Large-volume platinum ore deposits in zonal mafic-ultramafic complexes of the Ural-Alaskan type and the outlook for their development

The results of mineralogical-technological studies of PGM mineralization in zonal mafic-ultramafic complexes of the Ural-Alaskan type are given. All studied massifs in the Urals and Kamchatka are characterized by similar evolution of mineral assemblages. The chromite (platinum-chromitite-dunite) and dunite (platinum-pegmatoid dunite) geological-economic types of small platinum deposits and occurrences are separate enriched sites (ore shoots) of large-volume platinum ore deposits. These are rather thick and extended zones of recrystallized dunites with attributes of high-temperature structural deformations and intense fluid reworking. Low Pt grade in ore (<0.5 gpt) is determined by fine and very fine (grain size class — 80 μm) euhedral PGM crystals distributed rather uniformly in ore mass. The high and occasionally anomalous Pt contents (up to 1 kgpt and higher) are related to large xenomorphic segregations of PGM, which concentrate largely in the marginal parts of separate chromite segregations. The significant part of productive Pt-bearing mineralization is hosted in olivine matrix of igneous rocks, so that recovery of platinum cannot be associated only with separation of chromite ore. The direct gravity concentration of platinum ore without preliminary separation of chromite concentrate is recommended as the main technique of platinum recovery. The technological scheme provides for two-stage comminution of ore with between-cycle separation of coarse the PGM fraction into the concentrate as a commodity product. The results obtained allow us to regard the aforementioned mineralization as a new geological and economic type of lode platinum deposits, whose potential is comparable with active platinum reserves in the complex Cu-Ni ores of the Noril’sk district.     

岩浆硫化物矿床研究现状及重要科学问题

20世纪90年代,岩浆通道成矿模型的提出为岩浆硫化物矿床成因研究提供了崭新的思路,但对成矿机制和找矿标志的认识依然存在分歧。2000年以来,不同学者从岩浆通道形成的构造因素,外来硫加入的方式和控制因素,硫化物熔离、运移和沉降的热力学条件及动力学机制,区域找矿标志等方面对岩浆通道成矿机理进行了更深入的探讨。最近的研究发现,原来建立在热力学平衡假设基础上的一些认识需要纠正,硫化物熔离的化学动力学机制以及岩浆流体动力学状态对矿床的地质和地球化学特征具有不可忽视的影响,玄武岩铂族元素亏损的形成机制和找矿意义需要重新认识。     

锰矿主要类型、分布特点及开发现状

锰的用途非常广泛,世界上90%～95%的锰应用于冶金工业,其余应用于电池工业、陶瓷工业、化学工业等。根据成矿作用过程中的含矿岩系特征,将世界锰矿划分为海相沉积型、火山(热液)-沉积型、变质型、热液型和表生型5类,以海相沉积型、变质型和表生型为主。截至2019年,世界锰的储量达8.12亿t,但分布极不均匀,主要集中在南非、巴西、乌克兰、澳大利亚、加蓬、中国、印度、加纳等国,而优质锰矿石主要分布在南非、澳大利亚、加蓬、加纳。时间上,将锰的成矿作用分为7期,其中元古宙和新生代是主要的成矿期。空间上,锰矿床主要分布在南非德兰士瓦群、乌克兰尼科波尔盆地、澳大利亚格鲁特岛和皮尔巴拉克拉通、中国泛扬子区、西非克拉通等。目前,锰的生产主要集中在南非的卡拉哈里和波斯特马斯堡锰矿田、澳大利亚的格鲁特岛、加蓬的莫安达锰矿、加纳的恩苏塔锰矿等地。     

非洲磷矿资源格局与开发现状

磷是生物体所必需的营养元素,因其不可替代性及未来迅速枯竭性,被中、德、日、英、美等国相继列入战略性矿产资源清单。全球磷矿石资源丰富,但是分布极不均衡,70%以上集中在非洲,著名的磷矿资源国有摩洛哥及西撒哈拉地区,阿尔及利亚、南非、埃及、突尼斯、塞内加尔、多哥等国磷矿储量也较为丰富,非洲可谓是全球磷矿储量的绝对担当。矿床类型主要有沉积型、岩浆型和鸟粪型,以沉积型为主,同时具有储量大、品位高、伴生有其他具有经济价值元素等特点。近年来,非洲已成为全球重要磷矿产地与供应地,目前,在非洲从事磷矿勘查开发的矿业公司以本土矿业公司为主,摩洛哥磷酸盐集团是全球上最大的磷酸盐生产和出口商。非洲磷矿石主要出口大国为摩洛哥、埃及、多哥、阿尔及利亚等;出口至印度、印度尼西、墨西哥、巴西等国家。未来,非洲仍将为全球主要磷矿供应地之一,并将扮演更加重要的角色。     

地球科学与碳中和：现状与发展方向

碳中和是当前世界关注的热点,地球科学可以在其中发挥很大的作用。在国际上,政府间气候变化专门委员会、国际能源署、能源转型委员会,以及在国家层面,政策咨询小组已就CO_2减排可能的实现方式提出了一系列模型和预测情景,表明要实现碳中和,电将代替化石燃料成为全球能源的主要载体。在全球迫切需要减排的背景下,地球科学为实现《巴黎协定》气候目标提供地质解决方案至关重要,主要科学问题涉及:储热与地热;干热岩;水电储能;压缩空气储能;核能;碳捕集与储存;氢经济;能源转型需要的矿产原材料。这就需要地球科学:一是对岩石进行地球化学和地质体的岩石力学特征描述,以便在可能开展脱碳的地区储存CO_2和建立绿色能源系统;二是进一步揭示电动汽车电池和风力涡轮机等所需矿产资源的起源和成因;三是从小型实验室尺度扩大到试点、工业化和商业化全尺度规模;四是要了解公众对地下脱碳技术的态度,保证项目安全性。碳中和目标为地球科学研究提供了新的机遇,未来发展需要从多方面提供支持;提高对地球科学在实现脱碳方面关键作用的认识,并发展技术,打造产业链,实现可持续发展。     

