God-Emperor
Deity
Those would be produced by the Random Event system (the oil one is the "Man Named Jed" event and the whale is the "Whale of A Thing" event). Even if you use the game option that turns off random events it can still produce a resource from a mine since it doesn't use that system, it is done directly in the CvPlot::doImprovement function that is run on every improvement being worked by a city every turn.