EPMA U-Th-Pb monazite dating of metamorphic rocks from the Mogok Metamorphic Belt, central Myanmar

摘要

The Mogok Metamorphic Belt (MMB), situated in central Myanmar, contains an assemblage of high-grade metamorphic rocks believed to have been formed during a regional Early Eocene-Oligocene metamorphic event. We newly found Grt-Opx granulite in the Mogok area, which was formed under pressure-temperature (P -T ) conditions estimated as being 6.5-8.7 kbar and 800-950 °C. Based on the results of EPMA U-Th-Pb Mnz dating, the central MMB, which runs through the Mogok, Mandalay, and Meikthila areas, is characterized by an Eocene to Oligocene deformation and fluid infiltration event. In addition, several Mnz grains from the Meikthila and Mandalay areas record ages of the Late Triassic (～ 200 Ma) and Cretaceous (～ 80 Ma and 110 Ma) geologic events.