What you saw was just a plain normal crash recovery (aka instance recovery). What it means is that some changed blocks of commited data has not been written into the datafiles before the database crashed, but as those commited changes were available in redo log file, they were applied to the datafiles during crash recovery. This process made your database consistent again.

This is all done automaticaly during startup proces after any "unclean" shutdown of the database and it doesn't matter wether your database is in archlog mode or not - crash recovery works the same in both modes.