Influence of tectonics and neotectonics on the morphogenesis of the peak karst of Halong Bay, Vietnam

In northeast Vietnam, the karst of Halong Bay is characterized by very acti ve neotectonics. The directional distribution of fracturing of the calcareo us rocks is characterized by the influence of two major fault zones: the Re d River fault zone (N140) and the Tan-Lu fault zone (N050). Karst developme nt was favoured by intense fracturing, according to these two major directi ons, and reactived during recent tectonics by a compressional regime with s igma 1 N070, followed by an extensional regimes with ol near to EW that led to significant vertical movement. These tectonics, coupled with intense er asion, led to genesis and evolution of the spectacular morphology of this p eak karst. (C) Elsevier, Paris.