Document Type	Master's Dissertation
Author	Clark-Halkett, Chantelle Estelle
Email	chantellecharkhalkett@yahoo.com
URN	etd-06262012-142710
Document Title	An investigation into the formation of the lower Main Zone in the eastern limb of the Bushveld complex, South Africa
Degree	MSc
Department	Geology
Supervisor	Advisor Name Title Dr J Roberts Supervisor
Keywords	Bushveld Main Zone South Africa
Date	2012-04-13
Availability	unrestricted
Abstract The Main Zone is dominated by medium – grained, homogeneous gabbronorite, and anorthosites. The plagioclase compositions of the core is ((Na(0.227 – 0.353), K (0.012 – 0.046), Ca (0.651 – 0.777)) Al (1.630 – 1.752) Si (2.183 – 2.345) O8) and at the rim is ((Na (0.189 – 0.371), K (0.005 – 0.108), Ca (0.651 – 0.777)) Al (1.630 – 1.752) Si (2.183 – 2.345) O8). The composition of orthopyroxene is ((Mg (0.660 – 0.808), Fe (0.206 – 0.309), Ca (0.007 – 0.081)) Si (0.960 – 1.037) O3) and the compositions of clinopyroxene is ((Mg (0.229 – 0.678), Fe (0.092 – 0.427), Ca (0.012 – 0.475) Si (0.776 – 1.012) O3. The Mg# and An# varies with depth, where plagioclase increase in concentration the An# increases and the Mg# decreases. The variations in magma compositions are attributed to interlayering of different lithologies which are the result of fractional crystallisation in the magma chamber. This is supported by linear trends of the major and trace element bivariant plots. The magmatic event forming the Main Zone resulted in lateral expansion of the sheet – like magma chamber. The Main Zone formed through two magmas; first magma forming the lower Main Zone and the second magma, intruded the Main Zone at the level of the Pyroxenite Marker, forming the upper Main Zone. Copyright © 2010, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria Please cite as follows: Clark-Halkett, CE 2010, An investigation into the formation of the lower Main Zone in the eastern limb of the Bushveld complex, South Africa, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-06262012-142710 / > E12/4/464/gm
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