深部矿阶梯找矿方法:以胶东金矿集区深部找矿为例

Stepwise prospecting method for deep-seated deposits:Take deep prospecting of ore concentration area of gold in Jiaodong Peninsula,China as an example

【研究目的】胶东是中国率先开展深部找矿并取得重大突破的地区,阶梯找矿方法在深部勘查中发挥了重要作用,研究深部找矿方法,有利于推动为中国“攻深找盲”找矿战略实施。【研究方法】本文基于胶东深部金矿找矿工作,研究了深部金矿成矿模式,分析了可控源音频大地电磁测深(CSAMT)、频谱激电测量(SIP)、大地电磁测深(MT)和反射地震等方法在深部找矿中的作用和效果。【研究结果】深部矿体常赋存于控矿断裂沿倾向的倾角变缓段,构成阶梯成矿模式,这一模式是地质构造作用与成矿物理化学条件等多种因素耦合的结果。深部矿阶梯找矿方法的要点是:在地表通过高精度地球物理探测,查明控矿断裂的深部结构和倾角变化,根据阶梯成矿模式预测深部矿的位置、规模。【结论】阶梯成矿模式为深部找矿提供了核心技术前提和可以识别的探测目标,CSAMT、SIP、MT和反射地震等方法能够探测控矿断裂的深部特征,多种地球物理方法组合是阶梯找矿方法的有效技术手段。

[Objective]Jiaodong Peninsula is the first region to carry out deep-seated prospecting and made significant prospecting achievements in China. Stepwise prospecting method has played an important role in the deep-seated exploration. The study of deep-seated prospecting methods will be conducive to promoting the implementation of the prospecting strategy of“prospecting deep-seated deposits”in East China.[Methods]In this paper, based on the deep-seated gold deposits prospecting in Jiaodong, we studied the metallogenic model of deep gold deposits, and analyzed the role and effect of controlled source audio frequency magnetotelluric sounding(CSAMT), spectral excited electric sounding(SIP), magnetotelluric sounding(MT) and reflection seismic methods in deep gold deposits prospecting. [Results]Deep orebodies generally occur in the gently dipping parts of alternate change of steep-dipping to gentle-dipping of the ore-controlling fault, forming a step metallogenetic model. This metallogenetic model is a comprehensive reflection of tectonic activities and physicochemical conditions of mineralization. The technical process of the stepwise prospecting method is outlined below. First, through high precision geophysical detection in land surface, deep characteristics of ore-controlling fault are found out. Then, according to the step metallogenic model, the location and scale of the deep-seated gold orebodies are predicted. [Conclusions]The step metallogenic model provides a technical premise and key exploration target for the deep-seated gold deposits prospecting. CSAMT, SIP, MT and reflection seismic methods can detect the deep characteristics of ore-controlling faults. The combination of multiple geophysical methods is an effective technical means of the stepwise prospecting method.