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Software brand: Neoarchean to Paleoproterozoic high-pressure mafic granulite from the Jiaodong Terrain, North China Craton: Petrology, zircon age determination and geological implications
Author: ShoujieLiu
Mingzhu Ma
Dunyi Liu
Professional thesaurus: High-pressure granulite;Neoarchean
Date of first publication: 2014-07
Publisher: Institute of Geology Chinese Academy of Geological Sciences
Abstract: The North China Craton is anideal place for studying the transition of the Earth's thermal structure and tectonics at the Archean–Proterozoic boundary due to its good preservation of the ~2.5 Ga tectono-thermal events. We report the discovery of a high-pressure mafic granulite from the Jiaodong Terrain in the North China Craton. The mafic granulite occurs as garnet–clinopyroxene–orthopyroxene–hornblende gneiss enclaves within a late- Archean trondhjemite–tonalite–granodiorite (TTG) gneiss. Typical high-pressure mineral assemblage of garnet–clinopyroxene–plagioclase–quartz ± rutile has been identified. Plagioclase + clinopyroxene ± orthopyroxene ± hornblende symplectite surrounding garnet (“white eye”) is also observed. Using the conventional geothermobarometry and the pseudosection modeling, a clockwise metamorphic P–T path with thepeakconditionsat~17kbarand~880 °Cwasdetermined.ZirconU–Pbanalyses(SHRIMP)ontheovergrowth rimofzircongrainsoftwosamplesfromthesameoutcropyieldedametamorphicageof2473±6Ma(MSWD= 0.8). The analyses on magmatic core gave a probable magmatic age of 2527 ± 12 Ma (MSWD = 1.9). The high- pressuregranulitefaciesmetamorphismcorrespondstoacollisionaleventbetweenthe~2.5Gacrustand~2.9Ga crust at the dawn of Paleoproterozoic in the North China Craton. It also represents a new but rare case of a subduction–collision tectonics at the Archean–Proterozoic transition and provides insight into the change of the Earth's thermal structure.
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