I'm not a scientist in this field, but I was just wondering whether these two datasets could help each other for the benefit of a better understanding of human mobility in the past.
This simple answer is No and Maybe. 18O signatures obtained from human bio-apatite (bone and/or teeth) are correlated with 18O signatures of dietary water intake (directly as well as indirectly from fruit and vegetables). The precursor pool of 18O signatures in food and drink is precipitation and the 18O signature of precipitation varies with/depends on distance to open sea, latitude, altitude and temperature, which is why bio-apatite 18O signatures can be used to draw conclusions about human mobility in the first place.
However, even first landfall precipitation 18O composition differs from marine surface water 18O due to isotopic fractionation during cloud formation out at sea and isotopic fraction during precipitation.
Ice core 18O may provide helpful information but that would be limited to ice cores taken in alpine environments (glaciers), i.e. ice core records of terrestrial precipitation.
Marine 18O records as in climate / temperature change records may be useful if it can be shown that particular mass migration events correlate with significant (global) climate change events.
In archeology, we use 18O bioapatite signatures that can be used to draw conclusions about human mobility in the first place. From human bio-apatite (bone and / or teeth) 18O signatures are correlated with dietary intake water (directly and indirectly from fruit and vegetables).