• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文会议>International GeologicalCongress >Fractional Crystallization, Magma Mixing and Crustal Assimilation in the Evolution in Plateau and Rift Mgmatism in Ethiopia
【24h】

Fractional Crystallization, Magma Mixing and Crustal Assimilation in the Evolution in Plateau and Rift Mgmatism in Ethiopia

机译：埃塞俄比亚在高原和裂谷迁移中进化中的分数结晶，岩浆混合和地壳同化

获取原文
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Magmatic activity is widespread in Ethiopia. Oligocene to Pliocene flood basalts, ignimbrites and shield volcanoes cover an area of several hundred thousand square km. Recent to active basaltic to rhyolitic volcanism occurs within the Ethiopian Rift Valley and the Afar depression. Major and trace element studies, together with preliminary Sr isotopic investigations indicate that rhyolitic magmas from both the plateau and rift sequences have been formed by Fractional Crystallization (FC) and Assimilation plus Fractional Crystallization (AFC) processes, from basaltic parentalmagmas. Both plateau and rift basalts have undergone complex evolutionary processes, which have substantially modified their trace element composition. Mixing between basaltic magmas and associated acid liquids is responsible for the geochemical modifications of plateau and rift basalts. Hybrid malic magmas display variable ratios of elements such as Rb/Ba, Rb/Zr, etc., which have an incompatible behaviour in mafic systems. Interaction between acid and mafic melts is also indicated by the widespread occurrence of xenocrystal phases (e.g. sanidine, quartz, etc.) in several basaltic rocks. Bulk crust assimilation processes have affected rift basalts. The present data clearly indicate that many mafic magmas in the Ethiopian plateau and rift valley do not represent primary melts and, in most cases, their composition has been significantly modified by evolutionary processes. This places serious problems to the identification of mantle reservoirs and stresses the need for detailed investigations on single suites in order to discriminate between source and shallow level geochemical signatures.
机译：古典主义活动在埃塞俄比亚广泛普及。少妇到全茂洪水玄武岩，Ignimbrites和Shield火山覆盖面积数十万平方公里。近期对血管内火山的活性玄武岩发生在埃塞俄比亚裂谷和远程抑郁症中。主要和痕量元素研究与初步Sr同位素调查表明，来自高原和裂缝序列的血管岩岩浆已经通过分数结晶（Fc）和同化加上玄武岩孕妇Magmas的分数结晶（AFC）方法形成。两个平台和裂缝玄武岩都经历了复杂的进化过程，其基本上改变了它们的微量元素组成。玄武岩岩浆和相关酸液之间的混合负责高原和裂缝沼气的地球化学修改。杂交麦形岩浆显示器的可变比，例如RB / BA，RB / Zr等，其在MAFIC系统中具有不相容的行为。酸和乳头熔体之间的相互作用也被几个玄武岩岩石中的XenoCrystal阶段（例如Sanidine，石英等）的广泛发生。散装地壳同化过程影响了裂缝沼气。目前的数据显然表明，埃塞俄比亚高原和裂谷中的许多MAFIC岩浆不代表初级熔体，并且在大多数情况下，它们的组合物被进化过程显着修饰。这使得识别地幔水库的严重问题，并强调了对单套房的详细调查的需要，以区分源头和浅层地球化学签名。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号