Title: U-Pb ages and oxygen isotope compositions of zircons from gneiss of Huangtuling, Northern Dabie; old protolith and multi-stage evolution.
Abstract: The internal structure of zircons from gneiss of Huangtuling, Northern Dabie has been investigated by
cathodoluminescence imaging, and their U-Pb ages and oxygen isotope compositions have been determined by SIMS (Cameca 1270). Zircons display core-mantle-rim structure, the core is the magmatic domain which preserves oscillatory zoning, the mantle is the metamorphic zone induced by recrystallization, and the rim is the overgrowth domain which was precipitated from partial melt. These three domains have different ages: ~2800Ma for the core is the protolith age, -2000Ma for the mantle is the metamorphic age, and ~ 110Ma age for the rim reflects the influence of Cretaceous thermal event. ~ 2800Ma and ~ 2000Ma ages for Huangtuling gneiss and its included granulite and ~ 3400Ma age for relict zircon from Huangtuling granulite are comparable with the ages for Kongling group of Yangtze block, so it is inferred that Northern Dabie was a part of Yangtze block and the suture between Yangtze and North China blocks should be north of Northern Dabie. Oxygen isotope composition of the core, mantle and rim of zircons are different, δ18O values of the core are - 11.7‰, 11. 1‰ ~ 18.7‰ for the mantle and 5.5‰ ~8. 2‰ for the rim. From these oxygen isotope data we suggest that the protolith of Huangtuling gneiss was S-type granite and exotic fluid/melt involved in the system during both - 2000Ma and ~ 110Ma events.
Publication Year: 2003
Publication Date: 2003-01-01
Language: en
Type: article
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Cited By Count: 15
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