岩浆锆石和热液锆石成因对岩浆和成矿的限定:以毕力赫金矿为例

Problems concern on the genesis of magmatic and hydrothermal zircons are as follows: (1) How to effectively identify these two types of zircons? (2) Rarely try to use the U-Pb dating of hydrothermal zircon to constrain the metallogenic age. (3) lack the comparison between the characteristics of Lu-Hf isotope of the magmatic and hydrothermal zircons. (4) Rarely try to use mineral and fluid inclusions of the magmatic and hydrothermal zircons to constrain the composition and temperature-pressure conditions of the magma and fluid. (5) the data system of the magmatic and hydrothermal zircons as an indication to mineralization hasn't been established. The Bilihe gold deposit is the first large-scale high-grade concealed quartz vein type gold deposit in the northern margin of the North China Craton. Both the magmatic and hydrothermal zircons have been found in this deposit, and these two types of zircon have an obvious differences. Therefore, the Bilihe gold deposit is a good object to study the genesis of magmatic and hydrothermal zircons. This project concerns on the magmatic rock sequence and the gold-bearing quartz vein in the Bilihe deposit and would like to (1) establish the standard to identify these two types of zircons; (2) determine the origin and age of the magma activity by using magmatic zircon LA-ICP-MS U-Pb dating, Lu-Hf isotope analysis, the chemical composition of mineral inclusion and temperature testing of primary fluid inclusion in magmatic zircon, and establish the origin and age of hydrothermal activity through the aforementioned methods to hydrothermal zircon; (3) determine the relationship between the magmatism and hydrothermal process; (4) build a data system of the two types of zircons.

在岩浆锆石和热液锆石成因研究中存在如下问题：（1）如何有效识别这两类锆石？（2）很少尝试用热液锆石U-Pb定年来限定成矿时代。（3）缺乏这两类锆石的Lu-Hf同位素的共、异性研究。（4）很少尝试用这两类锆石中的矿物包裹体和流体包裹体来限定岩浆和流体组成、温压条件。（5）尚未建立一个具有矿床指示意义的这两类锆石的数据系统。毕力赫金矿是华北板块北缘首例大型高品位隐伏石英脉型金矿，矿区发育这两类锆石且区别明显，是研究这两类锆石的良好对象。本项目拟以矿区内发育的一套完整的岩浆岩和含金石英脉为对象：（1）建立识别这两类锆石的标准；（2）通过岩浆锆石LA-ICP-MS U-Pb定年、Lu-Hf同位素分析、矿物包裹体成分分析、原生流体包裹体测温，查明岩浆活动起源和时代。通过对热液锆石上述实验的开展，查明热液活动起源和时代。（3）查明金矿的岩浆作用和热液作用的耦合关系。（4）建立一个这两类锆石的数据系统。