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Subduction of Continental Crust in the Early Palaeozoic North Qaidam Ultrahigh‐Pressure Metamorphic Belt, NW China: Evidence from the Discovery of Coesite in the Belt
Author(s) -
Jingsui YANG,
Zhiqin XU,
Shuguang SONG,
Jianxin ZHANG,
Cailai WU,
Rendeng SHI,
Haibing LI,
BRUNEL Maurice,
TAPPONNIER Paul
Publication year - 2002
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2002.tb00071.x
Subject(s) - coesite , eclogite , geology , terrane , geochemistry , metamorphism , subduction , omphacite , metamorphic rock , gneiss , kyanite , zircon , continental crust , petrology , peridotite , crust , basalt , seismology , tectonics
Coesite was discovered as inclusions in zircon separates from pelitic gneiss associated with a large eclogite body in the North Qaidam ultrahigh‐pressure (UHP) terrane. Some graphite inclusions were also found. This finding suggested the occurrence of in‐situ UHP metamorphism and that the terrane was most likely recrystallized at pressures below the diamond stability field. It supported other previous indirect UHP evidence, such as polycrystalline quartz inclusions in eclogitic garnet, quartz lamellae in omphacite and P‐T estimates for both eclogite and garnet peridotite. The U‐Pb and Sm‐Nd ages of the North Qaidam eclogite indicated that subduction of continental crust occurred in the Early Palaeozoic, which probably recorded a collision between the Sino‐Korean and Yangtze plates.