Structural Style Analysis of the Semutang Anticline, Chittagong Hill Tracts, Eastern Fold Belt of the Bengal Basin, Bangladesh

The Semutang anticline is located in the northwestern side of the eastern fold belt (EFB) of Bangladesh. The anticline is typically an elongated brachy anticline, 25 km long and 5 km wide. The fold is wide and gentle, of having dips of 4-5° and amplitude of about 600 m. The axis of the fold runs along NNW-SSE direction. The geological map of the area has been constructed using Remote sensing data like Landsat Imagery (TM), SPOT and aerial photos. The different Beta values of the different sections of the area show that the axial trace of the anticline is a curvilineat unit. The subsurface demarcation of different formations and members have been made from the geophysical well log data and seismic and gravity data analysis. Six stratigraphic conventional sequences and several prominent faults are identified in the subsurface. The faulting and bedding flexuring intensity of the Upper Bhuban is more complex than the Lower Bhuban. The southern plunge of the anticline is more faulted and the faulted blocks are occasionally down thrown than that of adjacent beds. On the basis of seismic data, it is identified that the core of the Middle Bokabil is slightly chevron type but in the eastern side, it is monoclinal. The nature of crisscross complex faults of both Upper and Lower Bhuban indicate the evidence of shale flow or diapiric activities. Two potential hydrocarbon zones are identified from the well log information data.