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首页> 外文期刊>Oceanographic Literature Review >Grain Size Variations Record Segregation of Residual Melts in Slow-Spreading Oceanic Crust (Atlantis Bank, 57°E Southwest Indian Ridge)
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Grain Size Variations Record Segregation of Residual Melts in Slow-Spreading Oceanic Crust (Atlantis Bank, 57°E Southwest Indian Ridge)

机译：谷物尺寸变化在缓慢蔓延的海洋地壳中记录剩余熔体的偏析（亚特兰蒂斯银行，57°E西南印度山脊）

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Beneath slow-spreading ridges, melt bodies are generally considered to represent ephemeral magma reservoirs filled with crystal mushes. Formation of the oceanic crust requires at least partial extraction of melts from these crystal mushes. However, melts collection and extraction are processes yet to be fully constrained. We investigate olivine gabbros from the plutonic section recovered at the IODP Hole U1473A, in the Atlantis Bank Oceanic Core Complex (Southwest Indian Ridge), to unravel (ⅰ) the process of melt migration through lower crustal crystal mushes, and (ⅱ) the collection and segregation of melts forming discrete microgabbro intervals. Throughout the Hole, fine- to coarsegrained intervals are widespread in olivine gabbros. Along the contacts, coarse-grained minerals display resorbed grain boundaries against the fine-grained minerals, suggesting partial dissolution by the melt crystallizing the fine-grained material. Coarsegrained plagioclase and clinopyroxene are zoned, showing pro- gressive chemical evolution from more primitive crystal cores to more evolved crystal rims. Fine-grained minerals are un-zoned and chemically similar to rims of coarse-grained minerals, indicating a genetic relationship. We attribute significant enrichments in the most incompatible elements of plagioclase and clinopyroxene to a magma evolution process associated with reactive melt migration. As temperature decreased, melts residual from the reactive processes were segregated in magma pockets that ultimately crystallize the fine-grained intervals (microgab-bros). We document, for the first time, that these microgabbros are crystallization products of melts modified by reactive melt migration; the melts were extracted from the crystal mush and accumulated into discrete melt-rich zones. This process could have promoted partial extraction of those melts that in turn potentially contribute to Mid Ocean Ridge Basalts erupted at the seafloor.
机译：在慢速扩散的山脊下，熔体体通常被认为代表填充水晶糊剂的短暂岩浆储层。形成海外壳的形成需要至少部分地从这些水晶糊状物中提取熔体。然而，熔化收集和提取是尚未受到限制的过程。我们从Iodp Hole U1473A中恢复的浦项段调查Olivine Gabbros，在亚特兰蒂斯银行海洋核心复合物（西南印度山脊），以解吸（Ⅰ）通过较低的地壳晶体糊状物的熔体迁移过程，以及（Ⅱ）收集和融化的分离形成离散的微臂间隔。在整个孔中，细至粗鲁的间隔是橄榄石Gabbros的普遍存在。沿着触点，粗粒矿物显示器对细粒矿物的晶界进行了吸收，暗示通过结晶细粒材料的熔体部分溶解。划大甘露出的普发替氏酶和Clinocococexene，从更多原始晶体芯中显示出更加原始的晶体的化学进化。细粒矿物质是未分区和化学上类似的与粗粒矿物质的边缘，表明遗传关系。我们将显着的富集在Plagioclase和Closopococexene最不相容的内容中归因于与反应性熔体迁移相关的岩浆进化过程。随着温度降低，从反应过程中熔化残余物在最终将细粒间隔（MicroGab-Bros）结晶的岩浆袋中进行偏析。我们首次记载这些MicroGabbros是通过反应熔体迁移改性的熔体的结晶产物;将熔体从晶体糊中提取并积聚在离散的熔体区域中。这个过程可以促进部分融化的部分提取，又有可能导致海洋山脊的中海山脊沼泽。

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  • 来源
    《Oceanographic Literature Review》 |2021年第6期|1277-1278|共2页
  • 作者

    C. Ferrando; L. France; V. Basch;

  • 作者单位

    Universite de Lorraine CNRS CRPG Nancy France;

    Universite de Lorraine CNRS CRPG Nancy France;

    Universite de Lorraine CNRS CRPG Nancy France;

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