Sm-Nd Ages Determination by Mass Spectrometry on Eclogite from Xin Yi

Sm-Nd dating on three eclogite bodies from Tiqiushan, Xinyi in the northern Jiansu yield the following new age results: 212, 217and 222Ma, respectively. The isochron age of three eclogites and six minerals is 217(5Ma，MSWD=0.56, (Nd(T)=-2.9. The Sm-Nd age of 217 Ma is adopted as the formation of Tiqiushan eclogite body during ultrahigh pressure metamorphism. The petrogenesis of the eclogites shows a mantle origin with a small amount of lower crustal comtaimination. The evidences show that Su ad Lu blocks used to be a part of Qinling-Dabie fold zone. The collision period between the Sino-Korean and Yangtze blocks occurred in late Triassic.