Is there any source of data about where in the world are blocks being mined? Is that data stored for each block?
It is impossible to know how the hashrate is distributed geographically from just blocks alone. Geographic information is completely irrelevant to the blockchain, as are IP addresses. Thus these are not stored in blocks.
Furthermore, in general it is difficult to know how the hashrate is distributed geographically. Without miners actually announcing where they are located, we cannot know how the hashrate is distributed.
As far as I know, a large portion of miners are located in China. There are many miners also located in Canada and Iceland. There are some miners also in the United States. Generally miners will be located in colder places (as it is easier to cool machines there) with cheap electricity.