| Xiang-shan uranium ore field is located in collapse basin of Le-an and Dong-xiangmetallogenic belt which belongs to a greater volcano rock tectonic metallogenic belt inGan-hang. The location is in combine zone of North East fracture and North West fracture.Xiang-shan basin already becomes an important continental volcanic type uranium ore fieldin China with more than50years exploration. Recent years, Xiang-shan ore field wasdevoted to much more works for deep mine exploration. New perspectives are gained aboutthe basal structure of collapse basin, mineralization regularity of great uranium deposits, andore controlling factors. The ore body distribution law is that uranium is distributed above thelead zincore. The ore body is mainly distributed500m above. And deep mine exploration isrestricted seriously in the Xiang-shan uranium deposit because without related data aboutgeophysical characteristics and deep geological knowledge in this ore field.In order to investigate the geophysical characteristics and deep geological structure forthe uranium orefield, thisthesis is mainly research the rock physics and spatial distributionof metamorphic rock basement, strikes of great faults and basic framework of magmachannels. This thesis is supported by the Xiang-shan deep geological survey project.For the study of the physical characteristics of the major rock (ore) onxiangshanuranium ore field,establish the geophysical characteristics of xiangshan uraniumorefield,guideto select the deep mining area for mineral exploration method and interpretegeophysical data,collectedand measured more than1400typical rock specimens,and obtaindensity, magnetic susceptibility and resistivity,drew main the histogram of rock unit(porphyroclastic Lava,rhyodacite, granite porphyryand metamorphic rocks),There are singlepeak characteristic from the histogram,but the existence of magnetic susceptibility andresistivity granite porphyry of double peaks phenomenon.There are two obvious connectionregion fromthe intersection chartof the density and magnetic susceptibility of thegraniteanalysis, indicates that there are two types of granite porphyry by analyzing rockcores, high resistance, high susceptibility to light red meat thick spot granite porphyry, lowresistance, low susceptibility to thick grey spot granite porphyry were found.In order tofurther classify the typical rock unit by the test results,the inverse magnetic susceptibility(density/susceptibility) and density crossplot map analysis can be obviously dividedphysical rendezvous regions more obvious, can provide ideas for joint inversion of gravityand magnetic.Regional gravity and magnetic data include both regional anomalies and local anomaly,extractethe abnormal of the research objectfrom the superimposed anomaly, choose a reasonable method of the anomaly extraction,this paper makes a comparative study on theanomaly extraction method.First ground high resolution magnetic data with1:25000andgravity data with1:50000were collected in Xiang-shan district. Gravity and magneticanomalies were separated by use of data processing methods (eg: matched filtering, trendanalysis, analytic continuation and interpolating cut and so on) and the trend analysismethod divide single anomaly successfully.The results of matched filtering method containsmore high frequency components, local anomaly contains much more deep abnormalinformation because the local anomaly information is relatively less. The interpolating cutmethod showed abnormal field components are the surface, the local abnormal results morecomplicated, in combination with geological data of the study area, carries on the contrastanalysis to the separation results extraction, that analytic continuation method canreasonably gravity and magnetic anomaly of the study area.Based on the anomaly separation，three dimensional gravity and magnetic inversionresults were combined with rock physics analysis and geological situation to deduce theunderground parameters distribution. The slice maps of3-D inversion results with typicalanomalieswere used to determine the geology and geophysics phenomena. Through analysis,we delineatethe distribution of metamorphic rocks, rhyodacite, Porphyroclastic Lava andgranite porphyryof the typical section;by the3D inversion of gravity and magneticanomaliessuggests substrate, high density and the volcano, show that this set ofmetamorphic rocks of Qingbaikou system for measuring the area density of rock, theexistence of a density interface and volcano rock series. Fluctuation and the gravitybasement lithology value into a corresponding relation, gravity value higher, basementburied shallower, versus, buried deeper. High density body is mainly exposed in the northernand Western basin,speculate the high density of rock is rhyodacite and low density bodyappear in central area, western and the southeast corner of basin. We deduce that the basinuplift,implemented in the middle of the main volcano in Xiangshan basin. Two volcanoesmaybe existed in the southeast and west of Xiangshan district, respectively.Srong electromagnetic interference effect electromagnetic method application in deepprospecting In the ore district,in order to overcome the influence of electromagneticnoise,andimprove the quality of magnetotelluric data,this paper are analyzed the noisecharacteristics and noise sources on the study area,results show that noise of the study areacan be divided into six types whichcomprise pulse noise, industrial frequency harmonicnoise, square-wavenoise, triangle wave noise, step noise, changed and discharged mode noise. The noise includes mine interference, wireless communication interference, humanbeings disturbance, geological noise etc. We have evaluated the influence of these noises onMT data. Evaluate the quality of MT data by the cross reference,the proposed EMD basedthreshold denoising and morphological filtering denoising method for comparative analysisof the results, two methods are implemented to remove noise, and extract the useful signal,the signal noise separation purposes.The electromagnetic noise research is applied to two magnetotelluric profile dataprocessing on the Xiangshan uranium orefield, the denoised data was conducted2Dinversion, the results delineate sedimentary, metamorphic basement and intrusive rock andfracture structure in deep geological structure better. The research results can providetechnical support for the deep prospectingand deep geological structure of the similar area. |
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