OK, this is an old topic. And I'm not a geologist.
My understanding of your OP is that it's basalt
in continental plates that are unsuitable for dating because they are too old, which would cause concentrations of the elements you list to be too low.
OK, my understanding is that oceanic crusts are younger than continental crusts. Am I mistaken in this? Well, the Pacific plate is apparently older and is subtending under boundary plates, but the mid-Atlantic region is spreading, creating new crustal rock all the time. So why would that crust be too old to contain the concentrations of elements that you might expect?