Chronology, Geochemistry Research Of Permian Granite In Shang Du Dananfangzi And Erdaowa

Dananfangzi Pluton and Erdaowa Pluton from Shang Du，Inner Mongolia，islocated on the middle of the northern margin of the North China Plate. The Plutonmainly consists of granites. SHRIMP U-Pb zircon age of276.8±6.2Ma (MSWD=1.1)and279.8±5.1Ma (MSWD=0.89) from Dananfangzi Pluton and Erdaowa Plutonrespectively，implies they were emplaced during the stage of Early Permian. Allsamples are characterized by high contents of SiO2(68.71%~78.26%)， Al2O3(11.95%~14.57%)，K2O (3.06%~5.93%)，Na2O+K2O (6.19%~9.44%)，hence can beclassified into high-K calc-alkaline to shonite series，slightly peraluminous rocks(A/CNK=0.99~1.27). They invariably exhibit light earth elements (LREE) enrichmentwith significant negative Eu anomalies patterns (La/Yb)N=1.10~20.44，depletion ofNb，Ta，Ti，Ba，Sr，P and enrichment of Rb，K，Pb in the primitive mantle normalizedspidergram. The granites have relatively low εNd(t) values of-12.62to-12.12and oldNd depleted mantle model ages of1747.66Ma to3391.75Ma. εHf(t) values and Hftwo-model ages range from-26.83to-0.05and1301Ma to2976Ma. A combinationof Zircon Hf and whole-rock Nd isotopic compositons indicates old crustal rocks ofthe North China block as major source material for the granitic magmas whereas theremaybe mantle material mixed into the source for the granites and they are likely toform in post-collisional extension environment.