How much crossover is there between "weird" and adventure fiction? I'm thinking of books like The Lost World (and others by Sir Arthur Conan Doyle featuring Professor Challenger) and King Solomon's Mines (Allan Quartermain). In those books, the main character often encounters something unusual, but eventually explainable. For example, Professor Challenger finds a place in South America where dinosaurs still exist.
This even fits into films like the Indiana Jones series. If Dr. Jones were looking for the Necronomicon instead of the Ark of the Covenant or the Grail, that would be one step from a Lovecraft story. Could even melt the faces off the bad guys at the end still. I hate to admit to its existence, but Crystal Skull definitely has some weirdness going on.
Now I want a story about Nazis looking for the Necronomicon and being stopped by a two-fisted archeologist.