Research On Favorable Zones Of Lower Cretaceous Sandstone-type Uranium Mineralization In Key Areas In The North-central Songliao Basin

This paper takes the Lower Cretaceous in the upper part of the central anticline belt of the Songliao Basin and the lower part of the northeast uplift area as the research object.Based on seismic logging data and geological data,the sand-rich sedimentary microfacies,structural inversion,redox,and redox are analyzed.Hydrodynamic conditions are the necessity of sandstone-type uranium metallogenic conditions.The relationship between the distribution of the basin's sedimentary system,the characteristics of tectonic activity and the uranium metallogenic mechanism is summarized macroscopically,and the metallogenic laws of sandstone-type uranium deposits in the study area are discussed.The denudation range of the structural skylight was estimated,the unique uranium deposit metallogenic model in the study area was constructed,and the favorable metallogenic zone in the study area was predicted.The main sedimentary facies of the target interval in the study area are delta facies,shore-shallow lake facies and fluvial facies.The uranium-rich favorable sand bodies of the third and fourth members of the Quantou Formation are mainly developed in braided river facies,and the uranium-rich favorable sands from the Qingshankou Formation to the Nenjiang Formation The body is mainly developed in the delta front and delta plain and other sedimentary facies.The distribution range of sand bodies and particle size sorting are related to the suitability of uranium enrichment space.Large-scale inversion structures have played an important role in the formation and enrichment of sandstone-type uranium deposits in the study area.The denuded skylights formed by them gradually form interlayer oxidation zones after being leached by precipitation with oxygen.The oxygen precipitation remains in the stratum,provides power for the migration of uranium ions,and enriches uranium ore near the geochemical barrier.In addition,the tectonic reversal movement caused deep faults to be activated again.Oil and gas and groundwater from the basement entered the uranium-containing ore layer along the fault,causing the ore layer to suffer from kaolinization on a large scale,that is,acid alteration.The effect of fading,the rise of oil and gas and groundwater is accompanied by a large amount of reducing substances,such as hydrocarbons,hydrogen sulfide,etc.,dark sandstone is reduced to light color,and eventually sandstone-type uranium deposits are formed.And many unconformity strata with developed fault depressions will also form interlayer oxygenated water supplement-flow-discharge groundwater system due to structural reversal.According to the scale,it can also be divided into local interlayer groundwater system or regional groundwater system.The interlayer groundwater system.According to the material supply and mechanism involved in the uranium mineralization process,uranium mineralization is divided into four stages,namely the uranium source basement construction stage,the reducing material source rock series development stage,the ore-bearing sand body formation stage,and the denudation skylight.The main metallogenic stage of formation and interlayer oxidation.The northeast uplift area of the Songliao Basin has a wide range of favorable structural skylight denudation.There are denuded horizons from the Nenjiang Formation to the Quantou Formation,and delta facies sand bodies are developed,which is a very favorable uranium mineralization prediction area.The central inversion structural zone in the Songliao Basin has a relatively small distribution range,and the denuded horizon is relatively shallow.Most of the area denuded is the Nenjiang Formation.Although it is also a favorable uranium mineralization prediction area,it is slightly inferior to the northeast uplift area.