地震地质 ›› 2013, Vol. 35 ›› Issue (2): 328-346.DOI: 10.3969/j.issn.0253-4967.2013.02.012

• 专题综述 • 上一篇    下一篇

基性岩流变实验揭示出大陆下地壳流变的复杂性

周永胜   

  1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029
  • 收稿日期:2012-10-21 修回日期:2013-03-12 出版日期:2013-06-30 发布日期:2013-07-11
  • 基金资助:

    地震动力学国家重点实验室自主课题(LED2013A05)资助

RHEOLOGICAL COMPLEXITY OF CONTINENTAL LOWER CRUST BASED ON CREEP TESTS OF MAFIC ROCKS

ZHOU Yong-sheng   

  1. State Key Laboratory of Earthquake Dynamics,Institute of Geology, China Earthquake Administration, Beijing 100029,China
  • Received:2012-10-21 Revised:2013-03-12 Online:2013-06-30 Published:2013-07-11

摘要:

基性麻粒岩流变实验研究对认识大陆下地壳流变、板内构造变形和强震孕育等具有重要意义.大量基性岩流变实验数据表明,基性麻粒岩流变实验研究集中在单相矿物和两相矿物集合体,对天然基性麻粒岩流变研究很有限.基性麻粒岩流变实验结果的影响因素众多,除了实验条件(如温度、压力、应变速率)外,实验样品的矿物组分、样品颗粒粒度、微量水、熔体、矿物反应等都会影响其流变特性,这导致实验结果的复杂性.因此,根据单相或两相矿物集合体流变讨论大陆下地壳流变结构时,存在很多不确定性,不能满足下地壳流变研究的实际需求.而根据端元组分流变参数和经验方程估计由多相矿物组成的麻粒岩的流变强度,只是一种简单近似,无法完全取代麻粒岩流变实验研究.因此,开展多相矿物基性麻粒岩的流变实验,以获得更接近真实大陆下地壳流变的实验数据,并且用于定量研究下地壳流变,是大陆下地壳流变实验未来发展的方向.在基性麻粒岩流变实验研究中存在的科学问题与技术难题是多相矿物流变、高温部分熔融的影响、矿物反应-流变相互作用,这些问题都有待通过高温高压流变实验进行深入研究.

关键词: 基性岩, 流变, 大陆下地壳

Abstract:

It is crucial to research on creep tests of granulites in understanding rheology of lower crust,continental dynamics and seismogenic environment. However,based on analysis of creep data of mafic rocks,it was found that most of experimental studies of mafic rocks focused on creep of single-phase and two-phase aggregates,and creep data of mafic granulite is very limited. There are a lot of factors affecting rheology of mafic granulite. Besides the external causes of experimental conditions(temperature,pressure,strain rate),the internal causes,such as mineral components,grain size of samples,trace water,partial melt,mineral reactions,are very important influencing factors,which induced the results of creep tests on mafic rocks to be more complex. Therefore,there are a lot of uncertainties in discussing the rheological structures of lower crust according to creep data of single-phase and two-phase aggregates,which could not fulfill the requirement for studying lower crustal rheology. The calculation of the rheological strength of granulite constituted by multi-phase minerals based on end-member flow law parameters and empirical equation is only a kind of simple approximate,which could not replace experimental studies on rheology of granulite. The development trend of the experimental study on mafic rocks in the future will be to perform creep tests of multi-phase natural mafic granulite and obtain flow laws of samples which can be used to study the rheology of continental lower crust quantitatively. The scientific questions and technological problems during experimental studies of creep tests of mafic rocks are multi-phase mineral rheology,partial molten under high temperature and interactions of mineral reaction and rheology,and all of those need more detailed experimental studies under high temperature and pressure.

Key words: mafic rock, rheology, continental lower crust

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