Geochemical Characteristics of Eclogites and Garnet-amphibolites in East Kunlun High Pressure Metamorphic Belt and Their Geodynamic Setting(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2017年第06期
- Page:
- 735-750
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Geochemical Characteristics of Eclogites and Garnet-amphibolites in East Kunlun High Pressure Metamorphic Belt and Their Geodynamic Setting
- Author(s):
- GUO Xian-zheng; JIA Qun-zi; QIAN Bing; MI Jia-ru; LI Jin-chao; KONG Hui-lei; YAO Xue-gang
- 1. Xi’an Center of Geological Survey, China Geological Survey, Xi’an 710054, Shaanxi, China;2. Geological Survey Institute, China University of Geosciences, Wuhan 430074, Hubei, China
- Keywords:
- eclogite; high pressure metamorphic belt; geochemistry; thermobarometer; P-T path; metamorphic age; geodynamic setting; East Kunlun
- PACS:
- P588.3;P595
- DOI:
- -
- Abstract:
- High-ultrahigh pressure metamorphic belt of the continental orogenic belt is the convergent boundary of the paleoplate, and is an important indicator of the palaeo-ocean subduction and the continental collision. Combined with the eclogite and garnet-amphibolite discovered in recent years, such as Jiadang, Suhaitu, Wenquan, Langmurishangyou, Zongjia, West Wulonggou (Dagele), a high pressure metamorphic belt more than 500 km is found, which is an important paleoplate suture zone in the northern Qinghai-Tibet Plateau. Based on field investigation and comprehensive previous data, the petrography, mineralogy and lithogeochemistry of eclogites in East Kunlun were studied. The results show that the eclogite in East Kunlun high pressure metamorphic belt can be divided into eclogite and retrograded eclogite, respectively; the mineral chemical component of garnet indicates that the eclogites are all C-type; the eclogites mainly belong to the tholeiite series; chondrite-normalied REE patterns show that LREE is strongly enriched between E-MORB and N-MORB; primitive mantle-normalized trace element spider diagrams are basically consistent, showing the characteristics of MORB; the temperature and pressure conditions of eclogite and garnet-amphibolite are nearly consistent, the formation pressure is 1.2-2.0 Gpa or higher, and the temperature is not less than 575 ℃; the P-T path is a clockwise “card” type; the temperature and pressure of the peak metamorphic stage are eclogite facies; according to the histogram of peak metamorphic ages of eclogites, there are three peak metamorphic ages, including 451 Ma, 432 Ma and 412 Ma; the main peak metamorphic age of 432 Ma restrains the time of Early Paleozoic ocean basin closure in East Kunlun.
Last Update: 2017-12-15