Tunnel Gravity And Deep Prospecting Prediction In Baoshan Lead-zinc Polymetallic Mining Area, Hunan

Baoshan lead-zinc polymetallic mining area,built in 1996,is located about 2kilometers southwest of Guiyang County,Chenzhou City,Hunan Province.After more than 40 years of mining,the shallow mineral resources of the mine have gradually dried up.At present,the mining area reaches a depth of-190 meters,and is in urgent need to find sustainable resources.Gallery gravity has the advantages of being less subject to electromagnetic interference and closer to the detection target body observation,so the high-precision pit-tunnel gravity is chosen to carry out the research on mineral prospecting to predict and locate mining areas deep in Baoshan mining area.Through the measurement of the gravity of middle gallery(-110,-270 meters)and gravity gradients in X,Y,and Z directions,various corrections of the gravity observation data of the tunnel(including Earth Tide Correction,Temperature Correction,Tilt Correction,Zero Drift Correction,Terrain Correction,Normal Field Correction,Bouguer Correction,etc.),separation of regional and local fields,and researches on density feature,anomaly inference and interpretation,and deep ore prospecting,the author gets the following results and conclusions?(1)According to the gravity anomaly in the tunnel area,the deep strata and its structure are inferred as NNE spreading to NW,which is consistent with the existing deep drilling results.(2)According to the bouguer gravity anomaly gradient in the tunnel between the middle section of-110 and-270,it is inferred that there are high-density bodies between the two tunnels,indicating that there are ore bodies between the two tunnels or the known ore bodies have not been mined out,which is consistent with the fact.(3)According to the local gravity anomaly of the tunnel,it is inferred that there is a prospecting prospect in the deep part of the north-western mining area,which is consistent with the results of wide-area electromagnetic method and geological inference.Through the verification of deep hole,there is about 35 meters of lead and zinc polymetallic ore at the hole depth of more than 1600 meters below the surface.Good comprehensive prospecting results have been achieved by gravity detection in the tunnel.