| The study area is located in the south of Daba East, the eastern margin of the Sichuan Basin, the tectonic unit belonging to the concave fold bundle of Wuxi which in the overthrust belt of Yangze block Micang-Dabashan base. Wujiaping formation in the study area is nearly EW distributed in Wenfeng District measuring amplitude anticline of the Northern White Hart frame, Kongliang- Baolong anticline and lion package- Red Hat Mountain anticline core and wing, the sheep village in Liangzi anticline and more.Based on field geological survey and measured profile data, by the study of the Wujiaping formation lithology, structure and sedimentary environment, Stratigraphic correlation and Sedimentary facies division for it, Discussion and analysis for the Wujiaping formation of rare earth ore characteristics, metallogenic geological conditions and genesis.Wujiaping lithologic assemblage characteristics: At the bottom is equivalent to the Wang slope section, lithology is gray white medium-thin layer mudstone, Carbonaceous mudstone, dark grey-purple gray medium-thin layer silica rock grey-brown grey medium layer silica rock and dark grey medium layer silica rock, local area contain yellow gray-grey mudstone, silica rock after weathering become Loose porous, the weathering surface was mostly purple gray; middle lithology Mainly gray- dark grey medium- thick layer containing silica nodule microcrystalline-fine crystalline limestone, dark grey thick layer containing silica nodule or lump fine crystalline limestone, gray thick layer fine crystalline bio clastic limestone; upper part is light gray thick layer microcrystalline bio clastic limestone, thick layer bright crystal granular limestone, Silicon containing microcrystalline limestoneThe main ore of rare earth ore is Wujiaping formation at the bottom of the clay rocks and for powder sandy clay rock, siliceous clay rock, tuff clay rock or tuff, cryptocrystalline mud structure, micro crystal structure, mud crystal structure, block structure, layered structure, The main mineral is cryptocrystalline mud(clay mineral 50~88%), siliceous(15~50%), which is composed with A small amount of silt quartz,Calcite, limonite and other metal minerals etc. The mud is cryptocrystalline clay, uniform distribution, the very small number of the edge of fracture crystallization is silk mica, aphanitic siliceous, little crystals is radial chalcedony(Irregular clusters, short pulse distribution), Silt shaped quartz and particulate metal mineral is scattered distribution, rare earth mineralization clay rock weathering is relatively loose and fracture with iron staining.The main element of representative samples show that the wujiaping formation siliceous rocks belong to hydrothermal origin, element characteristics also expressed that there are terrigenous substances involved in it,and Consistent with the eruption period of the Mount Emei basalt in the area; and the study of the main elements of the clay rock sample shows that, the provenance may be derived from mafic rocks greatly combined with the regional tectonic events, it shows that the provenance area is Mount Emei basalt better. The rare earth and trace element characteristics show that, Samples of Zr, Nb, Ga, respectively arrived, Zr, Nb, Ga, the boundary grade requirements, With the exploitation value. Total amount of rare earth elements ∑REE is(781.22×10-6~934.65×10-6,average as 859.83×10-6) is 3 to 5 times of the other layers of shale, sandstone and sandstone, It is 20 times as much as that of carbonate rocks.The sum of rare earth metal oxide(TR2O3)(0.214%~0.279%,average as 0.247%) has reached and exceeded the weathering crust ion adsorption type rare earth ore boundary grade(0.08%)requirements,in which, the sum of light rare earth oxides(0.166%~0.2%,average as 0.18%)is much higher than that of weathering crust ion adsorption type of light rare earth ore’boundary grade(0.05%),and The sum of heavy rare earth oxides(0.047%~0.094%,average as 0.068%)is slightly higher than that of weathering crust ion adsorption type heavy rare earth ore’boundary grade(0.03%).The ∑LREE/∑HREE of the sample was between 6.42 and 10.64, It shows that they have obvious characteristics of light and heavy rare earth,which is light rare earth enrichment type rare earth ore, the abnormal coefficient of the sampleδEu is beteen 0.33~0.43,which is negative anomalous, δCe is beteen 0.62~0.82 is also with negative anomalous, surmised that the mineralization of rare earth ore is weathering effect before sedimentation, The cumulative thickness of the mineralized layer represented by the sample is 6.42 m, byond the mining thickness of the corresponding rare earth ore.The discovery of the mineralization points to find and Wujiaping group at the bottom(quite Wang Poduan) on clay rock type rare earth and rare, thin element mineral powder provides important clues and new prospecting direction, there is important significance to ore prospecting in the region. |
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