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| 河北承德盆地114 Ma大北沟组玄武岩地球化学及其对华北克拉通岩石圈地幔减薄作用的制约 | |
| 引用本文： | 汪方跃,高山,牛宝贵,张宏.河北承德盆地114 Ma大北沟组玄武岩地球化学及其对华北克拉通岩石圈地幔减薄作用的制约[J].地学前缘,2007,14(2):98-108. |
| 作者姓名： | 汪方跃 高山 牛宝贵 张宏 |
| 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. 西北大学,地质系,大陆动力学国家重点实验室,陕西,西安,710069;中国地质大学(武汉)地球科学学院,湖北,武汉,430074 3. 中国地质科学院,地质研究所,北京,100037 4. 沈阳地质矿产研究所,辽宁,沈阳,110032 |
| 基金项目： | 国家自然科学基金 , 教育部科学技术研究项目 |
| 摘 要： | 华北克拉通罕见年龄界于120～100Ma的火山岩。承德盆地大北沟组火山岩下部主要由柱状节理橄榄玄武岩组成,中上部主要由安山岩组成。对紧邻玄武岩的上覆安山岩的火山锆石U-PbLA-ICPMS定年结果表明,形成年龄为(113.6±0.87)Ma,代表了该套火山岩的喷发年龄,表明它们形成于早白垩世晚期。对3件玄武岩样品的分析结果表明,它们亏损高场强元素(Nb、Ta、Zr、Hf),初始87Sr/86Sr同位素比值为0.7059,εNd(114Ma)为-11.04,具有富集型岩石圈地幔的特征。但该套玄武岩的主量和微量元素特征则介于华北克拉通中生代年龄>120Ma具古老富集型地幔特征的玄武岩和年龄<100Ma具亏损软流圈性质的玄武岩之间,表明113.6Ma时华北克拉通岩石圈地幔在元素组成方面已具有由富集地幔向亏损型软流圈地幔转变的特征。大北沟组玄武岩的地球化学特征表明,114Ma时华北克拉通岩石圈地幔已减薄。 |
| 关 键 词： | 承德盆地 早白垩世 LA-ICPMS定年 富集地幔 亏损地幔 |
| 文章编号： | 1005-2321(2007)02-0098-11 |
| 修稿时间： | 2006年11月10 |
Geochemistry of Dabeigou basalt in Chengde Basin, Hebei Province and constrains on lithospheric mantle thinning of North China Craton |
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| Wang Fangyue,Gao Shan,Niu Baogui,Zhang Hong.Geochemistry of Dabeigou basalt in Chengde Basin, Hebei Province and constrains on lithospheric mantle thinning of North China Craton[J].Earth Science Frontiers,2007,14(2):98-108. | |
| Authors: | Wang Fangyue Gao Shan Niu Baogui Zhang Hong |
| Abstract: | Basalts between 120-100 Ma are rare in the North China craton. The Dabeigou Group consists of olivine basalt in the lower part and andesite in the middle and upper parts. Zircons from the andesite were dated by LA-ICPMS yielding a late Early Cretaceous age of (113.6±0.87) Ma. Geochemical analyses of 3 basalt samples show depletion in high field-strength elements (Nb, Ta, Zr, Hf). Their 87Sr/86Sr ratio and εNd value at 114 Ma are 0.705 9 and -11.04. These values are consistent with a source from enriched lithospheric mantle. The source of the Dabeigou basalts is intermediate between those of >120 Ma basalts with ancient enriched lithospheric mantle character and <100 Ma basalts with depleted asthenospheric mantle character. Our data suggest that the ancient enriched lithospheric mantle might have been thinned and converted to depleted asthenospheric mantle under the North China Craton at 114 Ma. |
| Keywords: | Chengde Basin early Cretaceous LA-ICPMS dating enriched mantle depleted mantle |
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