Archive logs generated much frequently ~for every minute

Hi
I recently cloned a prod database and noticed that there is lot of archival generation in the database even though there are no users logged on to the cloned db. There is an archive log generation for every 1 min. At the os level, using top I noticed a process that is consuming 100% of CPU and when I queried v$session, I came to know that it is SMON. When I used log miner on the archive logs, it contained the following output.

SQL> SELECT OPERATION, SQL_UNDO FROM V$LOGMNR_CONTENTS;
COMMIT commit;
START set transaction read write;
UPDATE update "SYS"."UNDO$" set "NAME" = '_SYSSMU20_4045053467$', "USER#
" = '1', "FILE#" = '5', "BLOCK#" = '272', "SCNBAS" = '1308346655'
, "SCNWRP" = '8', "XACTSQN" = '20660', "UNDOSQN" = '6922', "INST#
" = '2', "STATUS$" = '6', "TS#" = '5', "SPARE1" = '2' where "NAME
" = '_SYSSMU20_4045053467$' and "USER#" = '1' and "FILE#" = '5' a
nd "BLOCK#" = '272' and "SCNBAS" = '1308346655' and "SCNWRP" = '8
' and "XACTSQN" = '20660' and "UNDOSQN" = '6922' and "INST#" = '2
' and "STATUS$" = '6' and "TS#" = '5' and "SPARE1" = '2' and ROWI
D = 'AAAAAPAABAAAADhAAU';

COMMIT commit;
START set transaction read write;
................................................
...............................................

and the same thing repeating...

It would be grateful if I can get any kind of help to figure out what is causing the archivelog generation