Petrology and geochemistry of syenite at Kamaneri area, Salem district, Tamil Nadu Srinivas M.*, Prasad K. Rajendra, Sreenu K. Department of Geology, P.G. College of Science, Osmania University, Saifabad, Hyderabad-500004 (A.P.) *vaishnavi111@yahoo.com
Online published on 3 December, 2011. Abstract A syenite body corresponding to alkaline magmatism occurs as an isolated body at Kamaneri, 20 km, NW of Salem. It represents the northeastern extension of the alkaline-carbonatite-ultramafic complex of Pakkanadu in Tamil Nadu. It is found in a close spatial association with a diverse group of rocks of the Peninsular Gneissic Complex and is intruded by a late-stage porphyry syenite dyke. The syenite is leuocratic, medium to coarse grained, equigranular and exhibits hypidiomorphic texture and is composed of K-feldspar (represented by microcline perthite) clinopyroxene and amphibole, along with subordinate plagioclase feldspar. Magnetite, sphene, zircon calcite and apatite constitute the major accessory minerals. The syenite displays an overall silica saturated to oversaturated signature, with K2O > Na2O. Though the rock has a very low modal quartz, normative quartz is seen developing. The major and trace element geochemistry of this rock is comparable to the syenites of the other areas. The syenite of Kamaneri is enriched in Rb, Ba and Sr and exhibits LREE enriched and HREE depleted REE patterns, with a perceptible Eu anomaly and is supposed to have fractionated from an alkaline magma aided by a small degree of partial melting. Top Keywords Pakkanadu complex, Kamaneri, Syenite and Eu anamoly. Top |