辽南瓦房店地区金伯利岩航磁垂向梯度异常特征及找矿意义

Aeromagnetic Vertical Gradient Characteristics of Kimberlite in the Wafangdian Area of Southern Liaoning Province and Their Ore-Prospecting Significance

航磁垂向梯度数据较航磁ΔT数据优势明显,可以有效识别地磁场的微弱变化。辽南瓦房店地区40%的金伯利岩体具有明显的梯度异常显示,可验证航磁垂向梯度技术在金刚石找矿中的有效性。本文通过分析瓦房店地区获取的大比例尺航磁垂向梯度资料,研究航磁垂向梯度异常特征与已知金伯利岩体产状的关系,发现岩体多位于NEE向孤立梯度异常中,岩体走向与异常走向基本一致,异常形态多表现为拉长的椭圆状,长轴走向多为NEE向,异常梯度值一般不大于150 nT/km,异常规模通常比地表出露范围大,对岩体的分布范围反映清晰。区内地质背景相似的NEE向航磁梯度异常对今后的金刚石矿勘查部署具有重要的指导意义,建议结合其他地质资料优选重点异常,布置大比例地面磁法、电法等地球物理方法查明引起异常的原因并评价其找矿前景。

Aeromagnetic vertical gradient data has obvious advantages over aeromagnetic ΔT data,which can identify weak changes of geomagnetic field.About 40% of the kimberlite rock mass in the Wafangdian area of southern Liaoning Province displays obvious gradient anomalies,indicative of the effectiveness of aeromagnetic gradient technology in diamond prospecting.This work analyzed the large-scale aeromagnetic vertical gradient data obtained in the Wafangdian area,and determined the relationship between the abnormal characteristics of aeromagnetic vertical gradient and the occurrence of known kimberlite rock masses.The rock masses are mostly located in the NEE-trending isolated gradient anomalies,and the strike is basically the same to that of the anomalies.The anomalies generally display elongated elliptical shapes,and the long axis is mostly in NEE direction.The abnormal gradient value is generally not greater than 150 nT/km.The anomaly scale is usually larger than the surface exposure range,which clearly reflects the distribution of rock masses.The NEE-trending aeromagnetic gradient anomaly with similar geological background in the area has important guiding significance for future diamond ore exploration and deployment.It is recommended to combine other geological data to select key anomalies,and arrange geophysical methods such as large-scale ground magnetic method and electrical method to identify the cause of the anomalies and evaluate the prospecting prospects.