木兰山蓝片岩中两种文石的产出特征及其动力学意义

赵文俞; 刘嵘; 王勤燕; 彭长琪; 张清杰

Volume 26 Issue 6

Jun. 2001

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Article Navigation > Earth Science > 2001 > 26(6): 568-573

ZHAO Wenyu, LIU Rong, WANG Qinyan, PENG Zhangqi, ZHANG Qingjie, 2001. ARAGONITE FROM MULANSHAN GLAUCOPHANE SCHIST: IMPLICATIONS FOR REGIONAL EVOLUTION OF SOUTHWESTERN DABIE MOUNTAINS, CENTRAL CHINA. Earth Science, 26(6): 568-573.

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ARAGONITE FROM MULANSHAN GLAUCOPHANE SCHIST: IMPLICATIONS FOR REGIONAL EVOLUTION OF SOUTHWESTERN DABIE MOUNTAINS, CENTRAL CHINA

1.
Center of Material Research and Analysis, Wuhan University of Technology, Wuhan 430070, China
2.
Faculty of Earth Sciences, China University ofGeosciences, Wuhan 430074, China

Received Date: 2001-01-02
Publish Date: 2001-11-25

Abstract

Abstract

The aragonite, an index mineral of glaucophane schist facies, has not been confirmed in the Dabie Mountains high-pressure and ultrahigh-pressure metamorphic belts. The Mulanshan glaucophane schist in Huangpi County, Hubei Province, is located in the southwestern Dabie mountains, central China. The micro-sized inter-granular aragonite is confirmed with optical microscope (OM) and electron probe microanalysis (EPMA) in the glaucophane schist. The submicrometer-sized ellipse aragonite inclusion is observed by using bright-field image (BFI), X-ray energy-damage spectrograph (EDS), and selected area electron diffraction (SAED) with transmission electron microscope in the quartz lens of glaucophane-albite-epidote-chlorite schist from the Mulanshan. The presence of aragonite indicates not only the average geothermal gradient of the Mulanshan glaucophane schist less than 10 ℃/km, which is very close to that of eclogite in the Dabie Mountain metamorphic belts, but also the relatively higher concentration of CO₂ during the metamorphic process. In addition, the glaucophane schist free of such index minerals as lawsonite, prehnite, and pumpellyite, has been attributed to the effect of CO₂ on the stability of calcium aluminum silicate minerals during the low-grade metamorphism. EDS and SAED analysis results show that the host of aragonite inclusion is amorphous SiO 2. The occurrence of amorphous SiO 2 indicates a quick cooling process during the exhumation of the Mulanshan glaucophane schist. These results suggest that the rapid exhumation mechanism of the glaucophane schist, the same as that of eclogite in the Dabie Mountain metamorphic belts, occurred in the geodynamic context of subduction-obduction.
- Mulanshan glaucophane schist,
- intergranular aragonite,
- aragonite inclusion,
- calcium aluminum silicate minerals,
- rapid exhumation

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References(15)

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