The Research Of Geogas Field On Polymetallic Concealed Deposits

The geogas prospecting has beenresearched more than20years inour country, forits mechanism and characteristics geogas prospecting is very suitable for deepprospection, but the theory and analysis methods need to be further perfected becauseofthe method is easyto be interfered byvarietyof factors. The paper studies the currentsituation of the development of the geogas, found that there are some problems in theinference and interpretation of the geogas anomaly:1. Most applies of geogasprospecting only can solve mineral enrichment section above200-300meters, can’tpredict deeper;2. Most inference and interpretation are directly estimate the elementanomaly is caused by ore bodies without analysis which added some uncertainty tothe result;3. Inference and interpretation of geogas anomaly is limited to contrast theposition of the elements and ore body location, amplitude of anomaly, few to researchelements combination in the sample ingredients and the elements source.In order to solve the problems above, this paper based on the project of TheNational Natural Science Foundation of China: field of geogason concealed geologicaland fracture research (project numbers:41074094), and project the national ministry ofscientific "son project of the deep detection technology and experimental-radioactivedetection technology and experiment about deep metallogenic information the key oreset area of Nanling(project numbers: SinoProbe-03-01-4C), and The key project ofnatural science of education ministry of Sichuan province “research of geogas field onthe concealed metallica deposits”(project numbers:10ZA118), start a series of studieson the field of geogas which above the polymetallic deposit.The author separately did geogas measure on profile in Huangshaping lead-zincmine of Hunan province and area geogas measure in Dachang zinc-copper mine ofGuangxi province, there are4measure line in Dachang in Guangxi. Overallmeasurement of this subject length is62km,590samples. And put on a series of sample comprehensive research:1. Through the anomaly element and element contentanalysis, discussed whether the ore generate geogas abnormal;2. Through clusteringanalysis on elements in all sorts of different rocks in the region and geogas samples,discussed the elements source and combination characteristic in it;3. According to thefactorial analysis about rocks and geogas samples, the paper discussed the causescharacteristics of combinations of elements and coexisting elements of the mainore-forming elements;4. Throughthe analysis on REE, discussed the rock types in thisregion;5. Discussed the geogas prospecting effect on great depth of the ore predict;6.Discussed the geogas on predict the boundary of the ore body;7. Summarizedcharacteristics of the geogas field on concealed polymetallic deposits.Through the analysis, the author reaches the following results:1.Through the anomaly element and the content analysis shows that, the ratio ofthe main ore-forming elements different from the ratio in rocks which geogas passed,but the mixture ratios of different types of rock, fluctuating between the maximum andthe minimum ratio, the main ore-forming elements get the biggest proportion of allcomponents, which is much higher than the grade of any other elements in the variouskind of rocks, this shows that geogas prospecting has the ability of judgment for whatelement enrich in the region;2. The clustering analysis of elements in different kinds of rocks and geogassamples shows that, the element combination characteristic of geogas samples mostlike the element combination characteristic in the magmatic rocks and metamorphicrocks which geogas penetrated before it reached the earth surface, the elementcombination characteristic of rocks of different lithology characters near polymetallicore bodyare able to keepthe symbiosis characteristics of main ore-forming elements ofore, geogas can also reflect the symbiotic relationship, which indirect explained thegeogas anomaly’s emerge is effected by the ore;3. Through factor analysis on different lithology characters of rocks and geogasingredients found that, the first main factors of geogas have close relation withmagmatic rocks and magma evolution process of the area where geogas measured, byanalyzing the factors can infer that the origin cause and formation of various kinds ofelements combination and elements enrichment and ore-forming process in the areawhere geogas prospecting measured, and pointed out the symbiotic elements of themain ore-forming elements, for further geophysical prospecting clear direction;4. Through analysis on the rare earth elements of geogas ingredients, we can inferthat the granite type of the area, which can help understandthe regional metallogenic process;5. Through the analysis of geogas anomaly on number95th ore body of Dachangtown which located at position of800metres under the earth surface, found that geogascan reflect the depth of concealed orebodies very well, this provide the basis for thegeogas prospecting could be used on looking for the great depth concealed deposits;6. By the discussion of the possibility that whether geogas prospecting coulddelineate the ore bodie’s boundary, the geogas be found that could reflects the boundaryof the ore bodies on a certain degree, but for delineate accurately of the ore bodiesboundary it still need to do more further research;7. Summarizes the common features of the field of geogas onthe polymetallic oredeposit: inadditiontothe above1-4, the anomalyofgeogas are discontinuous, and mayeven appear only single point anomaly on the whole orebodies.