TIMEZONEを使用したOracleTIMESTAMPのクエリ

AT TIME ZONEを使用できるはずです 構文

SELECT column_name at time zone 'UTC'
  FROM your_table

つまり

SQL> select * from foo;

COL1
---------------------------------------------------------------------------
09-FEB-12 01.48.40.072000 PM -05:00
09-FEB-12 10.49.26.613000 AM US/PACIFIC

SQL> select col1 at time zone 'UTC'
  2    from foo;

COL1ATTIMEZONE'UTC'
---------------------------------------------------------------------------
09-FEB-12 06.48.40.072000 PM UTC
09-FEB-12 06.49.26.613000 PM UTC