Relative rates of shell dissolution and net sediment accumulation - a commentary: can shell beds form by the gradual accumulation of biogenic debris on the sea floor?
Article first published online: 9 OCT 2007
Volume 22, Issue 2, pages 207–212, April 1989
How to Cite
DAVIES, D. J., POWELL, E. N. and STANTON, R. J. (1989), Relative rates of shell dissolution and net sediment accumulation - a commentary: can shell beds form by the gradual accumulation of biogenic debris on the sea floor?. Lethaia, 22: 207–212. doi: 10.1111/j.1502-3931.1989.tb01683.x
- Issue published online: 9 OCT 2007
- Article first published online: 9 OCT 2007
- Shell dissolution;
- shell accumulation;
- sedimentation rate;
- shell bed;
- time averaging
Rates of shell production rarely exceed 500 g CaCO3.m-2yr-1 in clastic sediments. Loss of shell carbonate by dissolution greatly exceeds loss by bioerosion and abrasion in most habitats. Rates of shell dissolution in modern sediments, estimated from rates of organic carbon degradation or measured directly, usually exceed 1000 g CaCo3.M-2yr-1. This taphonomic loss is concentrated at or just below the sediment-water interface in the taphonomically-active zone (TAZ). Consequently, except where rates of shell production are very high or rates of organic carbon degradation very low, shells cannot permanently accumulate on the sea floor. Preservation requires rapid burial, usually by physical ‘event’ processes, to slow down taphonomic loss. Only near the base of the TAZ does the long-term sedimentation rate become an effective mediator of shell preservation as sediment accumulation gradually removes buried shell material from the taphonomically-active zone.