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 .
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 103.3. 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.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2001年第6期574-580,共7页
Earth Science-Journal of China University of Geosciences
基金
国家重点基础研究发展规划 (G199990 75 5 0 1)
大陆科学钻探项目
中国地质大学壳-幔开放实验室基金
美国自然科学基金(EAR -972 5 5 75 )资助
关键词
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
UHP eclogite, rheological strength, dislocation creep, high p T experiment, delamination, Dabieshan.
