大别山超高压榴辉岩流变强度——来自高温高压实验的证据

金振民; 章军锋; GreenH.W.; 金淑燕; 王永锋

大别山超高压榴辉岩流变强度——来自高温高压实验的证据

金振民^{1, 2},
章军锋^{1, 2},
GreenH.W.²,
金淑燕¹,
王永锋¹

1.
中国地质大学地球科学学院, 湖北武汉 430074
2.
加利福尼亚大学(Riverside 分校)地球物理和行星物理研究所, CA 92521, USA

基金项目:

国家重点基础研究发展规划 G19999075501

美国自然科学基金 EAR-9725575

详细信息

作者简介:
金振民(1941-), 男, 教授, 博士生导师, 1965年毕业于北京地质学院, 现从事岩石圈流变学和大陆深部构造研究

中图分类号: P588.34⁺2;P589
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出版历程
- 刊出日期: 2001-11-25

RHEOLOGICAL STRENGTH OF UHP ECLOGITE FROM DABIE SHAN: EVIDENCES FROM HIGH p-T EXPERIMENTS

1.
Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074
2.
Institute of Geophysics & Planetary Physics, University of California, Riverside, CA 92521, USA

摘要

摘要: 利用Griggs型5GPa高压仪器, 在柯石英稳定域围压条件下(>3GPa)完成大别山超高压榴辉岩流变学实验, 建立了榴辉岩流变状态本构方程(流动律) : ε=Aexp(-Q/RT)σⁿ, 应力指数(n)为3.4, 活化能(Q)为4 80kJ/mol, 结构常数(A)为10^3.3.实验结果表明: (1)作为两相矿物组成的榴辉岩, 其流变学强度在很大程度上取决于强相矿物(石榴石)和弱相矿物(绿辉石)含量比例; (2)天然榴辉岩塑性变形机制是以位错蠕变为主; (3)根据实验成果比较榴辉岩和上地幔方辉橄榄岩流变学强度相当, 两者耦合在大陆深俯冲10 0km左右深度发生拆沉作用可能性很小, 与上地幔上隆(upwelling)作用有关的造山期后伸展作用对超高压岩石折返更具有重要意义.
- 超高压榴辉岩 /
- 流变强度 /
- 位错蠕变 /
- 高温高压实验 /
- 拆沉作用 /
- 大别山
Abstract: The authors present here experimental study of the rheological properties of UHP eclogite from Dabie at a pressure of 3 GPa by utilizing the 5 GPa Griggs-type piston cylinder apparatus. The rheological constitutive equation of eclogite is determined with a stress exponent of 3.4, an activation energy of 480 kJ/mol and a pre-exponential factor of 10^3.3. The study shows that: (1) As a typical two-phase rock, the flow strength of eclogite depends on the proportions between the strong phase (garnet) and the weak phase (omphacite); (2) The plastic deformation of eclogite is dominated by dislocation creep; (3) The research result that eclogite has the same strength as does the upper mantle harzburgite suggests that the delamination of the subducting crust component from the underlying upper mantle is unlikely. Therefore, the stretching after the collision orogeny coupled with the upwelling of the upper mantle might play a more important role in the exhumation of UHP rocks.
- UHP eclogite /
- rheological strength /
- dislocation creep /
- high pressure and temperature experiment /
- delamination /
- Dabie Shan

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图 1 高压实验样品装置

Fig. 1. High-pressure sample assembly used in experiments

下载: 全尺寸图片幻灯片

图 2 实验原始榴辉岩(a)和实验变形榴辉岩(b)的显微构造比较

Grt.石榴石; Omp.绿辉石; Rt.金红石; Qz.石英

Fig. 2. Microstructural comparison of starting eclogite(a)and experimentally deformed eclogite(b)

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图 3 榴辉岩高温蠕变力学资料(围压3.0 GPa)

a.应力-应变曲线; b.应变速率-流动应力及其对数关系; c.应变与差异应力关系; d.应力与温度关系

Fig. 3. Mechanical results of high-temperature creep of eclogite under 3.0 GPa pressure

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图 4 在相同实验条件下, 石榴子石岩、干榴辉岩、湿榴辉岩和绿辉石岩的流变强度比较

Fig. 4. Comparison of the rheological strength of garnetite, dry eclogite, wet eclogite and omphacite under similar experimental comditions

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表 1 榴辉岩实验原始材料组成和化学成分

Table 1. Composition of starting materials used in experiments

表 2 榴辉岩高温高压流变实验条件和流变强度

Table 2. Summary of experimental conditions and rheological strength of eclogite

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