Zircon Dating And Hf Isotope Of Bainaimiao Area Inner Mongolia And Their Geological Implications

Bainaimiao and Baiyinduxi along the south of solonker suture zone, sited on the northern margin of the North China plate where are important region for important for the Xing-Meng Orogenic Belt research. Bainaimiao group is metamorphic arc magmatic.Baiyinduxi group is a set of medium metamorphic clasolite series develops on the north of Bainaimiao magmatic arc and on the south of Wenduermiao complex in the middle of Inner Mongolia.In order to determine the accurate age of Baiyingduxi group and Bainaimiao group, I collected two quartzose sandstone samples from Baiyinduxi Group, and a andesite sample from Bainaimiao Group, for LA-MCICPMS dating and Hf isotope test.100detrital zircons of the two metamorphosed quartz sandstone samples from Baiyinduxi Group have been analysed. The characteristics of these detrital zircons from the two samples are similar, which show that the protolith are submarginal sediment of weathered early or contemporauous magmatite. All the zircon apparent age are between518Ma to294Ma, which coincided well with the ages of paleozoic arc magmatite of northern margin of the North China plate, indicating that those paleozoic arc magmatite are main source of the sediment of Baiyingduxi group. The Baiyinduxi group of the original rock may be a fore-arc sedimentary formation, the formation time should be accompanied by the Paleo-Asian Ocean subduction and Paleozoic arc magmatism in the whole process, subsequent collision orogenic process of deformation and metamorphism.Bainaimiao group metamorphic andesite samples550Ma age, prove Bainaimiao group Paleozoic island arc.εHf(t) of the Baiyinduxi Group, two metamorphic quartz sandstone samples are mainly between7.9to15.5;176Hf/177Hf are mainly concentrated in0.282722-0.282983; model ages are mainly between481-786Ma. Metamorphic andesite samples, The Bainaimiao Group Hf isotope sHf (t) mainly between0.2to3.9;176Hf/177Hf ratio are mainly concentrated in0.282475-0.282739; model ages are concentrated between633-1119Ma. Both Hf isotopic characteristics significantly different from that understand the material source of the sediment are Baiyinduxi group is not from the south Bainaimiao group, but from the north of ondor temple group.Baiyinduxi group of Late Permian undeformed intrusion of granite (254Ma) indicate that the protolith of the final formation to occur should be between294Ma ～254Ma deformation and metamorphism. It is speculated that the along Soren suture with the collision suture effects may occur early in the Permian.