镁橄榄石多晶集合体样品的合成制备及流变学实验初步研究  

Synthesis and Rheological Experimental Study of Forsterite Aggregates

作　　者：郑小东 姜哲轩 李建峰[1] 肖璞 宋茂双[1] ZHENG Xiaodong;JIANG Zhexuan;LI Jianfeng;XIAO Pu;SONG Maoshuang(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所,同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049

出　　处：《大地构造与成矿学》2024年第6期1232-1239,共8页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(41874107、42172243);广东省自然科学基金项目(2022A1515011000)联合资助。

摘　　要：致密(低孔隙度)、细粒、粒度均一并且无初始优选组构的单相或多相矿物多晶集合体是高温高压流变学实验的理想样品,而制备理想流变实验样品是获得准确流变参数的基础。本文在前人工作基础上,完善了一种制备流变实验样品的方法,即以高纯度纳米SiO2和Mg(OH)2粉末为初始材料,采用真空烧结技术合成镁橄榄石多晶集合体。显微构造和拉曼光谱分析表明,合成样品具有纯度高、低孔隙度和颗粒细且均一等特点。对合成的镁橄榄石多晶集合体开展了流变实验,得到的流变参数与前人结果在误差范围内一致,表明采用真空烧结技术合成的镁橄榄石多晶集合体是开展流变实验的良好样品。真空烧结制备多晶集合体这一技术相较于传统的流变学实验样品热压合成技术,其过程更为简单,减少了流变样品合成制备的时间和工作量,提高了合成效率。Dense single-mineral or polymineral aggregates with low porosity,small grain sizes,and no preferred fabric are ideal samples for rheological experiments at high pressure and temperature to investigate the deformation mechanisms and flow laws of minerals and rocks in the Earth’s crust and mantle.Preparing such samples is crucial for obtaining accurate rheological data.In this paper,we introduce an improved method for obtaining good rheological samples for rheological experiments using forsterite as an example.On the basis of previous work,high-purity nanopowders(SiO2 and Mg(OH)2)were used as starting materials,and forsterite aggregates were sintered at high temperature under vacuum condition.The forsterite aggregates were prepared in a cylindrical shape before sintering using a specially designed three-split mold.Scanning electron microscopy and Raman spectroscopy analyses indicated that the synthesized samples were composed of high-purity forsterite with a density of~3.1 g/cm3 and a small grain size of~1μm.Rheological experiments on the synthesized forsterite aggregates showed comparable rheological strengths and parameters to those reported in previous studies,indicating that the forsterite aggregates synthesized by vacuum sintering technique are good for rheological experiments.Compared with the traditional hot-pressing technique of rheological sample preparation from sorted natural mineral powders,the vacuum sintering technique is much easier,greatly reducing the time and workload of sample preparation for rheological experiments.

关 键 词：流变学实验 样品准备 真空烧结 致密样品 细颗粒 

分 类 号：P574.12[天文地球—矿物学] P589.1[天文地球—地质学]