Global perturbation of the marine calcium cycle during the Permian-Triassic transition
A negative shift in the calcium isotopiccomposition of marine carbonate rocksspanning the end-Permian extinction horizonin South China has been used to arguefor an ocean acidification event coincidentwith mass extinction. This interpretationhas proven controversial, both because theexcursion has not been demonstrated acrossmultiple, widely separated localities, and becausemodeling results of coupl