鲁西归来庄金矿田碲金元素地球化学过程研究

Research on geochemical process of Te-Au elements in Guilaizhuang gold deposit of western Shandong

归来庄金矿田是中国重要的富碲型金矿田之一,金矿体产于燕山早期中-碱性次火山杂岩中,以富含碲化合物为特征,由于其碲金成矿机理尚不明确,而受到广泛关注。文章以归来庄金矿田代表性矿石为研究对象,探索成矿过程中的碲金元素地球化学过程。通过二次飞行时间离子探针、电子探针及矿石微量稀土元素分析等多种研究手段,试图揭示成矿过程中碲元素参与成矿的主要地球化学行为。研究认为,Te在中、低温条件下易置换S,而使Te以类质同象的形式分散于硫化物晶格中,在高碲逸度的条件下,Te易与Au、Ag、Cu、Pb等元素形成碲化物而参与成矿,这是碲元素参与成矿的主要地球化学行为。

Guilaizhuang gold orefield is a very important gold orefield found in western Shandong. The deposits distributed in this orefield occur mainly in the Yanshanian meta-alkalescence volcanic complex and are characterized by rich tellurides. The Te-Au ore-forming mechanism is often ambiguous and raises wide concerns. This work chose Guilaizhuang gold orefield as the research object with a focus on an analysis of tellurides characteristics and Te-Au ore-forming mechanism. The geochemical behavior of tellurium elements was systematically studied in the process of mineralization by various means such as the time of flight-secondary ion probe, electron microprobe, and whole rock analysis of trace and rare earth elements. Researches show that under the condition of medium or low temperature, Te tends to replace S, and Te is dispersed in the sulfide crystal lattice in the form of isomorphism whereas under the condition of high Te fugacity, Te tends to form telluride with Au, Ag,Cu, Pb and takes part in mineralization. This seems to be the major geochemical behavior for Te element to participate in mineralization.