| Datan volcanic basin in Fengning is located in the zone of the northern ancient north China plate,on the south of Xar Moron river fault zone,on the west of the Yan-Liao polymetallic(Mo-U-Ag-Pb-Zn),and on the southwest side of the Gu(yuan)-Hong(shanzi)uranium belts.Andit adjacent to the Guyuan basin where there is a large Zhangmajing U-Mo deposit.A number of uranium ore and uranium anomaly drilling were played in the Wuliying area in the northern part of the Datan volcanic basin,Uranium deposits occur in Dabeigou Formation of andesitic porphyrite near the contact zone.The zircon of andesitic porphyrite(sample numbers FN401)from Wuliying have obvious oscillatory belt,and high Th /U ratio which belong to the typical magmatic zircons.The zircon SHRIMP U-Pb dating of andesitic porphyrite was 134.6±2.3Ma,n=11,MSWD=1.5,which represents the emplacement age of the andesitic porphyrite was formed in the early Early Cretaceous.Wuliying andesitic porphyrite by structural characteristics can be divided into no porphyritic andesitic porphyrite and porphyritic andesitic porphyrite.no porphyritic andesitic porphyrite has a dark gray-grayish black,massive structure,The porphyritic andesitic porphyrite color was grayish brown,with a patchy structure,Porphyry is mainly plagioclase and amphibole and a small amount of quartz,dark minerals are biotite,pyroxene,etc.The K2 O,Na2O and SiO2 values of no porphyritic andesitic porphyrite are smaller than those of porphyritic andesitic porphyrite,but the TFeO and MgO are larger than porphyritic andesitic porphyrite,Showing that there is more basic geochemical characteristics.In the Harker diagram,there is a significant evolution trend in the no porphyritic andesitic porphyrite and porphyritic andesitic porphyrite.K2O?Na2O and Al2O3 are positively correlated with SiO2,and TFeO?P2O5?TiO2?CaO?MgO are negatively correlated with SiO2,Indicating that there are no porphyritic andesitic porphyrite magmatic is different from the porphyritic andesitic porphyrite magmatic.Andesitic porphyrite has the main elemental characteristics of high K2 O,low TiO2 and low Mg#,Enrichment of large ion lithophile element(Rb,Th,K,Pb?U)and High field strength elements(Nb,Ta,Zr and Hf)loss is not obvious,Andesitic porphyrite has high content of rare earth elements,the enrichment of light rate earth,light and heavy rare earth fractionation significantly and the negative Eu anomaly is not obvious.High(87Sr/86Sr)i(0.7066~0.7073),lower(143Nd/144Nd)i(0.51184~0.51196)?? Nd(t)(-12.21~-9.93),the larger TDM2(1916~1732Ma),lower(206Pb/204Pb)t(17.15~17.40),(207Pb/204Pb)t(15.38~15.43),(208Pb/204Pb)t(37.46~37.67).In(87Sr/86Sr)i-10000/Sr,?Nd(t)-SiO2,SiO2-(87Sr/86Sr)i diagram,andesitic porphyrite has a clear linear relationship,indicating that the magma rise during the process by the crust material mixed.In the(87Sr/86Sr)i-?Nd(t)plot,the samples fall on the EMI-direction evolution line and Hannuoba two-pyroxenne grain xenoliths area,indicating that magma is mainly derived from EMI the enrichment mantle.In the La-La/Sm,Ta/Yb-La/Yb,Nb/Yb-Tb/Yb plot,the trend of sample distribution is close to that of separation and crystallization,indicating that the magma undergoes separation and crystallization.In the Zr/Y-Zr diagram and the La/Zr-Nb/Zr diagram,the Andesite porphyrite falls within the plate-pull basalt area.It is known that the genesis of Ansan porphyrite: In the early Early Cretaceous tectonic environment,the magmatic mantle is partially fused by EMI to form magma.The magma intrudes into the near surface to form an orchid porphyrite along the rupture.It is contaminated by crustal matter during the ascending process,the crystallization of the role of differentiation.There are different uranium ore bearing horizons of the Wuliying area and the Zhangmajing(460),Daguanchang(534),Hongshanzi(470).Hongshanzi(470)ore-bearing rock is a combination of high-K calc-alkaline rhyolite and alkaline rhyolite in the early late jurassic Xinmin Formation,Zhangmajing(460)and Daguanchang(534)ore-bearing rock is a combination of high-K calc-alkaline rhyolite and alkaline trachyte in the early Early Cretaceous Zhangjiakou Formation.Wuliying uranium ore is mainly produced Dabeigou Formation of andesitic porphyrite rock veins and silicification zone where the intersection,This characteristic is similar to north guangdong Xiazhuang uranium deposits Have been in the basic dyke and silicide take control.The discovery of the new ore layer not only expanded the prospecting area but also pointed out the direction of uranium exploration after the region. |
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