کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4732544 1640430 2009 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
UHP metamorphic evolution and SHRIMP geochronology of a coesite-bearing meta-ophiolitic gabbro in the North Qaidam, NW China
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
UHP metamorphic evolution and SHRIMP geochronology of a coesite-bearing meta-ophiolitic gabbro in the North Qaidam, NW China
چکیده انگلیسی
We have for the first-time observed the well-preserved coesite inclusions in a kyanite-eclogite from the Shaliuhe terrane of the North Qaidam ultra-high pressure (UHP) metamorphic belt, NW China. This provides convincing evidence for UHP metamorphism for the North Qaidam eclogite. Detailed petrography indicates that the kyanite-eclogite records complex metamorphic histories that can be broadly described in terms of three stages: (1) a pre-peak metamorphic stage characterized by the mineral assemblage of Grt + Amp + Pl + Qtz at P = 0.49-0.67 GPa and T = 410-490 °C; (2) a peak eclogite-facies stage with a mineral assemblage of Grt + Omp + Ky + Phn + Rt ± Qtz/Coe at P = 2.7-3.4 GPa and T = 610-700 °C; (3) a retrograde “stage” represented by reaction texture which includes the garnet reaction rims, the breakdown of omphacite, the symplectitic breakdown of kyanite, the retrograded garnet amphibolite assemblage and the latest greenschist-facies overprint. Zircon U-Pb SHRIMP dating shows the peak UHP metamorphic age of the kyanite-eclogite to be ∼440 Ma. These data indicate that the kyanite-eclogite had ever been subducted to mantle depth of ∼100 km in the end of the Ordovician. All these observations allow the construction of a P-T path for the kyanite-eclogite, suggesting a cold geothermal gradient and rapid subduction, ultimately followed by rapid exhumation in response to continental collision in Shaliuhe terrane and throughout the North Qaidam UHP metamorphic belt.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Asian Earth Sciences - Volume 35, Issues 3–4, 1 July 2009, Pages 310-322
نویسندگان
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