Zircon U-Pb Geochronology and Typological Classification of Eclogites in the Hinterland of the Central Dabie
详细信息
- 责任者：Xu Xufeng (Geological Survey of Jiangsu Province ; Nanjing 210000 ; China) ; Shi Yonghong
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(5)
- 关键词：榴辉岩 ; eclogite ; 铀—铅计时 ; U-Pb dating ; 大别山 ; Dabie Mountains
- 页码：p.1559-1572
- 图表：illus., 3 tables, 86 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
According to the petrological analysis for eclogites of JS249 and JS250,the eclogites in Huanggang-Niutuling area have a clear characteristic of high-pressure metamorphism,garnets with zoning of compositions contain inclusions of earlier stage,the main mineral assemblage of peak metamorphic is Grt + Omp + Phn + Rt + Qtz + Ep + Ky,meanwhile the main mineral assemblage of amphibolite-facies metamorphic is Di + Mg-Hbl + Ab + Prg + Bt. The result of P-T conditions from eclogites of JS249 and JS250 shows that,T = 594 ± 61℃ and P = 2. 58 ± 0. 27GPa are for JS249,T = 616 ± 56℃ and P = 2. 14 ± 0. 14GPa are for JS250. LA-ICPMS zircon U-Pb geochronology and laser Raman spectroscopy of inclusions are determined for these two samples,the results show that,the inclusions of JS249 are amphibole,feldspar and other retrograde minerals with U-Pb age of 217. 3 ± 3. 5Ma,which is timing the age of amphibolite-facies metamorphism. The inclusions of JS250 are garnet,rutile,omphacite and other peak-metamorphism minerals; the weighted average age is 235. 2 ± 4. 2Ma,which is the age of peak metamorphism. Combined of petrology,thermodynamic and zircon U-Pb geochronology,Huanggang-Niutuling unit should be belong to lower-temperature and high-pressure unit,similar to the south Dabie Terrane.
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