X0101 EFFECT 33 LIVE 2014-04-09 16:00:00

S-4

0000866609 ION GEOPHYSICAL CORP 333-194110 0001600867 GX Technology Corp 333-194110-03 0001600906 ION EXPLORATION PRODUCTS (U.S.A.), INC. 333-194110-02 0001600904 I/O MARINE SYSTEMS, INC. 333-194110-01