Chronology And Significance Of Detrital Zircon From Matrix Of The Melange,and Its Tectonic In Central Inner Mongolia

Debate over the position of the final suture zone between North China Craton and Siberia Craton has long been existed among researchers all over the world.There are two representative views : one is that the final suture zone lies from Erenhot to Xilinhot or the Hegenshan ophiolitic mélange;the other one is that the Xar Moron suture zone is the final suture zone.This study collected samples from Tulinkai and Erdaojing district in the Xar Moron suture zone and Solonker suture zone for detrital zircon LA-MC-ICP MS dating. Ages of chlorite albite schist from Tulinkai district ranges from 239 to 2588 Ma, which is consistent with the age distribution of the north China Craton and the Bainaimiao Arc;and the ages of quartz chlorite sericite schist and sericite chlorite schist containing calcite from Erdaojing district ranges from 420 to 539 Ma, which is consistent with the age distribution of the Baolidao Arc.Further correlation between clastic rocks from Tulinkai and Erdaojing district reveals no source exchange,and the ocean basin represented by Erdaojing district had been closed before the Devonian,while the evolution of the ocean basin in Tulinkai district continued until Mid-Triassic.The conclusion is that the Xar Moron suture zone was the position where North China Craton and Siberia Craton finally got collided,and the time is later than the early Triassic.