2008 年 59 巻 9-10 号 p. 467-472
This is a first geologic report about Hirase, Tonpara Iwa and Sandon Iwa Rocks northeast of Amami-Oshima Island. Hirase Rocks is composed of mixed rock of sandstone, mudstone and felsic tuff. Tonpara Iwa Rocks is composed of basalt lava with chert. Sandon Iwa Rocks are composed of basalt lava with a small amount of basic tuff. These rocks contain a amall amount of actinolite and chlorite as metamorphic minerals. These rocks belong to the Naze Unit (Takeuchi, 1993) of the Shimanto Terrane on Amami-Oshima Island.