The kde use flag is masked for ppc*, which breaks marble. This prevents installation of kde-meta. Please unmask it, as the use.mask comment is vague and not apparently supported by a bug.
I guess you mean arch/powerpc/ppc64/64ul/use.mask: # Agostino Sarubbo <ago@gentoo.org> (22 Dec 2012) # mask kde since is not anymore keyworded for ppc64 kde
Yes, sorry.