中文摘要：

锆石U-Pb定年及Hf同位素测定结果表明,鄂尔多斯盆地周缘的华北板块北缘、兴蒙造山系及扬子板块—秦岭—大别—苏鲁造山带等构造单元系统具有明显不同的形成与演化历史。华北板块北缘锆石年龄平均值为1 837Ma,最强烈的岩浆活动出现于2 200～1 800Ma,该期锆石约占全部的40%;次为强烈的岩浆活动在2 800～2 200Ma,其众数在全部锆石中约占30%;1 500～1 200Ma、500～100Ma这两个阶段形成的锆石在全区所占比例各约为15%。华北板块北缘最突出的特征是基本不含1000～700 Ma期间形成的锆石,〉3 000Ma的锆石在全区分布极为有限。锆石Hf同位素亏损地幔模式年龄表明华北板块北缘平均值为2.55Ga,较U-Pb平均年龄老,说明2 200～1 800Ma期间形成的锆石含有较多的古老地壳再循环组分。Hf亏损地幔模式年龄最强峰值约为2.8Ga,与全岩Nd亏损地幔模式年龄的峰值相一致,Hf模式年龄为3.0～2.25Ga的颗粒占全部的近95%,证明华北板块北缘的地壳增生主要在太古宙至古元古代期间。Hf同位素亏损地幔模式年龄〉3.0Ga的锆石颗粒所占比例不到0.1%,另外近5%锆石的模式年龄分布于中元古代。晚古生代—中生代所形成的锆石均是先存地壳组分,尤其是中元古代增生地壳的熔融作用形成。兴蒙造山系中锆石U-Pb年龄平均值为497Ma,最强峰分布于石炭纪（约320Ma）,石炭纪—二叠纪末（350～250Ma）形成的锆石所占比例达30%以上。新元古代至早古生代（600～440Ma）形成的锆石占全部锆石的55%以上,而中元古代末—新元古代期间（1 200～600Ma）形成的锆石在全区仅占4%。中元古代以前形成的锆石非常有限,说明该区最早形成的地壳组分在兴蒙造山系的形成过程中较充分地参与到后期的岩浆作用过程中。兴蒙造山系中锆石相应的Hf同位素亏损地幔模式年龄平均为1.13Ga,明显较相应的U-Pb年龄老,最强峰值出现于约0.6Ga?

英文摘要：

U-Pb dating and Hf isotopic composition of zircons from the northern margin of North China Platform,the Great Hingan-Mongolian Orogen,and the Yangtze Platform-Qinling-Dabie-Sulu Orogen around the Ordos Basin show that its surrounding tectonic units have different histories of formation and evolution.Average age is 1837 Ma based on U-Pb dating of 885 zircon grains from the northern margin of North China Platform.The most intensive magmatism peak occurred between 2200 and 1800 Ma;the zircon grains within this range amount to 40% of the total.The secondary intensive period is between 2800 and 2200 Ma;percentage of zircon grains in this range is ~30%.The zircons crystallized in 1500-1200 Ma and 500-100 Ma occupy ~15% respectively.The northern margin of North China Platform is characterized by a lack of 1000-700 Ma zircons.The zircons older than 3000 Ma are very rare.The averaged Hf isotopic depletion mantle model age of zircons is 2.55 Ga,which is older than that of U-Pb ages,suggesting that zircons crystallized between 2200 and 1800 Ma contain older re-cycled precursor crustal components.The most intensive peak of Hf isotopic depletion model age is ~2.8 Ga,consistent with that of Nd isotopic depletion mantle model ages.The zircon grains with Hf model ages between 3.0 and 2.25 Ga account for ~95%,which implies that the crustal accretion from the depleted mantle took place between the Archean and the Paleoproterozoic.Other ~5% zircon grains were formed by Mesoproterozoic crustal accretion event.The Late Paleozoic-Mesozoic magmatism was predominately controlled by anatexis of precursor crustal components,especially the Mesoproterozoic juvenile crust.The percentage of zircon grains with the Hf model ages older than 3.0 Ga is less than 0.1%.The average U-Pb age of zircons in the Great Hingan-Mongolian Orogen is 497 Ma;the most intensive peak is around the Carboniferous,i.e.~320 Ma.Carboniferous-Permian zircons account for over 30% in the orogen.Another population of zircon U-Pb ages is around the Neoproteozoic-Early Pale