What happens to the improved resource with a district on top?

[SirLemonWinks]

Let's say it's built on top of improved cows with pasture. What happens to the tile bonus?

Can a district be built on a wonder?

 

[Larsenex]

If you put a district on a 'KNOWN' resource it will destroy the resource and you will get nothing.

however,

If you put a district on a tile and it is 'revealed' by a tech to have something then you get that resource and the district as well. This was done since you cannot destroy districts after you build them (something we need to mod).