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Amphibolite facies metamorphism and geochronology of the Paleoproterozoic Aketashitage Orogenic Belt, northwestern China

Authors :
Chun-Ming Wu
Yichao Chen
Qian W.L. Zhang
Jia-Hui Liu
Hui C.G. Zhang
Zhen M.G. Li
Hao Y.C. Wang
Meng-Yan Shi
Van-Tho Pham
Source :
Precambrian Research. 328:146-160
Publication Year :
2019
Publisher :
Elsevier BV, 2019.

Abstract

Garnet amphibolite and semi-pelitic gneiss preserving three stages of metamorphic mineral assemblages, i.e., the prograde metamorphic inclusion assemblage (M1) preserved in the garnet porphyroblast, metamorphic peak assemblage (M2) and retrograde symplectic assemblage (M3), have been recognized in the Aketashitage area, northwestern China. Geothermobarometric computation shows that the M1, M2 and M3 assemblages record the metamorphic P-T conditions of 600–700 °C/4.2–5.3 kbar, 730–790 °C/6.3–7.1 kbar, and 770 °C/5.6 kbar, respectively. These three metamorphic stages define clockwise P-T paths including nearly isothermal decompression (ITD) process, indicating typical orogenic metamorphism. The peak metamorphic P-T conditions reach the transition zone between the high amphibolite facies and granulite facies, and belong to intermediate P/T facies series. The SHRIMP and LA-ICP-MS U-Pb dating of metamorphic zircon implies that the subduction might occur as early as ∼1.97 Ga and last as late as 1.84 Ga. Combined with literature data, it is concluded that the Aketashitage area was a Paleoproterozoic orogenic belt, which is possibly related to the assembly of the basements of the Columbia supercontinent.

Details

ISSN :
03019268
Volume :
328
Database :
OpenAIRE
Journal :
Precambrian Research
Accession number :
edsair.doi...........239bc5f7b6093d337458fda8b3d53fc0