区域岩浆热液成矿的数值模拟——以熊耳山前河地区金矿为例

doi:10.7523/j.issn.2095-6134.2020.03.005

摘要/Abstract

摘要： 熊耳山前河地区金矿是熊耳山地区具有代表性的金矿之一，位于华北克拉通南缘，是中国重要的黄金产区。该金矿是典型的构造蚀变岩型金矿，成矿流体以岩浆水为主，成矿物质来源以深部幔源为主，属中低温热液矿床。以熊耳山前河金矿为例，搭建区域成矿的二维地质模型，分别进行稳态与瞬态数值模拟分析。结果显示：在合理的岩体和断层参数条件下，来自岩浆的高温成矿流体沿断裂带流动，加热断层及其围岩，可以达到成矿需要的温度和压力。热液成矿的主要影响因素是热液在断层带中流过携带的物质和热量。流体传递的总热量与断层宽度、热液源头的流体温度压力、断层渗透率的大小等有关。断层渗透率越高、源头压力越大、温度越高，断层内的热液流速就越大、平流传递的热流密度就越大；在同样热流密度下，如果断层越宽，则传输的总热量越大，更有利于在较短的时间段内，达到在特定压力下利于金矿生成的温度，形成金矿。在这些影响因素中，由于断层带的渗透率可以变化几个数量级，它的影响尤为显著。当断层渗透率较低时，前河地区热液成矿系统达到稳定的适合成矿条件需要~1 Ma；而断层渗透率较高时，只需要千年尺度就可以达到稳定的适合成矿的温压条件。

关键词: 金矿, 岩浆热液, 数值模拟, 成矿条件

Abstract: The Qianhe gold mine is one of the most representative gold deposits in the Xiong'ershan region, which is located in the southern margin of North China Craton and is also an important gold producing region in China. The deposit of Qianhe is a medium-low temperature altered catallactic rock type Au deposit. The ore-forming fluid is mainly magmatic hydrothermal fluid, and the ore-forming material source is mainly from deep mantle source. In this research, we take the Qianhe gold deposit as an example to simulate the dynamic mineralization process. Through establishing a two-dimensional geological model, the steady-state and transient numerical simulations are carried out, respectively. Simulation results show that high-temperature ore-forming fluid from magma flows along the fault zone, and it heats the fault and surrounding rock achieving the temperature and pressure condition of mineralization. Moreover, total heat transferred by fluid is related to fault width, fluid temperature and pressure at the source of hydrothermal fluid, and the fault permeability. The higher the permeability of faults and the greater the pressure and temperature at the source are, the higher the hydrothermal velocity and advection heat flow density in faults are. Under the same heat flow density, the wider the faults and the greater the total heat transferred are, the more favorable the formation of gold deposits is in a relatively short period time to reach the temperature favorable to the formation of gold deposits under a specific pressure. We find that the fault permeability which varies several orders of magnitude has the most significant effect among these influencing factors. When the fault permeability is low, the hydrothermal metallogenic system in Qianhe area would need about 1 Ma to reach a stable and suitable metallogenic condition, while it needs only a millennium to reach a long and stable temperature and pressure metallogenic condition when the fault permeability is high.

Key words: gold deposit, magmatic hydrothermal, numerical simulation, metallogenic condition

中图分类号:

P313

闵令帅, 程惠红, 石耀霖. 区域岩浆热液成矿的数值模拟——以熊耳山前河地区金矿为例[J]. 中国科学院大学学报, 2020, 37(3): 324-335.

MIN Lingshuai, CHENG Huihong, SHI Yaolin. Numerical simulation of regional magmatic hydrothermal mineralization: a case study on the Qianhe gold deposits in Xiong'ershan region[J]. , 2020, 37(3): 324-335.

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