A Preliminary Study on the Late Cenozoic Structural Characteristics of Arakan Fold Belt, Bay of Bengal

Tang, Pengcheng; Fuliang, Lu; Guozhang, Fan; Wang, Xuefeng; Sun, Hui; Li, Li

Arakan fold belt (Bay of Bengal) located at the west piedmont of Indo-Burman Ranges, comprising a series of NNW-SSE-trending anticlines, its structural characteristics is very poorly studied. Integration of well data and 2-D seismic reflection profiles are used to study the late Cenozoic structural characteristics of Arakan fold belt, focusing on the development characteristics of décollement and geometry and kinematics of anticlines. Arakan fold belt is characterised by consisting of multiple décollements: (1) basal décollement, which situated at about 6.5 s (Two-way traveltime); (2) intermediate décollements, which situated at the bottom of Quaternary or underlying upper Miocene at about 2.5 s. Those décollement horizons generate two sets of detachment folds under regional compression. The basal décollements controlled the development of Arakan fold belt, while the intermediate décollement affected the deformation locally, the deformation propagated from east to west with the leading edge formed in Quaternary. Based on structural analysis results we proposed two end-member kinematic models for folding in Arakan fold belt. Model 1 without intermediate décollement level, detachment fold formed above basal décollement; Model 2 with intermediate décollement level, two sets of detachment folds developed above basal and intermediate décollements, respectively. The wavelength of anticline in Model 2 is much shorter than that of Model 1, therefore, the wavelength of anticline can be used to judge whether intermediate décollement level developed or not in deformed strata pile. The geometry and kinematics of anticline is primarily controlled by underlying décollement level(s), the formation of overlapping anticlines or anticline bifurcation in Arakan fold belt would imply the underlying décollement level(s) changed along strike. Fluid overpressure could be an important deformation controlling factor in formation of Arakan fold belt.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013