The Discovery Of Continental Sedimentary Magnetite In Late Early Cretaceous In Southern Part Of Daxinganling In China

Southern section of Daxinganling Area in China is located in the structuralenvironment where the EW-trend Asian Paleozoic tectonic-metallogenic domain andNNE-trend western Pacific coast Cenozoic-tectonic metallogenic domain stronglysuperimposed and transformed with each other, providing superior conditions for thefrequency,strength and diversity of Mineralization of the District. Daxinganlingsouthern section is an important metallogenic belt of copper, lead and zincpolymetallic, iron ore deposit is often treated as the associated mineral of much of itsflagship deposits, volcanic-sedimentary iron deposits are extremely rare. This paperconducted field and laboratory work, using the methods of the regional geology, U-Pbdating aspect, rare earth, trace element analysis tests, microscopic analysis, and acomprehensive study special features of the Baiyinhuahanggai iron deposit inBainaimiao, Hanjiatun iron deposit inSuolun and Bayanhubeilehei basin in Xiwuqi.We get the age of sedimentary volcanic iron which is90±1Ma, the age of basalticandesite volcanic events which is99±1Ma and the age of underlying strata whichis127±1Ma. Geochemical data measured: major elements A/CNK=0.74~0.96,weak aluminum rock, Rittman index (δ)=2.11~3.11, which demonstratescalc-alkaline rocks; LREE are Enriched and heavy rare earths element are relative loss.Ba, Rb, K and other large LILE, Nb, P, Th are enriched and high field strengthelements are relative loss; Geochemical discrimination diagrams shows that themeiletu group andesite formed in the plate tectonic extensional tectonic background.From the above study we get the following conclusions:(1) The study found that the presence of the volcanic iron deposits in the southernpart of Daxinganling was in late period of early Cretaceous, iron ore is sedimentaryore types, mainly formed in volcanic basins and rift basins.(2) Volcanic rocks and underlying iron containing strata are angular unconformityin the southern part of Daxinganling, indicating that period of time there was a strong tectonic movement, combined with geochemical analysis of volcanic event that theiron formation in continental rift environment.(3) volcano sedimentary iron has the advantages of shallow, continuous distribution, and low grade.Although they rarely form large deposits, often has some economicsignificance. By analyzing the basin geological characteristics, era characteristics,mineral (phase) characteristics, and forming environment of the two iron deposits, we filled the research gaps of this type of iron deposts in the area,provides an indication for ore exploration of similar type of iron deposits in the area.