| Summary: | Morphological and chemical studies on zircon grains from gabbro and granite of the Pingtan magmatic complex, Fujian Province, eastern China, show that there are three stages of zircon growth. The early stage of zircon growth is characterized by colorlessness, high transparence and birefringence, low and dispersive I-pr and I-py, weak and homogeneous BSE brightness, lower Hf content and depletion of U, Th and Y; the middle stage is characterized by abruptly increasing Ipy, progressively strong and sectoral-zoning BSE brightness, higher Hf content and enrichment of U, Th and Y with Th/U > 1; the late stage of growth is characterized by brownish color, poor transparence, low birefringence, highest I-pr and I-py, middle and oscillatorily-zoning BSE brightness, highest contents of Hf, U and Y with Th/U <1. The stages are considered to be formed in a deep magma chamber, ascent passage and emplacement site, respectively. Due to the more or less long residual time of the magma chamber, the difference in age between the early and late stages of zircon might be great enough to be distinguished, which can be attributed to tectonic constraint for the magmatism.
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