内蒙古西拉木伦河河漫滩沉积物碎屑_省略_年龄_Hf同位素组成及其地质意义_包创.pdf

1000-0569 / 2013 /029 ( 09) -3159-72 Acta Petrologica Sinica 岩石 学报 内蒙古西拉木伦河河漫滩沉积物碎屑锆石 * U-Pb 年龄、Hf 同位素组成及其地质意义 ＊＊ 包创 陈岳龙 李大鹏 BAO Chuang ，CHEN YueLong ＊＊ and LI DaPeng ， 100083 中国地质大学地球科学与资源学院 北京 School of Earth Sciences and Ｒesources ，China University of Geosciences ，Beij ing 100083 ，China 20 12-05-14 收稿 ，20 12-12-15 改回 . Bao C ，Chen YL and Li DP. 2013. U-Pb ages ，Hf isotopic composition and its geological significance of detrital zircons in the floodplain sediments from the Xar Moron Ｒiver ，Inner Mongolia. Acta Petrologica Sinica ，29 (9):3159 － 3172 Abstract The Xar Moron Ｒiver ，which is the boundary between the North China plate and Xing-Meng Orogenic Belt ，flows above the fault of the Xar Moron. In this paper ，we applied the ICP-MS analytical techniques to date U-Pb ages and determine Hf isotopic composition of detrital zircons in the floodplain sediments from the Xar Moron Ｒiver. The detrital zircons U-Pb ages of sample XL show 4 populations :108 ～ 550Ma ，699 ～ 918Ma ，1789 ～ 2109Ma ，2347 ～ 2633Ma ，and the detrital zircons U-Pb ages of sample XL2 show 3 populations :122 ～ 526Ma ，1791 ～ 1969Ma ，2176 ～ 2692Ma ，respectively. There does not exist zircons with 700 ～ 900Ma age in the sample XL2 ，and the detrital zircons with ages of 1791 ～ 1969Ma and 2176 ～ 2692Ma also belong to the North China plate. Therefore ， the sample XL2 should have detrital zircons which originated from the North China plate. According to Lu-Hf isotopic composition ，a large proportion of detrital zircons show the characteristic of Xing-Meng Orogenic Belt ，whose Hf model ages (tDM2 )are less than 1000Ma and εHf (t)are greater than 0. tDM2 of some detrital zircons are close to 2. 7Ga ，which is the fastest growth period of the North China plate. From the above ，floo