Fluid inclusions in mantle xenoliths
Fluid inclusions in mantle xenoliths
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DOI：
10.1016/s0024-4937(00)00049-9
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发表时间：
2001-01-01
期刊：
影响因子：
3.5
通讯作者：
Neumann, ER
中科院分区：
文献类型：
--
作者：
Andersen, T;Neumann, ER
火山岩地幔超镁铁质包体中橄榄石和辉石中的流体包裹体中含有丰富的富CO2流体包裹体，以及硅酸盐玻璃包裹体、固化金属硫化物熔体和碳酸盐包裹体。这种包裹体代表了上地幔中流体和熔体相意外捕获的样品，因此对于了解地幔中矿物-流体-熔体相互作用过程具有独特的重要性。富CO2流体包裹体中的少量挥发性物质包括N-2、CO、SO2、H2O和惰性气体。在一些来自活动俯冲带上方水化地幔楔体的包体中，水实际上可能是主要的流体物种。包裹体流体中少量挥发性物质的分布可以提供有关上地幔的氧化状态、地幔脱气过程和俯冲物质向地幔循环的信息。超镁铁质包体中的熔体包裹体提供了上地幔内硅酸盐-硫化物-碳酸盐岩不混溶关系的信息。最近的熔体包裹体研究表明，高硅质熔体可以与地幔橄榄岩矿物组合共存。尽管从流体包裹体数据可以获得高达1.4 Gpa的圈闭压力，但由于在向地表输送过程中的泄漏或伸展，很少有富含二氧化碳的流体包裹体保持其在上地幔初始圈闭的密度。然而，流体密度在变质包裹体群体中的分布可能保存了从其宿主矿物中不易获得的火山管道系统的信息。由于流体包裹体和熔体包裹体是其寄主包体相组合的组成部分，因此也是上地幔本身的组成部分，本文作者强烈建议将他们的研究纳入任何与地幔包体有关的研究项目中。(C)2001 Elsevier Science B.V.保留所有权利。
Fluid inclusions in olivine and pyroxene in mantle-derived ultramafic xenoliths in volcanic rocks contain abundant CO2-rich fluid inclusions, as well as inclusions of silicate glass, solidified metal sulphide melt and carbonates. Such inclusions represent accidentally trapped samples of fluid- and melt phases present in the upper mantle, and are as such of unique importance for the understanding of mineral-fluid-melt interaction processes in the mantle. Minor volatile species in CO2-rich fluid inclusions include N-2, CO, SO2, H2O and noble gases. In some xenoliths sampled from hydrated mantle-wedges above active subduction zones, water may actually be a dominant fluid species. The distribution of minor volatile species in inclusion fluids can provide information on the oxidation state of the upper mantle, on mantle degassing processes and on recycling of subducted material to the mantle. Melt inclusions in ultramafic xenoliths give information on silicate-sulphide-carbonatite immiscibility relationships within the upper mantle. Recent melt-inclusion studies have indicated that highly silicic melts can coexist with mantle peridotite mineral assemblages. Although trapping-pressures up to 1.4 GPa can be derived from fluid inclusion data, few CO2-rich fluid inclusions preserve a density representing their initial trapping in the upper mantle, because of leakage or stretching during transport to the surface. However, the distribution of fluid density in populations of modified inclusions may preserve information on volcanic plumbing systems not easily available from their host minerals. As fluid and melt inclusions are integral parts of the phase assemblages of their host xenoliths, and thus of the upper mantle itself, the authors of this review strongly recommend that their study is included in any research project relating to mantle xenoliths. (C) 2001 Elsevier Science B.V. All rights reserved.