黔东南锦屏-天柱地区构造控岩控金特征模拟实验及其力学分析

在前人工作基础上,侧重研究石英脉型金矿床成矿的地质背景,建立了该类型金矿的成矿模式。进而开展三轴温压条件下的成岩成矿实验,构造形变特征及其与成矿物质活化、迁移、富集之间的相互关系的模拟实验。实验结果表明:(1)该区岩石、矿石在高温高压条件下,产生塑性变形(褶皱)和脆性变形(破裂);(2)在变形过程中使成矿物质活化、迁移和富集,形成顺层及穿层的含金石英脉,并在多期多次变形过程中使成矿物质叠加富集;(3)在褶皱(背斜)轴部形成富矿体。模拟实验结果与所建立的该类型金矿构造控矿和成矿模式非常相似。实验资料的力学分析表明,由轴压所产生的构造附加压力大大地提高了实际围压,从而促进了岩石流变、变形和物质的迁移,由此促进含矿流体向构造附加压力小的部位定向迁移、充填和成矿。构造附加压力是促进该区金成矿的重要动力条件。

FEATURES OF ROCK-CONTROLLING AND GOLD ORE-CONTROLLING STRUCTURES IN THE JINGPING-TIANZHU REGION, SOUTHEASTERN GUIZHOU: SIMULATION EXPERIMENT AND MECHANICAL ANALYSES

This paper was formulated based on the previous researches. The geological background and quart-vein type gold deposits occur widespread in the Jingping-Tianzhu region, Southeastern Guizhou, here the ore-controlling structures of gold mineralization in the studied region were emphasized and a genetic model was established for these quartz-vein type gold deposits. Moreover, ore-forming simulating experiments were carried out, and the results show that: 1) Ductile deformation (fold) and brittle deformation (fault) took place under high-temperature and high-pressure conditions; 2) Ore-forming materials were activated, transported and enriched during deformation, and finally concordant and discordant gold-bearing quartz veins were formed. Multiple deformation during the simulation experiments help the ore-forming materials to be concentrated; 3) Formation of enriched orebodies in the axles of complex anticlines was finally resulted. The experimental results are consistent with the genetic model proposed for gold deposits in the studied region. Through geomechanical analysis of the simulation experiments, the authors discovered that the axis pressure (b1) can produce tectonic hydrostatic overpressure to enhance the enclosure pressure, and to promote rock deformation, materials migration and deposition as well as metallogenesis of mineralizing fluid at locations that show little tectonic overpressure. The experiments also show that the tectonic overpressure is an important condition for gold metallogenesis in the study area.