Structural Growth Rate and Impact on Deep-Water Depositional Systems in Deep-Water Fold Belts

Abstract

Summary Examples of slope channels being diverted/deflected by growth folds, salt walls or thrusts are found at the modern seabed and in the subsurface in deep-water fold and thrust belts. We have quantified the shortening rate of thrust-related folds, salt-cored anticlines and faulted salt-detachment folds in three areas (Gulf of Mexico, Lower Congo Basin and Niger Delta), with the aim of investigating whether there are any predictive relationships between structural parameters such as structural relief, growth rate versus sediment accumulation rate, and depositional patterns. Shortening rates in the Niger Delta and t the Gulf of Mexico are comparable. The maxima recorded for the West African salt strutures are lower. However we note that the Pleistocene to Recent channels in the Niger Delta, and the buried Miocene channels in West Africa, are diverted and deflected. by growth rates as low as 30–50 m/Ma. In general, during periods of higher growth, channels are forced to deflect or divert around growing structures. Channels that have established a route through a fold or salt wall can continue to exploit that route down slope as long as the turbidity flows continue to have enough erosive power to keep pace with the growth of the structure.