Chronological record of the Early Mesozoic underplating in the northern margin of North China-U-Pb c

• 作 者: Shao Ji'an Zhang Hongfu Liu X
• 机 构: School of Earth and Space Sciences,Institute of Geology and Geophysics and Key Laboratory of Mineral
• 出 处: 自然科学进展（英文版）
• 发表日期: 2004年期
• 关键词: northern margin of North China Mesozoic volcanic rock U-Pb chronometry of zircon

Cathodoluminescence spectroscopic analysis of zircons in the uppermost sanukites of the early Cretaceous Yixian Formation in Western Liaoning reveals zoning structures of the zircons in the volcanic rocks. LA-ICP-MS chronometry shows that the central part of the zircons is remnant zircon with a U-Pb dating of 254 Ma, which is consistent with the age of the Early Mesozoic underplating granulites, and that the periphery is zircon crystallizing out of the host magma with a U-Pb dating of 116 Ma, which is highly consistent with the Ar-Ar dating of the host volcanic rocks. Compositions of the clinopyroxenes xenocrystals in the sanukites are similar to those of the clinopyroxenes in the underplating granulites, indicating that the granulites accreted to the lower crust in the Early Mesozoic have been reformed and disrupted by the upwelling diapers of the asthenosphere and taken part in formation of the sanukites in the Late Mesozoic.