Abstract: This study presents LA-ICP-MS Zircon U-Pb dating and whole-rock geochemical analysis of a diabase dyke in Hongtoushan area of Qingyuan County, Liaoning Province, which is located in the northeastern margin of the North China Craton, to explore tectonic evolution of the North China Craton in the Mesoproterozoic. The LA-ICP-MS magmatic zircon U-Pb dating results show an age of 1293 Ma±35 Ma for the Hongtoshan diabase , which represents the emplacement age of the diabase dyke. The diabase shows SiO₂=49.42%, MgO=3.56%-5.83%, Na₂O+K₂O=3.95%-6.2%, indicating transitional characteristics between alkaline and sub-alkaline series. The diabase is enriched in LREE, depleted in HREE and HFSE, and has no obvious Eu anomalies. The Hongtoushan diabase belongs to intraplate basalt that was formed in an extensional setting. The magma was derived from the enriched lithospheric mantle influenced by subducted materials and was assimilated by crustal rocks. Combined with available data on the Mesoproterozoic diabase dykes in the north and northeast of the North China Craton, it is suggested that the diabase was formed during the breakup of Columbia supercontinent.

Key words: geochemistry, diabase, zircon U-Pb dating, Columbia supercontinent, North China Craton, Mesoproterozoic