for diamond exploration.     

Normative quartz as an indicator of the mass transfer intensity during the postmagmatic alteration of the Botuobinskaya pipe kimberlites (Yakutia)

The intensity of postmagmatic processes in the Botuobinskaya pipe kimberlites was estimated from the calculated content of normative secondary quartz (Q). Several simple algorithms are proposed to calculate the Q content from chemical analyses of kimberlites. Ten groups of altered kimberlites have been recognized from the Q contents. The contents of MgO, some trace elements, and LREE in the groups, the contents of Cr and Ca of crimson garnets, the diamond contents of kimberlites, and the average weight of diamonds decrease as the Q content increases. It is shown that the negative SiO₂–MgO correlation is the most effective indicator of the postmagmatic alteration of kimberlites. As the degree of their secondary alteration increases, the kimberlites transform into an assemblage of quartz and clay minerals enriched in some trace elements and almost completely lacking REE and diamonds.     

Neoproterozoic ‘anomalous’ kimberlites of Guaniamo, Venezuela: Mica kimberlites of ‘isotopic transitional’ type

In Venezuela, kimberlites have so far only been found in the Guaniamo region, where they occur as high diamond grade sheets in massive to steeply foliated Paleoproterozoic granitoid rocks. The emplacement age of the Guaniamo kimberlites is 712±6 Ma, i.e., Neoproterozoic. The Guaniamo kimberlites contain a high abundance of mantle minerals, with greater than 30% olivine macrocrysts. The principal kimberlite indicator minerals found are pyrope garnet and chromian spinel, with the overwhelming majority of the garnets being of the peridotite association. Chrome-diopside is rare, and picroilmenite is uncommon. Chemically, the Guaniamo kimberlites are characterized by high MgO contents, with low Al₂O₃ and TiO₂ contents and higher than average FeO and K₂O contents. These rocks have above average Ni, Cr, Co, Th, Nb, Ta, Sr and LREE concentrations and very low P, Y and, particularly, Zr and Hf contents. The Nb/Zr ratio is very distinctive and is similar to that of the Aries, Australia kimberlite. The Guaniamo kimberlites are similar in petrography, mineralogy and mantle mineral content to ilmenite-free Group 2 mica kimberlites of South Africa. The Nd-Sr isotopic characteristics of Guaniamo kimberlites are distinct from both kimberlite Group 1 and Group 2, being more similar to transitional type kimberlites, and in particular to diamondiferous kimberlites of the Arkhangelsk Diamond Province, Russia. The Guaniamo kimberlites form part of a compositional spectrum between other standard kimberlite reference groups. They formed from metasomatised subcontinental lithospheric mantle and it is likely that subduction of oceanic crust was the source of this metasomatised material, and also of the eclogitic component, which is dominant in Guaniamo diamonds.     

Diamonds from placers in western and central Africa: A problem of primary sources

This paper discusses diamonds and their accessory minerals from the Koidu kimberlites, placers on the Bafit River in Sierra Leone, and Chikapa placers in the Democratic Republic of Congo. Minerals from the placers are characterized by fine preservation and bear no evidence of long-term transportation. In placers, garnet, ilmenite and zircon have been found, but the specific features of their chemical composition do not coincide with those of minerals from kimberlites. Diamonds from the placers are of a mantle origin, but they have no direct analogs in the known kimberlite and lamproite pipes.     

