陕西勉略地区铧厂沟造山型金矿构造控矿特征

Characteristics of Ore-controlling Structures of Huachanggou Orogenic Gold Deposit in Mianlue Area of Shaanxi,China

铧厂沟造山型金矿位于陕甘川金三角成矿区腹地勉县—略阳—宁强成矿带的西北侧。在矿区和外围构造以及显微构造综合研究的基础上,结合前人研究资料,探讨了该区构造对金矿的控制作用;结合区域构造演化,讨论了各期构造对成矿的影响及控制作用。结果表明:铧厂沟矿区及其附近在印支期至少存在两期构造运动,即俯冲-碰撞导致的SN向挤压(D1)以及近EW向走滑剪切(D2);SN向挤压(D1)形成了近EW向的片理及层间紧闭褶皱,这些EW向构造形成了矿区的构造格架,其中褶皱的发育造成了载金黄铁矿在转折端的富集,属于容矿构造;近EW向走滑剪切(D2)分为右行和左行剪切活动,造成了区内间隔分布的韧性剪切带,剪切带对其内部的黄铁矿进行了强烈改造,使其内部形成显微裂隙,成为Au沉淀富集的场所,从而控制了Au的进一步富集、沉淀,也属于容矿构造。这些认识表明铧厂沟金矿的形成与造山作用密切相关。

Huachanggou orogenic gold deposit is located on the northwest side of MianxianLueyang-Ningqiang metallogenic belt,which belongs to Shaanxi-Gansu-Sichuan metallogenic province.Macro-and micro-structural observations were conducted in the ore district and peripheral area;based on the previous results obtained in the orefield,the ore-controlling structures of Huachanggou gold deposit were analyzed accordingly;combined with the tectonic evolution,the effect and control of structures on mineralization were discussed.The results show that there are at least two stages of tectonic movements in Huachanggou mine during Indosinian,i.e.intensively SN-direction contraction（D1）results from the subduction-collision process and nearly EW-direction strike-slip（D2）;EW-direction strike structures（schistosity and tight folds）,which are formed by SN-direction contraction（D1）,are main host structures;metallogenic material（auriferous pyrite）transfers to the hinge of folds,causing the enrichment of orebodies;EW-directionstrike-slip（D2）contributes to the formation of ductile shear belts,including dextral shear and left shear movements;ductile shear belts intensely reform the auriferous pyrite,leading to the formation of microcracks,which may supply the room for gold;this plays an important role on the enrichment of orebodies and belongs to host structures.It is suggested that Huachanggou gold deposit is closely related to orogenic processes.