Stress states, faulting and their effects on the Papaghni Group, Cuddapah Basin, India: a study along Giddankivaripalle-Madyalabodu tract

摘要

Fault slip can perturb the local surrounding stress field in a manner that controls the orientations of induced secondary structures for example, joints. However, the angle between joints and faults is also influenced by the remote stress state, and is particularly sensitive to the ratio of fault-parallel to fault-perpendicular stress. As this ratio increases, joints can propagate away from faults at increasingly higher angles to fault strike and can become almost orthogonal to fault strike. The combination of remote stress state and perturbed local stress field associated with overlapping fault geometries resulted in joint growth at high angles to normal fault strike at field location along Giddankivaripalle-Madyalabodu tract in Papaghni sub-basin of Cuddapah Basin, Andhra Pradesh. The Papaghni sub-basin is deciphered as a rift basin from a sedimentary, structural and geochemical perspective. The area consists of basement granitoids and overlying Gulcheru Formation followed by Vempalle Formation. The tectonic setting suggests that a remote E-W compressional stress field related to Eastern Ghats Orogeny is responsible for development of initially normal Idupulapaya fault and other E-W normal faults. The later generation N-S compression leads to reactivation of Idupulapaya fault into high angle reverse fault movement and northerly shifting of basin margin along with right stepover fault patterns.