老挝南部帕莱通(PhLayThong)铁矿磁异常特征及找矿评价

Magnetic anomaly characteristics and prospecting evaluation of the PhLayThong iron deposit in southern Laos

勘查区位于老挝南部占巴色省帕同鹏县,帕莱通铁矿由流纹岩-玄武岩组成的双峰式火山岩组合,底部为流纹岩,上部为玄武岩,铁矿体出露地表,直接覆盖在玄武岩之上.由于老挝热带雨林气候植被茂密,部分地区覆盖严重,加上矿体及地层产状近似水平,且矿体层中见大型致密块状玄武岩角砾,杂堆于矿体中,难于分辨,导致地表地质填图对矿体及玄武岩界线不好厘定,为了准确划分地质界线、圈定矿体规模及储量分析,我们在该区开展了1∶25000地面高精度磁法测量,控制了玄武岩及赤铁矿体的范围、延伸、规模,后期勘探阶段开展2.5D磁异常人机交互正反演控制矿体深部延展情况.结果表明,在老挝南部地质勘查程度低、覆盖严重的帕莱通地区开展高精度磁法是控制该地区赤铁矿及玄武岩分布的有效地球物理方法.

The exploration area is located in Champasak province,the south Laos,The PhLayThong iron deposit is consist of bimodal volcanic rock association of rhyolitic and basalt,The bottom is rhyolite,and the upper part is basalt,the iron ore body outcrops to the surface,directly covered with basalt. Because of the tropical rain forests and dense vegetation in laos, some areas are seriously covered,and attitude of stratum and ore body are nearly horizontal,moreover,there ara some large dense and massive basalt breccia in the ore body,difficult to distinguish,it is difficult to determine the boundary between ore bodies and basalt by surface geological mapping,the size and reserves of ore bodies are not well calculated.Therefor,we have adopted the 1 ∶25000 high precision magnetic method to understand the scope,extension and scale of basalt and hematite ore bodies,In the later stage of exploration,2. 5 D interactive positive inversion work is carried out to understand the deep extension of the orebody. The results show that high precision magnetic scanning work was a effective method to control the area of hematite and basalt distribution of low degree of geological exploration in southern Laos.