Do microbes living deep in earth (say like a deep oil reservoir) have any C14 in them ? How about animals found in the deep sea trenches like the Mariana trench ? How do levels of C14 in the trench animals compare with surface animals ?
Don’t know, but given that carbon dating only works for items less than about 60,000 years old, and fossil fuel deposits are typically milions of years old, I’d guess deep-earth microbes feeding on ancient reservoirs of petroleum will be virtually depleted of C14.
Deep-sea animals? More speculation:
-Animal communities near hydrothermal vents are only weakly dependent on “marine snow,” so they may have much lower concentrations of C14 than surface-dwelling organisms, despite being of equal age.
-Benthic animals that are not dependent on hydrothermal vents might have C14 concentrations slightly lower than surface-dwelling critters, since they must subsist entirely on marine snow that may have residence times in the deep ocean of up to 1000 years, according to the Wikipedia article. C14 halflife is 5730 years, so 1000 years is enough time for a measurable fraction of C14 to be depleted before a benthic critter eats it.
Precious little. Carbon 14 dating doesn’t actually tell you when an organism died; it tells you when it stopped exchanging carbon with the atmosphere. For surface organisms, that’s basically the same thing, but deep in the sea or underground, the exchange is going to be much slower.
Any type of chemical or radiographic dating has to take a lot of factors into account before it’s useful.
I recall a discussion with a geology student (and creationist, argh) who didn’t put any faith in dating of rocks, because for a lab project they’d gathered some lava and submitted it to a lab for some dating technique, and the result came back obviously wrong. When the lab was consulted, their response was “Well, you didn’t tell us that the rock was surface rock rather than subsurface rock.” He took this to cast doubt on dating methods. I would take it as a lesson in “mineral dating isn’t trivial, you have to do it carefully, understanding the limitations and caveats”.
Heck, I remember a freshman physics lab where kids were launching ball bearings, photographing them, and many were calculating the same incorrect value for G. Obviously, Newton was wrong!