| The aeromagnetic is quick prospecting methods, without restriction of the watersarea, river systems, forests, swamps, high mountains. The plane have a certain heightfrom the ground, which weaken the impact of uneven surface magnetic, it’s better toreflect the magnetic field of the deep geological body. However, the delineated areas ofaeromagnetic anomalies usually have a large scale; vary from dozens and hundredssquare kilometers. Meanwhile, the center of anomaly maybe deviate from the actualposition because the influence of oblique magnetization. So, it is difficult to apply theaeromagnetic survey to ore prospecting directly. Ground check on aeromagneticanomaly is necessary to study the anomalies, discriminate the mineralized anomaly andunmineralized anomaly, and guide the following work for exploration. At present, thereare many kinds of anomaly inspection methods including geophysical and geochemicalways, which could apply to aeromagnetic anomalies investigation. But the key point isthat how to complete the aeromagnetic anomaly inspection quickly, accurately andeconomicly. With two years’ field work experience, a combination of groundhigh-precision magnetic survey, field X-ray fluorescence measurements, the field γ-rayspectrometry, the shallow surface uncovering, shallow drilling X-ray fluorescencemeasurements, micro-beam X-ray fluorescence microprobe analysis methods areapplied to the aeromagnetic anomaly inspection. Following the three class anomalyinspection criterion, field work divided into different stage. Shallow drilling X-rayfluorescence measurements, micro-beam X-ray fluorescence microprobe analysis arepromoted as brand new method during those stages. Finally, Tuoxun No.135aeromagnetic anomaly point is verified successfully, because two Cu-Zn anomalies arediscovered. The main results are:1. Determining the location of the aeromagnetic anomaly and discriminating lithology of different rock through the ground high-precision magnetic survey. TheChangjihe formation obtains low magnetic value, average-9.5nT, is gray-redcoarse-grained pebbled sandstone, sandstone interbedded with bioclastic limestone.The Dahalajunshan formation has moderate magnetic value, average68nT, is tuff. Themagnetic value change very little in intrusive rocks. The average magnetic value ofpale red fine-grained quartz monzonite is312nT. The average magnetic value of palered microcrystalline granite porphyry is220nT. The field X-ray fluorescencemeasurements is applied after the location of aeromagnetic anomaly is clear. Thedistribution of V、Cr、Mn、Fe、Ni、Cu、Zn、As、Pb、Sr are investigated in workingarea. Two valuable Cu-Zn anomalies are discovered. According to the field γ-rayspectrometry data, U, Th, K show normal distribution, coefficients of variation varyfrom0.1to0.2. It indicates that there is no U, Th, K anomalies in this area. The fieldγ-ray spectrometry is also used to the discrimination of strata. At last, the geologicmap is modified samply.2. Three muti-elements anomalies area are delineated through muti-methodscomprehensive study. First, Fe-Mn-Zn-As-U-Th-K muti-elements anomaly lies to theeast of positive magnetic anomaly, whose area is up to0.3square kilometer. It isunmineralized anomaly, because low anomaly intensity and location of elementanomalies occur discordantly. Second, Cu-Zn-U-Th-K muti-elements anomaly lies tothe south of the negative magnetic anomaly, the area is up to0.2square kilometer.Third, Cu-Zn-K muti-elements anomaly lies to southeast of the negative magneticanomaly, the area is up to0.15square kilometer. The last two anomalies have highCu-Zn intensity, and the location of Cu, Zn anomalies in accordance with each other.They are both mineralized anomalies distributing along the fault, and have closerelation to hydrothermal activity.3. The mineralized outcrops are discovered by reconnaissance in the delineatedanomalies area. The shallow surface uncovering project shows that the contents of Cuand Zn increase with depth, and achieving maximum in the contact zone. Theboundary of wall rock and altered rock is clear. Shallow drilling X-ray fluorescencemeasurement is proposed as field working method firstly. Combine with simple,portable and no topographical requirement drill and field, rapid and low cost X-rayfluorescence analysis, acquiring the mineralization information of4-5meters underthe earth’s surface. Two valuable copper mineralized bodies are delineated.4. micro-beam X-ray fluorescence microprobe analysis is applied toaeromagnetic anomaly survey for the first time. It can be used for mineral identification and testing of element content in minerals. Usually, instead of polishedsection and thin section, the rocks can be used to observation and measurementdirectly. In this paper, tetrahedrite is modified to pyrite through micro-beam X-rayfluorescence microprobe analysis, and the element content of minerals are studied inthe altered section.5. Integrated use of ground high-precision magnetic survey, field X-rayfluorescence measurements, the field γ-ray spectrometry, the shallow surfaceuncovering, shallow drilling X-ray fluorescence measurements, micro-beam X-rayfluorescence microprobe analysis, setting up a rapid method of aeromagnetic anomalysurvey. Different method complements and verifies each other, which improve theaccuracy of aeromagnetic anomalies survey.6. According to the muti-method verification, the high magnetic susceptibility ofrocks causes high positive aeromagnetic anomalies. The No.135aeromagneticanomaly lies in an area with magnetic value change slowly. There are two Cu-Znanomalies distributed along the fault in the southwest of No.135aeromagneticanomaly. The mineralization occurs in altered andesite of Dahalajunshan formation.Due to the strong tectonic movement, the rocks are very broken. With the microscope,the copper-bearing minerals mainly are bornite, chalcocite, chalcopyrite, azurite, bluechalcocite, malachite, etc.Discovered mineralization points are not sufficient to cause such a slow changeaeromagnetic anomaly, which indicate a greater potential for prospecting in the deep. |
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