The Distributive Features And Occurrence State Of Cesium Of The Pegmatite Contact Metamorphic Zone In The Jiajika Rare Metal Field

The deposit in the rare metal ore field of the jiajika pegmatite type,with the characteristics of large scale,rich taste,multi-mineral,shallow burial,good processing performance and typical geological features,is the typical representative among the national rare metals.The rich rare metal contact metamorphic is formed during the period of emplacements and formations of rare metal giant crystal dyke.Consequently,this thesis selects the representative deposits X03(super large lithium deposits)and NO.528 pegmatite vein(typical Nb-Ta deposits)as the research subjects.It contributes to make a detailed analysis about the zonality of the contact metamorphic zone and petrological characteristics,what's more,the distribution features and occurrence states of the rare element,such as cesium will also be probed.All the above provide certain ore prospecting orientations for Jiajika rare metal ore field to look for Cs-deposits,which also offer theoretical foundations for extracting Cs in this area of Jiajika rare metal ore.Main achievements acquired in this thesis are as follows:(1)The surrounding rocks of the X03 and No.528 rare metal deposits both suffering from contact metamorphism of close pulse,form the tourmalinization and cordierite from inside out.And tourmaline crystalline schist forms in tourmalinization belt.Those tourmalines are mostly long black columnar and acicular idiomorphic crystals.The cordierite hornfels and cordierite grenatite andalusite two mica schist form in the cordierite belt,boundaries of which with tourmalinization belt is clear.And the metasomatisms mainly include cordierite,biotitization,muscovitization(sericitization)and so on.(2)The contact metamorphic rocks of X03 and No.528 rare metal deposits are enriched of rare elements,such as Cs,Li and Rb,and moreover,there is a significant positive correlation between the three rare elements.The average content of Cs in X03 is 486×10-6,Cs2 O is 0.008~0.212% and the average value reaches to 0.052%,which achieves the lowest industrial grade0.05%~0.06% of comprehensive utilization of Cs2 O.A small amount of Cs elements sample the bottom of NO.528 pegmatite vein,hit the target ofreference industrial index of comprehensive recovery of Rb and Cs,and what's more,the content of Cs is higher than that of the pegmatite on the whole.(3)In the contact metamorphic rocks of X03 and No.528 rare metal deposits,the new mica(phengite,lithium cesium rubidium iron mica,haughtonite)is rich in rare elements,such as Cs,Li and Rb.Especially,the average of Cs can reach the lowest production grade,which are 1970.5 ppm,4406 ppm,and 882.29 ppm respectively.Besides,cordierite,ilmenite and rutile are endowed with a small amount of Cs.The Muscovite of No.528 has bits of Li,Rb and Cs,which formed by retrogressive metamorphism from Andalusite.(4)In contact metamorphic belt,Rb and Cs elements displace K elements which is a relative weak junction point between two compound silica layers in mica;Li,Mn and Fe,etc.displace Al in alumina octahedral.And Li,Rb and Cs rare elements are mainly composed of those two above K,Al and the rest elements in displacements,which are reserved in new mica formed by contact alteration and stays in the form of isomorphism.