You can enabled auditing in Oracle Apps as part of SOX compliance. There is Database Audit (audit_trail=yes) or who column (created_by, updated_by columns) , user access (Sign-on:Audit Level) , Oracle Alert or Audit Trail.
You can use Audit Trail to audit a particular module like HRMS or PO for SOX compliance. Oracle does not provides the list of tables that should be audited to maintain SOX compliance. You should check with the Auditing group within your business to understand their requirements and the way SOX processes are being designed and implemented and then come up with a list of tables that might require/need auditing.

Metalink note#737201.1

Oracle Auditing Whitepaper and Building an AuditTrail in Oracle Apps env

Also metalink has several notes of enabling AuditTrail for Oracle Apps Tables. (Example : Note:60828.1 , Note:848039.1 etc)

HTH