Geochemical characteristics of Cenozoic high-K igneous rocks from Liuhe-Xiangduo area, eastern Tibet

来源 :中国地球化学学报(英文版) | 被引量 : 0次 | 上传用户:liongliong546
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The major elements, trace elements and Nd-Sr isotopic composition of Cenozoic high-K igneous rocks and mafic deep-derived enclaves from the Liuhe-Xiangduo area, eastern Tibet, indicate the high-K igneous rocks are characterized as being enriched in Ca (CaO= 1.20% - 8.80% ), alkali (Na2O+K2O= 3.47% - 10.65% ), especially K (K2O up to 5.96% ) and depleted in Ti (TiO2= 0.27% - 1.50% ). Their REE contents are very high (REE= 91.29 - 231.11 μg/g). Their REE distribution patterns are of the right-inclined type, characterized by intense LREE enrichment [(La/Yb)N= 7.44 - 15.73 ]. The rocks are distinctly enriched in Rb, Sr and Ba ( 46.3 -316 μg/g, 349-1220 μg/g and 386-2394 μg/g, respectively), high in U and Th ( 1.17 - 8.10 μg/g and 2.58 - 27.0 μg/g, respectively), moderate in Zr and Hf ( 87.5 -241 μg/g and 2.83 - 7.52 μg/g, respectively), and depleted in Nb and Ta ( 4.81 - 16.8 μg/g and 0.332 - 1.04 μg/g, respectively). In the primitive mantle-normalized incompatible element spidergram, U, K, Sr and Hf show positive anomalies, whereas Th, Nb, Ta, P, and Ti show negative anomalies. The rocks are strongly depleted in Cr and Ni ( 21.4 -1470 μg/g and 7.79 -562 μg/g, respectively), and their transition element distribution curves are obviously of type-W. The ( 87 Sr/ 86 Sr)i ratios range from 0.704184 to 0.707539 ; ( 143 Nd / 144 Nd)i from 0.512265 to 0.512564 ; and ε Nd (t) from -6.3 to -0.4 . These geochemical features might suggest that the potential source of the high-K igneous rocks in the Liuhe-Xiangduo area is similar to the EM2, which may be similar to the material enriched K that is located under the crust-mantle mixed layer. The mafic deep-derived enclaves in the high-K igneous rocks belong to chance xenoliths. Their ( 87 Sr/ 86 Sr)i ratios range from 0.706314 to 0.707198 ; ( 143 Nd / 144 Nd)i from 0.512947 to 0.513046 ; and ε Nd (t) from +7.0 to +9.0 . These geochemical features might indicate that the enclaves probably came from the depleted mantle. The P-T conditions of the enclaves also showed that the enclaves are middle-lower crust metamorphic rocks, which were accidentally captured at 20-50 km level by rapidly entrained high-K magma, whose source is over 50 km in depth.
其他文献
从教学改革和教育部颁发的本科教学工作水平评估方案对人才培养要求出发,对实验室建设中关于综合性、设计性题目的建设问题,结合实验教学经验和体会,提出了新的见解.
介绍了我国参与式流域管理的发展及相关政策和措施.并分析了参与式流域管理的优点及其可解决的典型水问题;作为今后参与式流域管理的参考和借鉴.
在全面、协调、可持续发展的今天,我们必须抛弃长期以来主导我国经济建设中重发展速度和经济效益、轻生态环境和社会发展的模式,吸取以往的教训,实现科学决策,努力使新项目具
本文在深入研究金华酥饼传统生产工艺的基础上,采用燃气--电加热烤炉研究不同饼坯类型、不同季节的烤制工艺对感管品质影响,基本掌握了金华酥饼在新型烤炉中生产达到传统的色
文章介绍了接入Internet的几种常见形式和目前网站建设的操作系统平台及与之对应的Web平台,给出了适合教学实践的网络平台方案.
This paper presents the ways of comprehensive utilization of the natural magnesium-containing resources and the trends of the MgO-based refractories used in hig
The differential evolution (DE) algorithm is applied to solving the models equations of a whole missile power system, and the steady fault characteristics of th
在深入分析了分布式计算系统的主流解决方案J2EE技术特点及体系结构的基础上,针对海水养殖区域信息化管理的特点与要求,提出了基于J2EE规范的海水养殖区域管理信息系统的总体
本文介绍了在VC++应用程序中实现多视图的技术,着重介绍了在基于同一文档的SDI应用程序中利用静态切分窗口实现多视图,向视图中加入控制并实现视图间通讯的技巧.
期刊
在重型商用车方面,自动换档变速器在多年前已被接受并正在扩大其市场份额.在中型车方面,商用车辆主要由经过适当培训的驾驶员完成在城市和长距离的频繁装卸运输.这类车辆非常