内蒙古大梁金矿控矿构造的确定及勘查意义

Determination of the ore- controlling structures and significance for prospecting in the Daliang gold deposit,Inner Mongolia

综合利用各类勘查资料,采用覆盖—半覆盖区矿田构造解析的技术手段,查明大梁金矿的控矿构造发育特征,为矿区勘查工作提供基础地质支撑。研究表明,在早期指向北的分层剪切构造作用的晚期阶段,伴生退变质的强烈剪切变形于新元古界佳疙瘩组中形成富绢云母的S1(S1//S0)劈理及相关的网状脆韧性剪切带,构成大梁金矿的控矿构造;同构造递进变形中,热液沿剪切带运移,并在流体助力的次级剪张性破裂中沉淀富集、生成含矿的扩容交代石英细脉及旁侧的蚀变围岩。金矿(化)体主要产出于佳疙瘩组第三岩性段,多沿不同岩性界面附近发育,并被晚期褶皱、断裂等破矿构造叠加改造。同构造的硅化和绢云母化蚀变是大梁金矿勘查的重要标志。

Based on the integrated analysis of all kinds of exploration data, orefield structural analysis have been carried out to deal with the characteristics of ore - controlling structures in the Daliang gold deposit area where poor outcrops inhibit the direct obser- vation in the field. The study will provide the basic geological evidence for the exploration program. The structural analysis result indi- cates that the sericite- filling tectonic foliation S1 （S1//So ）and related veinlets ductile and shear zones in the Neoproterozoic Jiageda group formed in the intensive deformation period related to the retrograde metamorphism in the late - stage of early N - oriented delami- nation shearing, consist the ore- controlling structures in the deposit area. During upward migration of mineralized fluids along shear zone in the same progressive deformation event, the gold metal was deposited in the secondary shear zones or extension cracks formed by fluid - assisted cracking, meanwhile the auriferous dilational - metasomatic quartz veinlets and associated host rock alteration were formed. The gold orebodies usually occur along lithologic contacts and mainly distributed in the third unit of Jiageda group. The late stage folds and faults reconstruct the gold orebodies. The syntectonic sericitisation and silicification are key criteria for exploration in the Daliang gold deposit area.