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Mo‐related Adakitic Granitoids from Non‐island‐arc Setting: Jecheon Pluton of South Korea
Author(s) -
Ishihara Shunso,
Jin Myung Shik,
Terashima Shigeru
Publication year - 2005
Publication title -
resource geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 43
eISSN - 1751-3928
pISSN - 1344-1698
DOI - 10.1111/j.1751-3928.2005.tb00259.x
Subject(s) - geology , biotite , pluton , geochemistry , hornblende , partial melting , petrology , basement , continental arc , adakite , tectonics , crust , subduction , oceanic crust , volcanic rock , quartz , paleontology , volcano , civil engineering , engineering
. The Jecheon granitoids, having an elongated shape of NE‐SW 27 km and NW‐SE 13 km (190 km 2 ), are composed mostly of magnetite‐series hornblende‐biotite granodiorite and biotite granite, which intrude into the Neoproterozoic metamor‐phic and Paleozoic sedimentary rocks of the Ogcheon Belt. The granitoids have Triassic‐Jurassic age of 202.7 ±1.9 Ma with very high 87 Sr/ 86 Sr initial ratio of 0.7140. The granodiorite has 63–69 % SiO 2 , 15.1–17.3 % Al 2 O 3 , <1.6 % MgO, 6–15 ppm Y and Sr/Y ratios of 24–76, and is depleted in HREE. Biotite granite together, the Jecheon pluton has adakitic characteristics, which are unique in a continental tectonic setting. The granitoids may have been generated by partial melting of an older adakitic granitoid of I‐type basement, or by separation of early crystallized garnet and hornblende from an anatectic melt.