Kj. Sarma, PRELIMINARY GEOCHEMISTRY AND EMPLACEMENT MECHANISM OF MAFIC DYKES OF ANANTAPUR AREA, ANDHRA-PRADESH, Journal of the Geological Society of India, 49(4), 1997, pp. 409-416
The granite - gneiss terrain of Dharvar Craton in Anantapur area of An
dhra Pradesh is intruded by mafic dolerite dykes. These dykes are quar
tz or olivine-normative sub-alkalic tholeiites. Their Mg numbers range
between 0.34 and 0.70 with low Ni(50-150 ppm), Cr(50-337 ppm) and Co(
41-70 ppm), indicating some degree of fractionation. The REE abundance
s show LREE - enriched patterns (La/Yb-N - 2.7 to 5.5). These dykes ap
pear to be genetically related and were derived from a single magma.