Cratonic mantle eclogites as palaeo-dynamic archives

克拉通地幔榴辉岩作为古动力档案

基本信息

批准号：
327589446
负责人：
Dr. Sonja Aulbach
金额：
--
依托单位：
Abteilung Petrologie und Geochemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/327589446?language=en
关键词：
Cratonic mantle eclogites palaeo dynamic

项目摘要

Mineralogical, elemental and isotopic data show that most eclogite xenoliths, which sample the mantle lithosphere of ancient continental cores, have low-pressure protoliths that were emplaced in palaeo-ocean floors after decompression melting beneath spreading ridges. Like modern mid-ocean ridge basalts, they are therefore probes of the chemical, thermal and redox state of the uppermost convecting mantle (UCOM). Subsequent recycling and metamorphism led to interaction between various oceanic slab components and loss of a partial melt that may have contributed to continental crustal (CC) growth. As rare samples of Archaean and Proterozoic oceanic crust, mantle eclogites may therefore harbour invaluable information on various aspects of palaeo-geodynamics that still awaits full exploitation. The groundwork having been laid for recognising primary and secondary compositional signatures related to their complex multi-stage evolution, this study aims to (1) Investigate the variegated origins of large mantle eclogite suites from different cratons and tectonic settings, using an extensive list of major and trace elements, complemented by radiogenic and stable isotopes and Fe3+/Fe2+ analyses; (2) Use the least differentiated and modified samples to provide new constraints on the chemical, oxidation and thermal state of the ancient UCOM, which strongly affect geodynamics and chemical cycles; (3) Test the link between melt loss from mantle eclogites and regional CC formation from a compositional and chronological perspective. Investigation of eclogite xenoliths from the Colorado Plateau, which were part of the well-studied modern ocean floor subducted as part of the Farallon plate and represent unique modern analogues of ancient eclogites, will allow ascertaining that ancient mantle eclogites can reliably probe the UCOM through time.

矿物学，元素和同位素数据表明，对古代大陆岩心的地幔岩石圈进行采样的大多数叶绿石具有低压的质石材，它们在解压缩后在古生山地板中融化在散布山脊之下。因此，像现代的中山山脊一样，它们也是对流地幔（UCOM）的化学，热和氧化还原状态的探针。随后的回收和变质作用导致各种海洋板组件之间的相互作用以及可能导致大陆地壳（CC）生长的部分熔体丧失。因此，作为古细菌和原始海洋壳的稀有样品，地幔叶绿树可能具有关于古缘地位动力学各个方面的宝贵信息，这些信息仍在等待完全剥削。本研究旨在识别与其复杂的多阶段进化相关的初级和次要组成签名的基础，本研究的目的是（1）研究来自不同cratons和构造设置的大型地幔Eclogite套件的杂色起源，并使用广泛的主要主要列表和痕量元件，并由放射原和稳定的同位素和Fe3+/Fe2+分析互补；（2）使用最不区分和修改的样品对古代UCOM的化学，氧化和热状态提供新的约束，这强烈影响地球动力学和化学周期；（3）从结构和年代的角度来测试来自地幔eclogites的熔体损失与区域CC形成之间的联系。对科罗拉多高原的叶绿石的调查是，这是作为法拉隆板块的一部分良好的现代海底俯冲的一部分，代表了古代eclogite的独特现代类似物，可以确定古代地幔eclogite可以通过时间可靠地探究Ucom的时间。。