Metamorphic Evolution of Susong Metamorphic Complex in Dabie Orogenic Belt, China(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2018年第06期
- Page:
- 727-738
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Metamorphic Evolution of Susong Metamorphic Complex in Dabie Orogenic Belt, China
- Author(s):
- ZHOU An-tai; SHI Yong-hong; ZHAO Jun-xian; YANG Gen-shan
- School of Resources and Environment Engineering, Hefei University of Technology, Hefei 230009, Anhui, China
- Keywords:
- metamorphic complex; metamorphism; garnet-plagioclase amphibolite; peak metamorphic condition; P-T path; geothermobarometry; Dabie orogenic belt; Yangtze plate
- PACS:
- P588.34
- DOI:
- -
- Abstract:
- Susong metamorphic complex is located at the southernmost end of Dabie orogenic belt, and is one of the important components of the orogenic belt. Due to the relatively low degree of metamorphism and relatively little information of metamorphic evolution, the construction of metamorphic P-T path has challenged geologists for many years, which restricts the full understanding of the formation mechanism of Dabie orogenic belt. The detailed petrographic, mineralogical and thermodynamic evaluation of garnet-plagioclase amphibolite, which was a typical rock from Susong metamorphic complex, were carried out. the results show that this kind of rocks has four metamorphic stage mineral assemblages including Ts+Ep+Qz+Rt, Grt+Pl+Ts+Qz+Ep+Rt, Pl+Ts+Qz+Mag and mainly Chl+Qz, and the corresponding temperatures and pressures are 591 ℃-620 ℃, 606 ℃-636 ℃, 600 ℃-619 ℃ and 400 ℃-500 ℃, and 0.48-0.56 GPa, 1.01-1.12 GPa, 0.79-0.91 GPa and 0.1-0.3 GPa, showing a metamorphic P-T pattern of near-isothermal pressure lift→near-isothermal pressure reduction→temperature reduction and depressurization. The establishment of this P-T path indicates that Susong metamorphic complex experiences rapid subduction and exhumation in the early stage, and slow uplift in the late stage, suggesting that Susong metamorphic complex, as the leading edge block of Yangtze plate, subducts rapidly under the dragging action of the oceanic plate, returns rapidly due to the buoyancy of the plate fragments, stays at the upper crustal level for a long time, and then rises slowly to the surface.
Last Update: 2018-12-06