A Study on Mafic Dyke Swarms of Chittoor District- Southern India

The present work is a systematic study of Mafic Dyke Swarms (MDS) exposed in the vicinity of Cuddapah basin, Chittoor district, Andhra Pradesh, Southern India, to know the evolution of mafic dyke swarms. Based on field relations, petrography and geochemistry broadly four types of dykes have been delineated namely Olivine dyke, Normal dyke, Quartz dyke, and Micropegmatite dyke. The older olivine bearing dolerite dykes emplaced at deeper levels where temperature is high and resulting into clouding of feldspars leads to the formation of quartz dolerites, emplaced at crustal levels where the temperature is comparatively less. Calc-alkaline nature is due to the crustal contamination and also due to higher fractionation of tholeiites.