北部九州白亜紀花崗岩類,真崎花崗岩の化学組成と活動時期

摘要

Major and trace elements analysis, U-Pb zircon dating, rare earth elements analysis and Sr-Nd isotope analysis were conducted on the Masaki Granite in the eastern part of northern Kyushu, Southwest Japan. This granite is mainly composed of coarse-grained porphyritic biotite granodiorite to granite. Whole- rock chemical compositions of this granite indicate that the chemical variations can be mainly explained by fractional crystallization of plagioclase and biotite. The U-Pb zircon dating separated from the Masaki Granite gives an age of 103.73 ± 0.79 Ma. This age is thought to be a timing of activity of this granite. Initial Sr and Nd isotopic ratios corrected to 103. 73 Ma of the two samples of the granite are the almost same and plotted within the range of the North Zone defined by Kagami (2005).