South African Journal of Geology; December 2005; v. 108; no. 4;
p. 587-589; DOI: 10.2113/108.4.587
© 2005 Geological Society of South Africa
The platiniferous dunite pipes in the eastern limb of the Bushveld Complex: review and comparison with unmineralized discordant ultramafic bodies: reply to comment by R G Cawthorn
Roger N. Scoon
PO Box 2461, Rivonia 2128, South Africa, e-mail: rnscoon@iafrica.com
Andrew A. Mitchell
School of Geology, University of KwaZulu-Natal, Private Bay 54001, Durban, 4000, South Africa, e-mail: mitchaa@mweb.co.za
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Introduction
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Our review of the four platiniferous dunite pipes was primarily directed at presenting an overview of the principal geological features of these intriguing features, all of which are located in the eastern limb of the Bushveld Complex, South Africa (Scoon and Mitchell, 2004a). The comment by Cawthorn (2005) is directed at only one component of our review, namely a historical reconstruction of their discovery. This is unfortunate as the geology of the mineralized pipes is poorly known, in part because recent contributions have focussed on detailed mineralogical investigations without the field control of the original descriptions by Percy Wagner (e.g., Wagner, 1929). Cawthorn (2005) introduces his comment by referring to our work as dealing with "the origin of the dunite pipes of the Bushveld Complex", a subject investigated in the contribution of Scoon and Mitchell (2004b): the article under discussion dealt specifically with the mineralized pipes which differ from the unmineralized occurrences as they comprise, in addition to the magnesian dunite, core-zones consisting of iron-rich dunite and wehrlite. Moreover, it was primarily of a review nature and emphasized the geological relationships rather than a discussion of their genesis.
A discussion of the events in 1924 that led to the discovery of the mineralized pipes and culminated in the finding of the Merensky reef and Platreef deposits, like all historical reconstructions, is inevitably open to debate. Cawthorn (2005) has presented his work as representing the final word on this important event, implying that our "retelling" is both unnecessary and "abbreviated". The objective of the Scoon and Mitchell (2004a) article was to present to the reader our investigations into this subject, rather than the subjective approach adopted by Cawthorn (1999). Moreover, we suggest that our research is far more extensively referenced and we introduced numerous . . . [Full Text of this Article]
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