Abstract
The thesis for which a doctorate was awarded by Rhodes University at the beginning of 1974 was: "The Pilanesberg:Geology, Geochemistry and Economic Potential" and it forms a substantial part (65%) of this account. Some of the concepts are possibly somewhat outdated but it is felt that the validity of aspects such as the value of rare element studies for the elucidation of genetic relations between suites of igneous rocks remains. There are several reasons why this expanded version of the thesis has been prepared.
Firstly, as one of the classic alkali ring-complexes, there has been a demand for information regarding the Pilanesberg and its geology and over the years the author who holds the copyright has been requested from researchers abroad for permission to obtain copies of the thesis -the most recent in the current year (2004). The majority of these are persons with a particular interest in alkaline rocks. Secondly, the author did considerable additional work on the Complex some of which has appeared in a number of publications all of which are not easily come by at this stage. Included also are some results from a study visit to the alkali massifs of Lovozero and Khibini located on the Kola Peninsula, Russia in 1992.
Thirdly, a classification presented was based on all the whole rock analyses presented by previous workers. These analyses are presumably of 27 single samples (nothing in their reports suggest otherwise). Subsequent post-thesis results based on 50 composite serial samples (major units were represented by an average of 30 samples each) were in some respects, in gross contradiction to classification details and other aspects and updating is called for.
Fourthly, the account in the thesis ofthe economic potential ofthe Pilanesberg aroused the interest of several mining companies some of whom did considerable additional exploration work. The most important of these in terms of their detailed programmes was, without question, Johanneburg Consolidated Investment. Others were: Newmont Mining and Rio Tinto. Several other companies took an interest but made no contribution in respect of new knowledge. A colleague involved the author in Rare Earths Investment which obtained mineral rights over the more economically interesting areas and which awarded options to companies to do further exploration.
Finally, as virtually the whole of the area of the complex has been developed into a game reserve which has developed to the stage of including the "big five" in its game check list, the area is no longer easily accessible for detailed geological work. It seemed a great pity that all the additional information will not be available to researches and others who have interest in this, one of the geological wonders of the world.Some of the previous mapping was again revised,partly by senior students of the Technikon Witwatersrand under the author's supervision just prior to the introduction of lions into the reserve. Localities are still referred to original farm boundaries which no longer exist but for ease of reference are overprinted on the new map and, in addition, to ease the location of points of interest the game tracks established are included as are the positions of geo-sites unfortunately
one or two of the descriptions at the sites are incorrect (eg., site 3 is actually located on the Green Foyaite ring and not on a "porphyritic dyke").