Lag Time
This a period of the time following a marine across a carbonate platform surface and the initiation of carbonate accumulation across this surface. This lag time postdates a preceding period of subaerial exposure when earlier sediments may be have been eroded or modified.Tipper, 1997 identified that rates of carbonate accumulation on carbonate platforms are commonly found to lag behind relative sea-level change, and suggests this lag is a natural result of the time taken to establish colonization of an exposure surface. This lag time will vary as a function of the depth of water.Modelling time lags and accumulation rates is made complex by the fact that it is not known exactly what sediment was there before exposure or how long the exposure lasted before the earlier sediment was modified or removed. This makes studying the initiation of the carbonate factory very difficult.The reason the lag time period is controlled by the depth of water, is that a depth of water is required before effective circulation occurs and allows the development of an active carbonate factory. This depth commonly appears to be 1 to 2 meters.
Index to carbonate shelf sediments
Wednesday, April 03, 2013