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Native Gold in the Chudnoe Au-Pd-REE Deposit (Subpolar Urals, Russia): Composition, Minerals in Intergrowth and Genesis
Minerals ( IF 2.5 ) Pub Date : 2021-04-25 , DOI: 10.3390/min11050451
Galina Palyanova , Valery Murzin , Andrey Borovikov , Nikolay Karmanov , Sergei Kuznetsov

Composition of native gold and minerals in intergrowth with rhyolites of the Chudnoe Au-Pd-REE deposit (Subpolar Urals, Russia) was studied using optical microscopy, scanning electron microscopy, and electron microprobe analysis. Five varieties of native gold have been identified, based on the set of impurity elements and their quantities, and on intergrown minerals. Native gold in rhyolites from the Ludnaya ore zone is homogeneous and contains only Ag (fineness 720‰, type I). It is in intergrowth with fuchsite or allanite and mertieite-II. In rhyolites from the Slavnaya ore zone, native gold is heterogeneous, has a higher fineness, different sets and contents of elements: Ag, Cu, 840–860‰ (type II); Ag, Cu, Pd, 830–890‰ (III); Ag, Pd, Cu, Hg, 840–870‰ (IV). It occurs in intergrowth with fuchsite, albite, and mertieite-II (type II), or albite, quartz, and atheneite (III), or quartz, albite, K-feldspar, and mertieite-II (IV). High fineness gold (930–1000‰, type V) with low contents of Ag, Cu, and Pd or their absence occurs in the form as microveins, fringes and microinclusions in native gold II–IV. Tetra-auricupride (AuCu) is presented as isometric inclusions in gold II and platelets in the decay structures in gold III and IV. The preliminary data of a fluid inclusions study showed that gold mineralization at the Chudnoe deposit could have been formed by chloride fluids of low and medium salinity at temperatures from 105 to 230 °C and pressures from 5 to 115 MPa. The formation of native gold I is probably related to fuchsitization and allanitization of rhyolites. The formation of native gold II-V is also associated with the same processes, but it is more complicated and occurred later with a significant role of Na-, Si-, and K-metasomatism. The presence of Pd and Cu in the ores and Cr in fuchsite indicates the important role of mafic-ultramafic magmatism.

中文翻译:

Chudnoe Au-Pd-REE矿床中的原生金(俄罗斯亚极乌拉尔):共生和成因中的成分,矿物

利用光学显微镜,扫描电子显微镜和电子探针分析研究了与Chundeoe Au-Pd-REE矿床(俄罗斯亚极乌拉尔)流纹岩共生的天然金和矿物的组成。根据杂质元素的种类和数量以及共生矿物质,已经鉴定出五种原生金。来自卢德纳亚(Ludnaya)矿区的流纹岩中的原生金是均质的,并且仅包含Ag(细度720‰,I型)。它与紫铁矿或尿囊石和褐铁矿II共生。在Slavnaya矿区的流纹岩中,天然金是非均质的,具有较高的细度,元素的集合和含量不同:Ag,Cu,840-860‰(II型);银,铜,钯830-890‰(III); 银,钯,铜,汞840-870‰(IV)。它与紫铁矿,钠长石和陨铁II型(II型)或钠长石共生,石英,褐铁矿(III)或石英,钠长石,钾长石和褐铁矿II(IV)。Ag,Cu和Pd含量低或不存在的高纯度金(930-1000‰,V型)以天然金II-IV中的微静脉,条纹和微内含物的形式出现。四金(AuCu)在金II中以等距夹杂物形式存在,在金III和IV中以衰减结构形式存在血小板。流体包裹体研究的初步数据表明,在温度105至230℃,压力5至115 MPa的条件下,中低盐度氯化物流体可在丘德诺矿床形成金矿。天然金I的形成可能与流纹岩的紫杉醇化和尿囊化有关。天然金II-V的形成也与相同的过程有关,但它更为复杂,后来又以Na-,Si-和K-代瘤作用发挥重要作用。矿石中Pd和Cu的存在以及品铁矿中Cr的存在表明了镁铁质-超镁铁质岩浆作用的重要作用。
更新日期:2021-04-26
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