You can use this query to find the objects in the crroupt block,

select owner,substr(segment_name,1,30) segment_name,segment_type,tablespace_name from dba_extents where file_id=&file_id and
&blockid_id between block_id and block_id + blocks - 1;

where file_id, and block_id are the numbers that are show in the alert.log

If the segment_type is INDEX, it would be good to drop the index and create in a different tablespace. If its table, mark the block to be skipped using the DBMS_REPAIR package.

regards
anandkl