The "Champion Gneiss" in the Archaean Complex of Mysore, Southern India - A Review

Smeeth's classification of the granites and granitic gneisses comprising the major portion of the Archaean Complex of Mysore, into 4 separate epochs of plutonic intrusions starting with the" Champion Gneiss" as the earliest granitic intrusion into the Dharwar System, and his views that each of those intrusions comprise several types resulting from magmatic differentiation and crystallisation need some modifications as the author has already previously pointed out. This paper specially deals with the" Champion Gneiss"; and its position as an independent epoch of granitic intrusion is briefly reviewed and discussed.

Attention is drawn to the fact that the indiscriminate extension of the term "Champion Gneiss"-(the name originally given by Smeeth to a fine grained, opalescent quartz bearing micaceous gneiss, which he believed to be the highly crushed phase of the earliest granitic intrusion into the Dharwar System) to include several other types of schistose acidic and basic rocks which contain such opalescent quartz,:and even to some granites and other rock types which do not contain it, has led to much confusion in the classification, correlation, and correct interpretation of the origin of those types. Describing briefly the chief characteristics of the various types of rocks which have been included under the comprehensive term "Champion Gneiss", the author has now defined the term "Champion Gneiss". discarding from the group several types which cannot by any means be considered as granitic variants. The name is to be restricted only to the island-like exposures of granitic rocks within the schist belts, with their finer-grained marginal types and their undoubted crushed and altered phases.

The granites of this series are considered to have come up or intruded throwing aside their covers and crystallised directly from molten material (magma); the regions where we may expect to find the basement rocks of the Dharwar System, are also indicated.