摘要
单斜辉石作为大陆下地壳以及上地幔岩石的重要组成矿物,其在高温高压条件下的流变行为已有大量的实验研究。本文在综述以往对单斜辉石流变实验研究的基础上,讨论了影响其流变行为的各种因素及其地质意义,并指出了现存的问题及今后的研究趋势。影响单斜辉石流变性质的因素主要有流体(包括水和熔体)、粒度、化学成分、氧逸度以及温度与压力条件等。微量结构水可以显著增大单斜辉石单晶和多晶集合体的蠕变速率,降低其流变强度。熔体对单斜辉石强度的影响与熔体的含量和分布状态有关,呈三联点分布于矿物颗粒间的熔体对样品强度影响较小,只有当熔体呈薄膜状湿润颗粒边界时,熔体的弱化作用才显著。粒度主要影响单斜辉石的变形机制,单斜辉石集合体晶粒粒度的减小会促使变形机制由位错蠕变转变为扩散蠕变,较细粒的单斜辉石在扩散蠕变域内的应力与粒度呈线性负相关,而在位错蠕变域,应力与粒度无明显相关性。关于铁含量对单斜辉石的影响尚未有直接的实验研究,而对比前人在相同实验条件下采用不同铁含量的单斜辉石的扩散蠕变实验研究显示,单斜辉石中铁含量与蠕变速率可能呈正相关。氧逸度的升高对单斜辉石单晶的蠕变强度有轻微的弱化作用,而关于氧逸度对单斜辉石集合体流变性质的影响尚未有直接的定量研究。另外,以往对单斜辉石的实验研究多采用下地壳来源的样品作为研究对象,而对于上地幔来源的单斜辉石研究较少,为了准确约束上地幔的流变行为,需要对幔源单斜辉石开展高温高压变形实验研究。
Clinopyroxene is an important component mineral of continental lower crust and upper mantle rocks. The rheological behavior of clinopyroxene under conditions of high temperature high pressure(in the lithosphere environment)has been clarified by a large number of experimental studies.On the basis of summarizing previous studies of the rheological experiments of clinopyroxene, we have discussed various factors that had influenced rheological properties of clinopyroxene and their geological applications, also have pointed out the existing problems and the future research trends in this field. Main factors influencing rheological properties of clinopyroxene are fluid(including water and melt), grain size, chemical composition, oxygen fugacity, temperature, pressure, and so on. Of the factors, a small amount of textural water can significantly increase the creep rate but decrease the rheological strength of single crystal and polycrystalline aggregates of clinopyroxene. The effect of melt on the strength of clinopyroxene is dependent on its content and distribution. The melt distributed among mineral particles as a triple point has little influence on the strength of sample,while the weakening effect of melt is more obvious only when the melt distributed in the form of thin film wetting grain boundaries. The grain size mainly influences the deformation mechanism of clinopyroxene. The reduction of crystal grain size of clinopyroxene aggregate will cause the deformation mechanism to change from dislocation creep to diffusion creep,e.g., in diffusion regime, the flow stress has negative linear correlation with grain size of fine grained clinopyroxene, yet in dislocation regime, the creep strength is independent on grain size of clinopyroxene. There is no direct experimental study on the effect of iron content on clinopyroxene. The comparison among previous researches of diffusion-creep experiments of clinopyroxenes with different iron contents under the same experimental conditions shows that the iron content in clinopyr
作者
王晓宁
宋茂双
李建峰
王宝云
WANG Xiao-ning;SONG Mao-shuang;LI Jian-feng;WANG Bao-yun(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;College of Earth and Planetary Sciences,University of Chinese Academy of Science,Beijing 100049,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,China)
出处
《矿物学报》
CAS
CSCD
北大核心
2022年第4期440-452,共13页
Acta Mineralogica Sinica
基金
国家自然科学基金项目(编号:41874107,42172243)。
关键词
单斜辉石
流变性质
位错蠕变
扩散蠕变
影响因素
Clinopyroxene
rheological property
dislocation creep
diffusion creep
influence factors
