Imagine I travel back in time ~500 years, leave a modern ship/boat log book in a cave and the log book was discovered today. Since the book was discovered after it was possible to buy it off the shelf it could easily be a hoax. For example, a log book that was first produced in 2015 traveled back in time ~500 years and was found in an unexplored cave in 2017. Would it be possible to conclusively prove that it is ~500 years old and not just a convincing fake? Assuming of course someone actually took it serious enough to try to authenticate it...
If I wanted researchers/archivists to suspect it was really ~500 years old but no way to prove that it was actually ~500 years old what would I need to do?
For the purposes of the question you can use whatever type of log book is easiest to maintain the balance between impossible to prove but good enough to suspect. As such the actual log book can range anywhere from a spiral bound notebook to a waterproof floating log book.
I didn't talk about the content of the log book initially because I wanted the focus of the question to be on the physical analysis/dating of the book. However since it has come up once directly and once indirectly in answers; the content of the book will support the true age of the book of roughly 500 years. The log contains the experiences of the time traveler and will have things that appear to initially contradict history but will be shown to be true (like describing an animal that doesn't exist but later is found to have gone extinct). The content is to be used as a hook to investigate if the book is a hoax, but I want the lab tests to be inconclusive.