R6: Plutonic rocks, volcanic rocks and subduction factory

[R6P-05] Diversity of leucocratic rocks in serpentinite melange in the Omi area, Itoigawa City, Niigata Prefecture

*Shiori Okuyama¹, Shin-ichi Kagashima¹, Ko Takenouchi², Takahiko Ogawara² (1. Yamagata Univ., Sci, 2. Fossa Magna Museum)

Keywords:Serpentinite melange, metasomatism

The Omi area of Niigata Prefecture is located near the Itoigawa-Shizuoka Tectonic Line (ISTL), where a variety of leucocratic rocks are distributed in the serpentinite melange. From the petrography results, leucocratic rocks are divided into three types as follows, two mica-bearing, zoisite-bearing, and amphibole-bearing. As a result of the Sr content indicates the presence or absence of metasomatism. Therefore, zoisite-bearing and amphibole-bearing rocks underwent metasomatism, whereas other granitic rocks indicate primitive values.