大别山北部石榴二辉麻粒岩变质结构和水活度及其演化特征

苏文; 徐树桐; 江来利; 刘贻灿; 吴维平

Volume 25 Issue 2

Mar. 2000

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Article Navigation > Earth Science > 2000 > 25(2): 152-158

SU Wen, XU Shutong, JIANG Laili, LIU Yican, WU Weiping, 2000. METAMORPHIC STRUCTURE, WATER ACTIVITIES AND THEIR EVOLUTIONARY FEATURES OF PYRIGARNITE, NORTH OF DABIE MOUNTAINS, EAST OF CHINA. Earth Science, 25(2): 152-158.

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METAMORPHIC STRUCTURE, WATER ACTIVITIES AND THEIR EVOLUTIONARY FEATURES OF PYRIGARNITE, NORTH OF DABIE MOUNTAINS, EAST OF CHINA

1.
Anhui Institute of Geology, Hefei 230001, China
2.
National Key Laboratory of Mineralization, Nanjing University, Nanjing 210008, China

Received Date: 1999-05-28
Publish Date: 2000-03-25

Abstract

Abstract

The lithofacies research, the calculation of the mineral and geological temperature and pressure, and the thermodynamic calculation are all used in this paper to obtain the mineral association assemblies?, the temperature and pressure conditions and the corresponding water activity conditions that occurred in the four major metamorphic evolutionary stages of the pyrigarnite in the Dabie Mountains: (1) The ecologite facies stage (M₁) is characterized by the residual minerals represented by Cpx (jadeite_bearing)+Q+Ru+Gt that occur as inclusions in the garnets at t =612-750 ℃. (2) The granulite facies stage (M₂) is featured by the mineral assembly consisting of Opx+Cpx+Amp+Gt+Q+Ti+Mt at t =837-887 ℃, p =1.03-1.25?GPa. The water activity in this stage ranges between 0.718-0.799. (3) The amphibolite facies (M₃) is characterized by the mineral assembly consisting of Cpx+Gt+Amp+ Pl+Mt at t =530-660 ℃ and p =0.89-0.95?GPa. The water activity in this stage was reduced to 0.23-0.24. (4) The low amphibolite facies (M₄) occurred at t =495 ℃ and p =0.56-0.70?GPa. The water activity in this stage was 0.11-0.13. In conclusion, the metamorphic reaction, the metamorphic structure, the mineral assembly and evolution of the pyrigarnite are not only controlled by the temperature and pressure conditions, but also closely related in cause and effect to the evolution of water activity during its formation system. The evolutionary feature of the water activity shows that the metamorphic fluids may have played a buffering role in the metamorphic reaction temperature during the metamorphic stages.
- metamorphic structure,
- metamorphic reaction,
- water activity,
- granulite,
- Dabie Mountains

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References(21)

References

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