Proximal and distal stratabound ore deposits

Stratiform ore deposits associated with calc-alkaline and tholeiitic volcanism form as chemically precipitated sediments and, like other sediments, display facies variations. An attempt to characterise these vertical and lateral facies variations and to relate them to distance in time and space from the volcanic centre is presented here. With increasing distance in time and space from a volcanic centre, the proportions of volcanics to sediments and intensity of hydrothermal alteration decrease. Footwall alteration pipes, stringer and disseminated ore zones dominated by quartz-, sericite- and Mg-rich assemblages are spatially associated with proximal stratiform base metal deposits whereas slight alteration to quartz-, sericite- and Fe(Mn)-bearing assemblages are present associated with distal stratiform base metal deposits. With increasing distance in time and space from the volcanic centre the Fe, Cu and S content of base metal deposits decreases and the Zn, Pb, Ag, Mn, Ba and F content increases. The trend from copper-dominated to zinc-lead-dominated iron sulphide ores is probably a result of the increasing mixing of seawater with metal-bearing hydrothermal fluid with increasing distance from the volcanic centre.     

姻袭成矿与特大型矿床

姻袭成矿与特大型矿床ＡｆｉｌｉａｔｉｏｎａｌＭｅｔａｌｏｇｅｎｙａｎｄＧｉａｎｔＯｒｅＤｅｐｏｓｉｔｓ裴荣富（中国地质科学院矿床地质研究所，北京）烟袭成矿或称亲缘成矿。这一成矿概念早在中世纪（１６世纪中期以前）的矿石成因猜想年代就已萌芽［１］。例如当...     

界面矿床与峨眉山玄武岩

文章称发育在下二叠统茅口灰岩与覆盖其上的上二叠统峨眉山玄武岩之间界面上的众多矿床为界面矿床,并列出了各类代表性界面矿床的地质特征.从这些地质特征可以看出:界面是成矿的有利空间.富含成矿物质的峨眉山玄武岩的多期次喷发以及喷发-成岩-风化-喷发的多旋回机制使成矿物质得以逐渐富集而成矿,形成了一个以玄武岩为中心的Cu-Ag-Sb-S-Fe-Mo的成矿序列.     

New technologies of comprehensive recovery of valuable components from minerals: Current status and further progress

The main lines of basic research in the field of comprehensive processing of minerals are considered, and the current status of development of new technologies in Russia and abroad is compared. Alternative processes of intergranular disintegration of mineral complexes, as well as highly efficient and environmentally safe technologies of refractory ore processing, are discussed.     

找寻特大型隐伏矿床的衍生矿床导向和成矿轨迹追踪研究

本文通过对挡墙背滑动土楔体力矩平衡的分析，提出了一种求解压力合力作用的力矩平衡新方法。并给出了三种类型挡墙的土压力合力作用位置的计算公式；以供参考。     

Multi-stage enrichment processes for large gold-bearing ore deposits

A review of previous studies of the world's large hydrothermal gold deposits indicates that the largest deposits tend to show complicated parageneses where multiple gold enrichment events and processes have been involved in the deposit generation. These observations suggest that multistage processes may even be a requirement for the formation of large deposits. In some deposits (e.g. Witwatersrand, Boddington Cadia, Sukhoi Log or Carlin) the different enrichment processes occur millions of years apart. In others, such as many large porphyry deposits, the different stages are much closer in time. In many deposits, particularly sedimentary-hosted deposits, early diffuse enrichment occurs within a particular province that is then upgraded by more focused processes (e.g., Sukhoi Log; Kalgoorlie). The presence of this early diffuse enrichment could explain the tendency for gold deposits to cluster into camps.This model has important implications, as the presence or absence of multiple gold events could be used to discriminate, at the exploration and feasibility stages, between small deposits with single stage ore genesis and more complicated deposits with multistage enrichment and the potential for larger gold endowment.     

矿床形成深度与深部成矿预测

摘要：阐述了不同类型内生矿床的成矿深度和金属沉淀的垂直范围。热液成矿作用的深度下限可以下降到10000～12000m。不同类型矿床的成矿深度范围与成矿时的具体地质构造特征有关,且有很大的变化空间。金属矿床的形成深度受成矿母岩岩浆侵位深度的约束,而岩浆侵位的深度又与岩浆中挥发组分的数量、流体释放的时间、成矿元素的矿物/熔体和溶液/熔体分配系数等因素有关。据此可以解释斑岩铜－（钼）、斑岩钼-(铜)和斑岩钨矿床形成深度的差异。地温梯度和多孔岩石的渗透率也与成矿深度有关。CO2等挥发组分的溶解度对压力非常敏感,因此流体包裹体地质压力计对于成矿深度的确定有重要的应用价值。在开展深部成矿预测和找矿时,探寻隐伏岩体顶上带或岩钟是寻找深部与花岗岩有关的多金属矿床的捷径之一。