| 蓟县剖面杨庄组和雾迷山组形成年龄的研究 |
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| 引用本文： | 王松山,桑海清.蓟县剖面杨庄组和雾迷山组形成年龄的研究[J].地质科学,1995,30(2):166-173. |
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| 作者姓名： | 王松山 桑海清 |
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| 作者单位： | 中国科学院地质研究所, 北京100029 |
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| 摘 要： | 对蓟县剖面杨庄组和雾迷山组白云岩中条带状燧石采用40Ar/39Ar阶段加热技术和Cl-Ar相关性,消除了样品中次生流体包体及过剩Ar的干扰,从而获得燧石40Ar/39Ar等时年龄。结果表明高于庄组-杨庄组、杨庄组-雾迷组和雾迷山-洪水庄组的界限年龄分别是1380、1310和1207Ma.
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| 关 键 词： | 杨庄组 雾迷山组 形成年龄 |
| 收稿时间： | 1994-01-18 |
| 修稿时间： | 1994-01-18; |
THE FORMING AGES OF YANGZHUANG AND WUMISHAN FORMATIONS IN JIXIAN SECTION,NORTHERN CHINA |
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| Wang Songshan, Sang Haiqing, Qiu Ji, Chen Meng''''e, Li Mingrung.THE FORMING AGES OF YANGZHUANG AND WUMISHAN FORMATIONS IN JIXIAN SECTION,NORTHERN CHINA[J].Chinese Journal of Geology,1995,30(2):166-173. |
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| Authors: | Wang Songshan Sang Haiqing Qiu Ji Chen Meng'e Li Mingrung |
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| Institution: | Institute of Geology, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | The Middle-Upper Proterozoic section of Jixian, Northern China well known in the world owing to excellent outcrop, slight or unmetamorphism, simple deformation and aboundant fossils. The section is composed the Changcheng, Jixian and Qingbakou Systems from bottom to top, the total thickness is about 9200m. The uppper part of Changcheng System is Gaoyuzhuang Formation. And the Jixian System contains, in ascending order, the Yangzhuang, Wumishan, Hongshuizhuang and Tieling Formations. JX12 bedded chert in dolomite was collected from the top of the Gaoyuzhuang Formation i. e. the boundary between Gaoyuzhuang and Yangzhuang Formations. JX16 bedded chert in dolomite was collected from the upper part of Yangzhuang Formation, the distance between the sample locality and the top of this formation is 20m. JX26 bedded chert in dolomite was collected from the top of Wumishan Formitaon, i. e. the boundary between Wumishan and Hongshuizhuang Formations.For the 40Ar/39Ar measurements, irradiations were performed in 49-2 reactor in Beijing. Samples were shieled with 0.5mm of Cd during the irradiation, which had a duration of about 65 h. Ar isotopes derived from K, Ca and Cl has been corrected. BSP-1 hornblende, with a K-Ar age of(2060±8)Ma, was used as the flux monitor.All chens analysed contain excess(40Ar)e, although in variable amounts. And the(40Ar)e showed a strong correlation with the(38Ar)Cl relesed, and hence with chlorine. Based on the plot of(40Ar/39Ar)VS.(38Ar)Cl/39Ar, the intercept was obtained, and then the isochron age was calculated. The thin sections and electron microscope showed that all samples contain second fluid inclusions, hence the data from low temperature steps(≤800℃)were deleted when calculating isochron ages.The isochron ages of samples JX12 and JX16 are(1380 ±24)Ma and(1317±22)Ma respectively. The isochron ages of sample JX26 and its duplication determination result(JX26-1)are(1206±27)Ma and(1208±21)Ma respectively.Based on the four ages above, we assign(1380±24)Ma,(1310 ± 20)Ma and(1207 ± 10)Ma as the boundary ages between Gaoyuzhuang and Yangzhuang Forma tions, Yangzhuang and Wumishan Formations, as well as Wumishan and Hongshui.zhuang Formations, respectively. |
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| Keywords: | Yangzhuang Formation Wumishan Formation Forming ages |
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