Chromian omphacite from low‐grade metamorphic rocks, Nishisonogi, Kyushu, Japan
作者:
T. NISHIYAMA,
S. UEHARA,
I. SHINNO,
期刊:
Journal of Metamorphic Geology
(WILEY Available online 1986)
卷期:
Volume 4,
issue 1
页码: 69-77
ISSN:0263-4929
年代: 1986
DOI:10.1111/j.1525-1314.1986.tb00338.x
出版商: Blackwell Publishing Ltd
关键词: Key‐words:Chromian omphacite;low‐grade metamorphism;metasomatism;serpentinite melange;ureyite molecule
数据来源: WILEY
摘要:
AbstractChromian omphacite which contains up to 4 wt % Cr2O3has been identified from low‐grade metamorphic rocks in Nishisonogi, Kyushu, Japan. It occurs as aggregates, forming a thin horizon ([20 mm thick) in alayered metagabbro within a serpentinite melange zone, together with Cr‐free omphacite, actino‐lite, epidote and sphene. It may have been formed by the metasomatic introduction of Cr into the metagabbro from the serpentinite rather than by reaction with chromite. The structural formula, based on EPMA analyses, and the optical absorption spectrum of the chromian omphacite show that the Cr is positioned in the octahedral
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