综合找矿方法在深厚覆盖区的应用:以鲁西大张矽卡岩型富磁铁矿为例

    Application of comprehensive prospecting method in deep covered area: taking the Dazhang skarn type magnetic-rich deposit in Western Shandong as an example

    • 摘要: 深部找矿是我国未来矿产资源勘查的重要方向,然而深厚覆盖区找矿难度大,如何在深厚覆盖区勘查、精确定位矿体是找矿工作中需要突破的关键难题。以鲁西大张地区矽卡岩型富磁铁矿为例,总结了一套深厚覆盖区铁矿的综合找矿方法。首先通过区域面积性重磁测量成果及二次开发利用,推断断裂构造,圈定局部异常,完成勘查选区;其次在勘查选区内开展高精度重磁扫面,缩小目标体的平面分布范围,圈定找矿靶区;最后对找矿靶区施测大比例尺重磁电综合物探联测剖面,解剖定性局部异常,定位目标体的有利赋存空间。通过钻探深部验证,圈定的靶区中的5个钻孔中,有4个钻孔见矿,1个钻孔见矿化。“系统收集资料-区域物探资料二次开发利用-高精度面积性重磁测量-综合物探剖面测量-重点区异常钻探深部验证”的勘查流程和“地-磁-重-电-钻-测”的综合找矿方法简易且效果较好,最终探得富磁铁矿体,全铁平均品位55.59%,其中,磁性铁品位达52.25%。本文研究为类似深厚覆盖区矽卡岩型铁矿深部找矿提供参考。

       

      Abstract: Deep prospecting is an important direction for mineral resources exploration in the future in China. However, it is difficult to prospect in deep covered areas. How to explore and accurately locate ore bodies in deep covered areas is a key challenge that needs to be overcome in prospecting work. This paper takes the Dazhang skarn type magnetic-rich deposit in Western Shandong Province as an example, and summarizes a comprehensive prospecting method for iron ore in deep covered areas. Firstly, through the results of regional area gravity and magnetic surveys and secondary development and utilization, the fault structure is inferred, local anomalies are delineated, and the exploration and selection areas are completed; secondly, high-precision gravity and magnetic scanning is carried out in the exploration area to narrow the planar distribution range of the target body and delineate the prospecting target area; finally, re-conduct large-scale comprehensive geophysical prospecting combined with gravity, magnetic and electrical surveys on the prospecting target area, dissect and qualitatively analyze local anomalies, and locate favorable occurrence spaces for target bodies. Through drilling and deep verification, four of the five drill holes in the target area delineated shows mineral deposits, and one showed mineralization. The exploration process of “systematically collecting data-redeveloping and utilizing regional geophysical data-high-precision area gravity and magnetic surveys-comprehensive geophysical profile surveys-deep verification of anomalies in key areas through drilling” and the comprehensive prospecting method of “ground-magnetic-gravity-electric-drilling-survey” have achieved significant results that discovered the magnetite-rich body with an average grade of total iron of 55.59%, of which the magnetic iron grade is 52.25%. The comprehensive prospecting method has been hoped can provide a reference for deep prospecting of skarn type iron ore deposits in similar deep and thick covered areas.

       

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