The role of mixing processes in andesite genesis - deep sediment recycling versus shallow crustal contamination

混合过程在安山岩成因中的作用 - 深层沉积物回收与浅层地壳污染

• 批准号: 288974582
• 负责人: Professor Dr. Karsten Matthias Haase
• 金额: --
• 依托单位: GeoZentrum Nordbayern
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/288974582?language=en
• 关键词: role; mixing; processes; andesite; genesis

Andesites are the typical volcanic rocks at active continental margins and the average continental crust has an andesitic composition. Many andesitic magmas form by complex mixing processes involving sedimentary material that is either subducted into the mantle wedge or may be assimilated in the crust by the ascending magma. The Aegean arc represents the subduction zone with one of the highest sediment recycling rates on Earth and the magmas show whole-rock geochemical evidence of a significant sediment contribution. In order to define the depths of the magma sources and the mixing processes we suggest to study the major and trace element as well as Sr-Nd-Hf-Pb-O isotope composition of minerals like olivine, amphibole, clinopyroxene, and plagioclase and potential glass inclusions in lavas from the Methana/Aegina volcanoes in the Aegean arc. The mineral phases allow insights into the mixing processes of different end-members at different depths that can be determined by thermo-barometry. The Methana/Aegina lavas are well-suited for such a case study because they are geochemically well-described and variable with extreme compositions of the mixing end-members and they contain abundant mineral phases.

安山岩是活动大陆边缘典型的火山岩，大陆地壳的平均成分为安山岩。许多安山质岩浆是通过复杂的混合过程形成的，这些混合过程包括沉积物质，这些沉积物质要么俯冲到地幔楔中，要么被上升的岩浆同化到地壳中。爱琴海弧是地球上沉积物再循环率最高的俯冲带之一，岩浆显示出沉积物贡献显著的全岩地球化学证据。为了确定岩浆源的深度和混合过程，我们建议研究的主要和微量元素，以及Sr-Nd-Hf-Pb-O同位素组成的矿物，如橄榄石，角闪石，单斜辉石，斜长石和潜在的玻璃包裹体从爱琴海弧的甲烷/埃伊纳火山熔岩。矿物相允许洞察不同的端元在不同的深度，可以通过热气压测定的混合过程。甲烷/埃伊纳火山熔岩是非常适合这样的案例研究，因为它们是地球化学良好的描述和变量与极端的混合端元的组合物，他们含有丰富的矿物相。