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| 江西吉泰盆地碱性玄武岩的地球化学特征及其构造意义 | |
| 引用本文： | 余心起,舒良树,邓国辉,王彬,祖辅平.江西吉泰盆地碱性玄武岩的地球化学特征及其构造意义[J].现代地质,2005,19(1):133-140. |
| 作者姓名： | 余心起 舒良树 邓国辉 王彬 祖辅平 |
| 作者单位： | 1. 中国地质大学,地球科学与资源学院,北京,100083 2. 南京大学,地球科学系,江苏,南京,210093 3. 江西地质调查院,江西,南昌,330201 |
| 基金项目： | 国家自然科学基金项目(40172067)，国家自然科学重点基金项目(40132010)。 |
| 摘 要： | 吉泰盆地位于赣中地区, 目前尚无在该盆地中发现玄武岩的报道。新发现的玄武岩产于吉泰盆地南部泰和附近的南溪镇。玄武岩露头新鲜, 蚀变微弱, 属碱性玄武岩, 形成于板内快速拉张环境; 锆石U Pb年龄为 ( 139±0 7 ) ~(143±1 1)Ma, 表明岩石形成于早白垩世早期。玄武岩无明显的Nb、Ta负异常, Rb Sr、Sm Nd同位素组成分析结果显示N(87Sr) /N(86Sr) ]i=0 704 1~0 704 8, εNd(t) = +3 78~+4 38, 反映玄武岩浆起源于亏损地幔, 未经地壳物质混染。结合吉泰盆地边部存在中侏罗世 (168Ma) 玄武岩的事实, 表明赣中地区在早白垩世已经处于拉张背景, 吉泰盆地的碱性玄武岩可能是在板内岩石圈伸展减薄作用下, 由北东向的赣江断裂带拉张形成的。 |
| 关 键 词： | 碱性玄武岩 亏损地幔 板内拉张环境 早白垩世早期 赣江断裂 吴川—四会断裂 吉泰盆地 |
| 文章编号： | 1000-8527(2005)01-0133-08 |
| 修稿时间： | 2004年10月25 |
Geochemical Features and Tectonic Significance of the Alkali-Basalts from Ji' an-Taihe Basin, Jiangxi Province |
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| YU Xin-qi,SHU Liang-shu,DENG Guo-hui,WANG Bin,ZU Fu-ping.Geochemical Features and Tectonic Significance of the Alkali-Basalts from Ji'''' an-Taihe Basin, Jiangxi Province[J].Geoscience——Journal of Graduate School,China University of Geosciences,2005,19(1):133-140. | |
| Authors: | YU Xin-qi SHU Liang-shu DENG Guo-hui WANG Bin ZU Fu-ping |
| Institution: | YU Xin-qi~1,SHU Liang-shu~2,DENG Guo-hui~3,WANG Bin~2,ZU Fu-ping~2 |
| Abstract: | New found basalt crop is located near the Nanxi Town, Taihe County, south of Ji'an-Taihe Basin, middle Jiangxi Province. With brown-grey and dark green color, the fresh basalt has compacted texture and some blisters and amygdules. Microscope observation reveals that the rocks have intergranular textures,more than 60% basic plagioclases, filling with olivines and augites, less than 5% almond-shaped calcites, and weak corrosion. According to its geochemical features, the basalt belongs to alkali-basalt, produced by quick regional extension within a plate. Rb-Sr and Sm-Nd isotopic composition of the basalt are as follow:(~(87)Sr/~(86)Sr)_i =(0.704 1-0.704 8) and ε_(Nd)(t)=+3.78-+4.38, indicating that the magma came from the deficit mantle and had not mixed with crust material. The zircon solution U-Pb geochronological data of(139±0.7)to(143±1.1)Ma for the alkali-basalt indicates that mantle-reached strike-slip faulting along northeast-striking Ganjiang Fault and Wuchuan-Sihui Fault was active from early period of Early Cretaceous under the extensional background of the area. |
| Keywords: | alkali-basalt deficit mantle extension environment within a plate early period of Early Cretaceous Ganjiang Fault Wuchuan-Sihui Fault Ji'an-Taihe Basin |
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