对冀东司家营铁矿深部找矿问题的探讨

Discussion on deep prospecting of the Sijiaying iron deposit in eastern Hebei Province

司家营铁矿是冀东最大的单体铁矿床,其资源量约占冀东铁矿资源总量的六分之一,具有重要的经济意义和资源战略地位。司家营铁矿自1914年发现至今已有100多年,有悠久的勘查和研究历史,取得了一系列重要研究进展:矿床的成矿时代为新太古代晚期;矿质初始来源于海底高温热液与海水混合;矿区内的褶皱和断裂构造对矿体的最终定位有控制作用;矿床的原始成矿地质背景可能为弧后盆地;矿区有原生沉积和热液改造贫矿而成的富铁矿,后期构造运动可以导致进一步的富集。通过对司家营铁矿的研究进展和存在问题综述,本文认为:滦县岩群的中上层是后续深部找矿的目标层位,而富铁矿应在厚大的贫矿体中找;辨别断裂的性质有助于推断深部矿体位置,褶皱的转折端和断裂的交汇处有助于赋存富铁矿;磁异常和重力异常是找大矿、找富矿的重要标志;混合岩化和热液蚀变作用发育的位置更利于找富铁矿;后续的找矿工作建议在矿区西侧矿体延深方向上开展;随着埋藏深度的加大,弱小的磁异常也值得高度重视。

The Sijiaying iron deposit is the single largest iron deposit in China,with important economic and strategic resource significance,accounting for about one sixth of the total iron ore resources in eastern Hebei Province.It has been more than 100 years since the discovery of the Sijiaying deposit in 1914.It has a long history of exploration and research,and has provided a series of important research insights:the metallogenic material came from the mixed solution of submarine high temperature hydrothermal solution and seawater;the fold and fault structures in the mining area control the final location of the ore body;the original metallogenic geological setting of the deposit is probably a back-arc basin;there are two kinds of rich iron ores in the mining area;primary sedimentation and hydrothermal reformation,later tectonic movement may have led to further enrichment.Based on a review of the research progress and existing challenges of Sijiaying deposit,this paper proposes that the middle and upper strata of Luanxian Group are the target horizons for further deep prospecting,while the high-grade iron ore should be found in the thick and large low-grade ore body;identifying the character of faults is helpful to infer the location of deep ore bodies,and the turning end of folds and the intersection of faults are helpful to the occurrence of high-grade iron ores;magnetic anomaly and gravity anomaly are important marks for prospecting large and rich deposits;the location near migmatization and hydrothermal alteration is more conducive to the search for high-grade iron ore;it is suggested that a follow-up prospecting work should be carried out in the deepening direction of the orebody on the west side of the mining area;with the increase of burial depth,weak magnetic anomalies are also worthy of greater attention.