微重力法与可控源音频大地电磁法组合在豫西寻找隐伏铝土矿中的应用

Applications of combined microgravity survey and CSAMT sounding in search for concealed bauxite deposits in western Henan,China.

通过方法试验,在豫西地区已知铝土矿区的外围开展了1:5万高精度重力测量,发现绝大多数矿床点位于较平缓的重力梯度带上,基底相对稳定的地段可作为铝土矿的找矿靶区;采用CSAMT(可控源音频大地电磁)法测深剖面,卡尼亚电阻率-频率曲线拐点可直接反映出新生界覆盖层和奥陶系灰岩层的埋藏深度,进而推断石炭系本溪组(铝土矿)的埋深。经10余个钻孔验证,见矿率达80%以上。试验结果证明,在地质研究的基础上,微重力法加上CSAMT法测深是寻找隐伏铝土矿的有效的方法组合。

The authors carried out 1：50000 high-precision microgravity survey through methodological experiments at the peripheries of the known bauxite mining area in western Henan and found that most ore deposits are located in gentle gravity gradient zones and that areas with a comparatively stable basement are bauxite exploration targets. The burial depths of the Cenozoic cover （aluminiferous rocks） and Ordovician limestone （dolostone） bed can be directly reflected by the controllable source audio frequency magnetotelluric （CSAMT） sounding section and Kania resistivity-frequency curve inflexion and then further the burial depth of the carboniferous Benxi Formation （bauxite） may be deduced. Checks and verification of more than ten boreholes show that the ore encountering rate reaches more than 80%. The results of tests prove that the combined microgravity survey and CSAMT sounding carried out based on the geological study are an effective technique combination for looking for hidden bauxite deposits in western Henan.