The Prospecting Progress and Direction for Exhausted Lead-zinc Ore Resource Exploration in Dongpo Ore Field,Hunan Province

Although underground resources in Dongpo ore field are very abundance,the lead-zinc metal quantity is much short for further mining.Based on synthetic analysis of regional geological background,ore deposit feature and metallogenic regularity,three prospecting target are selected,which are Meizilong area,Niujiaolong area and Tangzhashui area.The ideas for prospecting have established by detailed investigation of geological characteristics of skarn-type W-Sn polymetallic and vain-type Pb-Zn ore deposits:(1) the areas nearby known ore deposit are favorable target,such as depth or rim of ore-body;(2) the favorable mine type are lead-zinc,while tungsten-tin polymetallic ore is also to be considered;(3) the geological methods is the most effective one,and geophysical method should also be useful.The high accuracy ground magnetic survey,electrical sounding,drilling or tunneling methods are used for exploration in Dongpo ore field.22 magnetic anomalies are found through geophysical operations,most exciting new is the finding of low electrical resistivity-high polarization geologic body-skarn-type W-Sn ore body in Meizilong area.The further exploration engineering proves up this skarn-type W-Sn ore body is 10.86 ~ 32.00 meters thick,which come to be a large scale deposit.In Tangzhashui area,the new 333+334 class Pb+Zn reserves of 8.23×104 t is added to Ⅱ4 ore body,and 103 meter thick skarn-type W-Sn polymetallic ore body are found in 500 meter level,those two new finding makes this deposit to be large scale.A large thickness(3.58 ~ 9.37 m) and high grade(in average: Pb 14.94%,Zn 2.22%,Ag 1 444.44 g/t) Pb-Zn ore body is found in Niujiaolong area,which maybe come to a medium scale deposit.The exploration work in Dongpo ore field illustrate that the depth and periphery of known ore deposit is the favorable prospecting target: skarn-type and greisen-type tin polymetallic ore body maybe found in depth of Hengshanling,Shexingping and Yuhuangmiao area;lead-zinc-silver ore-body may be in mid-shallow and skarn-type or altered rock-type ore-body may be in the depth of Shapingli,Jinshiling and Gutang area.