MINERALOGY AND TEXTURAL FEATURES OF SETTUPALLE SYENITES, PRAKASM DISTRICT, ANDHRA-PRADESH

The Settupalle igneous complex is characterised by syenitic variants with distinct mineralogical assemblages. The variable perthitic patterns, nature of plagioclase, fayalite-quartz assemblage in Settupalle syenites clearly suggest that the Settupalle igneous complex has evolved under fluctuating pressure and temperature conditions. The mineral chemistry of K-feldspar and plagioclase suggests that K-feldspar assemblage in these rocks indicates their subsolvus nature. The probable crystallization sequence of rocks is fayalite clinopyroxene syenite (FC-Syenite)- fayalite quartz syenite (FQ-Syenite)-hornblende syenite - quartz syenite - nepheline syenite in that order.