Ductile Shear Zone Between Shantlnagar Uppalchelka in Khammam District, Andhra Pradesh

摘要

This paper describes the results of field investigation arid structural geology of the rocks of the Men between Shantinagar - Uppalchelka In Khammam district of Andhra Pradesh (latitudes 17"14'15" to 17°1 S'43 N and longitudes 80°4r4Q",to 80"44'44" E). A zone of siliciHcation (quartx ? mylonlte with well preserved colour bnjnding) with patches of tectonic'conglomerate (quartz-pebble) is found to occur within the generally dominant amphibolites, Structural analysis indicates the dominant influence of folding deformation (plunge of fold axis 42° -> 74°) in theareo. All microstructural elements (e.g. polygonization, subgrain formation, "core-mantle" structure, ribbon like appearance of quartz grains) are deduced to be related to ductile deformation, recovery phenomena and recrystallisatlon process. Progressive development of tectonic conglomerate fabric and decrease in grain size are typically Indicative of incremental strain magnitude across shear zone in the studied area. A "thin skinned" tectonic model invoking a network of thrusts has been proposed.