Volcanic Rock Geochemistry of Neogene Check Baoma Formation in Nariniya Area, Qinghai-Tibetan Plateau

Nariniya Pb-Zn deposits is located mainly in the Neogene volcanic rock,with obviousmetallogenic layer controltype. Zhabaoma group volcanic rock is one of the main ore-bearing horizons.The geochemical characteristics of the Nariniya group volcanic rocks were researched in this work.The result shows that the volcanic rock is a set of calcium alkaline-alkaline series of acidic rock assemblages with a rich alkali high potassium content. Rare earth distribution pattern is different, the light and heavy rare earth element distilled obviously. δEu is between 0.73 and 0.97,and there is no obvious negative europium anomaly. Trace element distribution mode is approximately consistent,for the original mantle,big ion lithophile elements (K,Ba,Rb,Sr) and Th,U etc lively incompatible elements are enriched and Zr,Ti,Ta,P high field strength elements are relatively less. Rb/Sr is 0.07-0.27,Rb/Sr ratio is 0.07-0.27, which shows the crust-mantle mixing characteristics. The rock may be from EM Ⅱ type enrichment mantlegold bearing mica mantle peridotite of partial melting, crystallization after the separation of the magma chamber rich potassium magma along the tectonic weak part in invasion,and crustal material produce mixed form mixed magma in the earth′s crust shallow in place. Trace elements have high lead and zinc background value,for providing main ore-forming material sources. In the R1,R2 structure discrimination diagrams,sample mainly fall into the impact after the stretchand after collision environment. In the R1,R2 structure discrimination diagrams,sample mainly fall into the impact after the stretch and after collision environment grams,sample mainly fall into the impact after the stretch and after collision environment.