Delineation And Method Research Of Large Lithology Influence Of The Northern Hebei

The anomaly of geochemical explorative elements is an important technical means ofmineral discovering at present, more than80%new discovered mineral is found by this meansin China. The core of the data processing of geochemical exploration is the definition of theabnormal lower limit of ore-forming elements. Many scholars have come up with all kinds ofsolutions on the question, but the methods now available just analyze from the data’sregularity if distribution without considering the change of elements content’s spacedistribution that caused by the difference of lithology and stratum’s exposed thickness. This isthe fundamental reason that restricts and influences the elements’ space distribution. In recentyears although some scholars have raised to definite and differentiate the backgrounds andabnormal geochemical data processing according to geologic body, but they just extract andcalculate the mean value and standard deviation of the data in the range on the basis ofdifferent geologic body without considering the elements’ background value of the stratum,thus it may weaken the abnormal information of high geochemical。In addition, there existsmany personal factor when definite elements’ anomaly according to geologic body, such asthe definition and divisiory principle of geologic body. Then the geologic bodies consist ofdifferent lithostratigraphic units, like sedimentary cover, because there exists comparativelylarge change in different sedimentary rocks of sedimentary cover, which causes theasymmetry of element content’s space distribution in the same geologic body.After researching the geochemical exploration southwest five provinces of China theacademician Xie Xuejin made a conclusion that: when one ore-forming element’s backgroundcontent in one rock is more than determinate abnormal lower limit, it will bring interferenceto the predict. Xie Xuejin thinks this kind of element are those have comparatively largerinfluences to the comments on ore-forming long-range perspective (and propose toabbreviate this element to LLI, Large Lithology Influence). It caused that some mineral deposit having large economic value may not distribute in the range or the margin ofgeochemical anomaly at all, and abnormal district may only be the reflection of rock highbackground, this will lower the reliability of ore-forming predict, thus it is necessary tosearching and improve new definition methods of this kind of element. This method was putforward by academician Xie Xuejin for the first time, he divides the reaching area into equalgrid cell having the same sampling density as drainage deposit sediment and collects andanalyzes the rock sample in the grid cells to get the drainage deposit sediments’ contrast valuerelative to rocks and definite the abnormal ore-forming area. This method well overcomes thequestions and defects of the data processing of geochemical exploration before, and it hasenough theoretical base, simple and easily be realized operational process, thus it has highapplication and dissemination value.This paper will relate drainage deposit sediment’s elements content in researching areato different stratum (lithology) lay and its ore-forming elements content, definite this kinds ofelements’ abnormal distribution area by applying contrast method on the basis of ply weightedmean. This method well overcomes the questions and defects of the data processing ofgeochemical exploration before, starting from the essence of elements’ space distributiondifferential. This article regards stratigraphy as standard of classification by <Hebei areal rockreport>, evaluates to areal rock background of Hebei province and makes a comprehensiveanalysis on the basis of1:200000geochemical exploration data of Hebei province, and hopeto overcome the questions of geochemical anomaly before. And it will apply the comparativeanalysis to prove the scientificalness and effectiveness of this method.