西伯利亚地台西南部地区金矿带的地质环境和形成条件

在阿尔丹-斯坦洛沃依地盾的西伯利亚地台西南部地区划分出四个金矿带:(1)Ket-Kep带(主要由矽卡岩型、石英脉和网脉型、碳酸岩中的伊利石-褐铁矿型以及伊利石-绢云母交代型矿床或矿点构成);(2)Ulkan带(伊利石-云母交代型和石英脉型);(3)Dzhugdzhur带(石英脉型和矽卡岩型);(4)Dzhugdyr带(石英-硫化物脉型).含矿矽卡岩成矿时代为中生代,而与石英和石英-硫化物脉型有关的矿化形成于晚元古代、古生代和中生代.大多数中生代的金矿化都与岩浆作用有关.含金岩石的流体包裹体研究结果表明,高温成矿过程主要发生在Dzhugdzhur带的矽卡岩(500～715℃)和Ket-Kep带的热液交代型岩石(510～530℃)中,这些岩石的矿物流体包裹体中的水溶液盐度高达40% NaCl当量,其子矿物主要为Na,K,Ca的氯化物,并以存在CO2为特征.Ket-Kep带内高温(高达465℃)和中温条件形成的石英脉和网脉中的流体包裹体盐度达32% NaCl当量,包裹体中有时含低密度的CO2.Dzhugdzhur带中的含金石英脉形成于225～230℃,为低盐度成矿溶液(1%～2% NaCl当量).Dzhugdyr带中含金石英-硫化物脉的成矿温度为260～390℃,成矿溶液为低盐度(1.5%～7.5% NaCl当量)KCl水溶液.Ulkan带石英脉的成矿流体中含K-Na氯化物物种,所测定的盐度值为2%～10% NaCl当量,成矿温度在220～280℃之间.

GEOLOGICAL SETTING AND CONDITIONS OF FORMATION OF GOLD-BEARING OCCURRENCES IN THE SOUTHEASTERN PART OF THE SIBERIAN PLATFORM

A number of gold mines and occurrences are located in the regions of superimposed tectonic and magmatic activity in the southeastern part of the Siberian Platform, in the territory of the Aldan-Stanovoi Shield. They are concentrated in four metallogenic zones: Ket-Kap (skarns, quartz veins and stockworks, illite-limonite deposits in carbonate rocks, illite-sericitic metasomatites), Ulkan (illite-mica metasomatites, quartz veins), Dzhugdzhur (quartz veins, skarns) and Dzhugdyr (quartz-sulfide veins). The ore-bearing skarns are of Mesozoic age, but the mineralization connected with the quartz and quartz-sulfide veins may be Mesozoic, Paleozoic and Late Proterozoic. Generally, a connection is stated between Mesozoic occurrences and ore-producing magmatic complexes, but in some cases it has not been demonstrated.In this paper, besides the ore deposit's position, the preliminary results of fluid inclusion study of gold-bearing rocks are presented. It is shown that most high-temperature ore-forming and in the hydrothermal-metasomatic rocks of the Ket-Kap zone concentrations up to 40% NaCl eq. dominate in the fluid inclusions from minerals of these rocks. The presence of CO2 is characteristic of this fluid. The quartz veins and stockworks of the Ket-Kap zone concentrations of solutions reached 32% NaCl eq. Sometimes, inclusions of low-density CO2 are present in minerals of these rocks. The gold-bearing veins of the Dzhugdzhur zone formed at (1%～2% NaCl eq.). The quartz-sulfide gold-bearing veins of the Dzhugdyr zone crystallized from low-saline (1.5%～7.5% NaCl eq.) specifics and concentration of 2%～10% NaCl eq. are determined for the ore-forming solutions in the veins of the Ulkan zone; the