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THE MANGANESE FORMATION OF THE NEOPROTEROZOIC PENGANGA GROUP, INDIA—REVISION OF AN ENIGMA—A REPLY

J. Gutzmer and N. J. Beukes

Department of Geology, Rand Afrikaans University, P.O. Box 524, Auckland Park 2006, South Africa

Corresponding author: e-mail, njb@na.rau.ac.za

The first 20% of the full text of this article appears below.

Sir: We welcome the opportunity to reply to criticism raised by Roy to our publication on the origin of the Neoproterozoic Penganga manganese formation (Gutzmer and Beukes, 1998). Roy’s "strong misgivings" with our contribution center on only one point, namely our conclusion that the todorokite-rich oxide ores mined from shallow trenches by artisan miners is of supergene origin and formed at the expense of a carbonate protore that we discovered. Our interpretation is in obvious contrast to the results of work by Roy and coworkers (Roy, 1981; Bandopadhyay, 1988, 1989, 1996; Roy et al., 1990) who have classified the todorokite-rich ore to be of primary sedimentary origin.

We believe that Roy, with his discussion of our publication, enters into a dispute that has been resolved for many manganese deposits originally thought to comprise primary oxide ores that were later found to be the product of supergene alteration of a carbonate protore. The best example for such supergene development is the economically very important Nsuta manganese deposit, Ghana. This deposit, which has been exploited continuously for over 80 years, was originally thought to be composed of primary manganese oxides (Kitson and Junner, 1927; Service, 1943; Bates, 1958). The manganese carbonate protore was discovered beneath the lateritic oxide . . . [Full Text of this Article]