基于重力及多源资料的滇西南糯扎渡地区隐伏岩体推断

Inference of Concealed Rock Mass in the Nuozhadu Area of Western Yunnan province based on Gravity Anomaly

通过1∶20万区域重力调查,在南澜沧江糯扎渡地区发现一圈闭良好,幅值较高,形状呈椭圆形的剩余重力负异常,推测可能由隐伏花岗岩体引起.在异常中心局部有花岗岩体出露,岩浆热液活动强烈.已发现有多个铜多金属矿矿点,以及大平掌铜多金属矿床.化探也显示W、Bi、Cu、Pb、Zn、Ag等高中低温元素的分带异常,遥感在异常区有环状构造,航磁围绕该重力异常有较强磁异常.种种资料显示糯扎渡地区存在隐伏花岗岩体,范围以剩余重力负异常零值线圈定约308 km^(2).通过图切SN和WE两条剖面反演了该岩体的空间展布形态,也进一步证明只有下伏存在花岗岩体,才能拟合上述重力异常.由于该隐伏花岗岩体位于澜沧江构造带上,周围又有基性火山岩,因此无论从构造上,还是物质来源上,都具备成大矿的潜力,建议开展进一步的矿产调查工作.

Based on the results of 1∶200000 regional gravity survey,a residual negative gravity anomaly with good abundance,high amplitude and elliptical shape was found in the Nuozhadu area of the southern Lancangjiang zone,southwestern Yunnan,which may be caused by hidden granite bodies.The granite body has been exposed in the south of the anomaly center,and the magmatic hydrothermal activity is strong.Dapingzhang Cu-Pb-Zu ore deposit and several copper polymetallic ore spots have been found.Geochemical exploration also shows the zoning anomalies of high,medium and low temperature elements such as W,Bi,Cu,Pb,Zn,Ag,etc.The remote sensing has a ring structure in the anomalous area,and the aeromagnetic field has a strong magnetic anomaly around the gravity anomaly.All kinds of data show that there are hidden granite bodies in the Nuozhadu area,and the range is approximately 380 km^(2) with the residual gravity negative anomaly zero coil.The spatial distribution pattern of the rock mass is inferred by the two sections of SN and WE,and it is further proved that only the granite body is underneath to fit the gravity anomaly.Since the concealed granite body is located on the Lancangjiang tectonic belt and has basic volcanic rocks around it,it has the potential to become a large ore mine both in terms of structure and material source.It is recommended to carry out further mineral investigation work.