重力测量在老挝万象盆地固体钾盐矿勘查中的有效性分析

摘要

The ore-bearing stratum of potash mine in Vientiane Basin is lower section of Paleocene Tagong group,being concealed deposit,wide distribution,big thickness and high grade.Due to late reformation and substrate topography difference,the deposits are locally missing.Before drilling disclosure of controlled deposit,predicting the ore body occurrence location,can remarkably save prospecting costs.According to the density difference between Paleocene Tagong group rock salt,potassium and magnesium rock and mudstone.The gravity measurements were proved to be effective to distinguish salt deposit depth and thickness.Potash stratum often occurs in upper thick layer of Paleocene Tagong group,perfectly corresponding to negative gravity anomalies,where being the preferred area to drill and verify the possible potash mine.So the geophysical exploration is an essential methool for solid potash ore exploration in Vientiane basin of Lao.%老挝万象盆地钾盐矿赋矿地层为古近系古新统塔贡组下岩段,为隐伏矿层,分布面积广,厚度大,品位高.由于受钾盐矿层沉积基底地形差异及矿层的后期改造,钾盐矿层局部缺失.在钻探揭露控制矿层前预测矿体的赋存位置,可有效节约探矿成本.根据万象盆地古近系古新统塔贡组石盐岩、钾镁岩矿与泥岩之间存在密度差,认为重力测量能够有效区分盐类矿层的埋深、厚度,而钾盐矿层往往赋存于古近系古新统塔贡组巨厚层石盐矿层上部,重力负异常与钾盐矿层的对应性好,是钻探验证首选区域和万象盆地钾盐矿勘查较为有效的物探方法.