扬子地块西南铅锌矿床中分散元素富集机制与来源的镉和锗稳定同位素研究

Dispersed elements, a strategic resource of new century, have found wide applications in industry. However, few studies have focused on the enrichment mechanisms and the origins of dispersed elements in ore deposits, resulting in limited exploration and development of new dispersed elements resource. Compared with traditional stable isotope tracers, cadmium isotope and germanium isotope are considered as more powerful geochemical tracers for investigation of metallogenic physical-chemical condition and ore genesis. In this proposal, a systematic investigation will be carried out in three different genetic types of Zn-Pb deposits from southwestern margin of Yangtze platform, the ore-forming fluids of which are varied in metallogenic conditions. I expect to reveal the fractionation characteristics of Cd and Ge isotope in those fluids and figure out the favorable metallogenic conditions of Cd and Ge, providing new insights in the source of the ore-forming materials from typical Zn-Pb deposits. The results from this proposed study will offer critical information to ore genesis of dispersed elements-rich deposits. Moreover, the investigation of Cd and Ge isotope could provide new insights in the studies concerning on mineral deposits, and gives us new cases on the application of stable isotope of dispersed elements in deposits.

分散金属在国民经济中有着广泛的应用，是我国重要的战略资源。然而，由于分散元素矿床研究程度较低，分散元素矿床的富集和成因机制还不明确，限制了新的分散元素资源的寻找和开发。相对于传统的稳定同位素(如硫、氧等元素的同位素), 镉和锗稳定同位素在示踪分散元素的成矿物理化学条件和物质来源等方面已显示出独特的潜力和优势。本申请以扬子地块西南缘三个不同成因铅锌矿床为研究对象，立体对比镉和锗稳定同位素在不同流体中的分馏特征和机制，探讨镉和锗同位素组成特征与成矿物理化学条件之间的联系，示踪分散元素有利的富集和成矿条件，建立镉和锗稳定同位素示踪模型，为分散元素矿床的寻找提供重要的基础研究信息。同时，该项目的实施将丰富矿床学研究手段，为分散元素稳定同位素应用于矿床学研究提供重要案例。

镉和锗是典型的分散元素，也是战略性关键金属。本项目以镉和锗等稳定金属同位素为研究手段，通过对典型中低温热液矿床（包括云南会泽，四川乌斯河和广西箭猪坡矿床）的系统研究研究，探讨镉和锗在这些矿床中的来源。根据地层及玄武岩的地球化学特征，本人认为川滇黔地区铅锌矿可分为两种类型：（Ⅰ）地层型，金属物质主要来源于地层，以云南富乐铅锌矿床为代表；（Ⅱ）混合型，及来自地层和峨眉山玄武岩（或与峨眉山玄武岩相似的火成岩基底），以云南会泽和贵州杉树林矿床为代表。而广西箭猪坡矿床的研究支持了该矿床为矽卡岩型，其中铅锌等金属主要来自隐伏花岗岩，而锑等主要来自地层，并提出了成矿模型。总之，本项目的研究及相应的学术成果为镉和锗等金属稳定同位素应用于热液矿床研究提供了基础和应用范例。