In his 1973 Annals paper, Iwasawa proved that the weak Leopoldt Conjecture holds for the cyclotomic $\mathbb{Z}_p$-extension of any number field.

If $K$ is an imaginary quadratic field and $F/K$ is any finite extension, then one can construct the (unique) split prime $\mathbb{Z}_p$-extension of $F$. The split prime $\mathbb{Z}_p$-extension is known to have many properties similar to the cyclotomic extension. (eg. By an adaptation of the work of Sinnott, Schnepps and Gillard could show that $\mu=0$ conjecture holds for $p\neq 2,3$, when $K$).

Is there a known proof of the weak Leopoldt conjecture for the split prime $\mathbb{Z}_p$ extension (of a number field $F$ containing an imaginary quadratic field, $K$)?