Abstract:Objectives: In the Songpan orogenic belt, Indosinian granitoids are widespread. These granitoids provide significant insight into the regional tectono—magmatic events, basement nature and tectonic evolution. Methods: In this paper, we present wholerock major and trace elements, Sr—Nd isotopic compositions of the Guanyinqiao twomica granites in Jinchuan area from the eastern part of the Songpan orogenic belt Results:The granites are peraluminous highK calcalkaline Stype granites, with high SiO2(72.08%~73.95%)、K2O(4.44%~5.84%)and Na2O (3.29%~3.93%)contents, A/CNK=1.08 ~1.22。The granites exhibit an enrichment in large ion lithophile elements and a depletion in part of high field strength elements as well as a prominent negative Eu anomalies(δEu=0.26~0.38).Their εNd(t) is -7.9 to -10.1(average value is -8.9), and T2DM(Ga) varying from 1.45 to 1.57Ga, suggesting a Mesoproterozoic crustal origin. Conclusion: In combination with the geochemical characteristics, isotopic analysis results and regional geological data, we propose that the Guanyinqiao twomica granites were derived from the argillaceous source region. The granites were formed in the compressive tectonic setting during the postcollision of fold orogenic in Songpan orogenic belt.