R3: High-pressure science and deep Earth's material

[R3-11] UHP pseudotachylyte and nanodiamond

*Tadao NISHIYAMA¹, Kouhei Unoki¹, Ukyo Nishi¹, Tomoya Fujimoto¹, Akira Yoshiasa¹, Hiroaki Ohfuji², Masami Terauchi³ (1. Faculty of Advanced Science and Technology, Kumamoto University, 2. Geodynamics Reserach Center, Ehime University, 3. Institue of Multidisciplinary Reserach for Advanced Materials)

Keywords:pseudotachylyte, nanodiamond, ultrahigh-pressure metamorphism, The Nishisonogi metamorphic rock, The Higo metamorphic rock

This paper reports new findings of ultrahigh-pressure pseyudotachylytes from two metamorphic terranes in Kyushu, Japan. One is a pseudotachylyte in a quartz-magnesite rock associated with serpentinite from the Nishisonogi metamorphic rock, which is formed from serpentinite by the action of CO2 during metamorphism. This pseudotachylyte contains amorphous carbon, in which aggregates of nanodiamond is found. The other one is a pseudotachylyte in a marble from the Higo, consisting of dolomite domain and silicate domain (quartz and Al-Si clay mineral).