频率域位场分离技术在铁矿勘查中的应用——以莱州—安丘铁成矿带为例

The Application of Potential Field Separation Method in the Exploration of Iron Deposit—Setting LaizhouAnqiu Iron Ore-forming Belt as an Example

摘要:

莱州安丘铁成矿带已发现大量中小型铁矿床，重磁资料在找矿过程中起到了重要作用。实践表明，按成因划分的3种铁矿床类型所对应的重磁场特征在总场尺度上难以进行有效区分，不同类型的铁矿床分布规律不甚明显。岩石物性的统计分析表明，带内发育的各类岩（矿）石具有显著的密度及磁性差异，岩浆岩密度和磁性均较高，变质岩变化范围较大，而沉积岩以“低磁低密”为特征，磁铁矿石的磁性高于其他岩（矿）石，而且铁矿石与围岩密度差较大，具规模矿体能够引起显著重力异常。利用频率域滤波方法对重磁资料进行场分离处理，将重磁异常分为区域场和局部场，断裂构造在区域场中以梯级带为主要特征，在局部场中磁铁矿床均分布在高磁异常及周边区域，沉积变质型铁矿床、岩浆融离型铁矿床、岩浆期后热液型铁矿床在重力局部异常场中具有不同的特征，对不同类型铁矿床从重磁局部异常场尺度上进行特征总结，为今后带内铁矿床勘查方向提供了参考。

Abstract:

Many medium and small scale iron deposits have been found in LaizhouAnqiu iron ore-forming belt. Gravity and magnetic data has played an important role in the process. As showed by factual pratices, it is hard to distinguish effectively in TotalField scales for the gravity and magnetic features of three different iron ore deposit and the distribution regularities are not clear.The statistical analysis of rock properties shows that there are obviously distinctions about the density and magnetic of rocks in Belt, Magnetite and volcanic rocks which can cause notable anomalies have higher value of density and magnetic than the sedimentary and metamorphic rocks.Gravity and magnetic anomalies can be separated to regional and residual field with the process of potential field separation in frequency domain. Fracture can be identified with gradient belt in regional field and iron ore deposit is located in higher magnetic anomalies zone.There are different characteristics in gravity residual field about sedimentary metamorphic type, magma segregation type and postmagmatic hydrothermal type and summarize their features in gravity and magnetic residual anomalies scales.It can offer a orientation reference for iron ore deposit prospecting.