Chronological record of the Early Mesozoic underplating in the northern margin of North China - U-Pb chronometry of zircons in the Late Mesozoic andesite from Western Liaoning

Abstract

Abstract Cathodoluminescence spectroscopic analysis of zircons in the uppermost sanukites of the early Yixian Formation in Western Liaoning reveals zoning structures of the zircons in the volcanic rock. 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. *Supported by National Natural Science Foundation of China (Grant Nos. 40372103, ...