You are recovering a read-only tablespace that was writable when the last backup was performed. How would you recover this tablespace?
Restore the last backup and recover until the time that the tablespace was made read-only. When a tablespace becomes read-only, you should take a full backup so that this scenario never occurs. If you should need to recover a tablespace of this type, restore the last backup and apply the redo logs and archived logs to recover the tablespace to the point the tablespace became read-only.