STABLE CARBON ISOTOPIC TRENDS AT THE END-TRIASSIC MASS EXTINCTION RECORDED IN CONTINENTAL STRATA IN EASTERN NORTH AMERICA AND MOROCCO

The end-Triassic mass extinction (ETE) is one of the largest during the Phanerozoic. In non-marine deposits of eastern North America this extinction interval occurs below the oldest basalts, whereas in Morocco it appears to be synchronous with the oldest basalts. In marine and paralic strata of Europe, the extinction is marked by a distinct negative carbon isotopic (δ¹³C) excursion (CIE). This CIE is also apparent in organic carbon records from eastern North America and Morocco, coincident with the ETE. In the Passaic Formation, Newark basin, the negative excursion is associated with the palynofloral extinction level and a fern spore abundance anomaly (fern spike). In the Silver Ridge core (B-2) from the Hartford basin (Connecticut), the negative excursion is also associated with a fern spike. In the Fundy basin, at Partridge Island, the negative excursion occurs at the palynofloral extinction level, below the oldest basalts, and in Morocco it occurs just below the oldest basalts where Triassic pollen taxa are still present. One interpretation is that the CIE is synchronous globally and reflects a major anomaly in the Earth’s carbon cycle. However, it is also possible that this pattern is a coincidence of artifactual enrichments of ¹²C in depositional and early diagenetic environments cut off from the exchangeable global reservoirs, such as in eastern North American lakes and possibly in canonical shallow marine sections from the British Isles. Distinguishing between these two classes of hypotheses is a major challenge to understanding the mechanisms underlying one of the largest events in the history of life.