Mechanism maintaining polymetallic nodules at the sediment surface

Identify and quantify the mechanism(s) that maintain deep-ocean polymetallic nodules at or near the sediment surface despite growth rates lower than sedimentation, resolving the paradox of their surface occurrence (e.g., biological activity, seismic uplift, or other processes).

Background

Hydrogenetic and diagenetic models predict slow nodule growth, often slower than sedimentation rates, yet nodules are commonly found on the sediment surface. Proposed explanations include bioturbation, biological lifting, or seismic processes.

The review acknowledges that multiple hypotheses have been advanced but that the specific mechanism responsible for maintaining nodules at the surface has not been conclusively established.