Application Study Of The Walking Gamma Spectrometer Measurement Method In The Aeromagnetic Anomalies

In the aspect of the method of geophysical and geochemical exploration and thecheck of geological anomalies, the ground gamma spectrometer was been used forlarge scale abnormal examination, adopted the methods of fixed point measurement inthe past. The theoretical analysis shows that if it was used in more than1:10000largescale of the geological mapping, this measurement methods has low representativeand the working efficiency, can not meet the requirement of geological work. In orderto solve this problem and give full play to the ground gamma spectrometermeasurement in the abnormal verification and geological mapping, we propose thecontinuity walking measuring method.A new generation improved digital walking gamma spectrometer IED-3000-Bwas researched and developed by the Chengdu University of Technology, which isbased on the portable gamma ray spectroscopy surve instrument IED-3000-A. It usesthe continuity walking measuring methods to take place of the fixed-point measuringmethods. Walking gamma spectrometer integrated GPS navigation system, in theprocess of continuous measurement, it is able to record measurement results andmeasuring geographic coordinates automatically. Walking gamma spectrometerconsists of integrative host machine, intelligent PDA (with GPS satellite navigation,GSM Internet phone function), battery, accessories and so on.After the test of the prototype of the walking gamma spectrometer and it’sperformance, we will evaluate the geological effect of the successfully developedwalking gamma spectrometer by production experiment, so we can convert theresearch results into productive forces as soon as possible, and promote thepracticability of the domestic the ground gamma spectrometer. The content includes:the production measurements of the capacity spectrum experimental of the gammaspectrometer which was calibrated in the benchmark model. the control and evaluation the data of the measurement and quality of the walking gammaspectrometer, the processing and interpretation of the measurement data of thewalking gamma spectrometer, analyzing and researching the issues which arise in thetrial production like three-dimensional angle, effect range and so on, the productionexperimental measurements range of the walking gamma spectrometer is3km~2. Wechoose the aeromagnetic anomalies abnormal points C-2011-4Tex which is located inthe west part of the north mount Tianshan as the measuring area, because it hassignificance in prospecting. And we choose the ground gamma spectrometer as theaccurate and efficient verification method for the abnormal ground, and demonstrateits verification effect. This measuring area has a lot of natural resources. The workarea is located in high mountain-middle mountains regions, these regions were cutstrongly and has rolling topography. Therefore, this kind of measuring area hasstringent requirement to the measurement’s portability and stability of the walkinggamma spectrometer.According to the study, we mainly have the following cognition and conclusion:(1) Walking gamma spectrometer adopted the continuity measuring method,which makes the measuring curve more gently. The measuring result has morerepresentative. Contrasting to the designated survey in efficiency, it can save time andsave the cost, has better effect.(2) By means of correcting the three-dimensional angle, it weakened theinterference of the terrain to the measured data, and enabled the content isoclines mapof radioactive element reflect the overall effect of the data measured by gammaspectrometer.(3) The quality evaluation results and the descriptive statistics of the data whichshows that the improved walking gamma spectrometer has good stability, highreliability, and credible data.(4) When the measuring area involved in ground surface environment andgeological background has two or more obvious difference, by the means of separateblock mean normalization abnormal method to find out the lower limitation, In theaspect of the lithology divided, the gamma spectrometer can divide the lithology,according to the difference of the content of the radioactive elements of the soil androck in the work area.(5) In the verification of aeromagnetic anomalies’ measurement, the isoline mapof the U/Th and U/K has high numerical value (U/K>2.06and U/Th>0.35) on theboth sides of the north east fault zone, and it distributes and spreads like the cluster. All of the high magnetic anomaly centers distribute in the border of the big mountHalajun group and the Tiemulike group and are closely related to the fault zone. Bythe means of the prospecting in the fields, we found that the lithology of theTiemulike group (P2t) is the time andesites and this assise is rich of Fe which is themain cause of the magnetic anomaly. So we make this conclusion that the magneticanomaly is caused by the altered time andesites of abundant magnetite. Themeasurement data of the walking gamma spectrometer well reflected thecharacteristics of the aeromagnetic anomalies, and the verification effect of it is verygood.