Geological setting and origin of fuchsite‐bearing rocks near Menzies, Western Australia
作者:
J. E. Martyn,
G. I. Johnson,
期刊:
Australian Journal of Earth Sciences
(Taylor Available online 1986)
卷期:
Volume 33,
issue 1
页码: 1-18
ISSN:0812-0099
年代: 1986
DOI:10.1080/08120098608729346
出版商: Taylor & Francis Group
关键词: hydrothermal alteration;fuchsite;andalusite;chromium;Archaean geology;komatiites;Yilgarn;Eastern Goldfields
数据来源: Taylor
摘要:
Quartz‐andalusite‐fuchsite rocks in an Archaean greenstone belt at Menzies, Western Australia, are described in their geological setting. They are shown to have developed from intense metasomatism of layered rocks of komatiitic composition. Ratios of the immobile components A12O3, TiO2, Cr, V and Zr are consistent, despite wide variations in their absolute values, and compare closely with those of an underlying komatiite suite. Marked depletion of Ca, Na, Mg and Fe has led to a strongly peraluminous composition and enhanced Cr values. Silicification and introduction of K has also occurred. Most of the metasomatism took place before peak metamorphism, and the mineral assemblage is now dominated by andalusite, fuchsite, and recrystallized quartz. Schlieren or vein‐like segregations rich in andalusite, chromite, rutile and minor sulphides and tourmaline are interpreted as the original fluid pathways, where concentration of immobiles was achieved through solution of mobile components, and volume loss. They have been termed residual veins. Metasomatism is believed to have taken place by synvolcanic processes analogous to those operating in modern hot spring systems. The rocks were severely modified by metamorphism and tectonism. The fuchsitic rocks at Menzies are compared to similar rocks in other areas.
点击下载:
PDF (1775KB)
返 回