Two types of noble metal mineralization in the Kaalamo massif (Karelia)

Noble metal mineralization of the syngenetic (Southern Kaalamo) and epigenetic (Surisuo) types are defined in the Kaalamo massif. The ?Pt, Pd, Au content is as high as 0.9–1.1 g/t. Syngenetic mineralization started at the late magmatic stage (at around 800°C) gradually evolving to cease during the hydrothermal–metasomatic stage (<271°C). Epigenetic mineralization was formed at temperatures ranging from 500 to <230°C in zones of intense shear deformations and low-temperature metasomatosis during the collisional stage of the Svecofennian tectono-magmatic cycle (approximately 1.85 Ga ago). Taking into consideration the geological position of the Kaalamo massif in the Raakhe–Ladoga metallogenic zone with widely developed intense shear dislocations, the epigenetic mineralization type seems to be more promising with respect to noble metals.     

Relationship between mercury and arsenic mineralization in the Sarasa ore zone (Gornyy Altay)

Granite gneiss, gneiss, and granite domes of Central Karelia are developed near the junction zone between two tectonic structures, the Western anticlinorium of the Belomorides and the East Karelian zone of the Karelides, The established regular restriction of both shows and deposits of a number of mineral resources to the surroundings of the domes is of importance in forecasting and the future direction of exploration work in this region. —Authors.     

Rajkonkoski gold-telluride ore occurrence: A new high prospective type of complex noble metal mineralization in the Karelian Proterozoic

The Rajkonkoski ore occurrence is located within the region of the Karelian craton (AR₂) and the Svecofennian folded belt (PR₁) conjugation. It is presented by quartz-carbonate veins in metadoleriles and a zone of brecciation, crumple, and silification of carbonaceous shales within the volcanites of the Soanlakhtinsky suite (PR₁). Ore mineralization in black shales and quartz veins has features of genetic similarity presenting different levels of the ore system controlled by different range strike-slip fault dislocations. At the Rajkonkoski ore occurrence, 41 ore minerals have been identified: 12 tellurides (native tellurium, hedleyite, pilsenite, tsumoite, tellurobismuthite, hessite, stuetzite, radclidzhite, joseite-B, altaite, volynskite, petzite); 4 bismuth-tellurides of the following compositions Bi₃Te, Bi₃Te₂, BiTe₄, PbBiTe; 3 selenides (clausthalite, tellurolaitakarite, native selenium); and 12 native metals (gold, silver, electrum, copper, iron, lead, tin, bismuth, osmiridium). The contents of the main ore minerals in places exceed 10%, and the concentrations of elements reach as follows: Cu and Pb, 5%; Zn, Bi, 1%; Se, 219 ppm; Te, 171 ppm; Sb, 3 ppm; As, 5 ppm; Ag, >0.1%; Au, 35.28 ppm. Ore mineralization is formed during the temperature interval from 550°C up to <170oC in the conditions of high activity of Se and Te, and beginning from medium temperatures (>300°C) complete miscibilities galenite-clausthalite and galenite-altaite are observed. In aggregate with a wide temperature interval (>400°C) of ore process evolution and mineral specia variety of telluride and native metal mineralizations, the original “torsion” of different temperature mineralizations makes it possible to determine the affiliation of the Rajkonkoski ore occurrence to the xenothermal type deposits or epithermal “alkaline,” gold-telluride A-type characterized by a close connection with magmatism of increased alkalinity and the original geochemical (Te-V-F) and mineral (tellurides of gold, silver and other metals, fluorite, roscoelite, vanadium-containing sulfides) associations. Taking into consideration that many of the xenothermal and epithermal A-type gold and silver deposits are large commercial objects, the prospects of the Rajkonkoski ore occurrence and the region of the Karelian craton and Svecofennian folded belt conjugation seem to be significant for noble metal mineralization.     

A new type of noble metal mineralization in the Northern Caucasus

The weathering crust of the Beden ultrabasite massif (the basin of Big Laba River) is identified and studied. Anomalously high contents of noble metals (Au, Pt, Pd) are revealed in the basal horizon of the Jurassic part of the weathering crust. For this reason we suspect an existence of a belt of noble metal miner-alization in the Paleozoic ultrabasites in the Peredovoi Range of the Northern Caucasus.     

Distribution and formation conditions of noble metal mineralization in coal-bearing basins

Original data and a survey of the literature indicate that Au and Au-PGE mineralization are abundant in coal measures. Anomalous contents of noble metals have been established in basins with various types of basement, composed of granite, volcanic rocks, schist, and limestone. These basins are located in Au-and PGE-bearing ore districts, as well as at a considerable distance from known ore deposits and occurrences. Ore formation in coal-bearing basins may occur during sedimentation, peat accumulation, and diagenesis of organic matter or may be epigenetic. Noble metals are supplied to sedimentary basins as minerals that are transported by water and air and as ion species migrating along with surface and subsurface in-and exfiltration solutions of various chemical and genetic types. Ore mineralization concentrates in coal seams and host sedimentary beds of various grain size, including conglomerate, sand, and clay, as well as in zones of hydrothermal alteration superimposed on basement rocks and the sedimentary cover. The mode of occurrence of noble metals in coal basins is diverse as well (noble metal minerals, isomorphic admixtures in sulfides, and organic compounds). The data presented allow coal-bearing basins to be regarded as promising for economic noble metal mineralization fit for recovery as by-products in the course of coal mining.     

