Vd. Rao et al., GEOCHEMISTRY, AGE AND ORIGIN OF PERUR GRANITE, CHITTOOR DISTRICT, ANDHRA-PRADESH, Journal of the Geological Society of India, 44(6), 1994, pp. 637-643
The homophanous coarse-grained granite near Perur, Chittoor district,
Andhra Pradesh ranges in composition from granite (normative) to grani
te-quartzmonzonite (chemical) and records a Rb-Sr whole rock isochron
age of 2549 +/- 39 Ma. Variation observed in the major and trace eleme
nt concentrations (SiO2 = 67.09- 73.83%; Al2O3 = 12.76-14.51%; total i
ron = 2.31-4.97%; MgO = 1.03-3.66%; Cr = 7-102 ppm; Rb = 169-223 ppm a
nd Sr = 128-423 ppm) and the low CaO (less than 2%) in the granite sug
gest that it is a crustal remelting (CR) type granite formed by the an
atectic remelting of an intermediate source rock. The high total REE (
201.38-245.63 ppm), their well fractionated nature (La(N)/Yb(N) = 17.8
3-22.32) and the negative Eu anomaly of the granite support that the s
ource rock was intermediate in composition having hydroxyl-bearing min
erals like biotite and hornblende. The Rb-Sr whole rock age (2459 +/-
39 Ma) of the granite is similar to that of Closepet, Lepakshi and Hyd
erabad granites suggesting that this granite has formed along with the
other K-rich granites by extensive crustal remelting during the Archa
ean-Proterozoic Transition (APT).