SHRIMP U-Pb zircon 207 Pb/206 Pb ages were obtained from two drill cores from the basement of the Ordos Basin.A garnet-sillimanite-biotite-plagioclase gneiss(QI1-1) from the western Ordos Basin basement yielded an average age of 2031 10 Ma.Based on the mineral assemblages,the source material of the gneiss is speculated to be pelitic-felsic system.A gneissic two-mica granite(Long1-1) from the eastern Ordos Basin basement yielded an average age of 2035 10 Ma.The zircons from both samples exhibit magmatic growth pattern.The shapes of the zircons suggest that the zircons should crystallize from a granitic of felsic volcanic terrain.The ages and the characters of zircons are consisitent with the other researches in the Ordos Basin and indicate that the basement of the Ordos Basin had experienced an intensive magmatic epsode during the late Paleoproterozoic period.The date from this study suggest the possible existences of a Paleoproterozoic mobile tectonic belt in the region.The reconstruction of such a belt is critical for understanding the tectonomagmatic evolution of the western block of the North China Craton.
HU JianMinLIU XinSheLI ZhenHongZHAO YueZHANG ShuanHongLIU XiaoChunQU HongJieCHEN Hong
<正>华北地台北缘西段广泛分布新太古界乌拉山群、中-新元古界渣尔泰山群(狼山群)和海西期以来中亚造山过程中形成的大量中-酸性侵入岩。在渣尔泰山群(狼山群)中产有东升庙、炭窑口、甲生盘、霍各乞等重要大型~超大型Zn-Pb-Cu-Fe多金属硫化物矿床和朱拉扎嘎金矿床(图1)。该区经历了~新太古代结晶基底形成、中元古代被动大陆边缘裂解(翟裕生等,2002;翟裕生等,2004;翟明国等,2000;赵国春等,2002;Zhai Mingguo et al.,2007)。
