河南新蔡县练村一带地球物理特征及找矿远景

Geophysical characteristics and prospecting perspective of Liancun area in Xincai County of Henan

练村磁异常区位于豫东平原覆盖区,鲁山—舞阳—新蔡—霍丘铁成矿带上。为进一步确定练村磁异常地质体、对该区潜在铁矿资源进行评价,开展了1∶5万地面高精度磁法测量、1∶1万地面高精度磁法剖面测量、1∶1万可控源音频电磁测深及钻探等系统勘查工作。综合物探成果显示练村磁性地质体具高磁、低阻的特征,其与正常围岩太华岩群片麻岩系的低磁、高阻特征具明显区别。通过对物探异常的总体分析,认为当高磁异常区存在推测的磁性体时,视电阻率等值线断面图上表现为在30~35Ω·m之间垂向梯度变化较小,可将其作为推测区内磁性体存在的依据。钻探揭露多层铁矿化体,根据岩性组合自下而上将其分为C_(1)、D_(1)两个矿段,铁矿体赋存于太古宇太华岩群内,为沉积变质岩型矿床,具埋深浅、缓倾斜的特征。结合地质资料、矿化体信息、综合物探异常特征,分析了找矿远景,初步认为磁异常数据化极处理后圈定的DC04-1、DC04-2、DC04-3异常深部具有寻找大型沉积变质岩型铁矿床的前景。

The Liancun magnetic anomaly area is located in the coverage area of the East Henan Plain,which belongs to the Lushan-Wuyang-Xincai-Huoqiu iron metallogenic belt.In order to further determine the magnetic anomaly of Liancun geological body and evaluate the potential of iron ore resources in this area,systematic exploration work,such as 1∶50000 ground high-precision magnetic survey,1∶10000 ground high-precision magnetic profile survey,1∶10000 controllable source audio-frequency electromagnetic sounding and drilling project are carried out.The comprehensive geophysical exploration result shows that the magnetic geological body of Liancun has the characteristics of high magnetism and low resistivity,which is obviously different from the characteristics of the gneiss series of Taihua Group of normal surrounding rocks.Through the overall analysis of the geophysical anomalies,it is considered that when there is a speculated magnetic body in the high magnetic anomaly area,the contour map of apparent resistivity section shows a small change in the vertical gradient of the resistivity between 30-35Ω·m,which can be used as the basis for the existence of the magnetic body in the area.Drilling verification reveals the multi layers of iron mineralization,which can be divided into two ore sections C1 and D1 from bottom to top according to the rock layer combination.The iron orebody is hosted in the Taihua Group of Archean Eonothemis and the iron deposit belongs to the sedimentary metamorphic type with the characteristics of shallow buried depth and gentle dip.Combined with the geological data,mineralization body information and geophysical anomaly characteristics,the prospecting perspective is analyzed in the study area.It is preliminarily considered that the DC04-1,DC04-2 and DC04-3 anomalies delineated after the polarization treatment of magnetic anomaly data have the potential to explore for the large-scale sedimentary metamorphic iron deposit in the depth.