@array1 = qw(some_unique_key1 some_unique_key2 some_unique_key3);
@array2 = qw(meta_data_1 metadata_2 metadat_3);
@array3 = qw(submitted_date1 submitted_date2 submitted_date3);

my $hashref;
# @hash{@keys} = @values;
@$hashref{@array1} = map { {'Metadata' =>$array2[$_], 'Submitted Date'=>$array3[$_]} } 0..$#array1;

use Data::Dumper;
die Dumper $hashref;

##</code><code>##

$VAR1 = {
     'some_unique_key3' => {
                             'Submitted Date' => 'submitted_date3',
                             'Metadata' => 'metadat_3'
                           },
     'some_unique_key2' => {
                             'Submitted Date' => 'submitted_date2',
                             'Metadata' => 'metadata_2'
                           },
     'some_unique_key1' => {
                             'Submitted Date' => 'submitted_date1',
                             'Metadata' => 'meta_data_1'
                           }
   };