OHBA Tsukasa Graduate School of Science, Tohoku University Assist.Prof., 大学院・理学研究科, 助手 (10272014)
HASENAKA Toshiaki Graduate School of Science, Tohoku University Assist.Prof., 大学院・理学研究科, 助手 (50202429)
ISHIKAWA Ken-ichi Graduate School of Science, Tohoku University Assit.Prof., 大学院・理学研究科, 助手 (20158744)
YOSHIDA Takeyoshi Graduate School of Science, Tohoku University Assoc.Prof., 大学院・理学研究科, 助教授 (80004505)
|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1996 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1995 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1994 : ¥1,600,000 (Direct Cost : ¥1,600,000)
During the project term, many igneous rock samples were collected from various tectonic environments in order to analyze their rare earth element abundances and Sr isotopic compositions and to understand how the basic magmas are related with the differentiated magmas. The targeted areas are Izu-Ogasawara region, Pacific ocean, Tanzawa mountainland, Kanagawa-Shizuoka, central Japan, Shitara, Shizuoka, central Japan, Sambe Shimane, southwestern Japan, Kirishima, Kagoshima-Miyazaki, Kyushu, Japan.
As a whole, coexiting basic rocks and differentiated rocks have the parallel REE patterns. Good consistency was recognized and confirmed in all the investigated fields. However, the REE patterns of some of the differentiated rocks corss with the REE patterns for the presumably parental basic rocks. This conflict was rather frequently found in the rocks from Tanzawa area, Sanbe volcano, Ogasawara island. No such relation was recognized in the rocks from Kirishima volcano.
In combination with Sr isotopic composition as well as the other trace element characteristics, the differentiated rocks with parallel REE patterns to the basic oneshould have evolved from the parental magma. In contrast, thoes with non-parallel or even depleted REE abundances could have originated in the crust. They are possibly the products of crustal melting.