SQL> select * from dba_extents
  2  where file_id = 1
  3  and block_id < 438086
  4  and block_id + blocks > 438086;

OWNER
------------------------------
SEGMENT_NAME
--------------------------------------------------------------------------------
PARTITION_NAME                 SEGMENT_TYPE       TABLESPACE_NAME
------------------------------ ------------------ ------------------------------
 EXTENT_ID    FILE_ID   BLOCK_ID      BYTES     BLOCKS RELATIVE_FNO
---------- ---------- ---------- ---------- ---------- ------------
BSR
DR$CTX_SRH$I
                               TABLE              SYSTEM
       229          1     433417   67108864       8192            1