Kimberlites and lamproites: Criteria for similarity and differences

Based on original data on the East European and Siberian platforms and materials on the best studied foreign objects, a comparative analysis of kimberlites and lamproites was conducted and the criteria of their differences were formulated. Among most significant differences are the following: (1) the high-Mg potassic rocks (kimberlites and lamproites) show major-component variations, which are significantly wider in lamproites as compared to kimberlites. Kimberlites differ from lamproites not only in the content of SiO₂, but also in alkalis, volatiles, and some trace elements. Kimberlites are characterized by CO₂-dominated regime, whereas formation of lamproites was assisted by essentially H₂O fluid; (2) Kimberlites are localized within ancient cratons, while within-plate lamproites are restricted to adjacent Proterozoic belts. Kimberlites are produced in the low-heat flow regions, whereas lamproites occur in the high-heat flow regions; (3) Kimberlites and lamproites were formed in different time; in particular, most productive kimberlitic magmatism was observed in the EEP and SP in the Devonian; (4) Kimberlite and lamproite bodies have different morphology: lamproites compose small subvolcanic bodies with lava flows, while kimberlites form volcanic pipes with no lavas; (5) Kimberlites contain highly silica-undersaturated minerals, while ultrabasic lamproites—silica-undersaturated ones; priderite and wadeite, the characteristic accessory minerals of lamproites, are not observed in kimberlites; (6) The primary melts of kimberlites and lamproites were derived from different types of mantle. The moderate and low-Ti kimberlites were generated from BSE or EMI type mantle. Precisely these types of kimberlites host diamond deposits, including economic grade objects in EEP. The lamproite sources were localized only in the enriched mantle (EMI and EMII). At the same time, these rocks share some similarities, primarily, with respect to their genesis and classification. Diamonds are common accessory minerals of kimberlites (low-Ti and some other types), but are observed only in only lamproite variety—olivine lamproites.     

Oxide minerals in a layered kimberlite-carbonate sill from Benfontein,South Africa

The lower sill at Benfontein, South Africa, shows a high degree of magmatic sedimentation to kimberlite, oxide-carbonate, and carbonate layers. The iron-titanium oxide minerals are similar in the carbonate-rich and silicate-rich layers and are represented by titaniferous Mg-Al chromite, Mg-Al titanomagnetite, magnesian ilmenite, rutile, and perovskite. The spinel crystallization trend was toward enrichment in Mg and Ti and depletion in Cr; this trend is similar to that observed in many kimberlites. The ilmenite has Mg and Cr contents within the range observed in kimberlites and lacks the Mn enrichment observed in ilmenites from carbonatites. Perovskite in silicate-rich and carbonate-rich layers shows similar total REE contents and LREE enrichment and lacks the remarkable Nb enrichment observed in perovskite from carbonatites. These new data on the iron-titanium oxide minerals in the lower Benfontein sill do not support a genetic relationship between kimberlites and carbonatites.     

中国大陆岩石圈厚度特征研究及其在金刚石原生矿预测中的作用

依据中国大陆三维速度扰动图象,编制了中国大陆现代岩石圈和华北—扬子地台古岩石圈厚度图,并对含与不含金刚石的金伯利岩及钾镁煌斑岩中部分指示矿物和上地幔捕虏体地质特征进行分析,发现岩石圈底部某些地球物理特征与金刚石赋存部位有密切关系。在此基础上,从深部角度讨论了含金刚石的金伯利岩及钾镁煌斑岩时空分布特征,并作了预测研究。     

Garnets of crustal parageneses in alluvial deposits of the eastern Siberian Platform: genesis and search significance

We present results of study of the specific composition and parageneses of pyrope-almandine garnets from alluvial deposits of the Muna-Markha interfluve drainage in the Yakutian diamondiferous province. The data are correlated with the specific features of garnets (tentatively crustal) from Yakutian and Guinean kimberlites and their crustal xenoliths and from metamorphic rocks of the Anabar Shield. The conclusion is drawn that most of orange pyrope-almandine garnets from the alluvial deposits were generated from kimberlites with varying contents of disintegrated crustal material. This gives grounds to include the studied garnets into a complex of indicator minerals of kimberlites and use them in search for diamonds in the Yakutian diamondiferous province.     

On the Prospects of Diamond Content of the Southern Side of the Vilyui Syneclise

Geology of Ore Deposits - Abstract—The paper describes indicator minerals of kimberlites found on the southern side of the Vilyui syneclise in the Markha River basin, a tributary of the Lena...