Application Of Induced Polarization (IP) Method On Copper Ore Survey In Duolong Area Of Tibet,China

Based on the Induced polarization program carried out in Duolong area of Tibet,the thesis has explored the functions of the IP method on the prospecting of copper ore of Porphyry type in this area. On the basis of the electrical feature resulted from IP sounding method, we have detected and confirmed the electric abnormal structure,combined with the geology and the geochemical information in this region. Further,we set up effective survey using large scale IP method for the Porphyry copper prospecting.We classified the apparent polarizability into three classes though the IP survey which has scale of 1:25000. The low polarizability area located at the north of the survey line and the value is between 0 to 3%. Almost survey area feature as moderate polarizability and the value is 4% to 8%. The IP abnormal, which is 8% to 13%, is in local area. What's more, the feature of apparent resistivity in this survey region is also showed as there types: in the northwest of survey area, the apparent resistivity is relative low (n×10?100?·m); In some other areas are characteristic of medium resistivity(100?350?·m) and the higher (350?1450?·m). According to the calculated theory of equal-area distribution of abnormal surface, we plotted the counter maps of the high resistivity polarization and the low resistivity polarization,respectively. In this way, the IP abnormal of high resistivity polarization related to the sulfide and IP abnormal of low resistivity polarization, which may results from silication and dip-dye type mineralize, all can directly be detected.Combined with the geology, geophysical and geochemical prospecting information, we figured out 13 abnormal areas of local and classified them into 3 types: the first types are the metallogenic province of important and there are total 5 places labeled as ZH1, ZH3, ZH6, ZH8, ZH12. These five places are recommended as target regions; the second types are morderate abnormal regions, which are potential target regions to be further confirmed. There are labeled as ZH4, ZH7, ZH9, ZH10,ZH11 and ZH13; the third types may has little metallogenic prospect and correspondingly has two places which labeled as ZH2 and ZH5. For the third type of IP abnormal region, it is maybe unnecessary to carry out further prospecting and survey programs. Two mineralized bodies from the 13 target regions have detected giant copper ore. The 1:10000 scale of induced polarization intermediate gradient method can be further carried out in prospect segments to shrink the abnormal area and to add the additional data information. In that, the response from the IP effect will be more apparent and detail. The spatial distribution of abnormal can be detected using IP sounding method.Based on the metallogenic model of this survey area and the effective of geophysical prospecting methods, we have summarized the methods for the Porphyry copper prospecting in our survey area.