厄瓜多尔中部Beroen金银矿床构造特征及其控矿作用

Structures characteristic and their controls on ore mineralization in Beroen gold-silver deposit of central Ecuador

为了对厄瓜多尔中部Beroen金银矿床进行深边部资源勘察,对矿区多条矿脉的几何特征进行系统测量与分析,并建立矿区构造控矿模型。研究结果表明:主矿脉走向NEE,靠近主矿体发育走向为100°~115°的小规模张性石英脉;主矿体附近围岩发育NE走向片理化带,带内石英细脉具有顺时针揉皱特征;走向为NEE的断层及共轭的走向为NW断层形成于成矿前,在成矿期前者在压扭构造应力和高孔隙压力下倾斜张开,流体发生多次沸腾,孔隙压力骤降,形成矿脉和富矿带;穿切矿脉断层使矿脉在走向上不连续,成矿后滑脱构造对矿体破坏明显;矿区主矿体初始倾角近90°,富矿带倾角近0°,其形成主要受主构造带内的垂向构造空间分布的控制。本矿床构造控矿模型对区域内寻找同类型矿床具有参考价值。

In order to guide the deep and marginal exploration at the Beroen deposit,the structural occurrence of ore veins in the field was analyzed,and the structural ore control model was established combined with the latest geological exploration results of the mining area.The results show that the main ore vein system strikes NEE,and the ore bodies were damaged obviously by faults formed after mineralization.The quartz veinlets,which are close to the main orebody,are small in scale and poor in continuity,and have the tensile characteristics associated with gold mineralization with a strike of 100°−115°.Near the main orebody,NE-striking foliation zones are developed,and quartz veinlets in the zones are characterized by the development of Z-shape folds.The NE-striking faults are formed before the mineralization,and at the same time,conjugated NW-striking faults with negligible activity are developed.During the mineralization period,the former is inclined to open under transpressional tectonic stress and high pore fluid pressure and fluids boiled repeatedly with pores.The pressure drops sharply,forming the mineralization in ore bodies.The movement of post-mineralization faults results in the occasional lack of ore veins along the vein strike.The initial dip of the main ore body is nearly 90°,and the ore-body rich zones are nearly 0°.The formation of the deposit is mainly controlled by the spatial distribution of vertical structures in the main structural zone.The structural ore-controlling model of this deposit is of great significance to the exploration of similar deposits in the region.