| 辽西凌源地区义县组火山岩锆石U—Pb年代学和地球化学特征 |
| |
| 引用本文： | 孟凡雪,;高山,;柳小明.辽西凌源地区义县组火山岩锆石U—Pb年代学和地球化学特征[J].中国区域地质,2008(3):364-373. |
| |
| 作者姓名： | 孟凡雪 ;高山 ;柳小明 |
| |
| 作者单位： | [1]西北大学地质系大陆动力学国家重点实验室,陕西西安710069; [2]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074 |
| |
| 基金项目： | 国家自然科学基金项目（编号：40521001）和教育部项目（编号：B07039）联合资助. 致谢：感谢西北大学大陆动力学实验室的全体人员在实验过程中给予的帮助. |
| |
| 摘 要： | 对辽西凌源地区义县组的1件流纹岩样品进行锆石U—Pb年代学研究，获得的年龄为（124．4±1．4）Ma，与前人对辽西北票、义县、凌源等地区通过K—Ar、Ar—Ar、U—Pb等定年方法获得的义县组年龄基本一致，时代为早白垩世。7件典型火山岩样品的地球化学研究结果表明，该火山岩的SiO2=65．6％-73．4％，MgO=0．35％～1．23％，Mg^#=16～41，Al2O3=13．40％～16．79％，Na2O=3．54％-4．26％。Sr=（445～774）×10^-6，Yb=（0．51-0．97）×10^-6,V=（7～14）×10^-6,Sr／Y=49-66，LaN／YbN=33-48，高Sr和Sr／Y比值，低Y和Yb，轻重稀土元素分异明显，显示出埃达克岩的地球化学特征，但其Mg^#较低。它们可能是加厚的基性下地壳部分熔融的产物。
|
| 关 键 词： | 辽西凌源地区 义县组火山岩 埃达克岩 |
U-Pb zircon geochronology and geochemistry of volcanic rocks of the Yixian Formation in the Lingyuan area,western Liaoning,China |
| |
| Institution: | MENG Fan-xue , GAO Shan , LIU Xiao-ming(1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi＇an 710069, Shaanxi, China; 2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, Hubei, China) |
| |
| Abstract: | Zircon U-Pb dating of a rhyolite sample from the Yixian Formation in the Lingyuan area, western Liaoning, yields an age of 124.4±1.4 Ma, indicating an Early Cretaceous age. The age agrees with the previous results obtained using K-Ar, Ar-Ar and U- Pb methods for the Yixian volcanic rocks in the Beipiao and Lingyuan areas. Geochemical compositions of 7 samples of typical Yixian volcanic rocks from the Lingyuan area show that they consist of trachyte and rhyolite, with SIO2=65.6-73.4%, MGO=0.35-1.23%, Mg#=16-41, Al2O3=13.40-16.79% and Na20=3.54-4.26%. In addition, the volcanic rocks are characterized by enrichment in LREE and depletion in HREE, with high Sr （445-774）×10^-6 and Sr/Y （49-66） and low Y （7-14）×10^-6 and Yb （0.51-0.97）×10^-6 and LaN/ YbN=33-48, showing the geochemical characteristics of adakite. However, they are low in Mg#. The authors suggest that they may have originated by partial melting of the thickened mafic lower crust. |
| |
| Keywords: | Lingyuan area western Liaoning volcanic rocks of the Yixian Formation adakite |
| 本文献已被 维普 等数据库收录！ |
|
