CENTRAL INDIAN SHEAR ZONE - A MAJOR PRECAMBRIAN CRUSTAL BOUNDARY

The paper records the occurrence of mylonites along a major ductile shear zone in Nagpur-Bhandara-Balaghat-Bilaspur-Korba region of Central India, now named as Central Indian Shear/Suture zone (C.I.S.). The main shear zone extends from SSE of Nagpur to south of Korba over a distance of 500 km with a sinuous E-W trend and subvertical to steep northerly dips. Its northern branch extending in ENE direction from Amarkantak to north of Nagai has been named as the Tan Shear. The CIS separates the high-grade Sausar metasediments with a zone of granulites to its north from the dominant low-grade volcanogenic sequences to its south. Bouguer gravity trends over Central India suggest that the CIS probably extends eastwards into the Singhbhum shear zone of Bihar-Orissa and westwards, into the Delhi-Aravalli shear zone in Rajasthan.