地学前缘 ›› 2009, Vol. 16 ›› Issue (1): 146-154.

• 论文 • 上一篇    下一篇

950 ℃、1.0~3.5 GPa下斜长角闪岩脱水熔融——压力和时间对结构的影响

  

  1. 1中国科学院 地球化学研究所 地球深部物质与流体作用地球化学实验室, 贵州 贵阳 550002
    2中国科学院 研究生院, 北京 100049

  • 出版日期:2009-02-02 发布日期:2009-02-02
  • 作者简介:周文戈(1967—),男,研究员,从事实验岩石学研究。E-mail: wengezhou@sohu.com
  • 基金资助:

    国家自然科学基金项目(40873052);中国科学院知识创新工程重要方向项目(KJCX2SWN20)和西部之光联合学者项目(2008年度)

Textural development of dehydrationmelting in amphibolite at 1035 GPa and 950 ℃—Effect of pressure and time

  1. 1Institute of Geochemistry, Chinese Academy of Sciences, Guiyang  550002, China
    2Graduate School of Chinese Academy of Sciences, Beijing  100049, China

  • Online:2009-02-02 Published:2009-02-02

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摘要：

利用YJ3000t和JL3600t多顶砧压力机,以哀牢山造山带南部红河县大白能—乐育剖面上的天然块状斜长角闪岩为初始样品,在950 ℃、10~35 GPa、恒温20~300 h条件下进行了两个系列的斜长角闪岩块状样品脱水部分熔融实验:(1)保持温度T=950 ℃,加热时间t=100 h不变,改变压力(10~35 GPa)的实验;(2)保持温度T=950 ℃,压力p=30 GPa不变,改变加热时间(20~300 h)的实验。结果表明,10~35 GPa、950 ℃、恒温100 h的条件下,随压力升高,斜长角闪岩中依次生成了单斜辉石+石榴石+熔体的矿物组合(10~15 GPa)和单斜辉石+石榴石+熔体+硬玉+SiO2矿物+蓝晶石(20~35 GPa)的矿物组合。30 GPa、950 ℃条件下,随加热时间增加,实验产物中依次生成了单斜辉石+石榴石+熔体+硬玉+SiO2矿物+蓝晶石的矿物组合(20~100 h)和单斜辉石+石榴石+熔体的矿物组合(150~300 h)。斜长角闪岩的原岩结构决定了实验产物中新生矿物和熔体的分布。依据实验产物的矿物组合和新生矿物的分布特征,讨论了950℃、10~35 GPa、恒温(20~300 h)条件下,斜长角闪岩部分熔融过程的结构变化、变质反应以及石榴石冠状体的成因。

关键词: 高温高压;斜长角闪岩脱水熔融;结构变化;变质反应;石榴石冠状体

Abstract:

Abstract:  Two sets of dehydrationmelting with a natural solid amphibolite(56vol.% hornblende, 43vol.% plagioclase), collected from the DabainengLeyu profile in the southern Ailaoshan orogenic belt, Honghe County, Yunnan Province, have been carried out in multianvil apparatus(YJ3000t and JL3600t) at 1035 GPa and 950 ℃ for 20300 h. One is keeping the temperature at 950  ℃ and the annealing time of 100 h, varying the pressure (1035 GPa). The other is keeping the pressure at 30 GPa and temperature at 950 ℃, varying the annealing time (20300 h). The products are inspected with microscope and electron probe. The results indicate that at 950 ℃, annealing time of 100 h, as the pressure in the range of 1015 GPa, the mineral assemblage in the products is clinopyroxene+garnet+melt. As the pressure larger than 15 GPa, the mineral assemblage in the products is clinopyroxene+garnet+melt+Jadeite+SiO2±kyanite. However, at 30 GPa and 950 ℃, as the annealing time in the range of 20100 h, the mineral assemblage of clinopyroxene+garnet+melt+Jadeite+SiO2±kyanite appears successively with time  in the products. As the annealing time longer than 100 h, the mineral assemblage of clinopyroxene+garnet+melt appears in the products. The distribution of the newlyformed minerals and melt is restricted by the texture of the started amphibolite. Based on the mineral distribution and assemblage in the run products at 1035 GPa and 950 ℃ for 20300 h, the textural development of amphibolite during the partial melting process,  the metamorphic reaction, and the garnet corona generation are  discussed.

Key words:

Key words: high temperature and high pressure; dehydrationmelting in amphibolite; textural development; metamorphic reaction; garnet corona

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