石川県南部地域の手取層群に産する黒色珪質岩脈

抄録

Black-colored rocks (Black-colored Rocks hereafter) occur as veins and a volcanic dike in the Tetori Group, southern Ishikawa Prefecture. The Black-colored Rocks are composed of angular lithic clasts in a fine-grained (<10-50 µm) matrix. The lithic clasts in veins are derived from the Tetori Group (mudstone, sandstone, and conglomerate), whereas those in the volcanic dike are derived from both the volcanic dike and the Tetori Group. The matrix of the Black-colored Rocks consists mainly of very fine-grained quartz (usually 10 µm in size) with minor amounts of feldspar, maghemite, and unidentified carbon-bearing fine-grains. The Black-colored Rocks contain abundant SiO2 relative to the host rocks. The chondrite-normalized rare earth element (REE) pattern of the Black-colored Rocks is similar to that of their host rocks, although the REE abundance is lower in the former.