A Reinterpretation of the Geological History of the Singhbhum Shear Zone, Bihar

Abstract

Abstract The Singhbhum shear zone represents a deep seated fracture that probably extended up to the upper mantle through which basic rocks poured out continuously and extensively together with some ultrabasic rocks. The northern block gradually subsided and received sediments interlayered with basic rocks and tuffs, with a conglomerate horizon at tbe base. Subsequently the movements were reversed along the line of fracture and it was transformed into a zone of shearing within which migma-magma activity and mineralisation took place. Residual stresses within the shear zone were released through wrench faulting after which the shearing movements resumed locally and continued even up to recent times at some places.