INCIPIENT DIAPIRISM COEVAL TO BHUBAN SEDIMENTATION - A NEW HYDROCARBON EXPLORATION PLAY IN CACHAR FOLD BELT, ASSAM

Reflection seismic facies analysis pertaining to southern part of Kata khal syncline, Cachar Fold Belt, Assam, has brought out an anomalous z one of chaotic reflections bounded by high amplitude, continuous, corr elatable reflection events. This anomalous zone displays an elliptical shape in plan view and is aligned with the associated folds. The gene sis of this anomaly, developed along the eastern flank of the syncline , bracing the synclinal axis is assigned to the non piercement type of shale diapirism within Middle Bhuban Formation of Middle Miocene age. The geological model envisaged has further led to the delineation of supra and lateral diapiric traps in the overlying Upper Bhuban and Bok abil Formations of Mio-Pliocene age. The reconstruction of structural evolution has brought out a phase of inversion during Plio-Pleistocene where the anticlines within Miocene and Mio-Pliocene sequences turned into synclines. The delineated supra and lateral diapiric traps have not been obliterated during inversion episodes. The identified prospec ts are new type of plays to be tested in Cachar Fold Belt, and form a step forward in focusing the thrust areas of exploration on the gentle r synclinal flanks.