1. A paleotemperature proxy record across the end-Permian extinction horizon and through the Triassic recovery interval from oxygen isotopes in conodont apatite
Adina Paytan, Institute of Marine Sciences, University of California, Santa Cruz
The end-Permian mass extinction was the greatest catastrophe in the history of macroscopic life, eliminating more than half of marine invertebrate families, nearly 90% of marine animal species, and a substantial fraction of terrestrial vertebrate and vascular plant diversity. The precise cause(s) of extinction remain controversial, but substantial global warming is predicted in nearly all proposed Permian-Triassic (PT) scenarios. Increases in global temperatures across the Permian-Triassic boundary (PTB) can help to account for features in the rock record as disparate as widespread marine anoxia, shifts in plant biogeography, and changes in paleosol composition at high latitudes. Permian-Triassic global warming likely required increased pCO2, widespread submarine dissolution on carbonate platforms, and the preferential extinction of heavily calcified marine invertebrate taxa. Despite this wealth of indirect evidence, there are few isotope proxy constraints on the nature or magnitude of climate change across the PTB and through the Early and Middle Triassic recovery interval, thus the timing, duration, and magnitude of paleotemperature change across the Permian-Triassic boundary remains highly speculative.
To obtain such data, we measure the d18O composition of phosphate in the biogenic apatite of Late Permian, Early and Middle Triassic conodonts from well-constrained stratigraphic sections through an isolated carbonate platform in South China.
Preliminary results suggest temperatures of 23.3°C (19.5‰) to 18.5°C (20.6‰). This indicates a change of 4.8°C in mean temperature at that locality over the time interval represented by our samples. Higher temporal resolution sampling and isotope analyses are underway.
The results of this study will help to constrain PTB carbon cycle models, and extinction and recovery scenarios.