Life Sciences Essay: Analysis of How Coriolis Forces Can Limit the Spatial Extent of Sediment Deposition of a Large-Scale Turbidity Current

Analysis of How Coriolis Forces Can Limit the Spatial Extent of Sediment Deposition of a Large-Scale Turbidity Current
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Wells, M. G. (2009). How Coriolis forces can limit the spatial extent of sediment deposition of a large-scale turbidity current. Sedimentary Geology, 218, 1-5.
Introduction
The rotation of the earth is a major influence on the deposition scale of turbidity current when their flow transit-time is equal to one day. In this study, laboratory experiments were conducted and proved that the “maximum length-scale L of deposition is n is set by the scale where the Rossby number of the current is equal to one. The dimensionless Rossby number is defined as Ro=U/fL, where U is a depth-averaged velocity of the turbidity current and f is the Coriolis parameter” (Wells, 2008, p. 1). It has been argued that the turbidity of currents under the water allows the carrying of massive volumes of sediments. In the geological perspective, these waves usually form large-scale features that include submarine fans and massive layers of sedimentary rocks within the deepest regions of the ocean basin. In this regard, understanding the impact of these currents and how Coriolis force impacts the spatial deposition of sediments within the ocean is important. Studies have also established that there are many deposits of subsurface oil and gas that is directly associated with the movement of these turbidity currents. Therefore, the processes that influence and control the spatial scale distribution of sediments is important.
In order to understand the influence of Coriolis force on turbidity currents depositional patterns, the study included a series of ten experiments that were carried out on a platform that was rotating, and the turbidity current was released using sediment-laden flow within a corner of a square tank (Wells, 2008). The volume and density of the sediment laden flow was maintained at a constant, and the dynamic of the current were observed whenever there was an increasing background rotation. The results of the experiment were recorded using photographs, which show that deposition pattern of the black silicon carbide clearly standing out against the white background. Whenever there was an increase in the rotation, there was a significant decrease in the radius where deposition occurred. Moreover, there was a slow settling velocity compared to when the rotation was slower. In this regard, we can deduce that the dynamics that control the turbidity current spread under the influence of rotation were found to be analogous with the situation being experienced whenever there is a buoyant river flowing into the denser parts of the salty oceanic waters.
Mathematical Derivation and Physical Explanation
For a constant inflow velocity:
a Rossby number scaling implies that L~U/f,
where U is the inflow velocity of the plume, and the Coriolis parameter on a rotating sphere is defined as f= 2О©sin(Оё), with О© the rotati...