西太平洋弧后盆地火山岩中熔体包裹体研究进展

Advances in melt inclusion studies in back-arc basin volcanic rocks in Western Pacific

  • 摘要: 熔体包裹体是在矿物生长过程中被包裹的硅酸盐小液滴,由于寄主矿物的保护,受最小程度的后期岩浆作用影响,可以有效的保留原始岩浆组成、地幔源区性质及岩浆演化过程等重要信息。熔体包裹体的研究可以弥补传统全岩因受后期复杂地质过程影响而导致部分信息失真的不足。文章简要总结了熔体包裹体的主要研究领域及分析测试技术,概述了国内外关于西太平洋典型弧后盆地火山岩中熔体包裹体研究的相关进展。冲绳海槽、劳海盆及北斐济海盆内熔体包裹体的研究证明了地幔源区不均一性的特征,明确了岩浆物质来源及俯冲物质在源区的加入;马里亚纳海槽和马努斯海盆熔体包裹体内挥发份研究指示了俯冲板片物质对弧后盆地岩浆源区挥发份组成的贡献;马努斯海盆熔体包裹体中金属元素浓度分析表明岩浆流体可为海底热液系统提供成矿金属;此外,马里亚纳海槽和冲绳海槽熔体包裹体测温实验反映出岩浆多期次的演化过程。尽管熔体包裹体在西太平洋弧后盆地岩浆活动的很多方面有了一定研究,但各弧后盆地研究参差不齐、综合研究程度低。将来在进一步完善熔体包裹体测试分析手段基础上,加大熔体包裹体在弧后盆地的研究力度,有助于我们更清晰地认识弧后盆地岩浆源区物质组成,明确俯冲作用下弧后盆地岩浆来源及物质转化机制。

     

    Abstract: Melt inclusions are small silicate droplets trapped in minerals during growth. Due to the protection of host minerals, they are little affected by the late magmatic process, and thus can effectively retain the important information such as the original magmatic composition, the nature of the mantle source and the magmatic evolution process. The study of melt inclusions may make up for the deficiencies in the partial information distortion of traditional whole rocks due to the influence of complex geological processes in the later period. This article briefly summarizes the main research fields and current status of melt inclusions. The current research progress of melt inclusions in volcanic rocks in the typical back-arc basins in the western Pacific is reviewed. The study of melt inclusions in the Okinawa Trough, the Lau Basin and the North Fiji Basin has proved the heterogeneity of the mantle source area, and clarified the source of magma material and the addition of subducted material in the source area. The study of volatiles in melt inclusions in Mariana Trough and Manus Basin indicates the contribution of subducted slab materials to the volatile composition of the magma source area in the back-arc basin. The analysis of the concentration of metal elements in the melt inclusions in the Manus Basin indicates that the magmatic fluid can provide metallogenic metals for the submarine hydrothermal system. In addition, the temperature measurement experiments of melt inclusions in the Mariana Trough and Okinawa Trough reflect the multi-phase evolution of magma. Although melt inclusions have been studied in many aspects of magmatic activity in the western Pacific back-arc basins, the researches in the back-arc basins are uneven and the degree of comprehensive research is low. In the future, on the basis of further development of the testing and analysis technology of melt inclusions, increasing the research intensity of melt inclusions in the back-arc basin will help us to clearly understand the material composition of the magma source in the back-arc basin and clarify source and transformation of magma material in the back-arc basin under subduction.

     

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