Your work incorporating the Wikipedia material appears to be an "Adaptation" as defined in CC-BY-SA 3.0 Unported 1.a:
"Adaptation" means a work based upon the Work, or upon the Work and other pre-existing works, such as a translation, adaptation, derivative work, arrangement of music or other alterations of a literary or artistic work, or phonogram or performance and includes cinematographic adaptations or any other form in which the Work may be recast, transformed, or adapted including in any form recognizably derived from the original, except that a work that constitutes a Collection will not be considered an Adaptation for the purpose of this License. For the avoidance of doubt, where the Work is a musical work, performance or phonogram, the synchronization of the Work in timed-relation with a moving image ("synching") will be considered an Adaptation for the purpose of this License.
Now see 4.b:
You may Distribute or Publicly Perform an Adaptation only under the terms of: (i) this License; (ii) a later version of this License with the same License Elements as this License; (iii) a Creative Commons jurisdiction license (either this or a later license version) that contains the same License Elements as this License (e.g., Attribution-ShareAlike 3.0 US)); (iv) a Creative Commons Compatible License.
4.b(ii) clearly gives you the right to relicense the work as CC-BY-SA 4.0 which in turn, I believe, allows you to relicense the work as GPLv3.
4.b(iv), at least on my interpretation, allows you to relicense the work directly as GPLv3.
Either way, you appear to have a valid route to license the resulting combined work as GPLv3.
See also @unor's answer on FOS.SE, which reaches a similardifferent conclusion.
