Study On The Geological Characteristics And Genesis Of Dabai-Shitougou Titanium Magnetite Deposit In The Middle Qilian Moutain

The Dabai-Shitougou titanomagnetite deposit is located in the northern margin of the South Tolai mountain in the middle Qilian,and the geotectonic position is in the magmatic arc zone of the middle Qilian.The metallogenic belt belongs to the Caledonian tungsten,rare and copper(titanium,antimony and gold)metallogenic belt.In 2012,three aeromagnetic anomalies were found in the da Dabai-Shitougou area in the northern margin of the Tolai mountains in the Central Qilian.It was found that the aeromagnetic anomaly is caused by magnetization and accompanied by titanium mineralization.However,there are still some problems in the area,such as the composition,existing state,whether it is a Panzhihua type vanadium-titanium magnetite deposit and the source of titanium magnetite,which restrict the progress of geological and mineral exploration and related research work.In the light of the project of"Preliminary Investigation of Titanium Iron Polymetallic Ore in Dabai-Shitougou Area,Tianjun County,Qinghai Province",with depth analysis of regional geological,geophysical,geochemical background and regional mineral characteristics,as well as detailed field geological survey,the author discusses the geological characteristics of strata,intrusive rock,metamorphic rock,structure and wall rock alteration in Dabai-Shitougou area,and also found that its metamorphic facies is high greenschist facies,intrusive rock is mainly granite pegmatite vein,and structure is mainly NW trending ductile brittle fracture.Then the author focuses on the study of the characteristics of the titanium magnetite mineralized body,which is mainly produced in the gneiss section of the Paleoproterozoic trust rock group,the schist section and quartzite section of the Middle Proterozoic Huangshigou group.The mineralized body is obviously controlled by lithology,consistent with the occurrence of the surrounding rock,and has the characteristics of multi-stage mineralization.There are three mineralized bodies with a thickness of 2-10 m and an extension of 100-600 m.The content of TiO₂ is generally between 2.5%and 4.5%,and the content of TFE is generally between 10%and 15%.The research results are as follows:(1)Based on the petrographic observation,electron probe microanalysis and artificial heavy sand analysis of titanium minerals,it is determined that titanium minerals are mainly titanomagnetite((Fe,Ti)₃O₄),containing a small amount of titanomagnetite(FeTiO₃)and trace rutile(TiO₂),etc.(2)The enrichment and mineralization of Ti elements are mainly influenced by strata,structure,metamorphism and other factors.The metallogenic type belongs to volcanic exhalation sedimentary type.(3)On the basis of depth study of metallogenic characteristics and occurrence state of titanomagnetite,the source of titanium minerals is discussed,which proves that pegmatite is not the source of metallogenic materials,and the most likely source of metallogenic materials is the titanium rich ultrabasic basic basic volcanic rocks brought by volcanic eruption,and points out that the metallogenic materials are formed by stacking crystals after early separation and crystallization.(4)It is the first time to find titanium magnetite in Dabai-Shitougou and its surrounding areas in the Central Qilian Mountains,which provides a theoretical basis for further exploration and related work.