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Chemical Evolution of Zircons in the Paleogene Naegi Granite, Central Japan
Author(s) -
Ishihara Shunso
Publication year - 2008
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.1751-3928.2008.00074.x
Subject(s) - geology , pegmatite , geochemistry , zircon , metamorphic rock , magma , chemical composition , gneiss , electron probe microanalysis , mineralogy , electron microprobe , volcano , chemistry , organic chemistry
The chemical composition of zircons from S‐ and I‐type ilmenite‐series granitic rocks in the Chubu district is summarized based upon recent electron probe microanalysis. Zircons in S‐type Busetsu granite of the Ryoke Metamorphic Belt have a homogeneous composition with minimum impurities, whereas those of I‐type Naegi granite in the non‐metamorphic Sanyo Belt are enriched in Hf, Y, REE, Th and U along the crystal rims. Similar enrichment has been observed in a variety of zircon called Naegite. These minor components are concentrated in the F‐rich fluid phase of residual melts of the Naegi granite magma, and are crystallized in pegmatites during the latest magmatic stage. High values of Nb and Ta in some Naegite reported previously are attributed to micro‐inclusion of fergusonite.