The vein pattern resembles modern Dogwoods.

May be of Betula 

Yes but the bottom of the leaf is asymmetric. And as far as i can see the leaf of dogwoods has symmetric bottom. The other option is elm.

Betula again has symmetric bottom, on the picture is asymmetric.

For me it seems like Peepal leaf. (Ficus religiosa)

The same spot similar leaf, but this time there is better view of the leaf top. Based on previous pictures and this one maybe the leaf is from elm tree - ulmus minor.

Can somebody tell me from which period are the first records of ulmus minor in East Europe.  

Here is the picture.

I'm staying with Dogwood (Cornus).  Just checked my tree; about 50% of leaves are symmetric; other 50% are asymmetric at base.  Lateral veins also alternate off the midvein as in photos.

The sediment deposits at the spot suggesting warm and humid conditions, small swamp near big braided river. Is this ok for the dogwood.