U-Th-total Pb monazite chemical dating protocol: application to Gneiss from Wilson metamorphic complex (WMC), Northern Victoria Land (NVL), Antarctica

Abstract

The present study introduces a novel protocol for U-Th-total Pb monazite chemical dating using JEOL JXA-8530F fieldemission electron microprobe at the Electron Microprobe Laboratory of the Division of Glacier and Earth Sciences, Korea Polar Research Institute (KOPRI), Incheon, Republic of Korea. U-Th-total Pb chemical dating by electron microprobe method is an in situ technique with potentially higher spatial resolution. The consistent chemical-chronological data from the well-dated RW1 and COM-1 monazites validate the reliability of the analytical protocol used for U-Th-total Pb chemical age dating of monazite. The new protocol has been applied to quartzofeldspathic biotite/±cordierite gneiss from the Wilson Metamorphic Complex (WMC), Northern Victoria Land (NVL), Antarctica. The application of this method to WMC quartzofeldspathic gneiss has yielded refined age estimates that reveal multiple thermal phases from texturally constrained in situ monazite age data. Based on new age data, we argue that the thermal history in the WMC occurred in a span of ca. 496？455 Ma with the evidence of inherited older age domain of ca. 515 Ma. These results offer new insights into the geologic history of Northern Victoria Land to improve our understanding of the thermal evolution within the broader context of Antarctic tectonics.