Deadlock happens when one query acquires a lock on a object (rows, data pages, extent, tables etc) and other resource tries to access it. Smallest unit in SQL Server is data pages and SQL holds a lock on page while working on it. So, yes it is possible that two select statement can create deadlock.

Does SELECT cause deadlock?

Shared locks may conflict exclusive locks from update/delete/insert statements. Two SELECT statements are not going to deadlock, but a SELECT can deadlock with an UPDATE. When such deadlock occurs, the SELECT is usually the victim as it did not perform any update so is always going to loose the draw.

What are causes of deadlock?

A deadlock occurs when 2 processes are competing for exclusive access to a resource but is unable to obtain exclusive access to it because the other process is preventing it. This results in a standoff where neither process can proceed. The only way out of a deadlock is for one of the processes to be terminated.