Anorthosites and Associated Rocks of Nellore-Gudur, South India

Structural, petrographic and geochemical characters of several anorthosite bodies exposed over a length of eight km in the eastern margin of India are presented. From the asymmetry of parasitic folds and cleavage/bedding relationship in the host rocks, it is concluded that these were emplaced into anticlinal cores of isoclinally folded Precambrian schistose formations.

Textural variation from centre to border, mafic enrichment towards the margins. alignment of linear structures combined with steeply dipping foliation of arcuate nature parallelling the boundaries. suggest that anorthositic bodies are plug-shaped and viscous magmatic fluid moved vertically upwards. The progressive variation in mineralogy. grain-size and some of the major oxides is attributed to flow differentiation.