小秦岭东闯金矿S507脉地质特征及构造控矿分析——S507单脉储量过半的启示

Geological and Structural Characteristics of the S507 Gold Vein Group in the Dongchuang Gold Deposit,Xiaoqinling,China

小秦岭矿集区东闯金矿为石英脉型矿化类型,其最突出的特点是矿脉延伸长、延深大,且矿体连续性好,仅S507一条矿脉在矿区走向延长超过3.2km,垂向延深超过1600m(深部尚未圈闭),单脉勘探提交黄金储量达47.2t,约占该矿黄金储量的70.35%。研究表明,该区从早到晚经历了四期褶皱-剪切作用,表现为从塑性流变到晚期构造隆升。其中五台期褶皱翼部的构造薄弱带发育成了压扭性脆韧性剪切带,又被燕山早期第三期褶皱作用改造成张扭性韧脆性剪切带,并为含矿流体的大规模贯入和成矿提供了有利的容矿空间。来自于深部的成矿流体,在较高温度、压力等物理化学条件控制下,快速贯入到区域性韧脆性剪切带中积聚、沉淀成矿。也正是由于含矿流体快速贯入区域性韧脆性剪切带,而导致含矿流体物理化学条件的快速改变,使得某条矿脉储量达到全矿黄金储量的50%以上。

The Dongchuang gold deposit in the Xiaoqinling deposit concentration area is an auriferous quartz vein-type deposit.The ore bodies in the deposit are characterized by long horizontal and vertical extension and good continuity.The S507 vein group in the mining area is the largest orebody with horizontal and vertical extensions over 3.2 km and 1.6 km,respectively.The proved gold reserve for the S507 vein group is 47.2 t,which is account for about 70.35% of the total gold reserves of the deposit.Studies indicate that this area experienced four stages of folding-shearing structural movement,ranging from plastic deformation to brittle uplift.The weak belts of fold wings,which were folded during the Wutainian movement,followed by compresso-shear brittle-ductile shearing and tenso-shear ductile-brittle shearing in the early Yanshanian,provide favorable spaces for the hydrothermal fluid concentration and mineralization.The hydrothermal fluid derived from depth rapidly migrated into regional ductile-brittle shearing zones and formed the gold ore bodies under the high temperature and pressure conditions.The rapid penetration of ore-bearing fluid into the regional ductile-shear zones resulted in rapid changes of physiochemical conditions,and led to the formation of the more than 50% gold reserves in a single ore vein group.