R8: Metamorphic rocks and tectonics

[R8-12] Heat source of the late Neoproterozoic-Cambrian ultrahigh temperature terrane: constraints from chemical composition of prograde melt inclusions in zircon

[Presentation award entry]

*Kota Suzuki¹, Tetsuo Kawakami¹, Tetsu Kogiso², Shuhei Sakata³ (1. Kyoto Univ. Sci., 2. Kyoto Univ. HES., 3. Tokyo Univ. ERI.)

Keywords:melt inclusion, glassy inclusion, zircon, piston-cylinder, rare earth element

We performed piston-cylinder remelting experiments of prograde melt inclusions in zircon in an ultrahigh temperature (UHT) granulite from Rundvågshetta, Lützow-Holm Complex, East Antarctica. The diffusion-controlled chemical trend characteristic to rapid heating was absent in the Qz-Ab-Or normative diagram. Therefore, the external heat from the mantle is unlikely involved in attaining the UHT, but rather the radiogenic heat may be the viable heat source in this region. This is supported by the long-lived anatexis (~40 Myr) and the lack of syn-metamorphic igneous activities.