Clinopyroxene exsolution in wollastonite from Namaqualand granulite, South Africa

被引：6
|
作者：
Seto, Y
Ohi, S
Shimobayashi, N
Kitamura, M
Miyake, A
Hiroi, Y
Grantham, GH
机构：
[1] Kyoto Univ, Dept Geol & Mineral, Kyoto 6068502, Japan
[2] Chiba Univ, Dept Earth Sci, Chiba 2638522, Japan
[3] Council Geosci, ZA-0002 Pretoria, South Africa
来源：
AMERICAN MINERALOGIST | 2006年 / 91卷 / 2-3期
关键词：
wollastonite; exsolution; clinopyroxene; TEM; EBSD;
D O I：
10.2138/am.2006.2063
中图分类号：
P3 [地球物理学]; P59 [地球化学];
学科分类号：
0708 ; 070902 ;
摘要：
Chem\ical and crystallographic properties of clinopyroxene exsolution in wollastonite are described from metamorphosed calc-silicate granulite, Namaqualand, South Africa. The wollastonite is Ca1.9Fe0.01Al0.01Si2.01O6 belonging to space group P2(1)/a (2M polytype) and the clinopyroxene is Ca0.99Mg0.75-0.80Fe0.17-0.2tNa0.02Al0.03Si1.99-2.00O6 belonging to C2/c. An electron backscattered diffraction investigation suggests that the clinopyroxene lamellae elongated along [111] lie on (120) and (100) of the wollastonite-2M, and [110] of both lamellae are parallel to [00 1] of the wollastonite-2M. The formation of the exsolution probably results from the relatively high peak metamorphic temperature (800-860 degrees C) of the Namaqualand granulite and its slow cooling rate.
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页码：446 / 450
页数：5
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