重力勘探在沉积型铝土矿床调查中的应用研究

The application research on the gravity exploration in sedimentary bauxite deposit survey

我国北方沉积型铝土矿主要赋存于奥陶系灰岩与石炭系中统本溪组接触面的凹斗处,由于该接触面存在一定的密度差,故可以利用布格重力异常的低值区来圈定靶区。但由于观测面的起伏变化以及中间层校正和地形校正时密度选择不准的影响,使得布格重力异常会出现与地形成镜像或同向关系的"虚假异常",这给靶区的圈定造成了一定的影响。为消除或削弱这种"虚假异常",采用曲面处理方法和回归分析方法对布格重力异常进行处理。结果表明,通过这两种处理方法很好地消除了布格重力异常中的"虚假异常",正确地反映了奥陶系灰岩与石炭系接触面凹斗的起伏形态,准确地圈定了靶区,达到了高效找矿的目的。

Sedimentary bauxite deposit in the northern part of China mainly locates in the sag of the touching area between Ordovician limestone and Carboniferous Benxi Group. For the reason that there is a density difference between the sides of the above touching re-gion, the target areas can be located by the low bouguer gravity anomaly. However, due to the influence by the observation on undulated surface and by the difficulties in density selection when apply the middle layer and the terrain corrections, the bouguer gravity anomaly may appears several mirroring or positive correlative false anomalies regarding to the topography, which gives troubles to determine the target areas. In order to eliminate or weaken this false anomaly, we obtained a new gravity anomaly by using a potential field on curved surface processing method and a moving window regression analysis method, and reinterpret it. The results show that the false anomalies can be well eliminated in bouguer gravity anomaly by these two methods, and the undulating topography of the above touching area is correctly reflected, and the target areas is accurately determined, which helps to achieve the efficient prospecting purpose.