I don't recall you making that point, but what I mean by time periods is the millions of years currently assigned to the layers of the Geo Column otherwise known as the Geo Time Scale, the Eras and so on. Time gaps of hours or even days are something else, and would fit into a Flood scenario that takes wave action and tides into account.
Wave action and tides do not add Ar, Sr, or Pb to rocks and minerals. Layers are not dated by depth. They are dated by the ratio of isotopes in the igneous rocks that make up those layers. Water is incapable of sorting these rocks by such small differences in rare isotopes. A recent flood is completely incapable of producing the measured ages found in the rocks themselves.
For example, If an asteroid did hit the Earth 4,000 years ago, then the tektites produced by that asteroid would date to 4,000 years ago, or at the lower age limit of hte K/Ar dating method. They don't. Instead, the K/T tektites at the K/T boundary date to 65 million years before present. A flood can not falsely age these tektites, and it certainly can't decide to only put these tektites of a specific age right above the last dinosaur fossils.