Turbiditt

Turbiditt is a sedimentary rock deposited by a turbidity current. Turbidity currents are underwater avalanches of sediment-laden water. These currents are denser than the surrounding water, causing them to flow down submarine slopes. As the current loses energy, it deposits its sediment load in a characteristic sequence known as a turbidite deposit.

The classical turbidite deposit exhibits a Bouma sequence, named after Swiss geologist Arnold Bouma. This sequence, from bottom to top, typically includes: graded bedding (coarse grains at the bottom, finer grains at the top), parallel lamination, ripple lamination, finer parallel lamination, and finally, a pelagic mud layer. Not all turbidite deposits display the complete Bouma sequence, as the upper layers are often eroded by subsequent turbidity currents.

Turbidite deposits are common in deep-sea environments, such as continental slopes, submarine fans, and ocean basins. They are significant in the geological record because they indicate past periods of seismic activity, such as earthquakes, which can destabilize sediment on slopes and trigger turbidity currents. Studying turbidites helps geologists understand ancient oceanographic conditions, tectonic events, and the distribution of hydrocarbon reservoirs, as they can trap oil and gas. The composition of turbidites varies depending on the source of the sediment, but they commonly include sandstones, siltstones, and mudstones.