Identification And Evaluation Of Geochemical Anomalies Of Stream Sediments In West Yanbian

The west of Yanbian belongs to typical forest landscape area, the vegetationcover is large and natural outcrop is rare. Therefore it is difficult to find mineralresources. A large number of mineral sources finding practices show that geochemicalexploration is the main way to find mineral resources in this kind of landscape area. Inthis landscape area, the sample with coarse grain tends to be adopted to avoidinfluencing of organic matter. Meanwhile, the strong influence of lithology makes itmore difficult to determine the element background value, and directly affects theidentification of geochemical anomaly, especially the identification of low and weakanomaly.The study area is located in the boundary between marginal active belt ofLonggang block and marginal active belt of Jiamusi. The north-east Dunmi fractureruns through this area. The exposure strata mainly include Algonkian, Palaeozoic,Mesozoic and Cenozoic. The study area has experienced magmatic intrusion for manyperiods, of which the strongest is magmatic activity during Yanshan period and themost complicated is the intrusive rock. It also provides favorable tectonic setting formineral deposit of industrial value.In this thesis, he characteristic of spatial distribution of stream sediment elementcontent and its relation with geological background is analyzed, and the probabilitydistribution of major stream sediment element (oxide) content and relation betweenore-forming element and chemical composition of rocks are studied. On the basis of it,the geological classification method and multivariate statistical classification methodfocused on dynamic clustering of K value are adopted to delineate the streamsediment element anomaly in the study area. It shows through comparative researchof routine and anomaly delineation method, that the geological classification methodcan remove the influence of lithology background to some extent in an effective way, but also has the shortage of low accuracy, while the multivariate statisticalclassification method can remove the influence of lithology background in aneffective way and can better extract the low and weak anomaly.Based on the research above, the major geochemical anomaly in study area isevaluated according to the evaluation criteria of geochemical anomaly. What’s more,the metallogenic prospective area is delineated according to the comprehensiveanomaly of geochemical anomaly, mineral occurrence distribution and its geologicalbackground.