New data on mineral composition of noble metal mineralization of the stoilo iron ore deposit of KMA,Central Russia

Doklady Earth Sciences -     

西藏纳木错—嘉黎断裂带铜多金属矿化特征及找矿模型

西藏纳木错—嘉黎断裂带是狮泉河-申扎-嘉黎结合带的重要组成部分,该断裂带为区内的控岩控界断裂,具有规模大、切割深的特点,是西藏念青唐古拉山地区铜多金属成矿的重要导矿构造.断裂带西起纳木错,东至嘉黎县城以东,全长320km以上,沿该带及两侧分布有大量地化异常及大、中型矿床(点).通过对区内地、物、化、遥资料的综合研究,分...     

Nature of graphitization and noble metal mineralization in metamorphic rocks of the northern Khanka Terrane, Primorye

Elevated contents of noble metals (NM) have been established in the Riphean-Cambrian graphite-bearing complexes of the northern Khanka Terrane, which metamorphosed under conditions of greenschist to granulite facies. At the previously known graphite deposits of the Turgenevo-Tamga group, NM comprise (ppm): Pt (0.04–62.13), Au (0.021–26), Ag (0.56–4.41), Pd (0.003–5.67), Ru (0.007–0.2), Rh (0.001–0.74), Ir (0.002–0.55), and Os (0.011–0.09). Analyses of graphitized rocks carried out with various methods (IMS, INAA, AAS, AES, fire assay) reveal a wide scatter of the results related to the specifics of sample preparation, in particular, due to a significant loss of NM by thermal oxidation decomposition. Analysis of a low-soluble graphite residue obtained by treatment of graphitized rocks allowed us to establish genetic links between NM mineralization and carbonic alteration of various igneous, granulite- and amphibolitefacies metamorphic rocks, which occur over a vast area. The nonuniform distribution of graphite and NM in rocks, their fine dispersivity, and compositional variability of NM indicate that their origin is related largely to endogenic processes with the participation of deep reduced fluids. In greenschist-facies rocks, fluorine, bromine, and iodine are associated both with ore minerals and graphite, providing evidence for transport of NM by halogene- and carbon-bearing fluids. The inhomogeneous distribution of metals in graphite, microglobular structure, and carbon isotopic composition are the guides for its gas-condensate crystallization. At the same time, thermal analysis and Raman spectroscopy show that graphite formed by metamorphism of carbonaceous matter contained in sedimentary rocks also occurs. It is concluded that the predominant mass of NM is of fluid-magmatic origin with the participation of exogenic and metamorphic sources of metals.     

中国成矿区（带）的划分

成矿区（带）是区域成矿学的核心内容。当今以矿床成矿系列理论为中心的区域成矿学新理论的形成标志着地学各分支学科理论的相互融通，从更高层次上深化了区域成矿规律的研究。成矿区（带）的标定并和矿床成矿系列的研究相结合，开拓了区域成矿规律研究的新领域，已经成为当今区域成矿学研究的热点。已知矿床空间分布的集中性和据此提出的矿化集中区概念是圈定各级成矿区（带）的实际依据之一。成矿区（带）内对应的地质构造单元、成矿地质环境的类别和矿床的空间分布特征标志着成矿区（带）内部的物质结构、成矿作用特点和成矿作用的规律性。区域成矿学研究已经表明，成矿物质的巨量富集与成矿地质环境关系密切。从成矿地质环境和产出的矿床成矿系列入手及引入矿床成矿谱系的新概念，有可能揭示成矿区（带）内成矿地质环境的分异变迁对成矿元素巨量富集的控制作用和区域成矿作用的演化过程，深化认识中国多旋回成矿作用的自然规律。     

Gold mineralization of the Khaak-Sair gold-quartz ore occurrence in listwanites (western Tuva)

We consider mineral assemblages and mineralogical and geochemical peculiarities of hypogene gold from the Khaak-Sair multistage low-sulfide gold-quartz ore occurrence in listwanites. Three productive substages of Au-and Ag-mineral formation have been recognized on the basis of mineralogical studies: gold-sulfosalt-sulfide-quartz, gold-mercury-quartz, and gold-selenide-telluride-sulfide-quartz. These substages were characterized by the following sequences of mineral formation: (1) ultrahigh-fineness gold → high-fineness gold → argental gold (medium- and low-fineness gold) → electrum + Ag-bearing and argental fahlores (up to 50 wt.% Ag) ± acanthite ± hessite; (2) high-fineness gold → Hg-bearing and mercurian gold → mercurian electrum → mercurian kustelite → Au-bearing mercurian silver; and (3) high-fineness gold → mercurian gold → mercurian electrum + naumannite + Te-bearing naumannite + fischesserite + tiemannite + hessite + coloradoite + Ag-bearing minerals of the galena-clausthalite series (up to 6 wt.% Ag) ± Se-cinnabar ± Se-imiterite. Productive mineral assemblages of the ore occurrence formed in the hypabyssal facies (depth ~ 1.5 km, P ~ 0.5 kbar) on the background of a temperature decrease from 290 to 160 °C and variations in f(O₂), f(S₂), f(Se₂), and f(Te₂).