Genesis and prospecting significance of Caledonian peraluminous granite in Kunlunhe area,East Kunlun
The Early Paleozoic peraluminous granites in the Kunlunhe area can provide important constraints on the Paleozoic collisional process and rare metal metallogenic genesis of the East Kunlun Orogenic Belt.This paper introduces the newly discovered Early Devonian(418～416Ma)peraluminous granite in the Kunlunhe area,whose lithology is biotite granodiorite,two-mica granodiorite and two-mica granite with its dark minerals all composed of biotite(≤5vol％).The peraluminous granites belong to a sodium-rich,weak peraluminous,high potassium and calc-alkaline series.These granite samples have averaged Na2O/K2O=1.13,and varied values of A/CNK=1.03～1.10,(La/Yb)N=9.7～28,Y=8.69 ×10-6～23.4 ×10-6 and Yb=0.67 ×10-6～2.43 × 10-6 with enrichment of LREE and weak depletion of HREE.They also have obvious Eu negative anomaly(Eu/Eu*=0.48～0.86),with relatively lower Rb/Sr(0.34～1.12)and Rb/Ba(0.18～0.32)ratios.Their(87Sr/86Sr)i,εNd(t)and tDM2 values are 0.7045～0.7083,-4.94～-1.64 and 1.56～1.29Ga,respectively.Their measured zirconεHf(t)and tDM2 are-3.3～2.7and 1.61～1.28 Ga,respectively.Its magma is originated from the partial melting of the ancient Proterozoic crust with the participation of mantle material or new crustal material from mantle.Combined with previous researches,there are two peraluminous granites series in the Kunlunhe area:the Late Silurian(425～422Ma)series and the Early Devonian(418～416Ma)series.Both of them are related to the melting of crust caused by subduction lithospheric slab break-off and mantle magma penetration in the Caledonian collision orogenic belt of East Kunlun.There is high Li,Be and Sn backgrounds with some obvious anomalies in the peraluminous granites distributed area,showing a good prospecting potential in the Kunlunhe area.
万方数据
维普
