| Guided by the tectonic geology,modern sedimentary and sandstone type uranic metallogeny theory,The article introduces the location,zonation and every subzone’s feature,discriminant symbol and its lithological characteristics of Yuanyanghu uranium deposit’s interlayer oxidized zone in east Yinchuan area,the sandstone’s features which the oxidized zone lies in,then analyze the controlling geological factor to the development of the interlayer oxidation zone,finally summarizes how the interlayer oxidation zone influence the uranic metallogeny.The field work comprise erosion zone and surface surveying,core recording,sampling and researching on the uranium source,single drill microfacies and representative profile;the indoor work is composed of collecting the petroleum,coal and hydrographic core drilling data,and regional survey and general survey report and sampling data about the studying area in uranium branch and so on.The article concludes the geochemical symbol and metallogenic model to the uranium exploration and has guidance meaning to the sandstone uranium exploration to some extent,obtaining some outcome and cognition as follows:1.The study area is located in the west margin fold thrust belt of Ordos basin,mainly controlled by a bracky ancline named Fengjigou-Yuanyanghuin Majiatan-Tianshuipu tectonic belt,the anticline is cut by Maliu fault and play a role of discharge source to the oxygen and uranium-bearing water.2.The target stratum which is braided river sediment in the study area is zhiluo formation in middle Jurassic.the palaeo river stretch from west to east,mainly in the east limb of the anticline with a sandstone thickness from 9.50 to 64.30 m,average 35.55m;The lithological type is feldspar sandstone and feldspar-quartz sandstone that showing they are near the source and low degree of maturation;grain size probability accumulative curve is mainly two phase form which indicates its strong hydrodynamic force.3.Completely oxidized zone is bounded by the overlap line of the gray sandstone whose rock is mainly pale yellow,yellow and tawny,epigenetic alteratioin are ferritization,hematitization,kaolinnization,sericitization,chloritization;completely reduced zone’s main color are graywhite,pale grey,grey and grayblack,that is no oxidized color rock,full of organic matter and pyrite,which is separated from the transitional zone by the oxidation front;the transitional zone is between the overlap line of the gray sandstone and oxidation front.4.The interlayer oxidized zone of the study area extend to the Meihuajing northerly and Shicaocun village southerly,in an irregular ―snake‖ form,with a length of 8km from north to south and 1~3km from west to east.It has zoning characteristics vertically and horizontally.The interlayer is mainly located in the Fengjigou-Yuanyanghu anticline’s east limb Spatially,and its fully oxidized zone is developed near the core,fully induced zone near the concealed part,so the transitional zone is between them which is uranium enriching zone found so far;According to its special color,mineral combination features and geochemical characteristics,the interlayer oxidized zone in Yuanyanghuarea can be divided into fully oxidized zone,incomplete oxidized zone,transitional belt and unoxidized zone(reduction zone)5.The Fengjigou-Yuanyanghu anticline and Maliu faule together control the interlayer oxidized zone’s scale in the study area,moreover the braided river sandstone spatial form determines the interlayer oxidized zone’s locus,and differentia of the grain,sandstone thickness,the quantity of the induced medium along with the ratio of the oxidized sandtone control the transition form of the interlayer oxidized zone jointly.6.The industrial orebody in the study area is distributed in beads-shape along the interlayer oxidized zone dispersedly;mainly tabular and lentoid;uranium is mainly adsorbtive form existing in the matrix and cement,and the unattached uranium mineral is mostly pitchblende and coffinite.7.The place that has Large scaled sandstone(20~25m),appropriate oxidized sandstone ratio,good permeability,the upper and lower water-resisting layer and fluvial sandstone differential position which bears lots of induced medium is most likely to uranium enriching;The mid-coarse grain feldspar quartz sandstone that is full of induced organic material and pyrite is main ore-bearing rock.8.The Yuanyanghu deposit is small scale now,but such type deposits which is controlled by anticline in west magint folded thrust sheet is numerous.After analysis,this type anticline’s concead part or syncline’s tilted part is the best position to uranic metallogeny because of their weak tectonic movement and gentle occurrence. |
