  A growing number of recent observations have revealed that the Galactic
globular cluster (GC) omega Cen is not the only GC that shows abundance spread
in heavy elements (e.g., Fe). In order to understand the origin of the Galactic
GCs with heavy element abundance spread ("HEAS"), we investigate the formation
processes of massive GCs (MGCs) with masses larger than 10^6 M_sun in gas-rich
dwarf galaxies interacting and merging with the very young Galaxy. We find that
massive and compact stellar clumps with masses larger than 10^6 M_sun, which
can be regarded as progenitors of MGCs, can form from massive gas clumps that
are developed through merging of gaseous regions initially at different regions
and thus with different metallicities. Therefore it is inevitable that MGCs
formed in dwarfs have HEAS. The abundance spread in each individual MGC depends
on the radial metallicity gradient of the host dwarf such that it can be larger
for the steeper metallicity gradient. For example, MGCs formed in a dwarf with
a central metallicity of [Fe/H]=-1.1 and the radial gradient of -0.2 dex
kpc^{-1} can have the abundance spread of Delta [Fe/H] ~.2. The simulated MGCs
appear to be significantly flattened owing to their dissipative formation from
gas disks of their host dwarfs. Based on these results, we discuss possibly
diverse formation mechanisms for the Galactic GCs such as M22, M54, NGC 2419,
omega Cen, and Terzan 5.
