摘要
长江中下游成矿带是我国重要的铁铜多金属矿产资源基地,基于成矿系统理论,研究其在成矿带尺度,矿集区尺度和矿田尺度上的地球物理场特征,对于发现类似巨型成矿带和寻找同类大型矿床具有重要意义.本文结合区域重磁资料和深反射地震资料,分析了长江中下游成矿带的地球物理特征,发现长江中下游成矿带的地球物理标志是重磁同高的条带状异常,认为地幔流通道是形成此类巨型成矿带的根本原因.通过庐枞矿集区的深地震反射资料分析,认为深反射地震探测能有效识别Moho破裂及地幔流通道,重磁与地震结合寻找地幔流通道是发现此类成矿带的有效途径.在矿集区尺度上,重力高值带上的相对重力低地区对应金属矿床集中分布的拉分盆地.为有效筛选找矿靶区,我们提出了一种改进的重磁交叉梯度方法,通过模型试验,发现该方法能很好的区分不同组合的重磁异常.利用该方法,在九瑞矿集区和铜陵矿集区开展了找矿预测,结果表明该方法是一种圈定找矿靶区的有效方法.
The middle and lower Yangtz River metallogenic belt is an important resources basement of iron and copper polymetallic mineral in China.Based on the mineral system theory, the study of the characteristics of geophysical field in the metallogenic belt scale, ore concentration scale and ore field scale is of great significance for discovering similar giant metallogenic belts and finding similar large ore deposits. In this paper, we combined with the regional gravity and magnetic data and deep seismic reflection data, analyzed the geophysical characteristics of the middle and lower Yangtze River metallogenic belt, that geophysical indication of the tbelt is banding shape high gravity and magnetic anomaly, mantle flow channel is the root cause of the formation of such huge metallogenic belt. Deep reflection seismic method can reveal Moho break and mantle flow channel,the combination of gravity and magnetic and seismic method is an effective way for search mantle flow channel.On the scale of ore concentration area, the relatively low gravity area on the high gravity value zone shows the pull-apart basin of deposit concentrated distribution.In order to find the target area effectively, an improved gravity and magnetic cross gradient method is put forward. Through the synthesis model test, it is found that the method can well distinguish the positions of different combinations of gravity and magnetic anomalies. By using this method in Tongling and Jiujiang-Ruichang ore concentration area to carry the results show that magnetic and gravity cross gradient is an effective method for the delineation of ore prospecting targets.