The Study Of Magnetic Anomaly Characteristics Of The Interlayer Oxidation Zone Sandstone Type Uranium Deposit In The Meso-cenozoic Basin

The sandstone type uranium of interlayer oxidation zone is produced inMesozoic to Cenozoic basin， this kind of uranium ore bodies exist characteristics oflarger buried depth， small scale， scattered distribution. they are not obvious in theinstructions，of the surface， There is a certain degree of difficulty to looking for thesandstone type uranium of interlayer oxidation zone. For a long time， depending ondrilling means to distinguish the geochemical zoning stratification of the sandstonetype uranium of interlayer oxidation zone to looking for this type of uraniumdeposits，the high cost，low efficiency has greatly restricted the prospecting process.Geophysical method is an important means to searching for the sandstone typeuranium of interlayer oxidation deposits in the northern area of our country at presentand future， including magnetic exploration is one of the methods that are widelyused， but no matter the magnetic anomaly formation mechanism or the abnormalexplanation， still need to further deepen the understanding， summed up the pattern.For how to improve the prospecting effect of magnetic exploration， delineating theuranium metallogenic target fast and accurate.Magnetic prospecting is a geophysical method that through the observation andanalysis of the magnetic anomaly that caused by the magnetic differences betweenrock and surrounding rock to infer the underground geological structure and thedistribution of mineral resources. In the interlayer oxidation zone sandstone typeuranium deposit， iron content is the primary or secondary mineral that wasextensively developmented. Because of the iron content is very sensitive togeochemical environment change， there is iron a slight difference mineral contentbetween deposit area， transition zone and primary zone in the oxidation zonesandstone type uranium， that laid the foundation for the magnetic prospecting work.This article is through largely collect the data that was obtained from the aerialmagnetic survey in the sandstone type uranium deposit in the north of our countryfrom recent years. Combined with the experience of forefathers’ research andore-forming mechanism of in-situ leachable sandstone-type uranium deposits， basedon the sandstone type uranium deposit geochemical zoning and the characteristics offerromagnetism mineral content of borehole core specimen in each zoning. And then applicate the high precision magnetic survey of Honghaigou mining area， Wukuerqimining area and Zhajisitan mining area that all in the southern margin of Yili basin topreliminary analysis the micro characteristics of magnetic anomaly in the in-situleachable sandstone-type uranium deposits and the relationship between magneticanomaly and uranium ore district. From these， then discuss magnetic anomaly’sformation mechanism in the sandstone type uranium deposit ore body. And then wecan use the micro magnetic anomaly as the effective method to distinguishgeochemical zoning in the sandstone type uranium deposit.In the process of research， the author combined with the study area geologicalbackground conditions and actual geological and physical properties to make aforward model. In the model， we fully consider magnetic susceptibility differencesbetween the sandstone and magnetic mudstone in the design of the sandstone typeuranium deposit area. By means of forward modeling method， we have obtained thatnegative anomaly exists in the oxidation-reduction transition and its due to thesusceptibility differences between permeability sandstone and mudstone magnetic thatto the area will cause±10nT to±20nT abnormal fluctuations above the surface of theearth， all of these have provide the basis for knowning the magnetic anomalyregularity in sandstone type uranium deposit zone.