Cite this article:
Nathan and Amer (1990). Geochemistry and petrogenesis of dykes and sills of south arcot district, Tamil Nadu. Journal of Ravishankar University (Part-B: Science), 3(1), pp. 14-20.
Ravishankar University, Vol. 3, No. B (Science), 1990,
Geochemistry and petrogenesis of dykes and sills of south arcot district, Tamil Nadu
S Rama Nathan and Ali Amer,
. Department of Geology, Presidency College, Madras
MS received 1
November 89; revised 11 March 90.
In the study area of South Acrot district, bearing sills and dolerite dykes are found to have intruded the migmatitic country rocks. A detailed
study of these rocks
reveals that these basic rocks are related to each other and have undergone moderate differentiation. Petrochemical studies indicate less variability in composition and in their trace-element
patterns. The range of Mg ratio (MgO/MgO + FeO + Fe2O3) between 0.35 and 0.46 also confirms this view. Sills are considered to have
formed after oiliivine bearing dolerites
followed by the two types of dolerite dykes. The parental magma of the
rock types is considered to the tholeiitic. The ta value indicates that the crust might have been thinner at the time of emplacement of dykes.
NOTE: Full version of this manuscript is available in PDF.