| 华北克拉通南缘太古宙地壳生长和再造:登封地区五指岭组碎屑锆石U-Pb-Hf同位素制约 |
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| 引用本文： | 师江朋,杨浩田,杨德彬,王枫,霍腾飞.华北克拉通南缘太古宙地壳生长和再造:登封地区五指岭组碎屑锆石U-Pb-Hf同位素制约[J].大地构造与成矿学,2018(2):379-391. |
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| 作者姓名： | 师江朋 杨浩田 杨德彬 王枫 霍腾飞 |
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| 作者单位： | 吉林大学 地球科学学院,吉林 长春,130061 |
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| 基金项目： | 国家自然科学基金(41472052)，中央高校基本科研业务费和吉林大学研究生创新基金项目(2016195) |
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| 摘 要： | 对登封地区嵩山群五指岭组二云石英片岩和石英岩中碎屑锆石进行了LA-ICP-MS U-Pb年代学和原位Hf同位素分析,为探讨华北克拉通南缘太古宙地壳生长和再造提供了制约。结果显示,碎屑锆石多数呈自形–半自形,发育振荡生长环带,结合相对高的Th/U比值(0.07~1.87),暗示它们多数为岩浆成因。二云石英片岩和石英岩中碎屑锆石具有类似的年龄和Hf同位素组成,它们的207Pb/206Pb谐和年龄分别介于2879~2027 Ma和3346~1903 Ma之间,峰期年龄分别为2524 Ma和2528 Ma。~2.5 Ga锆石的εHf(t)值多数为正值,介于+0.10~+9.22之间,tDM2C变化于3028~2453 Ma之间,4颗碎屑锆石的εHf(t)值为负值,变化于-1.68~-0.03之间,tDM2C介于3132~3032 Ma之间。根据上述结果并结合相邻地区的相关研究资料,表明嵩山群沉积于古元古代晚期,五指岭组中碎屑锆石的物源主要为华北克拉通南缘~2.5 Ga具有新生地壳属性的结晶基底物质。华北克拉通南缘存在中–新太古代时期的地壳生长,同时发育中太古代古老地壳物质的再造。
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| 关 键 词： | 华北克拉通南缘 地壳生长 新太古代 五指岭组 碎屑锆石 southern margin of NCC crustal growth Neoarchean Wuzhiling Formation detrital zircons |
Archean Crustal Growth and Reconstruction of the Southern Margin of North China Craton: Constraints from the U-Pb-Hf Isotopic Compositions of Detrital Zircon from the Wuzhiling Formation at the Dengfeng Area |
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| SHI Jiangpeng,YANG Haotian,YANG Debin,WANG Feng,HUO Tengfei.Archean Crustal Growth and Reconstruction of the Southern Margin of North China Craton: Constraints from the U-Pb-Hf Isotopic Compositions of Detrital Zircon from the Wuzhiling Formation at the Dengfeng Area[J].Geotectonica et Metallogenia,2018(2):379-391. |
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| Authors: | SHI Jiangpeng YANG Haotian YANG Debin WANG Feng HUO Tengfei |
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| Abstract: | The systematic LA-ICP-MS U-Pb dating and in-situ Lu-Hf isotope analyses of the detrital zircons from both two mica quartz schist and quartzite in the Wuzhiling Formation of Songshan Group in the Dengfeng area provide new constraints on the Archean crustal growth and reconstruction of the southern margin of the North China Craton (NCC). The study shows that most detrital zircons from the Wuzhiling Formation are euhedral-subhedral, and the oscillatory zoning in CL images and high ratios of Th/U (0.07?1.87) indicate that they are of magmatic origin. The two mica quartz schist and quartzite of Wuzhiling Formation have similar U-Pb ages and in-situ Hf isotopic compositions. Specifically, their 207Pb/206Pb ages are varying from 2879 to 2027 Ma and from 3346 to 1903 Ma, with peak ages at 2524 Ma and 2528 Ma, respectively. Additionally, the detrital zircons with age of ca. 2.5 Ga from the Wuzhiling Formation mostly have positive εHf(t) values (+0.10 to +9.22) with correspondingtDM2C ages of 3028?2453 Ma except four zircon grains with negative values (-1.68 to -0.03) and tDM2C ages of 3132?3032 Ma. Combining with the previous results in the adjacent areas, it can be inferred that the Songshan Group was deposited in the Late Paleoproterozoic while the provenance of the Wuzhiling Formation are mainly the ca. 2.5 Ga crystalline basement material with juvenile crustal properties in the southern NCC. In conclusion, the Archean crustal growth at the southern margin of NCC constitutes both of juvenile crustal increment and reworking of the ancient crust. |
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