Yankuang ceshi (Jan 2013)
Laser Ablation-Inductively Coupled Plasma-Mass Spectrometric Analysis Methods of Melt Inclusions and Its Geological Applications
Abstract
Melt inclusions in phenocrysts play a very important role in petrological research for reserving the only direct information available on the temperature, pressure and chemical compositions of the magmatic system at the time that the host minerals crystallized. However, due to the limitation of techniques on sampling method, the resolution and sensitivity of the instrument, the study of melt inclusions (especially the chemical composition) is a relatively slow process. The melt inclusions properties and classifications generally are introduced in this paper, along with a summary of the analytical methods, applications and sample preparation, and an extensive description of the technique of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS), especially the elemental fraction, matrix effects and principal points for laser ablation. The development of an in-situ micro-analytical technique by LA-ICP-MS, which can analyse the multi-phase inclusions up to 100 μm beneath the surface of the complex minerals, and avoids the prerequisite conditions of heating homogenization and sample preparation for the routine method is described. With the advantages of rapidity, efficiency and accuracy, the newly developed technique allows more analysis for melt inclusions in the same sample and comprehensively provides evolvement information for magma. Data accuracy can be comparable with Electron Microprobe Analysis and Secondary Ion Mass Spectrometry. Recently, this technique has been applied widely in research fields of geology and ore deposit geology. Furthermore, the significant achievements were obtained in the deep earth magmatic processes and magmatic hydrothermal metallogenic theory. The development of the equipment and quantitative methods will improve the accuracy of this technique. Meanwhile, the development and application of in-situ isotopic analysis of melt inclusions by LA-MC-ICP-MS will revolutionize melt inclusions research.
