I've been curious about this for a long time. Nowadays, we know that oceanic trenches aren't the desolate aquatic wastelands we thought them to be, and there are animals living down there. Considering their rather extreme geologic environment I'm wondering, if it is even possible, whether they left any discernible fossil-bearing facies in the record at all? Or just discernible facies, period. A cursory search yielded no results for me.
As far as I can see, sedimentation rates would be low, and any newly-formed sedimentary rocks would just get subducted and destroyed very quickly (in geological time). The only mechanism I could imagine for their preservation would be if marine snow was deposited in big enough amounts to form limestone, and if said limestone was then accreted onto the neighboring plate, rather than subducted under it. Could something like this work? Is there any literature concerning this topic, at all?