Final answer:
While the question seems to imply a relation between submarine propulsion systems and submarine canyons, the two are not directly related.
Step-by-step explanation:
Magnetohydrodynamic (MHD) propulsion systems in submarines can create currents in the form of a silent propulsion mechanism. These currents are a result of the force experienced by charged particles (sodium and chlorine ions from salt) moving in a magnetic field within a channel of salt water that runs through the submarine's structure.
However, it turns out that such propulsion systems are not very practical due to the need for either extraordinarily high magnetic fields or extraordinarily high electric currents for reasonable thrust.
A prototype of the MHD drive indicates significant drawbacks. This system would generate noise through electrolysis, creating bubbles of hydrogen and oxygen, and leave a detectable trail of chloride ions and metal chlorides. Additionally, the chloride ions tend to quickly corrode metal parts, making it a less viable option for stealth operations.
Although summing the state of MHD propulsion system, this does not directly answer the question regarding the type of currents produced in some submarine canyons, which are actually referring to oceanic currents shaped by geological and environmental factors rather than being related to submarine propulsion systems.