Geological And Geochemical Characteristics And Genesis Of Jiaotongshe Niobium And Tantalum Deposits In Qinghai Province

Aljin metallogenic belt is the concentration area of mineral resources in qinghai province.Jiaotongshe niobium and tantalum deposit is the first niobium and tantalum deposit related to alkali feldspar discovered by aljin.The discovery of jiaotong she niobium and tantalum deposit and its mineral significance have opened up a new idea of searching for niobium and tantalum deposit in aljin and even the whole qinghai province.The jiaotongshe niobium and tantalum deposit is located in the aljin orogenic belt,which is a newly discovered niobium and tantalum deposit in recent years.This paper takes this deposit as the research object,conducts a survey on the geological characteristics of the deposit,and USES zircon u-pb chronology and petrogeochemical characteristics to explore the genetic types of alkalifeldspathic rocks closely related to mineralization and the diagenetic and ore-forming tectonic background,so as to explore the genesis of the deposit.The achievements and understanding are as follows:Jiaotongshe niobium and tantalum ore deposit is located in the northwest margin of qaidam basin,belonging to the proterozoic Paleozoic land block of oboliang,and the aljin fault in the north.The outcrop layer of the mining area is ancient and far ancient darken daban rock group.The structural framework is divided into 5 phases.The intrusive rocks are mainly granitic diorite,English cloud diorite,alkali feldspar and monzonite veins.The niobium-tantalum ore body is controlled by alkali feldspar and F9 fault.The ore bearing lithology is dimica schist and silicified marble.Zircon LA-ICP-MS U-Pb isotope dating results show that the alkali feldspar is 453±4 Ma Ma,and the alkali feldspar belongs to the high kali-calc-alkali series with a high degree of magma evolution.The alkali feldspar tectonic background is the post-collision tectonic environment.The trace elements showed that the light and light rare earth fractionation was not obvious,and the rare earth elements partition diagram showed that the light and light rare earth elements were relatively flat with obvious Eu/Eu* negative anomaly.Combined with the identification of the main elements,isotopic analysis shows that the diagenesis and mineralization materials are mixed sources of crust and mantle.Through comparative study,combined with the geotectonic environment and metallogenic conditions of the deposit,it is concluded that the jiaotong she niobium tantalum deposit was formed in the late ordovician,and the intrusion of alkali feldspar resulted in the formation of the deposit.The deposit type is preliminarily defined as alkali granite-type niobium tantalum deposit.