The protein localization process in which two MCM complexes become associated with chromatin at replication origins. MCM loading begins when origin-bound ORC and Cdc6 (Cdc18 in fission yeast) recruit one MCM2-7/Cdt1 complex to the origin, includes formation of a succession of intermediate complexes and ATP hydrolysis-dependent Mcm2-7 ring closure, and ends when two MCM hexamers fully encircle DNA, and are oriented head-to-head. The double hexamer is inactive for DNA unwinding. MCM loading takes place during G1 phase, and precedes CMG complex assembly.
MCM complex loading at replication origin