Mechanisms of sea transgression and regression

I believe that most geologists would attribute inter-regional transgressions to plate tectonics in that a surge of mid-ocean ridge volcanism would swell the ridges to such an extent that they would displace seawater onto the continental masses.ETA: This would be supported by the fact that the Cretaceous Period seems to be a time of increased ocean ridge volcanism (i.e., wide bands of Cretaceous sea floor on either side of the mid-ocean ridges) that would correspond to the Zuni transgression.This would, of course result in global dimensions for the transgressions and yet we don't see evidence of such on all continents.I recently read of the possibility that depending on climate, the degree of erosion going on at any one place might mask the effect of a transgression and/or regression. That would make some sense.I'm also of the opinion that some continents might be undergoing a significant degree of orogeny due to the local effects of subduction or continental collision that would also affect the amount of both erosion and deposition. Edited by edge, : No reason given.

The width of the Cretaceous seafloor bands extending away from the mid-ocean ridges are wider for the number of years than other periods. This is known due to radiometric dating and correlation of magnetic signature of the oceanic crust. This suggests a temporary increase in the amount of seafloor spreading and the volcanism that would accompany it.

Most probably are more local or regional.Cratonic Sequences are a unifying theory that blend a lot of data but don't provide a lot of details. In a way, it's kind of like evolution, but on a more modest level.

That's a good question. I don't know, but the Pacific Basin shows it more readily because the plates are moving so much faster. When there are continents associated with the plates they tend to move more slowly. For western NA, most definitely. You see an increase in volcanism into the Tertiary and you see several orogenic episodes starting in the Jurassic. These are mostly related to increased subduction rates along the western edge of the NA Plate.While these are regional effects, one might expect some global consequence since sea level is more or less a global feature. However, there are a lot more variables than just seafloor spreading activity.

Most absolute dates are radiometric. I think some are bioichronological. Relative ages are still how we describe them, such as Ordovician or Cretaceous.

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(And is anyone paying attention to all this in relation to the movement of the Supercontinents and the breakup of Pangaea and all that?

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Yes, that's the whole idea. We are not like YECs in applying ad hoc solutions to questions. I'm not sure what you are asking. Well, yes that's pretty much what happened. For instance, there basically isn't much seafloor older than Jurassic unless it's been accreted to the continents. Part of that is due to more recent rifting as you suggest, but much is due to subduction which is kind of the ultimate fate of old, thick oceanic crust.So, likewise, if rifting started in the Cretaceous, there would be less Cretacesous and no Jurassic seafloor.