Hi Viktor, have you looked at reports from the Ocean Drilling Program (ODP)? They sample many marine recent sediments around the world. Mudstones get lithified relatively quickly. I have personally seen drill core from Oligocene and Miocene from offshore Brazil, in which the sandstone was almost entirely unconsolidated, but the mudstones and marls were quite consolidated. Of course it depends on the pressure and temperature, so subsidence rates and local variations to geothermal gradients will affect the consolidation state.

Thanks for the shared thinking ;) soonly I will have a conference paper about this topic, I have some new results too :)